neuropeptide-y and Epilepsy

Gene therapy may represent an effective alternative to standard pharmacological approaches for certain forms of epilepsy. Currently, the best candidates for this therapeutic approach appear to be epilepsies characterized by a focal lesion. Gene therapy has been attempted to produce antiepileptogenic (prevention of development of epilepsy in subject at risk after having received an epileptogenic insult), antiseizure (reduction of frequency and/or severity of seizures), and disease-modifying (alteration of the natural history of the disease) effects. An example of gene therapy aimed at producing antiepileptogenic effects is a combination therapy based on the supplementation of the neurotrophic factors brain-derived neurotrophic factor (BDNF) and fibroblast growth factor 2 (FGF-2). Antiseizure effects have been obtained by increasing the strength of inhibitory signals (by supplementing specific GABAA receptor subunits or inhibitory neuropeptides like galanin or neuropeptide Y) or by reducing the strength of excitatory signals (by knocking down NMDA receptor subunits). This review summarizes the results obtained to date using gene therapy in epilepsy models and discusses the challenges and the opportunities that this approach can offer for the treatment of human epilepsies.

Topics: Animals; Brain-Derived Neurotrophic Factor; Epilepsy; Fibroblast Growth Factor 2; Galanin; Genetic Therapy; Humans; Neuropeptide Y

Neuropeptides play an important role in modulating seizures and epilepsy. Unlike neurotransmitters which operate on a millisecond time-scale, neuropeptides have longer half lives; this leads to modulation of neuronal and network activity over prolonged periods, so contributing to setting the seizure threshold. Most neuropeptides are stored in large dense vesicles and co-localize with inhibitory interneurons. They are released upon high frequency stimulation making them attractive targets for modulation of seizures, during which high frequency discharges occur. Numerous neuropeptides have been implicated in epilepsy; one, ACTH, is already used in clinical practice to suppress seizures. Here, we concentrate on neuropeptides that have a direct effect on seizures, and for which therapeutic interventions are being developed. We have thus reviewed the abundant reports that support a role for neuropeptide Y (NPY), galanin, ghrelin, somatostatin and dynorphin in suppressing seizures and epileptogenesis, and for tachykinins having pro-epileptic effects. Most in vitro and in vivo studies are performed in hippocampal tissue in which receptor expression is usually high, making translation to other brain areas less clear. We highlight recent therapeutic strategies to treat epilepsy with neuropeptides, which are based on viral vector technology, and outline how such interventions need to be refined in order to address human disease.

Topics: Animals; Dynorphins; Epilepsy; Galanin; Ghrelin; Humans; Mice; Neuropeptide Y; Neuropeptides; Rats; Somatostatin; Substance P

The aim of epilepsy treatment is to achieve complete seizure freedom. Nonetheless, numerous side effects and seizure resistance to antiepileptic drugs (AEDs) affecting about 30-40% of all patients are main unmet needs in today's epileptology. For this reason, novel approaches to treat epilepsy are highly needed. Herein, we highlight recent progress in stem-cell-based and gene transfer-based therapies in epilepsy according to findings in animal models and address their potential clinical application. Multiple therapeutic targets are described, including neuropeptides, neurotrophic factors, and inhibitory neurotransmitters. We also address new molecular-genetic approaches utilizing optogenetic technology. The therapeutic strategies presented herein are predominately aimed toward treatment of partial/focal epilepsies, but could also be envisaged for targeting key seizure propagation areas in the brain. These novel strategies provide proof-of-principle for developing effective treatments for refractory epilepsy in the foreseeable future.

Topics: Animals; Epilepsies, Partial; Epilepsy; Galanin; Gene Transfer Techniques; Genetic Therapy; Humans; Nerve Growth Factors; Neuropeptide Y; Stem Cell Transplantation

Anticonvulsant neuropeptides are best known for their ability to suppress seizures and modulate pain pathways. Galanin, neuropeptide Y, somatostatin, neurotensin, dynorphin, among others, have been validated as potential first-in-class anti-epileptic or/and analgesic compounds in animal models of epilepsy and pain, but their therapeutic potential extends to other neurological indications, including neurodegenerative and psychatric disorders. Disease-modifying properties of neuropeptides make them even more attractive templates for developing new-generation neurotherapeutics. Arguably, efforts to transform this class of neuropeptides into drugs have been limited compared to those for other bioactive peptides. Key challenges in developing neuropeptide-based anticonvulsants are: to engineer optimal receptor-subtype selectivity, to improve metabolic stability and to enhance their bioavailability, including penetration across the blood–brain barrier (BBB). Here, we summarize advances toward developing systemically active and CNS-penetrant neuropeptide analogs. Two main objectives of this review are: (1) to provide an overview of structural and pharmacological properties for selected anticonvulsant neuropeptides and their analogs and (2) to encourage broader efforts to convert these endogenous natural products into drug leads for pain, epilepsy and other neurological diseases.

Topics: Analgesics, Opioid; Anticonvulsants; Blood-Brain Barrier; Dynorphins; Epilepsy; Galanin; Molecular Structure; Nervous System Diseases; Neuropeptide Y; Neuropeptides; Neurotensin; Seizures; Sequence Homology, Amino Acid; Somatostatin

Neuropeptide Y (NPY) is a highly conserved neuropeptide belonging to the pancreatic polypeptide family. Its potential role in the etiology and pathophysiology of mood and anxiety disorders has been extensively studied. NPY also has effects on feeding behavior, ethanol intake, sleep regulation, tissue growth and remodeling. Findings from animal studies have delineated the physiological and behavioral effects mediated by specific NPY receptor subtypes, of which Y1 and Y2 are the best understood.. Physiological roles and alterations of the NPYergic system in anxiety disorders, depression, posttraumatic stress disorder (PTSD), alcohol dependence and epilepsy. For each disorder, studies in animal models and human investigations are outlined and discussed, focusing on behavior, neurophysiology, genetics and potential for novel treatment targets.. The wide implications of NPY in psychiatric disorders such as depression and PTSD make the NPYergic system a promising target for the development of novel therapeutic interventions. These include intranasal NPY administration, currently under study, and the development of agonists and antagonists targeting NPY receptors. Therefore, we are proposing that via this mode of administration, NPY might exert CNS therapeutic actions without untoward systemic effects. Future work will show if this is a feasible approach.

Topics: Alcoholism; Animals; Anxiety Disorders; Drug Delivery Systems; Drug Design; Epilepsy; Humans; Mood Disorders; Neuropeptide Y; Receptors, Neuropeptide Y

Results from animal models suggest gene therapy is a promising new approach for the treatment of epilepsy. Several candidate genes such as neuropeptide Y and galanin have been demonstrated in preclinical studies to have a positive effect on seizure activity. For a successful gene therapy-based treatment, efficient delivery of a transgene to target neurons is also essential. To this end, advances have been made in the areas of cell transplantation and in the development of recombinant viral vectors for gene delivery. Recombinant adeno-associated viral (rAAV) vectors in particular show promise for gene therapy of neurological disorders due to their neuronal tropism, lack of toxicity, and stable persistence in neurons, which results in robust, long-term expression of the transgene. rAAV vectors have been recently used in phase I clinical trials of Parkinson's disease with an excellent safety profile. Prior to commencement of phase I trials for gene therapy of epilepsy, further preclinical studies are ongoing including evaluation of the therapeutic benefit in chronic models of epileptogenesis, as well as assessment of safety in toxicological studies.

Topics: Cell Transplantation; Embryonic Stem Cells; Epilepsy; Feasibility Studies; Galanin; Gene Transfer Techniques; Genes, Viral; Genetic Therapy; Genetic Vectors; Humans; Neuropeptide Y

Gene therapy may represent a promising alternative treatment of epileptic patients who are resistant to conventional anti-epileptic drugs. Among the various approaches for the application of gene therapy in the treatment of CNS disorders, recombinant adeno-associated viral (AAV) vectors have been most widely used. Preclinical studies using a selection of "therapeutic" genes injected into the rodent brain to correct the compromised balance between inhibitory and excitatory transmission in epilepsy, showed significant reduction of seizures and inhibition of epileptogenesis. In particular, transduction of neuropeptide genes, such as galanin and neuropeptide Y (NPY) in specific brain areas in experimental models of seizures resulted in significant anticonvulsant effects. Recent findings showed a long-lasting NPY over-expression in the rat hippocampus by local application of recombinant AAV vectors associated with reduced generalization of seizures, delayed kindling epileptogenesis, and strong reduction of chronic spontaneous seizures. These results establish a proof-of-principle evidence of the efficacy of gene therapy as anticonvulsant treatment. Additional investigations are required to address safety concerns and possible side effects in more detail.

Topics: Adenoviridae; Animals; DNA, Recombinant; Epilepsy; Genetic Therapy; Genetic Vectors; Humans; Neuropeptide Y

Topics: Animals; Dentate Gyrus; Disease Models, Animal; Epilepsy; Epilepsy, Temporal Lobe; gamma-Aminobutyric Acid; Hippocampus; Humans; Mossy Fibers, Hippocampal; Nerve Degeneration; Neuronal Plasticity; Neuropeptide Y; Rats; Receptors, GABA-A; Status Epilepticus; Synaptic Transmission

The ketogenic diet (KD) is a high-fat, low-carbohydrate, low-protein diet used to treat refractory epilepsy. Despite its efficacy and many years of investigation, the mechanism by which the KD exerts its anticonvulsant effect remains controversial and poorly understood. The purpose of this article is to review the available data considering two classes of molecules that may contribute to the anticonvulsant effect of the KD: norepinephrine and the orexigenic neuropeptides galanin and neuropeptide Y.

Topics: Animals; Anticonvulsants; Diet, Ketogenic; Epilepsy; Galanin; Humans; Mice; Neuropeptide Y; Norepinephrine

Gene therapy represents an innovative and promising alternative for the treatment of epileptic patients who are resistant to conventional antiepileptic drugs. Among the various approaches for the application of gene therapy in the treatment of CNS disorders, recombinant viral vectors have been most widely used so far. Several gene targets could be used to correct the compromized balance between inhibitory and excitatory transmission in epilepsy. Transduction of neuropeptide genes such as galanin and neuropeptide Y (NPY) in specific brain areas in experimental models of seizures resulted in significant anticonvulsant effects. In particular, the long-lasting NPY over-expression obtained in the rat hippocampus using intracerebral application of recombinant adeno-associated viral (AAV) vectors reduced the generalization of seizures from their site of onset, delayed acquisition of fully kindled seizures and afforded neuroprotection. These results establish a proof-of-principle for the applicability of AAV-NPY vectors for the inhibition of seizures in epilepsy. Additional investigations are required to demonstrate a therapeutic role of gene therapy in chronic models of seizures and to address in more detail safety concerns and possible side-effects.

Topics: Epilepsy; Genetic Therapy; Humans; Neuropeptide Y

In the epileptic brain, hippocampal dentate granule cells become synaptically interconnected through the sprouting of mossy fibers. This new circuitry is expected to facilitate epileptiform discharge. Prolonged seizures induce the long-lasting neoexpression of neuropeptide Y (NPY) in mossy fibers. NPY is released spontaneously from recurrent mossy fiber terminals, reduces glutamate release from those terminals by activating presynaptic Y2 receptors, and depresses granule cell epileptiform activity dependent on the recurrent pathway. These effects are much greater in rats than in C57BL/6 mice, despite apparently equivalent mossy fiber sprouting and neoexpression of NPY. This species difference can be explained by contrasting changes in the expression of mossy fiber Y2 receptors; seizures upregulate Y2 receptors in rats but downregulate them in mice. The recurrent mossy fiber pathway may synchronize granule cell discharge more effectively in humans and mice than in rats, due to its lower expression of either NPY (humans) or Y2 receptors (mice).

Topics: Animals; Epilepsy; Humans; Mice; Mossy Fibers, Hippocampal; Neuronal Plasticity; Neuropeptide Y; Pilocarpine; Rats; Receptors, Neuropeptide Y; Species Specificity; Status Epilepticus; Synaptic Transmission

A substantial amount of experimental evidence implicates neuropeptide Y (NPY) in the pathophysiology of epilepsy. Over the past 20 years, remarkable progress has been made in unraveling the mechanisms and receptors involved in the anticonvulsant effect of this abundantly expressed neuropeptide. Activation of Y(2) and/or Y(5) receptors and blockade of Y(1) receptors in the central nervous system suppresses seizures in a variety of animal seizure models. Orally available, brain penetrating Y(2) and/or Y(5) agonists, and possibly Y(1) antagonists, may therefore constitute a novel class of antiepileptic drugs, which could greatly benefit patients with medically refractory epilepsy. Significant progress has been made in identifying non-peptidergic Y(1) antagonists that fulfill these criteria, but suitable Y(2) and/or Y(5) agonists have proven to be more elusive. Innovative oral and parental drug delivery strategies which are currently under development may offer a means of using the more readily available peptidergic NPY receptor ligands in a clinical setting. Finally, gene therapy, antisense probes or RNA interference strategies which alter the expression of NPY or its receptors in specific brain regions may also be of use in the treatment of epilepsy, but will probably benefit a smaller subgroup of epilepsy patients, since they typically require an invasive procedure.

Topics: Animals; Anticonvulsants; Epilepsy; Humans; Ligands; Neuropeptide Y; Receptors, Neuropeptide Y

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, has drawn much attention as a potential therapeutic target for temporal lobe epilepsy (TLE). TLE seizures are produced by synchronized hyperactivity of neuron populations due to the disruption of a balance between excitatory and inhibitory synaptic transmissions. In epileptogenesis-related brain areas, including the hippocampus, BDNF is up-regulated in the course of the development of epilepsy and induces a collapse of balanced excitation and inhibition, eventually exerting its epileptogenic effects. On the other hand, several reports demonstrate that intrahippocampal infusion of BDNF can attenuate (or retard) the development of epilepsy. This antiepileptogenic effect seems to be mediated mainly by an increase in the expression of neuropeptide Y. These contrasting effects of BDNF have prevented us from concluding whether inhibition or enhancement of BDNF signaling finally achieves the prevention of TLE. To address this question, it is essential to evaluate how BDNF changes its influences depending on conditions, for example, cell specificity, neural networks, and expression timing and loci. In this article, the authors review BDNF-induced acute and long-lasting changes seen in epileptic circuits from the anatomical and functional points of view.

Topics: Animals; Animals, Genetically Modified; Brain-Derived Neurotrophic Factor; Epilepsy; gamma-Aminobutyric Acid; Hippocampus; Humans; Models, Neurological; Neuropeptide Y

Neuropeptide Y (NPY) is one of the most abundant and widely distributed neuropeptides in the mammalian central nervous system (CNS). An overview of the distribution of the G-protein coupled NPY receptor family (Y(1), Y(2), Y(4), Y(5) receptors) in the brain is described. The coexistence of NPY with other neurotransmitters and its wide distribution in several brain areas predict the high importance of NPY as a neuromodulator. Thus, the effect of NPY on the release of several neurotransmitters such as glutamate, gamma-aminobutyric acid (GABA), norepinephrine (NE), dopamine, somastotatin (SOM), serotonin (5-HT), nitric oxide (NO), growth hormone (GH) and corticotropin releasing factor (CRF) is reviewed. A neuroprotective role for NPY under physiological conditions and during hyperactivity such as epileptic-seizures has been suggested. We have shown previously that NPY inhibits glutamate release evoked from hippocampal nerve terminals and has a neuroprotective effect in rat organotypic hippocampal cultures exposed to an excitotoxic insult. Moreover, changes in NPY levels have been observed in different pathological conditions such as brain ischemia and neurodegenerative diseases (Huntington's, Alzheimer's and Parkinson's diseases). Taken together, these studies suggest that NPY and NPY receptors may represent pharmacological targets in different pathophysiological conditions in the CNS.

Topics: Animals; Brain; Cell Survival; Epilepsy; Humans; Ischemia; Neurodegenerative Diseases; Neuropeptide Y; Neuroprotective Agents; Rats; Receptors, Neuropeptide Y; Tissue Distribution

Interneurons are often classified according to neuropeptide content. However, it is becoming increasingly clear that neuropeptides are more than convenient neurochemical markers and can act as important modulators of neuronal activity. Recent advances in understanding neuropeptide release and physiological actions suggest that the interneuronal system of neuropeptides is crucial for maintaining appropriate brain function under normal and pathophysiological conditions. In particular, interneuronal neuropeptides appear to play roles in cognition and as endogenous anti-epileptic agents. This article describes current understanding of the conditions under which neuropeptides are released from interneurons, their specific effects on neuronal excitability and synaptic transmission, and the consequences of their loss of function.

Topics: Animals; Brain; Brain Diseases; Epilepsy; Interneurons; Neural Inhibition; Neuropeptide Y; Neuropeptides; Somatostatin; Synaptic Transmission

Neuropeptide Y (NPY), a 36 amino-acid member of the pancreatic polypeptide family, has received considerable attention in recent years as an endogenous modulator of epileptic activity. Prominently expressed in brain regions involved in seizure generation and propagation, NPY can exert powerful effects on synaptic transmission. Here, we discuss the anti-epileptic actions of NPY and receptor subtypes responsible.

Topics: Animals; Brain; Epilepsy; Neuropeptide Y; Receptors, Neuropeptide Y

The aim of this study was to investigate whether oxcarbazepine (OXC) monotherapy causes weight gain in epileptic children.. A total of 22 children with epilepsy (age 3.0-16.4 years) were assigned to OXC therapy. Serum levels of glucose, insulin, cortisol, leptin, neuropeptide Y (NPY), galanin and ghrelin were assessed before OXC therapy (month 0) and after the 6th and 18th months.. There was no statistically significant difference in weight-standard deviation score (SDS), Height-SDS, BMI-SDS, serum glucose, insulin, cortisol, leptin, NPY, galanin and ghrelin levels between initial values (month 0) and those in the 6th and 18th months after OXC therapy (p > 0.05).. Our results indicate that OXC therapy causes neither weight change nor alterations in serum glucose, insulin, cortisol, leptin, NPY, galanin and ghrelin levels in children with epilepsy.

Topics: Adolescent; Anticonvulsants; Blood Glucose; Body Weight; Carbamazepine; Child; Child, Preschool; Epilepsy; Female; Galanin; Ghrelin; Humans; Hydrocortisone; Insulin; Male; Neuropeptide Y; Oxcarbazepine

Weight gain is a common side effect of valproate treatment. The potential mechanisms of valproate-associated weight gain are not yet clear. Decreased blood glucose level, impairment of beta-oxidation of fatty acids, and increased insulin levels are some of the possible mechanisms. The aim of the present study is to evaluate the role of insulin, leptin, and neuropeptide Y in valproate-related weight gain in epileptic children. In 20 epileptic children treated with valproate before treatment and after a follow-up period of 3 and 6 months, body mass index and fasting insulin glucose ratio were calculated and serum glucose, insulin, cortisol, leptin, and neuropeptide Y levels were measured. At the end of 3 months, the mean body mass index values and the mean serum insulin, fasting insulin glucose ratio, and neuropeptide Y levels increased, whereas the serum glucose levels decreased. After 6 months of treatment, the mean serum cortisol and leptin levels were high, in addition to the body mass index, neuropeptide Y, and fasting insulin glucose ratio. These results suggest that weight gain during valproate treatment might be related to low glucose and high insulin, cortisol, leptin, and neuropeptide Y levels.

Topics: Anticonvulsants; Blood Glucose; Body Mass Index; Child; Child, Preschool; Epilepsy; Female; Humans; Hydrocortisone; Hypoglycemic Agents; Insulin; Leptin; Male; Neuropeptide Y; Valproic Acid; Weight Gain

Topics: Animals; Epilepsy; Genetic Therapy; Hippocampus; Humans; Male; Neuropeptide Y; Rats; Rats, Wistar; Seizures; Serogroup

Neuronal nitric oxide synthase (nNOS) plays a pivotal role in the pathological process of neuronal injury in the development of epilepsy. Our previous study has demonstrated that nitric oxide (NO) derived from nNOS in the epileptic brain is neurotoxic due to its reaction with the superoxide radical with the formation of peroxynitrite. Neuropeptide Y (NPY) is widely expressed in the mammalian brain, which has been implicated in energy homeostasis and neuroprotection. Recent studies suggest that nNOS may act as a mediator of NPY signaling. Here in this study, we sought to determine whether NPY expression is regulated by nNOS, and if so, whether the regulation of NPY by nNOS is associated with the neuronal injuries in the hippocampus of epileptic brain. Our results showed that pilocarpine-induced temporal lobe epilepsy (TLE) mice exhibited an increased level of nNOS expression and a decreased level of NPY expression along with hippocampal neuronal injuries and cognition deficit. Genetic deletion of nNOS gene, however, significantly upregulated hippocampal NPY expression and reduced TLE-induced hippocampal neuronal injuries and cognition decline. Knockdown of NPY abolished nNOS depletion-induced neuroprotection and cognitive improvement in the TLE mice, suggesting that inhibition of nNOS protects against hippocampal neuronal injuries by increasing neuropeptide Y expression in TLE mice. Targeting nNOS-NPY signaling pathway in the epileptic brain might provide clinical benefit by attenuating neuronal injuries and preventing cognitive deficits in epilepsy patients.

Topics: Animals; Epilepsy; Epilepsy, Temporal Lobe; Hippocampus; Mammals; Mice; Neuropeptide Y; Nitric Oxide; Nitric Oxide Synthase Type I

Neuropeptide Y (NPY) is a polypeptide sequence useful in regulating physiological functions like homeostasis, feeding, etc., but its usage is restricted due to its short half-life. β-cyclodextrin-crosslinked nanosponges improve the drug release and stability due to its wide cavity, which is helpful to deliver therapeutics. The present work aimed to formulate synthetic NPY-based nanocarriers as sponges by polymer condensation mechanism using design experiment to improve the peptide release and stability. The validated nanosponges exhibited a particle size of 423.42 ± 5.32 nm, 75.82 ± 7.43 % entrapment efficiency and 83.50 ± 6.54 % NPY release for 24 h. The NPY and β-cyclodextrin interaction was confirmed by X-ray diffraction, Fourier transform infrared and nuclear magnetic resonance spectroscopy. The NPY-loaded nanosponges were found stable for 6 months at two conditions (5 ± 2 °C and 25 ± 2 °C). The cross-linked nanocarriers of synthetic peptide-based nanosponges powder at different doses were administered intranasally using a metered-dose inhaler in the animal model to check its antiepileptic activity. The synthetic NPY-loaded nanosponges at higher doses showed significant antiepileptic effects equivalent to the standard drug (administered orally) in maximal electroshock and chemically-induced seizures with an increase of NPY in the brain directly proportional to GABAergic signalling by increase in GABA levels resulting in convulsions attenuation.

Topics: Animals; Anticonvulsants; beta-Cyclodextrins; Epilepsy; gamma-Aminobutyric Acid; Nanostructures; Neuropeptide Y; Polymers; Powders; Solubility

The present experiments reveal the alterations of the hippocampal neuronal populations in chronic epilepsy. The mice were injected with a single dose of pilocarpine. They had status epilepticus and spontaneously recurrent motor seizures. Three months after pilocarpine treatment, the animals were investigated with the Barnes maze to determine their learning and memory capabilities. Their hippocampi were analyzed 2 weeks later (at 3.5 months) with standard immunohistochemical methods and cell counting. Every animal displayed hippocampal sclerosis. The neuronal loss was evaluated with neuronal-N immunostaining, and the activation of the microglia was measured with Iba1 immunohistochemistry. The neuropeptide Y, parvalbumin, and calretinin immunoreactive structures were qualitatively and quantitatively analyzed in the hippocampal formation. The results were compared statistically to the results of the control mice. We detected neuronal loss and strongly activated microglia populations. Neuropeptide Y was significantly upregulated in the sprouting axons. The number of parvalbumin- and calretinin-containing interneurons decreased significantly in the Ammon's horn and dentate gyrus. The epileptic animals displayed significantly worse learning and memory functions. We concluded that degeneration of the principal neurons, a numerical decrease of PV-containing GABAergic neurons, and strong peptidergic axonal sprouting were responsible for the loss of the hippocampal learning and memory functions.

Topics: Aging; Animals; Calbindin 2; Cell Proliferation; Cell Survival; Densitometry; Epilepsy; Hippocampus; Interneurons; Maze Learning; Memory Disorders; Mice; Microglia; Neurons; Neuropeptide Y; Parvalbumins; Peptides; Pilocarpine; Reaction Time; Sclerosis; Spatial Learning; Status Epilepticus

Post-ischemic stroke epilepsy (PISE) is one of the common complications of stroke.. Methods To determine the risk factors of PISE, in this study, 78 patients with PISE and 86 patients without PISE were recruited. Clinical data and serum neuropeptide Y (NPY) levels were collected and the relative factors including clinical data and serum were analyzed.. Logistic regression showed that low serum NPY was significantly associated with PISE. Every 5 ng/ml increment of serum NPY was associated with 62% risk decrease in patients with PISE. The area under curve of serum NPY was 0.910 with a sensitivity of 84.62% and a specificity of 86.05%. The cut-off value of serum NPY was 90 ng/ml. According to cut-off value of serum NPY, the percentage of patients with PISE decreased from 84.6% in low serum NPY group to 14.0% in high serum NPY group. Furthermore, patients were divided into different tertiles according to serum NPY. The percentage of patients with PISE reduced from 90.0% in the lowest tertile (NPY < 85 ng/ml) to 3.5% in the highest tertile (NPY ≥ 105 ng/ml). Compared with patients with normal video-electroencephalogram (VEEG), serum NPY levels significantly decreased in patients with abnormal VEEG; however, serum NPY levels were not associaated with epileptic seizure subtypes.. Serum NPY was an independent risk factor for PISE. Targeting serum NPY may be used to the prevention and treatment of PISE.

Topics: Aged; Aged, 80 and over; Biomarkers; Case-Control Studies; Electroencephalography; Epilepsy; Female; Humans; Male; Middle Aged; Neuropeptide Y; Predictive Value of Tests; Risk Assessment; Risk Factors; Stroke

Sudden unexpected death in epilepsy (SUDEP) is typically unwitnessed but can be preceded by seizures in the period prior to death. Peri-ictal respiratory dysfunction is a likely mechanism for some SUDEP, and central apnea has been shown following amygdala stimulation. The amygdala is enriched in neuropeptides that modulate neuronal activity and can be transiently depleted following seizures. In a postmortem SUDEP series, we sought to investigate alterations of neuropeptidergic networks in the amygdala, including cases with recent poor seizure control.. In 15 SUDEP cases, 12 epilepsy controls, and 10 nonepilepsy controls, we quantified the labeling index (LI) for galanin, neuropeptide Y (NPY), and somatostatin (SST) in the lateral, basal, and accessory basal nuclei and periamygdala cortex with whole slide scanning image analysis. Within the SUDEP group, seven had recent generalized seizures with recovery 24 hours prior to death (SUDEP-R).. Galanin, NPY, and SST LIs were significantly lower in all amygdala regions in SUDEP cases compared to epilepsy controls (P < .05 to P < .0005), and galanin LI was lower in the lateral nucleus compared to nonepilepsy controls (P < .05). There was no difference in the LI in the SUDEP-R group compared to other SUDEP. Higher LI was noted in epilepsy controls than nonepilepsy controls; this was significant for NPY in lateral and basal nuclei (P < .005 and P < .05).. A reduction in galanin in the lateral nucleus in SUDEP could represent acute depletion, relevant to postictal amygdala dysfunction. In addition, increased amygdala neuropeptides in epilepsy controls support their seizure-induced modulation, which is relatively deficient in SUDEP; this could represent a vulnerability factor for amygdala dysfunction in the postictal period.

Topics: Adult; Aged; Aged, 80 and over; Amygdala; Cadaver; Cause of Death; Epilepsy; Female; Galanin; Humans; Male; Middle Aged; Nerve Net; Neuropeptide Y; Neuropeptides; Somatostatin; Sudden Unexpected Death in Epilepsy; Tissue Banks; Young Adult

This paper aims to investigate the possible roles of a set of neurotrophic factors (brain-derived neurotrophic factor-BDNF, nerve growth factor-NGF) and neuropeptides (neuropeptide Y-NPY, and galanin) in children with active epileptogenesis. The cerebrospinal fluid (CSF) levels of BDNF, NPY, NGF and galanin were measured with enzyme-linked immunosorbent assays in epileptic children (n = 73) and controls (n = 64). There were no significant alterations in the CSF levels of BDNF, NPY and NGF in epileptic children with active clinical seizures compared with the levels of controls. However profoundly depressed galanin levels were found in infants with epileptic encephalopathy (mean ± SD:0.63 ± 0.19 pg/ml) and significantly increased galanin levels were measured in children with drug resistant epilepsy during the period of status epilepticus (mean ± SD: 6.92 ± 1.19, pg/ml pg/ml) compared with the levels of controls. Depressed levels of galanin might reflect a defective anti-epileptogenic effect of galanin in infants with epileptic encephalopathy. On the contrary, increased CSF levels of galanin might be a result of anti-epileptogenic effects of this peptide in epileptic children with status epilepticus.

Topics: Animals; Brain-Derived Neurotrophic Factor; Child; Epilepsy; Female; Galanin; Humans; Infant; Male; Nerve Growth Factor; Neuropeptide Y; Status Epilepticus

Hippocampal sclerosis is a hallmark of mesial temporal lobe epilepsy (MTLE), comprising gliosis and neuronal loss in the hippocampus. However, dentate granule cells and CA2 pyramidal cells (PCs) survive, as they share physiological characteristics that may render them less sensitive to hyperexcitation in MTLE. Here, we asked whether both engage similar molecular plasticity mechanisms to support their resilience in MTLE. We chose brain-derived neurotrophic factor (BDNF), correlated the expression with activity, and used neuropeptide Y (NPY) and principal cell dispersion as plasticity readout.. Adult male mice received a unilateral intrahippocampal kainate injection to induce status epilepticus (SE) and bilateral electrodes into the dentate gyrus and CA2 for in vivo recordings and quantification of epileptiform activity. To assess the time course of Bdnf mRNA expression in these regions, we performed fluorescence in situ hybridization, complemented by immunohistochemistry for NPY and quantification of principal cell dispersion.. We show that Bdnf expression was transiently up-regulated during SE in the granule cell layer (GCL) and CA2 and, after a slight reduction at 2 days, increased persistently in both regions ipsilaterally. Intrahippocampal recordings revealed a threshold for the duration of SE to induce these changes. Recurrent epileptiform activity developed in the ipsilateral dentate gyrus and CA2 over time and was correlated with Bdnf mRNA levels, although more pronounced in the dentate gyrus. The dispersion of the GCL and CA2 correlated with Bdnf mRNA expression. NPY protein expression was only increased in granule cells and mossy fibers, remaining unchanged in CA2.. Our study reveals differential molecular plasticity changes in granule cells and CA2 PCs despite many similarities (epileptiform activity, somatic mossy fiber input, dispersion). These findings contribute to the understanding of common as well as individual characteristics of the cell populations underlying the epileptic hippocampal network.

Topics: Animals; Brain-Derived Neurotrophic Factor; CA3 Region, Hippocampal; Dentate Gyrus; Electrocorticography; Electrodes, Implanted; Epilepsy; Kainic Acid; Male; Mice; Mice, Inbred C57BL; Neuronal Plasticity; Neuropeptide Y; Status Epilepticus; Up-Regulation

Although some drugs used in the treatment of epilepsy are known to affect body weight, the hormonal factors responsible have not been sufficiently described. The purpose of this study was to compare insulin, leptin, neuropeptide Y and ghrelin levels in children with epilepsy receiving monotherapy with topiramate (TPM) and valproic acid (VPA), the drugs whose effects on body weight have been most discussed, with those of a control group.. 48 patients (25 VPA, 23 TPM) aged between 6 and 15.5 years, presenting to the Karadeniz Technical University Medical Faculty Pediatric Neurology Clinic, diagnosed with idiopathic epilepsy or location-related idiopathic epilepsy, and receiving VPA or TPM monotherapy for at least 6 months were included in the study. Twenty-five healthy subjects with similar demographic characteristics were enrolled as the control group. Blood samples were collected from the patient and control groups after fasting for at least 10-12 h and again 1 and 2 h postprandially. Body mass index (BMI) values were calculated for all cases. VPA levels, glucose, insulin, leptin, neuropeptide Y and ghrelin were investigated in all three separate blood samples.. Age, height, weight and BMI were similar between the patient and control groups. Significant weight gain was observed throughout treatment in the VPA group compared to the TPM group. High fasting and postprandial insulin levels were observed in the VPA group. VPA group leptin and neuropeptide Y (NPY) levels were also higher than in the TPM and control groups. No significant difference was determined in ghrelin levels in the patient groups compared to the controls.. Low blood sugar not being observed, even though insulin levels are high, after fasting and in the postprandial period in epileptic children receiving VPA is indicative of insulin resistance. The elevation in leptin and neuropeptide Y levels observed in the VPA group also suggest this.

Topics: Adolescent; Anticonvulsants; Biomarkers; Blood Glucose; Body Mass Index; Child; Epilepsy; Fructose; Ghrelin; Humans; Insulin; Leptin; Neuropeptide Y; Topiramate; Treatment Outcome; Valproic Acid; Weight Gain

Inhibitory GABAergic interneurons are fundamental elements of cortical circuits and play critical roles in shaping network activity. Dysfunction of interneurons can lead to various brain disorders, including epilepsy, schizophrenia, and anxiety. Based on the electrophysiological properties, cell morphology, and molecular identity, interneurons could be classified into various subgroups. In this study, we investigated the density and laminar distribution of different interneuron types and the co-expression of molecular markers in epileptic human cortex. We found that parvalbumin (PV) and somatostatin (SST) neurons were distributed in all cortical layers except layer I, while tyrosine hydroxylase (TH) and neuropeptide Y (NPY) were abundant in the deep layers and white matter. Cholecystokinin (CCK) neurons showed a high density in layers IV and VI. Neurons with these markers constituted ~7.2% (PV), 2.6% (SST), 0.5% (TH), 0.5% (NPY), and 4.4% (CCK) of the gray-matter neuron population. Double- and triple-labeling revealed that NPY neurons were also SST-immunoreactive (97.7%), and TH neurons were more likely to express SST (34.2%) than PV (14.6%). A subpopulation of CCK neurons (28.0%) also expressed PV, but none contained SST. Together, these results revealed the density and distribution patterns of different interneuron populations and the overlap between molecular markers in epileptic human cortex.

Topics: Adolescent; Adult; Brain Chemistry; Cerebral Cortex; Child; Cholecystokinin; Epilepsy; Female; Gene Expression Regulation; Humans; Interneurons; Male; Middle Aged; Neuropeptide Y; Parvalbumins; Phosphopyruvate Hydratase; Somatostatin; Tyrosine 3-Monooxygenase; Young Adult

The present study aimed to investigate the effects of neuropeptide Y (NPY) on the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor glutamate receptor 2 (GluR2) subunit in epileptiform discharge hippocampal neurons. Hippocampal neurons were harvested from neonatal Sprague‑Dawley rats aged <24 h and primarily cultured in vitro. At day 12 following culture, hippocampal neurons were divided into the following groups: Control, Mg2+‑free, NPY+Mg2+‑free and BIBP3226+NPY+Mg2+‑free. The action potential of neurons was measured using the whole cell patch clamp technique in the control, Mg2+‑free and NPY+Mg2+‑free groups. AMPA current (IAMPA) was detected and peak current density was calculated in each group. Alterations in total protein and phosphorylation of the GluR2 subunit were detected by western blot analysis, and GluR2 mRNA expression levels were detected by reverse transcription‑quantitative polymerase chain reaction, in each group. The whole cell patch clamp technique demonstrated an abnormal action potential in the Mg2+‑free group. The frequency and amplitude of the action potential were significantly greater in the Mg2+‑free group compared with the control group, and significantly reduced in the NPY+Mg2+‑free group compared with the Mg2+‑free group (P<0.05). In the Mg2+‑free group, compared with the control group, peak current density was significantly reduced (P<0.05), GluR2 subunit protein content was slightly reduced (P>0.05), phosphorylation levels of GluR2 subunit were significantly greater (P<0.05) and GluR2 mRNA was significantly reduced (P<0.05). In the NPY+Mg2+‑free group, compared with the Mg2+‑free group, peak current density was significantly greater (P<0.05), phosphorylation levels of GluR2 subunit were significantly reduced (P<0.05) and GluR2 mRNA expression was significantly greater (P<0.05). In the BIBP3226+NPY+Mg2+‑free group, compared with the NPY+Mg2+‑free group, peak current density was significantly reduced (P<0.05), phosphorylation levels of GluR2 subunit were significantly greater (P<0.05) and GluR2 mRNA expression was significantly reduced (P<0.05). After 3 h of treatment with Mg2+‑free extracellular fluid, epileptiform discharge was detected in the cells. NPY inhibited the discharge and its underlying mechanism may be that epileptiform discharge suppressed the function of the AMPA receptor GluR2 subunit. NPY relieved the inhibition of the GluR2 subunit via the Y1 receptor. This may provide a novel direction fo

Topics: Action Potentials; Animals; Biomarkers; Cells, Cultured; Disease Models, Animal; Epilepsy; Fluorescent Antibody Technique; Gene Expression; Male; Neuropeptide Y; Patch-Clamp Techniques; Phosphorylation; Pyramidal Cells; Rats; Receptors, AMPA

Medial ganglionic eminence (MGE) progenitors give rise to inhibitory interneurons and may serve as an alternative cell source for large-scale cell transplantation for epilepsy after in vitro expansion. We investigated whether modifications in the culture medium of MGE neurospheres affect neuronal differentiation and expression of MGE-specific genes. In vivo, we compared anticonvulsant effects and cell differentiation pattern among neurospheres grown in different culture media and compared them with freshly harvested MGE cells.. We used four variations of cell culture: standard, containing growth factors (EGF/FGF-2) (GF); addition of retinoic acid (GF-RA); withdrawal of EGF/FGF-2 (WD); and addition of retinoic acid and withdrawal of EGF/FGF-2 (WD-RA). Based on in vitro results neurosphere-grown (WD-RA or GF conditions) or fresh MGE cells were transplanted into the hippocampus.. In vitro WD-RA showed increased neuronal population and higher expression of Dlx1, Nkx2.1, and Lhx6 genes in comparison with GF culture condition. After transplantation, fresh MGE cells and neurospheres (GF) showed anticonvulsant effects. However, fresh MGE cells differentiated preferentially into inhibitory neurons, while GF gave rise to glial cells.. We conclude that freshly isolated and neurosphere-grown MGE cells reduced seizures by different mechanisms (inhibitory interneurons vs. astrocytes). Fresh MGE cells appear more appropriate for cell therapies targeting inhibitory interneurons for conferring anticonvulsant outcomes.

Topics: Animals; Cell Differentiation; Cells, Cultured; Creatine; Disease Models, Animal; Embryo, Mammalian; Epidermal Growth Factor; Epilepsy; Fibroblast Growth Factor 2; Glial Fibrillary Acidic Protein; LIM-Homeodomain Proteins; Median Eminence; Muscarinic Agonists; Neurons; Neuropeptide Y; Parvalbumins; Phosphopyruvate Hydratase; Pilocarpine; Rats; Rats, Sprague-Dawley; Tretinoin

The efficiency of most of the new antiepileptic drugs (AEDs) on clinical trials still falls short the success reported in pre-clinical studies, possibly because the validity of the animal models is insufficient to fully represent the human pathology. To improve the translational value for testing AEDs, we propose the use of non-human primates. Here, we suggest that triggering limbic seizures with low doses of PTZ in pilocarpine-treated marmosets might provide a more effective basis for the development of AED. Marmosets with epileptic background were more susceptible to seizures induced by PTZ, which were at least 3 times longer and more severe (about 6 times greater frequency of generalized seizures) in comparison to naïve peers. Accordingly, PTZ-induced seizures were remarkably less attenuated by AEDs in epileptic than naïve marmosets. While phenobarbital (40mg/kg) virtually abolished seizures regardless of the animal's background, carbamazepine (120mg/kg) and valproic acid (400mg/kg) could not prevent PTZ-induced seizures in epileptic animals with the same efficiency as observed in naïve peers. VPA was less effective regarding the duration of individual seizures in epileptic animals, as assessed in ECoG (p=0.05). Similarly following CBZ treatment, the behavioral manifestation of generalized seizures lasted longer in epileptic (p<0.05), which were also more frequent than in the naïve group (p<0.05). As expected, epileptic marmosets experiencing stronger seizures showed more NPY- and ΔFosB-immunostained neurons in a number of brain areas associated with the generation and spread of limbic seizures. Our results suggest that PTZ induced seizures over an already existing epileptic background constitutes a reliable and controllable mean for the screening of new AEDs.

Topics: Animals; Anticonvulsants; Brain; Callithrix; Carbamazepine; Chronic Disease; Disease Models, Animal; Electrocorticography; Epilepsy; Female; Immunohistochemistry; Male; Neuropeptide Y; Pentylenetetrazole; Phenobarbital; Pilocarpine; Proto-Oncogene Proteins c-fos; Seizures; Valproic Acid

Excessive excitation or loss of inhibitory neurotransmission has been closely related to epileptic activity. Somatostatin (SST) and Neuropeptide Y (NPY) are members of endogenous neuropeptides which are recognized as important modulator of classical neurotransmitter, distributed abundantly in mammalian central nervous system. Abnormal expression of these two neuropeptides evidenced in some epileptic models highlights the relevance of SST or NPY in the pathogenesis of epilepsy. The tremor rat (TRM) is a genetic epileptic animal model which can manifest tonic convulsions without any external stimuli. The present study aimed to investigate the distribution and expression of SST and NPY in TRM brains, including hippocampus, temporal lobe cortex and cerebellum. Our RT‑PCR data showed that up-regulated mRNA expression of SST and NPY was discovered in TRM hippocampus and temporal lobe cortex compared with control (Wistar) rats. The peptide levels of these neuropeptides in brain areas mentioned above were both apparently higher than that in normal Wistar rats as well. However, in cerebellums, neither SST nor NPY was significantly changed compared with control group. The immunohistochemical data showed that SST and NPY were widely present throughout CA1, CA3 and the hilus of hippocampus, the entorhinal cortex of temporal lobe cortex, as well as cerebellar Purkinje layer. In conclusion, our results discovered the aberrant changes of SST and NPY in several TRM brain regions, suggesting that the peptidergic system might be involved in TRM epileptiform activity.

Topics: Animals; Brain; Disease Models, Animal; Epilepsy; Female; Gene Expression Regulation; Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; Male; Mutation; Neuropeptide Y; Potassium Channels; Rats; Rats, Mutant Strains; Rats, Wistar; RNA, Messenger; Somatostatin; Tremor

Epilepsy is a frequent neurological disorder that affects directly 0.5-1.5% of the world's population. Despite advances regarding therapy, about 30% of patients cannot be relieved of seizures, mainly because the pathophysiological mechanisms are still not elucidated completely. Basket, axo-axonic, bistratified, oriens-lacunosum moleculare (O-LM) and Ivy cells exert spatially and temporary different inhibition on principal neurons. Our aim was to evaluate the alterations of these interneuron populations during epileptogenesis. We induced status epilepticus in male Wistar rats using intraperitoneal pilocarpine injection, which was followed, after a latency period, by spontaneous recurrent seizures (SRS). Nissl staining was used for the analysis of gross morphological changes, whereas triple immunofluorescent-labeled sections (parvalbumin, somatostatin, neuropeptide-Y) were used for differentiation of the selected interneuron types. Putative interneurons identified by their neurochemical contents were quantified, and the cell density was calculated. Although animals developing SRS showed similar behavior, the degree of hippocampal sclerosis was different. In animals with hippocampal sclerotic cell death pattern the density of perisomatic inhibitory neurons was higher, but not significantly. The dendritic inhibitory bistratified cells were preserved, whereas the number of O-LM cells showed a significant decrease. A substantial loss was observed in the number and density of Ivy cells. We suggest that the loss of hippocampal input modulatory O-LM cells, and overall excitation controlling Ivy cells, has a role in the emergence of hyperexcitability. In the same time, alterations of output controlling interneurons might contribute to the propagation of the pathological synchronization to the cortex.

Topics: Animals; Axons; Epilepsy; Epilepsy, Temporal Lobe; Hippocampus; Interneurons; Male; Neurons; Neuropeptide Y; Parvalbumins; Pilocarpine; Rats; Rats, Wistar; Reproducibility of Results; Sclerosis; Somatostatin; Video Recording

Development of novel disease-modifying treatment strategies for neurological disorders, which at present have no cure, represents a major challenge for today's neurology. Translation of findings from animal models to humans represents an unresolved gap in most of the preclinical studies. Gene therapy is an evolving innovative approach that may prove useful for clinical applications. In animal models of temporal lobe epilepsy (TLE), gene therapy treatments based on viral vectors encoding NPY or galanin have been shown to effectively suppress seizures. However, how this translates to human TLE remains unknown. A unique possibility to validate these animal studies is provided by a surgical therapeutic approach, whereby resected epileptic tissue from temporal lobes of pharmacoresistant patients are available for neurophysiological studies in vitro. To test whether NPY and galanin have antiepileptic actions in human epileptic tissue as well, we applied these neuropeptides directly to human hippocampal slices in vitro. NPY strongly decreased stimulation-induced EPSPs in dentate gyrus and CA1 (up to 30 and 55%, respectively) via Y2 receptors, while galanin had no significant effect. Receptor autoradiographic binding revealed the presence of both NPY and galanin receptors, while functional receptor binding was only detected for NPY, suggesting that galanin receptor signaling may be impaired. These results underline the importance of validating findings from animal studies in human brain tissue, and advocate for NPY as a more appropriate candidate than galanin for future gene therapy trials in pharmacoresistant TLE patients.

Topics: Adolescent; Adult; Epilepsy; Excitatory Postsynaptic Potentials; Female; Galanin; Guanosine 5'-O-(3-Thiotriphosphate); Hippocampus; Humans; In Vitro Techniques; Male; Membrane Potentials; Microtubule-Associated Proteins; Middle Aged; Neuropeptide Y; Patch-Clamp Techniques; Radioligand Assay; Receptors, Galanin; Receptors, Neuropeptide Y; Sulfur Isotopes; Synapses; Synaptic Transmission; Young Adult

Our objective is to explore the effects of levetiracetam on the levels of neuropeptides, serum activity and concentrations of oxidative stress and inflammatory response proteins, and levels of brain injury marker in patients with refractory epilepsy. Seventy-two patients with refractory epilepsy received levetiracetam treatment. Neuropeptides galanin (GAL) and neuropeptide Y (NPY) in plasma and cerebrospinal fluid (CSF) were detected using double-antibody sandwich immunoassay and radioimmunoassay, respectively. Enzyme-linked immunosorbent assay was used to detect serum activity of paraoxonase (PON1) and serum concentrations of oxidized low-density lipoprotein (ox-LDL) and S100B. Arylesterase (ARE) activity was measured by colorimetric assay, and immune scatter turbidimetry was used to detect a high-sensitivity C-reactive protein (hs-CRP). After treatment, NPY and GAL in plasma and CSF of the patients were significantly decreased as compared to concentrations before treatment (P < 0.05). Levetiracetam reduced serum activities of PON1 and ARE (P < 0.05) and led to markedly increased serum levels of ox-LDL (P < 0.05). Serum concentrations of hs-CRP and S100B protein were significantly lower after levetiracetam administrations than before treatment (P < 0.05). Levetiracetam treatment had a clear beneficial effect on the overall quality of life (QOL) scores of the patients, as indicated by significantly improved cognitive functioning, behavior problems, emotional conditioning, physical condition, social functioning, self-assessed life quality score, self-assessed health score, and the total QOL score (P < 0.05). Levetiracetam can improve life quality of patients with refractory epilepsy, decrease NPY and GAL in plasma and cerebrospinal fluid, serum PON1 and ARE activities, and serum levels of ox-LDL, hs-CRP, and S100B. Levetiracetam therefore may be considered a drug of choice for treating refractory epilepsy.

Topics: Adolescent; Adult; Aryldialkylphosphatase; C-Reactive Protein; Enzyme-Linked Immunosorbent Assay; Epilepsy; Female; Galanin; Humans; Levetiracetam; Lipoproteins, LDL; Male; Middle Aged; Neuropeptide Y; Piracetam; Quality of Life; Radioimmunoassay; S100 Calcium Binding Protein beta Subunit; Young Adult

As an endogenous inhibitor of glutamate-mediated synaptic transmission in mammalian central nervous system, neuropeptide Y (NPY) plays a crucial role in regulating homeostasis of neuron excitability. Loss of balance between excitatory and inhibitory neurotransmission is thought to be a chief mechanism of epileptogenesis. The abnormal expression of NPY and its receptors observed following seizures have been demonstrated to be related to the production of epilepsy. The tremor rat (TRM) is a hereditary epileptic animal model. So far, there is no report concerning whether NPY and its receptors may be involved in TRM pathogenesis. In this study, we focused on the expression of NPY and its three receptor subtypes: Y1R, Y2R and Y5R in the TRM brain. We first found the expression of NPY in TRM hippocampus and temporal lobe cortex was increased compared with control (Wistar) rats. The mRNA and protein expression of Y1R was down-regulated in hippocampus but up-regulated in temporal lobe cortex, whereas Y2R expression was significantly increased in both areas. There was no significant change of Y5R expression in either area. The immunohistochemistry data showed that Y1R, Y2R, Y5R were present throughout CA1, CA3, dentate gyrus (DG) and the entorhinal cortex which is included in the temporal lobe cortex of TRM. In conclusion, our results showed the altered expression of NPY, Y1R and Y2R but not Y5R in hippocampus and temporal lobe cortex of TRM brain. This abnormal expression may be associated with the generation of epileptiform activity and provide a candidate target for treatment of genetic epilepsy.

Topics: Animals; Disease Models, Animal; Epilepsy; Female; Hippocampus; Male; Neuropeptide Y; Rats, Mutant Strains; Rats, Wistar; Receptors, G-Protein-Coupled; Receptors, Neuropeptide; Receptors, Neuropeptide Y; Temporal Lobe; Tremor

Weight loss is one of the most frequent side effects of topiramate treatment. The aim of our study was to investigate the effect of topiramate on body mass index, serum glucose, insulin, cortisol, leptin, and neuropeptide-Y levels and the role of these variables on the pathogenesis of weight loss in prepubertal children with epilepsy.. Twenty prepubertal children with epilepsy who were treated with topiramate were enrolled in the study. Topiramate was used at a daily dose of 5 mg/kg. Body mass index and fasting insulin-to-glucose ratio were calculated. Serum glucose, insulin, leptin, neuropeptide-Y, ghrelin, and cortisol levels were measured for all patients before the treatment and at the third and sixth months of the treatment.. There were significant decreases in mean body mass index, fasting insulin-to-glucose ratio, and serum cortisol and leptin levels at the third and sixth months of the treatment compared with pretreatment levels. No significant changes were observed in serum glucose, ghrelin, neuropeptide-Y, or insulin levels.. The exact mechanism of topiramate on energy balance regulation is not clearly understood. Topiramate affects body mass index, fasting insulin-to-glucose ratio, and serum leptin and cortisol levels in prepubertal children. These changes may be key factors in weight loss due to topiramate.

Topics: Anticonvulsants; Blood Glucose; Body Mass Index; Body Weight; Child; Child, Preschool; Epilepsy; Female; Fructose; Ghrelin; Humans; Hydrocortisone; Insulin; Leptin; Male; Neuropeptide Y; Topiramate

Antiepileptic drugs may affect the endocrine system. We investigated the effects of valproic acid and topiramate on the levels of insulin, c-peptide and adipocytokines in pre-pubertal patients with idiopathic partial and generalized epilepsy.. Forty-one children with epilepsy were included. The patients were divided into two groups (valproic acid; n = 21, topiramate; n = 20). The weight, height, body mass index and homeostasis model assessment of insulin resistance (HOMA-IR) were recorded and insulin, c-peptide, leptin, neuropeptide Y, adiponectin, visfatin and resistin levels were determined at 0, 6 and 12 months of therapy.. In the valproate group, weight and height increased significantly. Seven of 21 patients were overweight at the end of one year. Leptin was higher in the overweight subgroup. Although insulin and HOMA-IR increased (p < 0.05), none of the patients showed hyperinsulinism or IR. Resistin had decreased at the 6th and 12th months (p < 0.05). In the topiramate group, some statistically nonsignificant changes were demonstrated.. The mechanisms behind valproate and topiramate-related weight control are still unclear, especially in children. Valproate and topiramate affect the weight, BMI, and insulin, leptin and adipocytokine levels in prepubertal children. We suggest that further studies including more patients with a long follow-up period are necessary to draw a firm conclusion regarding an association between the treatment with these drugs and the levels of leptin, insulin and adipocytokines.

Topics: Adiponectin; Anticonvulsants; Body Mass Index; Body Weight; C-Peptide; Child; Epilepsy; Female; Fructose; Humans; Insulin; Leptin; Male; Neuropeptide Y; Nicotinamide Phosphoribosyltransferase; Resistin; Topiramate; Valproic Acid

Epilepsy is one of the most common neurological disorders, characterized by recurrent seizures, which may increase the content of reactive oxygen and nitrogen species. The objective of this study was to investigate the effects of Neuropeptide Y on oxidative and nitrosative balance and brain-derived neurotrophic factor levels induced by pentylenetetrazole (a standard convulsant drug) in the hippocampus of Wistar rats. Three groups of seven rats were treated intraperitoneally as follows: group 1 (saline + saline) 1 ml saline, group 2 (salin + Pentylenetetrazole) 1 ml saline 30 min before Pentylenetetrazole; and group 3 (Neuropeptide Y + Pentylenetetrazole) 60 μg/kg Neuropeptide Y 30 min before 60 mg/kg Pentylenetetrazole. After 24 h, the animals were euthanized by decapitation. Hippocampus were isolated to evaluate the malondialdehyde, glutathione, nitric oxide, and brain-derived neurotrophic factor levels in three rat groups. The results of this study demonstrated that while intraperitoneally administered neuropeptide Y did not result in a statistically significant difference in BDNF levels, its administration caused a statistically significant decrease in malondialdehyde and nitric oxide levels and an increase in glutathione levels in rats with pentylenetetrazole-induced epileptic seizure. Neuropeptide Y were able to reduce nitroxidative damage induced by pentylenetetrazole in the hippocampus of Wistar rats.

Topics: Animals; Brain-Derived Neurotrophic Factor; Convulsants; Disease Models, Animal; Epilepsy; Glutathione; Hippocampus; Male; Malondialdehyde; Neuropeptide Y; Nitric Oxide; Pentylenetetrazole; Rats; Rats, Wistar

An early but transient decrease in oxygen availability occurs during experimentally induced seizures. Using pimonidazole, which probes hypoxic insults, we found that by increasing the duration of pilocarpine-induced status epilepticus (SE) from 30 to 120 min, counts of pimonidazole-immunoreactive neurons also increased (P < 0.01, 120 vs 60 and 30 min). All the animals exposed to SE were immunopositive to pimonidazole, but a different scenario emerged during epileptogenesis when a decrease in pimonidazole-immunostained cells occurred from 7 to 14 days, so that only 1 out of 4 rats presented with pimonidazole-immunopositive cells. Pimonidazole-immunoreactive cells robustly reappeared at 21 days post-SE induction when all animals (7 out of 7) had developed spontaneous recurrent seizures. Specific neuronal markers revealed that immunopositivity to pimonidazole was present in cells identified by neuropeptide Y (NPY) or somatostatin antibodies. At variance, neurons immunopositive to parvalbumin or cholecystokinin were not immunopositive to pimonidazole. Pimonidazole-immunopositive neurons expressed remarkable immunoreactivity to hypoxia-inducible factor 1α (HIF-1α). Interestingly, surgical samples obtained from pharmacoresistant patients showed neurons co-labeled by HIF-1α and NPY antibodies. These interneurons, along with parvalbumin-positive interneurons that were negative to HIF-1α, showed immunopositivity to markers of cell damage, such as high-mobility group box 1 in the cytoplasm and cleaved caspase-3 in the nucleus. These findings suggest that interneurons are continuously endangered in rodent and human epileptogenic tissue. The presence of hypoxia and cell damage markers in NPY interneurons of rats and patients presenting with recurrent seizures indicates a mechanism of selective vulnerability in a specific neuronal subpopulation.

Topics: Animals; Anticonvulsants; Biomarkers; Cell Hypoxia; Cerebral Cortex; Convulsants; Diazepam; Disease Progression; Drug Resistance; Epilepsy; HMGB1 Protein; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Interneurons; Male; Nerve Tissue Proteins; Neuropeptide Y; Nitroimidazoles; Parvalbumins; Pilocarpine; Rats; Rats, Sprague-Dawley; Recurrence; Seizures; Status Epilepticus

Hydrocarbon stapling is an effective strategy to stabilize the helical conformation of bioactive peptides. Here we describe application of stapling to anticonvulsant neuropeptides, galanin (GAL) and neuropeptide Y (NPY), that are implicated in modulating seizures in the brain. Dicarba bridges were rationally introduced into minimized analogs of GAL and NPY resulting in increased α-helical content, in vitro metabolic stability and n-octanol/water partitioning coefficient (logD). The stapled analogs retained agonist activities towards their respective receptors and suppressed seizures in a mouse model of epilepsy.

Topics: Amino Acid Sequence; Animals; Anticonvulsants; Cyclization; Drug Stability; Epilepsy; Galanin; Male; Mice; Molecular Sequence Data; Neuropeptide Y; Protein Stability; Protein Structure, Secondary; Rats

Topics: Adiponectin; Anticonvulsants; Carotid Intima-Media Thickness; Epilepsy; Female; Ghrelin; Humans; Leptin; Male; Neuropeptide Y; Valproic Acid

Topics: Adiponectin; Anticonvulsants; Carotid Intima-Media Thickness; Epilepsy; Female; Ghrelin; Humans; Leptin; Male; Neuropeptide Y; Valproic Acid

Parahippocampal brain areas including the subiculum, presubiculum and parasubiculum, and entorhinal cortex give rise to major input and output neurons of the hippocampus and exert increased excitability in animal models and human temporal lobe epilepsy. Using immunohistochemistry and in situ hybridization for somatostatin and neuropeptide Y, we investigated plastic morphologic and neurochemical changes in parahippocampal neurons in the kainic acid (KA) model of temporal lobe epilepsy. Although constitutively contained in similar subclasses of γ-aminobutyric acid (GABA)-ergic neurons, both neuropeptide systems undergo distinctly different changes in their expression. Somatostatin messenger RNA (mRNA) is rapidly but transiently expressed de novo in pyramidal neurons of the subiculum and entorhinal cortex 24 hours after KA. Surviving somatostatin interneurons display increased mRNA levels at late intervals (3 months) after KA and increased labeling of their terminals in the outer molecular layer of the subiculum; the labeling correlates with the number of spontaneous seizures, suggesting that the seizures may trigger somatostatin expression. In contrast, neuropeptide Y mRNA is consistently expressed in principal neurons of the proximal subiculum and the lateral entorhinal cortex and labeling for the peptide persistently increased in virtually all major excitatory pathways of the hippocampal formation. The pronounced plastic changes differentially involving both neuropeptide systems indicate marked rearrangement of parahippocampal areas, presumably aiming at endogenous seizure protection. Their receptors may be targets for anticonvulsive drug therapy.

Topics: Animals; Entorhinal Cortex; Epilepsy; Hippocampus; Interneurons; Kainic Acid; Male; Neuronal Plasticity; Neuropeptide Y; Parahippocampal Gyrus; Rats; Rats, Sprague-Dawley; Somatostatin

Weight gain is a common side effect of valproate (VPA) treatment, although the mechanism is not clear. Abnormal weight gain and obesity are associated with dyslipidemia, hypertension, and atherosclerosis. Measurement of the common carotid artery intima media thickness (CAIMT) gives a picture of early arterial wall alterations and, currently, is considered a noninvasive marker of premature atherosclerosis. The aim of the present study was to evaluate plasma insulin, leptin, neuropeptide Y (NPY), ghrelin, and adiponectin levels in children with epilepsy treated with VPA and to evaluate these parameters for early atherosclerosis.. Twenty prepubertal children with idiopathic epilepsy treated with VPA were enrolled in this study. Body mass index (BMI) and fasting insulin glucose ratio (FIGR) were calculated, and the plasma insulin, leptin, NPY, ghrelin, and adiponectin levels; the lipid profiles; and CAIMT were measured for all subjects before the treatment and after a follow-up period of 6 and 12 months.. When pretreatment values were compared with those at the end of 6 and 12 months, the mean BMI values, plasma insulin, leptin, NPY levels, and FIGR were increased, whereas the plasma ghrelin and adiponectin levels, lipid profiles, and CAIMT did not change significantly at the end of 6 and 12 months.. These results suggest that weight gain during VPA treatment may be related to increases in insulin, leptin, and NPY levels. Additionally, in this study, no increase in the risk for early atherosclerosis was determined by CAIMT in children with epilepsy treated with VPA.

Topics: Adiponectin; Age Factors; Anticonvulsants; Blood Glucose; Body Mass Index; Carotid Intima-Media Thickness; Child; Epilepsy; Female; Follow-Up Studies; Ghrelin; Humans; Insulin; Leptin; Male; Neuropeptide Y; Valproic Acid

We investigated the mechanism of topiramate-related appetite loss and exposed its relationship to body weight, body mass index, body fat index, and serum insulin, lipid, leptin, neuropeptide-Y, cortisol, ghrelin, and adiponectin levels. Twenty children with epilepsy were evaluated at baseline and months 3 and 6 of treatment. Their body fat index, leptin, and neuropeptide-Y levels significantly decreased at month 3, whereas significant decreases occurred in body weight, body mass index, body fat index, neuropeptide-Y, cholesterol, and cortisol levels of patients at month 6 compared with baseline. Weight loss during topiramate treatment was attributed to loss of appetite and reduced food intake caused by reductions in neuropeptide-Y. To the best of our knowledge, this study is the first to describe reductions in neuropeptide-Y with topiramate use in humans.

Topics: Adiponectin; Adiposity; Anticonvulsants; Appetite; Body Mass Index; Body Weight; Child; Epilepsy; Female; Fructose; Ghrelin; Humans; Insulin; Leptin; Male; Neuropeptide Y; Topiramate

Neuropeptide Y (NPY) network effects in hippocampus and frontal cortex and its impact on epileptiform neocortical discharges were investigated in rat juvenile brain slices. NPY (1 μM) reduced amplitudes of paired pulse stimulation in hippocampal brain tissue (p<0.05) whereas NPY (1 nM-2 μM) had no effect in neocortex. Late stage epileptiform activity in the neocortex was unaffected by NPY (1 μM). Our results point to a region dependent effect of NPY with a high impact on hippocampal and minimal impact on neocortical networks.

Topics: Action Potentials; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Electric Stimulation; Epilepsy; Hippocampus; In Vitro Techniques; Male; Neocortex; Neuropeptide Y; Patch-Clamp Techniques; Rats; Rats, Sprague-Dawley

The objective of this study was to investigate the cause of valproate (VPA)-associated weight gain in children.. Eighteen children (10.94 ± 3.78 years) with epilepsy were assigned to VPA therapy. Serum levels of glucose, insulin, cortisol, leptin, neuropeptide Y (NPY), galanin and ghrelin were assessed before (month 0) and after 18 months of therapy. Eighteen age- and gender-matched patients (10.78 ± 3.95 years) were enrolled as the control group.. Excess per capita weight of 2.3 kg was determined in the children receiving VPA over 18 months compared to the control group. In these patients, a statistically significant increase in standardized weight score, Homeostasis Model Assessment index, serum leptin, NPY and galanin values was determined at the 18th month compared to those before VPA treatment and in the control group, and there was also a significant decrease in ghrelin values.. Increased serum levels of leptin, NPY and galanin play an important role in VPA-associated weight gain in children. While ghrelin is not directly associated with weight gain, its serum levels decline as a response to weight gain.

Topics: Adolescent; Child; Child, Preschool; Epilepsy; Galanin; Ghrelin; Humans; Hydrocortisone; Insulin; Leptin; Neuropeptide Y; Valproic Acid; Weight Gain

The neuropeptides galanin (GAL), neuropeptide Y (NPY) or neurotensin (NT) exhibit anticonvulsant activities mediated by their respective receptors in the brain. To transform these peptides into potential neurotherapeutics, their systemic bioavailability and metabolic stability must be improved. Our recent studies with GAL analogs suggested that an introduction of lipoamino acids in the context of oligo-Lys residues (lipidization-cationization motif) significantly increases their penetration into the brain, yielding potent antiepileptic compounds. Here, we describe an extension of this strategy to NPY and NT. Rationally designed analogs of NPY and NT containing the lipidization-cationization motif were chemically synthesized and their physicochemical and pharmacological properties were characterized. The analogs NPY-BBB2 and NT-BBB1 exhibited increased serum stability, possessed log D > 1.1, retained high affinities toward their native receptors and produced potent antiseizure activities in animal models of epilepsy following intraperitoneal administration. Our results suggest that the combination of lipidization and cationization may be an effective strategy for improving systemic bioavailability and metabolic stability of various neuroactive peptides.

Topics: Animals; Anticonvulsants; Blood-Brain Barrier; Cations; Epilepsy; Lipids; Neuropeptide Y; Neurotensin; Rats; Receptors, Neuropeptide Y; Receptors, Neurotensin

Recently, hippocampal neuropeptide Y (NPY) gene therapy has been shown to effectively suppress both acute and chronic seizures in animal model of epilepsy, thus representing a promising novel antiepileptic treatment strategy, particularly for patients with intractable mesial temporal lobe epilepsy (TLE). However, our previous studies show that recombinant adeno-associated viral (rAAV)-NPY treatment in naive rats attenuates long-term potentiation (LTP) and transiently impairs hippocampal learning process, indicating that negative effect on memory function could be a potential side effect of NPY gene therapy. Here we report how rAAV vector-mediated overexpression of NPY in the hippocampus affects rapid kindling, and subsequently explore how synaptic plasticity and transmission is affected by kindling and NPY overexpression by field recordings in CA1 stratum radiatum of brain slices. In animals injected with rAAV-NPY, we show that rapid kindling-induced hippocampal seizures in vivo are effectively suppressed as compared to rAAV-empty injected (control) rats. Six to nine weeks later, basal synaptic transmission and short-term synaptic plasticity are unchanged after rapid kindling, while LTP is significantly attenuated in vitro. Importantly, transgene NPY overexpression has no effect on short-term synaptic plasticity, and does not further compromise LTP in kindled animals. These data suggest that epileptic seizure-induced impairment of memory function in the hippocampus may not be further affected by rAAV-NPY treatment, and may be considered less critical for clinical application in epilepsy patients already experiencing memory disturbances.

Topics: Analysis of Variance; Animals; Biophysical Phenomena; Chi-Square Distribution; Disease Models, Animal; Electric Stimulation; Electrodes, Implanted; Electroencephalography; Epilepsy; Excitatory Postsynaptic Potentials; Genetic Therapy; Hippocampus; Long-Term Potentiation; Male; Neuropeptide Y; Rats; Rats, Sprague-Dawley; Transduction, Genetic

Urokinase-type plasminogen activator receptor (uPAR) is functionally a pleiotropic mediator involved in cell adhesion, proliferation, differentiation and migration as well as in matrix degradation, apoptosis, and angiogenesis in cancer tissue. Comparable cellular alterations occur in the brain during post-injury tissue repair. As the first step to assess the role of uPAR in brain tissue remodeling, we tested a hypothesis that uPAR expression is altered in the hippocampus during epilepsy-related circuitry reorganization. Epileptogenesis was triggered by inducing status epilepticus (SE) with electrical stimulation of the amygdala in rats. To monitor the development of SE and the occurrence of spontaneous seizures animals were continuously video-EEG monitored until sacrificed (1, 2, 4 or 14 days after SE). The hippocampal expression of uPAR was studied with real time qPCR and immunohistochemistry. Double-immunohistochemistry and confocal microscopy were used to investigate the expression of uPAR in astrocytes, microglia and neurons. We show that in the normal hippocampus the expression of uPAR was low and confined to small population of astrocytes and interneurons. In animals undergoing SE, uPAR expression increased dramatically, peaking at 1 and 4 days after SE. According to double-immunohistochemistry, uPAR was highly expressed in parvalbumin positive interneurons in the hippocampus and dentate gyrus, and in a subgroup of somatostatin and neuropeptide Y positive hilar interneurons. Increased uPAR expression during post-injury phase supports its contribution to tissue remodeling in the brain. Surviving hilar interneurons that are known to be denervated due to loss of afferent inputs in post-SE brain provide a target for future studies to investigate the contribution of uPAR in reinnervation of these cells, and to identify the signaling cascades that mediate the effects of uPAR.

Topics: Animals; Astrocytes; Cell Line; Disease Models, Animal; Electric Stimulation; Epilepsy; Gene Expression Regulation; Hippocampus; Humans; Immunohistochemistry; Interneurons; Kindling, Neurologic; Male; Nerve Degeneration; Neuropeptide Y; Parvalbumins; Rats; Rats, Sprague-Dawley; Receptors, Urokinase Plasminogen Activator; RNA, Messenger; Signal Transduction; Somatostatin; Up-Regulation

GABA synapses play a critical role in many aspects of circuit development and function. For example, conditions that perturb GABA transmission have been implicated in epilepsy. To identify genes that regulate GABA transmission, we performed an RNAi screen for genes whose inactivation increases the activity of C. elegans body muscles, which receive direct input from GABAergic motor neurons. We identified 90 genes, 21 of which were previously implicated in seizure syndromes, suggesting that this screen has effectively identified candidate genes for epilepsy. Electrophysiological recordings and imaging of excitatory and inhibitory synapses indicate that several genes alter muscle activity by selectively regulating GABA transmission. In particular, we identify two humoral pathways and several protein kinases that modulate GABA transmission but have little effect on excitatory transmission at cholinergic neuromuscular junctions. Our data suggest these conserved genes are components of signaling pathways that regulate GABA transmission and consequently may play a role in epilepsy and other cognitive or psychiatric disorders.

Topics: Acetylcholine; Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Endocrine System; Epilepsy; Excitatory Postsynaptic Potentials; gamma-Aminobutyric Acid; Genetic Testing; Inhibitory Postsynaptic Potentials; Mitogen-Activated Protein Kinases; Motor Neurons; Movement; Muscles; Neuropeptide Y; Receptors, GABA; RNA Interference; Signal Transduction; Synapses; Synaptic Transmission; Transforming Growth Factor beta

This study characterized morphological changes in the cortex and hippocampus of Sprague-Dawley rats following photothrombotic infarction and epileptogenesis with emphasis on the distribution of neuropeptide Y (NPY) expression. Animals were lesioned in the left sensorimotor cortex and compared with age-matched naive and sham-operated controls by immunohistochemical techniques at 1, 3, 7, and 180 days post-lesioning (DPL). NPY immunostaining was assessed by light microscopy and quantified by the optical fractionator technique using unbiased stereological methods. At 1, 3, and 7 DPL, the number of NPY-positive somata in the lesioned cortex was increased significantly compared to controls and the contralateral cortex. At 180 DPL, lesioned epileptic animals with frequent seizure activity demonstrated significant increases of NPY expression in the cortex, CA1, CA3, hilar interneurons, and granule cells of the dentate gyrus. In addition to NPY immunostaining, neuronal degeneration, cell death/cell loss, and astroglial response were assessed with cell-specific markers. Nissl and NeuN staining showed reproducible infarctions at each investigated time point. FJB-positive somata were most abundant in the infarct core at 1 DPL, decreased markedly at 3 DPL, and virtually absent by 7 DPL. Activated astroglia were detected in the cortex and hippocampus following lesioning and the development of seizure activity. In summary, NPY protein expression and morphological changes following cortical photothrombosis were time-, region-, and pathologic state-dependent. Alterations in NPY expression may reflect reactive or compensatory responses of the rat brain to acute infarction and to the development and expression of epileptic seizures.

Topics: Animals; Astrocytes; Brain; Brain Infarction; Dentate Gyrus; Disease Models, Animal; DNA-Binding Proteins; Epilepsy; Fluoresceins; Gliosis; Hippocampus; Immunohistochemistry; Intracranial Thrombosis; Light Coagulation; Nerve Degeneration; Nerve Tissue Proteins; Neurons; Neuropeptide Y; Nuclear Proteins; Organic Chemicals; Rats; Rats, Sprague-Dawley; Somatosensory Cortex; Time Factors; Up-Regulation

Alzheimer's disease is a devastating neurological disorder. The role of hyperexcitability in the disease's cognitive decline is not completely understood. In this issue of Neuron, Palop et al. report both limbic seizures and presumed homeostatic responses to seizures in an animal model of Alzheimer's.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Cognition Disorders; Dentate Gyrus; Disease Models, Animal; Epilepsy; Homeostasis; Humans; Mutation; Neural Inhibition; Neuropeptide Y

The potent anticonvulsant properties of neuropeptide Y (NPY) are generally attributed to a Y2 receptor-mediated inhibition of glutamatergic synaptic transmission. Independent studies have shown that NPY increases brain dopamine content, possibly via interaction with sigma 1 receptors. Recently, we showed that increased extracellular hippocampal dopamine attenuates pilocarpine-induced limbic seizures via activation of hippocampal D2 receptors. Our aim in this study was to elucidate the role of increased hippocampal dopamine in the mechanism of the anticonvulsant action of NPY and to investigate the involvement of Y2 and sigma 1 receptors in this process. Limbic seizures were evoked in freely moving rats by intrahippocampal administration of pilocarpine via a microdialysis probe. NPY was administered intracerebroventricularly, intrahippocampally via the microdialysis probe, or coadministered intrahippocampally with the D2 receptor antagonist remoxipride, the Y2 receptor antagonist BIIE0246 or the sigma 1 receptor antagonist BD1047. Changes in hippocampal extracellular dopamine were monitored, and behavioural changes indicative of seizure activity were scored. Intracerebroventricular (10 nmol/3 microL) and intrahippocampal (20-50 microm) NPY administration increased hippocampal dopamine and attenuated pilocarpine-induced seizures. Hippocampal D2 receptor blockade (4 microm remoxipride) reversed the anticonvulsant effect of NPY. Y2 receptor blockade (1 microm BIIE0246) reversed the anticonvulsant effect of NPY but did not prevent NPY-induced increases in hippocampal dopamine. Sigma 1 receptor blockade (10 microm BD1047) abolished NPY-induced increases in hippocampal dopamine and reversed the anticonvulsant effect of NPY. Our results indicate that NPY-induced increases in hippocampal dopamine are mediated via sigma 1 receptors and contribute to the anticonvulsant effect of NPY via increased activation of hippocampal D2 receptors. This novel mechanism of anticonvulsant action of NPY is separate from, and may be complementary to, the well established Y2 receptor-mediated inhibition of hippocampal excitability.

Topics: Analysis of Variance; Animals; Anticonvulsants; Behavior, Animal; Chromatography, High Pressure Liquid; Disease Models, Animal; Dopamine; Dopamine Antagonists; Dose-Response Relationship, Drug; Epilepsy; Ethylenediamines; Hippocampus; Male; Microdialysis; Neuropeptide Y; Pilocarpine; Rats; Rats, Wistar; Receptors, sigma; Remoxipride; Severity of Illness Index; Sigma-1 Receptor; Time Factors

To study the effects of Annao tablet (main component is beta-asarone) on S100B and NPY of cortex in chronic epilepsy rats.. The remedy was administered orally. The effects were observed in convulsion model induced by PG, then S100B protein and NPY of cortex were determined.. Annao tablet could depress the epileptic degree, postpone spasm latent period and reduce the wet dog sample (WDS) times. The remedy could decline S100B and NPY of cortex in chronic epilepsy rats.. Annao tablet has obvious antiepileptic effects and can reduce the nerve cell damage induced by epilepsy.

Topics: Acorus; Allylbenzene Derivatives; Animals; Anisoles; Anticonvulsants; beta-Cyclodextrins; Cerebral Cortex; Drug Carriers; Epilepsy; Female; Male; Neuropeptide Y; Plants, Medicinal; Rats; Rats, Sprague-Dawley; S100 Proteins; Tablets

Kainate-induced epilepsy has been shown to be associated with increased levels of neuropeptide Y (NPY) in the rat hippocampus. However, there is no information on how increased levels of this peptide might modulate excitation in kainate-induced epilepsy. In this work, we investigated the modulation of glutamate release by NPY receptors in hippocampal synaptosomes isolated from epileptic rats. In the acute phase of epilepsy, a transient decrease in the efficiency of NPY and selective NPY receptor agonists in inhibiting glutamate release was observed. Moreover, in the chronic epileptic hippocampus, a decrease in the efficiency of NPY and the Y(2) receptor agonist, NPY13-36, was also found. Simultaneously, we observed that the epileptic hippocampus expresses higher levels of NPY, which may account for an increased basal inhibition of glutamate release. Consistently, the blockade of Y(2) receptors increased KCl-evoked glutamate release, and there was an increase in Y(2) receptor mRNA levels 30 days after kainic acid injection, suggesting a basal effect of NPY through Y(2) receptors. Taken together, these results indicate that an increased function of the NPY modulatory system in the epileptic hippocampus may contribute to basal inhibition of glutamate release and control hyperexcitability.

Topics: Animals; Disease Models, Animal; Drug Interactions; Epilepsy; Glutamic Acid; Hippocampus; Kainic Acid; Male; Neuropeptide Y; Peptide Fragments; Potassium Chloride; Rats; Rats, Wistar; Receptors, Neuropeptide Y; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors; Up-Regulation

In adult mice, intrahippocampal administration of kainic acid induces a structural modification of the granule cell layer reminiscent of granule cell dispersion (GCD) seen in humans with temporal lobe epilepsy. We tested that GCD might be involved in the patterns of granule cell responses to perforant path stimulation by recording field potentials in vivo after kainic acid-induced status epilepticus until the phase of chronic seizure activity in presence of GCD or after its alteration by K252a co-treatment, an inhibitor of tyrosine kinase activities. Stimulation triggered bursts of multiple population spikes, the number of which progressively increased with time whereas their amplitude decreased in parallel with the progressive decrease in granule cell density. The population spike threshold was reached for a lower excitatory synaptic drive than in controls, as assessed by the initial slope of the field excitatory post-synaptic potential. This indicates that, for identical synaptic responses, granule cells were closer to the firing threshold. Fast inhibition, assessed by paired pulse stimulation, was compromised immediately after the initial status epilepticus, consistent with the rapid loss of most hilar cells. Neither the epileptic course nor the epileptiform responses of the granule cells were modified and manipulation by alteration following GCD manipulation while granule cell neuropeptide-Y immunostaining was substantially decreased. In this mouse model of TLE, granule cells display a progressive increase in epileptiform responses to afferent input until the occurrence of spontaneous seizures. The population spike amplitude decreases in parallel with GCD while the granule cell excitability is enhanced. Consequently, data from field potentials in epilepsy experiments should be interpreted with care, taking into account the possible variations in the neuronal density in the recorded area.

Topics: Action Potentials; Animals; Behavior, Animal; Carbazoles; Cell Count; Disease Models, Animal; Dose-Response Relationship, Radiation; Drug Interactions; Electric Stimulation; Enzyme Inhibitors; Epilepsy; Hippocampus; Immunohistochemistry; Indole Alkaloids; Kainic Acid; Mice; Neurons; Neuropeptide Y; Perforant Pathway; Staining and Labeling; Time Factors

Major aspects of temporal lobe epilepsy (TLE) can be reproduced in mice following a unilateral injection of kainic acid into the dorsal hippocampus. This treatment induces a non-convulsive status epilepticus and acute lesion of CA1, CA3c and hilar neurons, followed by a latent phase with ongoing ipsilateral neuronal degeneration. Spontaneous focal seizures mark the onset of the chronic phase. In striking contrast, the ventral hippocampus and the contralateral side remain structurally unaffected and seizure-free. In this study, functional and neurochemical alterations of the contralateral side were studied to find candidate mechanisms underlying the lack of a mirror focus in this model of TLE. A quantitative analysis of simultaneous, bilateral EEG recordings revealed a significant decrease of theta oscillations ipsilaterally during the latent phase and bilaterally during the chronic phase. Furthermore, the synchronization of bilateral activity, which is very high in control, was strongly reduced already during the latent phase and the decrease was independent of recurrent seizures. Immunohistochemical analysis performed in the contralateral hippocampus of kainate-treated mice revealed reduced calbindin-labeling of CA1 pyramidal cells; down-regulation of CCK-8 and up-regulation of NPY-labeling in mossy fibers; and a redistribution of galanin immunoreactivity. These changes collectively might limit neuronal excitability in CA1 and dentate gyrus, as well as glutamate release from mossy fiber terminals. Although these functional and neurochemical alterations might not be causally related, they likely reflect long-ranging network alterations underlying the independent evolution of the two hippocampal formations during the development of an epileptic focus in this model of TLE.

Topics: Action Potentials; Animals; Brain Chemistry; Calbindins; Chronic Disease; Disease Models, Animal; Down-Regulation; Electroencephalography; Epilepsy; Epilepsy, Temporal Lobe; Functional Laterality; Galanin; Hippocampus; Kainic Acid; Mice; Mossy Fibers, Hippocampal; Nerve Degeneration; Neural Pathways; Neuropeptide Y; Neurotoxins; Pyramidal Cells; S100 Calcium Binding Protein G; Sincalide; Status Epilepticus; Theta Rhythm; Up-Regulation

Neuropeptide Y (NPY) prominently inhibits epileptic seizures in different animal models. The NPY receptors mediating this effect remain controversial partially due to lack of highly selective agonists and antagonists. To circumvent this problem, we used various NPY receptor knockout mice with the same genetic background and explored anti-epileptic action of NPY in vitro and in vivo. In Y2 (Y2-/-) and Y5 (Y5-/-) receptor knockouts, NPY partially inhibited 0 Mg2+-induced epileptiform activity in hippocampal slices. In contrast, in double knockouts (Y2Y5-/-), NPY had no effect, suggesting that in the hippocampus in vitro both receptors mediate anti-epileptiform action of NPY in an additive manner. Systemic kainate induced more severe seizures in Y5-/- and Y2Y5-/-, but not in Y2-/- mice, as compared to wild-type mice. Moreover, kainate seizures were aggravated by administration of the Y5 antagonist L-152,804 in wild-type mice. In Y5-/- mice, hippocampal kindling progressed faster, and afterdischarge durations were longer in amygdala, but not in hippocampus, as compared to wild-type controls. Taken together, these data suggest that, in mice, both Y2 and Y5 receptors regulate hippocampal seizures in vitro, while activation of Y5 receptors in extra-hippocampal regions reduces generalized seizures in vivo.

Topics: Animals; Cells, Cultured; Convulsants; Cyclohexanes; Disease Models, Animal; Epilepsy; Epilepsy, Temporal Lobe; Excitatory Amino Acid Agonists; Female; Gene Expression Regulation; Genetic Predisposition to Disease; Hippocampus; Kainic Acid; Male; Mice; Mice, Inbred BALB C; Mice, Knockout; Neurons; Neuropeptide Y; Organ Culture Techniques; Receptors, Neuropeptide Y; Synaptic Transmission; Xanthenes

Neuropeptide Y (NPY) inhibits seizures in experimental models and reduces excitability in human epileptic tissue. We studied the effect of long-lasting NPY overexpression in the rat hippocampus with local application of recombinant adeno-associated viral (AAV) vectors on acute kainate seizures and kindling epileptogenesis. Transgene expression was significantly increased by 7 d, reached maximal expression by 2 weeks, and persisted for at least 3 months. Serotype 2 AAV vector increased NPY expression in hilar interneurons, whereas the chimeric serotype 1/2 vector caused far more widespread expression, also including mossy fibers, pyramidal cells, and the subiculum. EEG seizures induced by intrahippocampal kainate were reduced by 50-75%, depending on the vector serotype, and seizure onset was markedly delayed. In rats injected with the chimeric serotype 1/2 vector, status epilepticus was abolished, and kindling acquisition was significantly delayed. Thus, targeted NPY gene transfer provides a potential therapeutic principle for the treatment of drug-resistant partial epilepsies.

Topics: Animals; Dependovirus; Disease Models, Animal; Electroencephalography; Epilepsy; Gene Expression; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Hippocampus; Injections, Intraventricular; Kainic Acid; Kindling, Neurologic; Male; Neuropeptide Y; Rats; Rats, Sprague-Dawley; Seizures; Treatment Outcome

Neuropeptide Y (NPY) and galanin are neuropeptides that are regulated by energy states and are also anticonvulsant. We tested the hypothesis that the anticonvulsant efficacy of the ketogenic diet (KD) is mediated by increased expression of NPY and galanin via alterations in food intake and energy metabolism. In situ hybridization revealed no effect of the KD on NPY or galanin mRNA expression, suggesting that increased expression of NPY and galanin do not contribute to the anticonvulsant effect of the KD.

Topics: 3-Hydroxybutyric Acid; Animals; Brain Chemistry; Eating; Energy Metabolism; Epilepsy; Galanin; In Situ Hybridization; Ketones; Mice; Mice, Inbred C57BL; Neuropeptide Y; RNA, Messenger; Seizures

In adult diabetic patients, periods of hyperglycemia may be associated with exacerbation of focal seizures. Our objective was to determine in the adult rats the correlation between seizure susceptibility and extracellular glucose concentration in two models of seizures. Male rats were injected with two doses of streptozocin (40 mg/kg IP) on 2 consecutive days to induce diabetic hyperglycemia. Controls either received vehicle or were not injected. After 2 weeks, blood glucose concentration was measured, and the rats were subjected to flurothyl seizure test. Another group of rats received glucose solution (20%, 5 ml IP) 30 minutes before testing to induce nondiabetic hyperglycemia. Thresholds for flurothyl-induced clonic and tonic-clonic seizures were determined. Finally, in vitro epileptiform activity was induced in the entorhinal cortex-hippocampal slices from naive rats by perfusing with magnesium-free medium with various glucose concentrations. In additional slices, paired-pulse paradigm was determined in the perforant path. Susceptibility to clonic and tonic-clonic flurothyl-induced seizures positively correlated with blood glucose concentrations as the increased glucose concentration was associated with proconvulsant effects. Similarly, in the in vitro experiments, epileptiform activity was promoted by increased and suppressed by decreased glucose concentrations. Data indicate that, in the adult rats, high glucose concentrations are associated with proconvulsant effects.

Topics: Age Factors; Animals; Blood Glucose; Convulsants; Diabetes Mellitus, Experimental; Disease Susceptibility; Epilepsy; Extracellular Space; Flurothyl; Glucose; Hippocampus; Hyperglycemia; Male; Neuropeptide Y; Rats; Rats, Sprague-Dawley; Synaptic Transmission

The anticonvulsant effect of NPY may depend on Y(2) and/or Y(5) receptor-mediated inhibition of glutamate release in critical areas, such as the hippocampus. However, Y(2) and Y(5) receptor levels have been reported to increase and decrease, respectively, in the epileptic hippocampus, implicating that the profile of NPY effects may change accordingly. The aim of this study was to evaluate the differential effects of NPY on glutamate release in the normal and in the epileptic hippocampus. Thus, we pharmacologically characterized the effects of NPY on the release of [(3)H]D-aspartate, a valid marker of endogenous glutamate, from synaptosomes prepared from the whole hippocampus and from the three hippocampal subregions (dentate gyrus and CA1 and CA3 subfields) of control and kindled rats, killed 1 week after the last stimulus-evoked seizure. In the whole hippocampus, NPY does not significantly affect stimulus-evoked [(3)H]D-aspartate overflow. In synaptosomes prepared from control rats, NPY significantly inhibited 15 mM K(+)-evoked [(3)H]D-aspartate overflow only in the CA1 subfield (approx. -30%). Both Y(2) and Y(5) receptor antagonists (respectively, 1 microM BIIE0246 and 1 microM CGP71683A) prevented this effect, suggesting the involvement of both receptor types. In contrast, in synaptosomes prepared from kindled rats NPY significantly inhibited 15 mM K(+)-evoked [(3)H]D-aspartate overflow in the CA1 subfield and in the dentate gyrus (approx. -30%). Only the Y(2) (not the Y(5)) antagonist prevented these effects. These data indicate a critical role for the Y(2) receptor in the inhibitory control of glutamate release in the kindled hippocampus and, thus, suggest that the anticonvulsant effect of NPY in the epileptic brain is most likely Y(2), but not Y(5), receptor-mediated.

Topics: Animals; D-Aspartic Acid; Disease Models, Animal; Epilepsy; Hippocampus; Kindling, Neurologic; Male; Neuropeptide Y; Rats; Rats, Sprague-Dawley; Tritium

The rodent pilocarpine model of epilepsy exhibits hippocampal sclerosis and spontaneous seizures and thus resembles human temporal lobe epilepsy. Use of the many available mouse mutants to study this epilepsy model would benefit from a detailed neuropathology study. To identify new features of epileptogenesis, we characterized glial and neuronal pathologies after pilocarpine-induced status epilepticus (SE) in CF1 and C57BL/6 mice focusing on the hippocampus. All CF1 mice showed spontaneous seizures by 17-27 days after SE. By 6 h there was virtually complete loss of hilar neurons, but the extent of pyramidal cell death varied considerably among mice. In the mossy fiber pathway, neuropeptide Y (NPY) was persistently upregulated beginning 1 day after SE; NPY immunoreactivity in the supragranular layer after 31 days indicated mossy fiber sprouting. beta2 microglobulin-positive activated microglia, normally absent in brains without SE, became abundant over 3-31 days in regions of neuronal loss, including the hippocampus and the amygdala. Astrogliosis developed after 10 days in damaged areas. Amyloid precursor protein immunoreactivity in the thalamus at 10 days suggested delayed axonal degeneration. The mortality after pilocarpine injection was very high in C57BL/6 mice from Jackson Laboratories but not those from Charles River, suggesting that mutant mice in the C57BL/6(JAX) strain will be difficult to study in the pilocarpine model, although their neuropathology was similar to CF1 mice. Major neuropathological changes not previously studied in the rodent pilocarpine model include widespread microglial activation, delayed thalamic axonal death, and persistent NPY upregulation in mossy fibers, together revealing extensive and persistent glial as well as neuronal pathology.

Topics: Amyloid beta-Protein Precursor; Animals; Axons; Behavior, Animal; Cell Death; Disease Models, Animal; Disease Progression; Epilepsy; Gliosis; Hippocampus; Mice; Mice, Inbred C57BL; Neuroglia; Neurons; Neuropeptide Y; Pilocarpine; Species Specificity; Survival Rate

Chronic intrahippocampal infusion of the neurotrophin brain-derived neurotrophic factor (BDNF) has been shown to delay kindling epileptogenesis in the rat and several lines of evidence suggest that neuropeptide Y could mediate these inhibitory effects. Chronic infusion of BDNF leads to a sustained overexpression of neuropeptide Y in the hippocampus, which follows a time course similar to that of the suppressive effects of BDNF on kindling. In vivo, acute applications of neuropeptide Y or agonists of its receptors exert anticonvulsant properties, especially on seizures of hippocampal origin. In this study, we examined how chronic infusion of this neuropeptide in the hippocampus affected kindling epileptogenesis. A 7-day continuous infusion of neuropeptide Y in the hippocampus delayed the progression of hippocampal kindling in the rat, whereas anti-neuropeptide Y immunoglobulins had an aggravating effect. These results show that neuropeptide Y exerts anti-epileptogenic properties on seizures originating within the hippocampus and lend support to the hypothesis that BDNF delays kindling at least in part through upregulation of this neuropeptide. They also suggest that the seizure-induced upregulation of neuropeptide Y constitutes an endogenous mechanism counteracting excessive hippocampal excitability.

Topics: Animals; Antibodies; Brain-Derived Neurotrophic Factor; Disease Models, Animal; Epilepsy; Hippocampus; Kindling, Neurologic; Male; Neurons; Neuropeptide Y; Rats; Rats, Wistar; Reaction Time; Synaptic Transmission; Up-Regulation

Previous studies show that neuropeptide Y (NPY) inhibits in vitro seizures in rodent hippocampus. Here, we explored the effect of NPY application on epileptiform discharges induced by perfusion with magnesium-free solution in slices of entorhinal cortex from two different mouse strains. NPY significantly reduced the duration of epileptiform discharges with a peak effect of 36-50%. This is the first study showing anti-epileptiform effect of NPY in the entorhinal cortex and also the first evidence that NPY inhibits seizures in a cortical region in mice. The entorhinal cortex has a central role in transferring information between the hippocampus and the rest of the brain. Therefore our data further strengthen the concept of NPY and its receptors as widespread regulators of epileptiform activity and as a potential future target for antiepileptic therapy.

Topics: Action Potentials; Animals; Anticonvulsants; Culture Media; Entorhinal Cortex; Epilepsy; Magnesium Deficiency; Male; Mice; Neuropeptide Y; Organ Culture Techniques; Patch-Clamp Techniques

Neuronal migration disorders (NMDs) can be associated with neurological dysfunction such as mental retardation, and clusters of disorganized cells (heterotopias) often act as seizure foci in medically intractable partial epilepsies. Methylazoxymethanol (MAM) treatment of pregnant rats results in neuronal heterotopias in offspring, especially in hippocampal area CA1. Although the neurons in dysplastic areas in this model are frequently hyperexcitable, the precise mechanisms controlling excitability remain unclear. Here, we used IR-DIC videomicroscopy and whole cell voltage-clamp techniques to test whether the potent anti-excitatory actions of neuropeptide Y (NPY) affected synaptic excitation of heterotopic neurons. We also compared several synaptic and intrinsic properties of heterotopic, layer 2-3 cortical, and CA1 pyramidal neurons, to further characterize heterotopic cells. NPY powerfully inhibited synaptic excitation onto normal and normotopic CA1 cells but was nearly ineffective on responses evoked in heterotopic cells from stimulation sites within the heterotopia. Glutamatergic synaptic responses on heterotopic cells exhibited a comparatively small, D-2-amino-5-phosphopentanoic acid-sensitive, N-methyl-D-aspartate component. Heterotopic neurons also differed from normal CA1 cells in postsynaptic membrane currents, possessing a prominent inwardly rectifying K(+) current sensitive to Cs(+) and Ba(2+), similar to neocortical layer 2-3 pyramidal cells. CA1 cells instead had a prominent Cs(+)- and 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyrimidinium chloride-sensitive I(h) and negligible inward rectification, unlike heterotopic cells. Thus heterotopic CA1 cells appear to share numerous physiological similarities with neocortical neurons. The lack of NPY's effects on intra-heterotopic inputs, the small contribution of I(h), and abnormal glutamate receptor function, may all contribute to the lowered threshold for epileptiform activity observed in hippocampal heterotopias and could be important factors in epilepsies associated with NMDs.

Topics: Abnormalities, Drug-Induced; Animals; Electrophysiology; Epilepsy; Excitatory Postsynaptic Potentials; Female; Hippocampus; Histocytochemistry; Membrane Potentials; Methylazoxymethanol Acetate; Neocortex; Neuropeptide Y; Potassium Channel Blockers; Potassium Channels; Pregnancy; Pyramidal Cells; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Synaptic Membranes; Teratogens

The anti-convulsive effects of neuropeptide Y have been suggested in several animal models of epilepsy. We have found the sustained increase of neuropeptide Y contents and the seizure-induced elevation of hippocampal messenger RNA in a novel spontaneous epileptic mutant rat: Noda epileptic rat. In the present study, we investigated the change of neuropeptide Y Y1 and Y2 receptor messenger RNA expressions and binding sites in the hippocampus following a spontaneous generalized tonic-clonic seizure of Noda epileptic rat. Furthermore, the binding sites of a more recently isolated receptor subtype, neuropeptide Y Y5 receptors, were also evaluated by receptor autoradiography. A marked elevation of neuropeptide Y immunoreactivity in the mossy fiber, and Y2-receptor up-regulation in the dentate gyrus were observed in the hippocampus of Noda epileptic rat, which coincided with the previous results of the other epileptic models. In contrast, Y1-receptor down-regulation was not found after a spontaneous seizure of Noda epileptic rat while this occurs in kindling and after kainic acid-induced seizures. [125I][Leu31, Pro34]peptide YY/BIBP 3226-insensitive (Y5 receptor) binding sites in CA1 stratum radiatum were significantly decreased following a spontaneous seizure of Noda epileptic rat. The present results suggest that a spontaneous seizure of Noda epileptic rat induces significant changes in neuropeptide Y-mediated transmission in the hippocampus via Y2 and Y5 receptors, but not Y1 receptors. Therefore, specific subset of neuropeptide Y receptor subtypes might be involved in the epileptogenesis of Noda epileptic rat.

Topics: Animals; Dentate Gyrus; Disease Models, Animal; Epilepsy; Gene Expression Regulation; Hippocampus; Immunohistochemistry; Iodine Radioisotopes; Male; Mossy Fibers, Hippocampal; Neurons; Neuropeptide Y; Peptide Fragments; Pyramidal Cells; Rats; Rats, Mutant Strains; Receptors, Neuropeptide Y; RNA, Messenger

Previous insult, for example, sustained epileptic seizures, confers a substantial temporary protection against the cellular damage induced by subsequent epileptic challenge. Here we describe a useful model of this so-called 'epileptic tolerance'. Expression of a status epilepticus was triggered by infusing the excitotoxic agent, kainate, into the right hippocampus of adult rats. An appropriate dose of kainate was used to cause brain damage in the homolateral, but not contralateral, hippocampus. At various times following this preconditioning insult, kainate was then re-administered into the lateral ventricle and neuroprotection was observed in the contralateral side between 1 and 15 days later. This model can be used to investigate the mechanisms of this endogenous neuroprotection. It is also particularly suitable for studying the epileptic susceptibility, as reflected by the modifications of the after-discharge threshold, as well as any changes in gene expression induced associated with the preconditioning episode.

Topics: Animals; Cell Death; Cell Survival; Disease Models, Animal; Epilepsy; Excitatory Amino Acid Agonists; Gene Expression Regulation; Hippocampus; Ischemic Preconditioning; Kainic Acid; Male; Neuronal Plasticity; Neuropeptide Y; Pyramidal Cells; Rats; Rats, Wistar; Status Epilepticus

Brain derived neurotrophic factor (BDNF) has been suggested to be involved in epileptogenesis. Both pro- and antiepileptogenic effects have been reported, but the exact physiological role is still unclear. Here, we investigated the role of endogenous BDNF in epileptogenesis by using transgenic mice overexpressing truncated trkB, a dominant negative receptor of BDNF. After induction of status epilepticus (SE) by kainic acid, the development of spontaneous seizures was monitored by video-EEG system. Hilar cell loss, and the number of neuropeptide Y immunoreactive cells were studied as markers of cellular damage, and mossy fibre sprouting was investigated as a plasticity marker. Our results show that transgenic mice had significantly less frequent interictal spiking than wild-type mice, and the frequency of spontaneous seizures was lower. Furthermore, compared to wild-type animals, transgenic mice had less severe seizures with later onset and mortality was lower. In contrast, no differences between genotypes were observed in any of the cellular or plasticity markers. Our results suggest that transgenic mice with decreased BDNF signalling have reduced epileptogenesis.

Topics: Action Potentials; Animals; Brain-Derived Neurotrophic Factor; Dentate Gyrus; Down-Regulation; Epilepsy; Epilepsy, Temporal Lobe; Excitatory Amino Acid Agonists; Female; Growth Cones; Male; Mice; Mice, Transgenic; Mossy Fibers, Hippocampal; Nerve Degeneration; Neuronal Plasticity; Neuropeptide Y; Receptor, trkB; Signal Transduction

Functional studies in epileptic tissue indicate that neuropeptide Y and some of its peptide analogs potently inhibit seizure activity. We investigated seizure susceptibility in transgenic rats overexpressing the rat neuropeptide Y gene under the control of its natural promoter. Seizures were induced in adult transgenic male rats and their wild-type littermates by i.c.v. injection of 0.3 microg kainic acid or by electrical kindling of the dorsal hippocampus. Transgenic rats showed a significant reduction in the number and duration of electroencephalographic seizures induced by kainate by 30% and 55% respectively (P<0.05 and 0.01). Transgenic rats were also less susceptible to epileptogenesis than wild-type littermates as demonstrated by a 65% increase in the number of electrical stimuli required to induce stage 5 seizures (P<0.01). This phenotype was associated with a strong and specific expression of neuropeptide Y mRNA in area CA1, a brain area involved in the seizure network. We conclude that endogenous neuropeptide Y overexpression in the rat hippocampus is associated with inhibition of seizures and epileptogenesis suggesting that this system may be a valuable target for developing novel antiepileptic treatments.

Topics: Animals; Animals, Genetically Modified; Electric Stimulation; Electroencephalography; Epilepsy; Epilepsy, Temporal Lobe; Excitatory Amino Acid Agonists; Gene Expression Regulation; Genetic Predisposition to Disease; Hippocampus; Kindling, Neurologic; Male; Neurons; Neuropeptide Y; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; RNA, Messenger; Up-Regulation

Neuropeptide Y (NPY) has been shown to suppress synaptic excitation in rat hippocampus by a presynaptic action. The Y(2) (Y(2)R) and the Y(5) (Y(5)R) receptors have both been implicated in this action. We used the non-peptide, Y(2)R-selective antagonist, BIIE0246, to test the hypothesis that the Y(2)R mediates both the presynaptic inhibitory and anti-epileptic actions of NPY in rat hippocampus in vitro. NPY and the Y(2)R-selective agonist, [ahx(5-24)]NPY, both inhibited the population excitatory postsynaptic potential (pEPSP) evoked in area CA1 by stratum radiatum stimulation in a concentration-dependent manner. BIIE0246 suppressed the inhibitory effects of both agonists, suppressing the maximal inhibition without causing a change in the agonist EC(50), in a manner inconsistent with competitive antagonism. BIIE0246 washed out from hippocampal slices extremely slowly. Application of agonist at high concentrations (1 - 3 microM) for prolonged periods did not alter the rate of washout, but did partially overcome the antagonism, inconsistent with an insurmountable antagonism by BIIE0246. In the stimulus train-induced bursting (STIB) model of ictal activity in hippocampal slices, both NPY and [ahx(5-24)]NPY inhibited primary afterdischarge (1 degrees AD) activity. BIIE0246 (100 nM) completely suppressed the actions of NPY and [ahx(5-24)]NPY in this model. In contrast, the potent Y(5)R-selective agonist, Ala(31)Aib(32)NPY, affected neither 1 degrees AD activity in the presence of BIIE0246, nor, by itself, even the pEPSP in CA1. BIIE0246 potently suppresses NPY actions in rat hippocampus, suggesting a dominant role for Y(2)R there. The apparently insurmountable antagonism observed may result from the lipophilic nature of the antagonist.

Topics: Animals; Arginine; Benzazepines; Dose-Response Relationship, Drug; Electric Stimulation; Epilepsy; Excitatory Postsynaptic Potentials; Hippocampus; In Vitro Techniques; Male; Neuropeptide Y; Patch-Clamp Techniques; Rats; Rats, Sprague-Dawley; Receptors, Neuropeptide Y; Synaptic Transmission

Prior epileptic episodes have been shown to decrease markedly the neuronal damage induced by a second epileptic episode, similar to the tolerance following an episode of mild ischemia. Endogenous neuroprotective effects mediated by various mechanisms have been put forward. This study investigated whether neuroprotection against the excitotoxic damage induced by re-exposure to an epileptic challenge can reflect a change in epileptic susceptibility. Tolerance was elicited in rats by a preconditioning session using intrahippocampal kainic acid (KA) administration followed at 1, 7 and 15-day intervals by a subsequent intraventricular KA injection. The degree of pyramidal cell loss in the vulnerable CA3 subfield contralateral to the KA-injected hippocampus was extensively reduced in animals experiencing KA ventricular administration. This neuroprotection was highly significant 1 and 7 days after injection, but not 15 days after injection. In preconditioned animals, the after-discharge threshold was assessed as an index of epileptic susceptibility. It increased significantly from 1 to 15 days after intrahippocampal KA administration. Finally, an enhancement of neuropeptide Y expression in both non-principal cells and mossy fibers was detected, occurring at the same time as the decrease in epileptic susceptibility. These results provide further evidence of an 'epileptic tolerance' as shown by the substantial neuroprotective effect of a prior episode of epileptic activity upon subsequent epileptic insult and suggest that the prevention of excitotoxic damage after preconditioning results from an endogenous neuroprotective mechanism against hyperexcitability and seizures.

Topics: Adaptation, Physiological; Animals; Behavior, Animal; Cell Death; Disease Models, Animal; Disease Susceptibility; Epilepsy; Excitatory Amino Acid Agonists; Hippocampus; Immunohistochemistry; Kainic Acid; Male; Nerve Degeneration; Neuropeptide Y; Neurotoxins; Pyramidal Cells; Rats; Rats, Wistar

Intracerebroventricular injection of NPY inhibits epileptiform seizures and seizure-related "wet dog shakes" (WDS) following electrical stimulation of the dentate gyrus or subiculum. This study examined the effects of NPY on seizures and WDS elicited in hippocampal CA3. Like in the other hippocampal regions, NPY significantly inhibited both seizures and accompanying WDS consistent with in vitro data. The identification of an additional antiepileptic hippocampal target for NPY could prove therapeutically relevant considering that the hippocampal formation is a frequent seizure focus in human epilepsy. The effects of NPY were found to persist on seven repeated NPY injection days. Thus tolerance to the anti-seizure effects of NPY does not appear to develop rapidly. Tolerance being a problem with several current antiepileptic drugs, this further strengthens the concept of NPY receptors as a potential future antiepileptic target.

Topics: Animals; Anticonvulsants; Dentate Gyrus; Epilepsy; Hippocampus; Male; Neuropeptide Y; Rats; Rats, Wistar; Seizures; Time Factors

In vitro and in vivo experiments suggest antiepileptic properties for NPY. In this study, the pharmacology of these effects was examined and compared in different rat models of seizures. Agonists for Y(1), Y(2) and Y(5) receptors reduced seizure-like activity in hippocampal cultures. Intracerebral injection of NPY or Y(5) agonists reduced the expression of focal seizures produced by a single electrical stimulation of the hippocampus. Conversely, NPY agonists increased the duration of generalized convulsive seizures induced by pentylenetetrazol. These results suggest that NPY reduces seizures of hippocampal origin through activation of Y(5) receptors. They also point to probable modulatory effects of NPY in brain structures other than the hippocampus, involved in initiation, propagation or control of seizures.

Topics: Animals; Anticonvulsants; Cells, Cultured; Epilepsy; Hippocampus; Male; Neuropeptide Y; Pentylenetetrazole; Rats; Rats, Wistar; Receptors, Neuropeptide Y; Seizures; Time Factors

Neuropeptide Y (NPY) potently inhibits excitatory synaptic transmission in the hippocampus, acting predominantly via a presynaptic Y(2) receptor. Recent reports that the Y(5) receptor may mediate the anticonvulsant actions of NPY in vivo prompted us to test the hypothesis that Y(5) receptors inhibit synaptic excitation in the hippocampal slice and, furthermore, that they are effective in an in vitro model of anticonvulsant action. Two putative Y(5) receptor-preferring agonists inhibited excitatory postsynaptic currents (EPSCs) evoked by stimulation of stratum radiatum in pyramidal cells. We recorded initially from area CA1 pyramidal cells, but subsequently switched to cells from the subiculum, where a much greater frequency of response was observed to Y(5) agonist application. Both D-Trp(32)NPY (1 microM) and [ahx(8-20)]Pro(34)NPY (3 microM), a centrally truncated, Y(1)/Y(5) agonist we synthesized, inhibited stimulus-evoked EPSCs in subicular pyramidal cells by 44.0 +/- 5.7% and 51.3 +/- 3.5% (mean +/- SE), in 37 and 58% of cells, respectively. By contrast, the less selective centrally truncated agonist, [ahx(8-20)] NPY (1 microM), was more potent (66.4 +/- 4.1% inhibition) and more widely effective, suppressing the EPSC in 86% of subicular neurons. The site of action of all NPY agonists tested was most probably presynaptic, because agonist application caused no changes in postsynaptic membrane properties. The selective Y(1) antagonist, BIBP3226 (1 microM), did not reduce the effect of either more selective agonist, indicating that they activated presynaptic Y(5) receptors. Y(5) receptor-mediated synaptic inhibition was more frequently observed in slices from younger animals, whereas the nonselective agonist appeared equally effective at all ages tested. Because of the similarity with the previously reported actions of Y(2) receptors, we tested the ability of Y(5) receptor agonists to suppress stimulus train-induced bursting (STIB), an in vitro model of ictaform activity, in both area CA3 and the subiculum. Neither [ahx(8-20)]Pro(34)NPY nor D-Trp(32)NPY were significantly effective in suppressing or shortening STIB-induced afterdischarge, with <20% of slices responding to these agonists in recordings from CA3 and none in subiculum. By contrast, 1 microM each of [ahx(8-20)]NPY, the Y(2) agonist, [ahx(5-24)]NPY, and particularly NPY itself suppressed the afterdischarge in area CA3 and the subiculum, as reported earlier. We conclude that Y(5) receptors appea

Topics: Action Potentials; Animals; Anti-Anxiety Agents; Arginine; Binding, Competitive; Epilepsy; Excitatory Postsynaptic Potentials; Hippocampus; In Vitro Techniques; Male; Neuropeptide Y; Patch-Clamp Techniques; Peptides, Cyclic; Rats; Rats, Sprague-Dawley; Receptors, Neuropeptide Y; Synapses

Male Sprague-Dawley rats received a daily injection of 60 mg/kg of lidocaine (> 30 days). Twenty percent of rats developed convulsions (kindled rats) and remaining rats did not show convulsions (non-kindled rats). The level of immunoreactive somatostatin (IR-SRIF) in kindled rats was significantly increased in amygdala than that in non-kindled rats and control rats. Immunoreactive neuropeptide Y (IR-NPY) contents in kindled rats were significantly increased in amygdala, hippocampus, cortex and striatum compared to non-kindled and control rats. The expression of SRIF mRNA in kindled rats produced a significant increase in amygdala, while NPY mRNA in kindled rats showed an elevated expression in both amygdala and hippocampus. These results coincide with the previous findings with the elevated expression of SRIF and NPY mRNA in electrically and pharmacologically kindled models, suggesting the important role of these peptides in the kindling phenomenon.

Topics: Amygdala; Animals; Anti-Arrhythmia Agents; Cerebral Cortex; Corpus Striatum; Epilepsy; Gene Expression; Hippocampus; Iodine Radioisotopes; Kindling, Neurologic; Lidocaine; Male; Neuropeptide Y; Protein Precursors; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Somatostatin

Brain-derived neurotrophic factor (BDNF) plays an important role in hippocampal neuroplasticity. In particular, BDNF upregulation in the hippocampus by epileptic seizures suggests its involvement in the neuronal rearrangements accompanying epileptogenesis. We have shown previously that chronic infusion of BDNF in the hippocampus induces a long-term delay in hippocampal kindling progression. Although BDNF has been shown to enhance the excitability of this structure upon acute application, long-term transcriptional regulations leading to increased inhibition within the hippocampus may account for its suppressive effects on epileptogenesis. Therefore, the long-term consequences of a 7-day chronic intrahippocampal infusion of BDNF (12 microg/day) were investigated up to 2 weeks after the end of the infusion, on the expression of neurotransmitters contained in inhibitory hippocampal interneurons and which display anti-epileptic properties. Our results show that BDNF does not modify levels of immunostaining for glutamic acid decarboxylase, the rate-limiting enzyme for gamma-aminobutyric acid (GABA) synthesis, and somatostatin. Conversely, BDNF induces a long-lasting increase of neuropeptide Y (NPY) in the hippocampus, measured by immunohistochemistry and radioimmunoassay, outlasting the end of the infusion by at least 7 days. The distribution of BDNF-induced neuropeptide Y immunoreactivity is similar to the pattern observed in animals submitted to hippocampal kindling, with the exception of mossy fibres which only become immunoreactive following seizure activity. The enduring increase of neuropeptide Y expression induced by BDNF in the hippocampus suggests that this neurotrophin can trigger long-term genomic effects, which may contribute to the neuroplasticity of this structure, in particular during epileptogenesis.

Topics: Animals; Brain-Derived Neurotrophic Factor; Epilepsy; Gene Expression Regulation; Hippocampus; Interneurons; Kindling, Neurologic; Male; Nerve Tissue Proteins; Neuronal Plasticity; Neuropeptide Y; Rats; Rats, Wistar; Time Factors

Neuropeptide Y reduced spontaneous and stimulation-evoked epileptiform discharges in rat frontal cortex slices perfused with a magnesium-free solution and with the GABA(A) receptor antagonist picrotoxin. To investigate the mechanism of that action, effects of neuropeptide Y on intrinsic membrane properties and synaptic responses of layer II/III cortical neurons were studied using intracellular recording. Neuropeptide Y (1 microM) had no detectable effect on the membrane properties of neurons. The evoked synaptic potentials were attenuated by neuropeptide Y. Moreover, the pharmacologically isolated excitatory postsynaptic potentials, mediated by N-methyl-D-aspartate and non-N-methyl-D-aspartate receptors, were reversibly depressed by neuropeptide Y. The most pronounced inhibitory effect of neuropeptide Y was observed on late polysynaptic excitatory postsynaptic potentials. To assess a putative postsynaptic action of neuropeptide Y, N-methyl-D-aspartate was locally applied in the presence of tetrodotoxin. The N-methyl-D-aspartate-evoked depolarizations were unaffected by neuropeptide Y, which suggests that the depression of excitatory postsynaptic potentials was due to an action at sites presynaptic to the recorded neurons. These data show that neuropeptide Y attenuates epileptiform discharges and the glutamate receptor-mediated synaptic transmission in the rat frontal cortex. The above results indicate that neuropeptide Y may regulate neuronal excitability within the cortex, and that neuropeptide Y receptors are potential targets for an anticonvulsant therapy.

Topics: Animals; Electrophysiology; Epilepsy; Excitatory Postsynaptic Potentials; Frontal Lobe; Male; Neurons; Neuropeptide Y; Rats; Rats, Wistar; Synaptic Transmission

By in situ hybridization and immunocytochemistry, expression of neuropeptide Y (NPY), somatostatin and glutamate decarboxylase 65 (GAD65) was studied in the hippocampus of two different epileptic mutant rats, Ihara's epileptic rat (IER) and the spontaneously epileptic rat (SER). GAD65 mRNA expression was enhanced in interneurons of the hippocampus in young IER, that had not yet developed generalized seizures. In older IER and older SER that both showed spontaneous seizures, marked increases of NPY mRNA in hippocampal granule cells and interneurons were found, as well as elevated GAD65 mRNA levels in interneurons. NPY immunoreactivity was enhanced in hilar interneurons and the dentate gyrus of older IER. In addition, some older IER stained heavily for NPY in mossy fibers. These findings suggest that up-regulation of NPY and GAD65 synthesis may be important in epileptogenesis.

Topics: Animals; Epilepsy; Female; Gene Expression Regulation, Enzymologic; Glutamate Decarboxylase; Hippocampus; In Situ Hybridization; Male; Neuropeptide Y; Rats; Rats, Mutant Strains; Rats, Wistar; RNA, Messenger; Somatostatin

Repeated electroconvulsive stimulations and other seizure modalities produce an increase in neuropeptide Y synthesis and local release in the rat hippocampus, and perhaps as a consequence, a change in the concentration of neuropeptide Y binding sites in the same region. The aim of the present study was to determine possible changes in the expression of neuropeptide Y receptor subtypes affected by repeated stimulations in the hippocampus. Rats were exposed to 14 daily stimulations, and the brains were removed 24h after the last stimulation. For in vitro receptor autoradiography and in situ hybridisation histochemistry, the brains were frozen, sectioned, and levels of neuropeptide Y binding sites and messenger RNA expressions were determined quantitatively on sections from the same animals. In order to determine the contribution of different neuropeptide Y receptor subtypes, serial sections were incubated with either 125I-labelled peptide YY alone or the same radio-labelled peptide mixed with an excess of a number of displacing compounds with affinity for either neuropeptide Y receptor subtype Y1, Y2, or both. Binding studies revealed that the majority of peptide YY binding sites was represented by Y2, and that electroconvulsive stimulations reduced the binding capacity or the concentration of this receptor. A prominent reduction of Y1-preferring binding sites was determined in the dentate gyrus, and to a lesser extent in the CA1 and CA3 regions. Similarly, the treatment produced a significant reduction of Y2-preferring binding sites in the CA1 and CA3 region, but not in the granular cell layer of the dentate gyrus. Using semi-quantitative in situ hybridization, Y1 receptor messenger RNA level in the granular cell layer of the dentate increased by the stimulations. In the same region, Y2 receptor messenger RNA was expressed in low to undetectable amounts, but after the repeated stimulations, this transcript was found in moderate to high levels. These data suggest that the neuropeptide Yergic system in the dentate gyrus and the pyramidal cell layer are affected by the treatment, and that this includes both Y1 and Y2 receptor subtypes. Because levels of messenger RNA and binding are distinctly regulated, the turnover of both Y1 and Y2 molecules is strongly increased under electroconvulsive stimulations, suggesting that the intrahippocampal neuropeptide Yergic neurotransmission is also increased under the stimulations.

Topics: Animals; Anti-Anxiety Agents; Arginine; Autoradiography; Down-Regulation; Electric Stimulation Therapy; Epilepsy; Gene Expression; Hippocampus; In Situ Hybridization; Iodine Radioisotopes; Male; Neuropeptide Y; Radioligand Assay; Rats; Rats, Wistar; Receptors, Neuropeptide Y; RNA, Messenger; Seizures

Recent studies reported changes in neuropeptide Y (NPY) expression induced by seizures in the experimental epileptic models. However, there have been few reports of the alteration of NPY expression in hippocampal complexes of genetic epilepsy models. In the present study, we performed spatial and temporal analyses of NPY expression in the hippocampal complexes of the seizure-resistant (SR) and seizure-sensitive (SS) gerbils, one of the genetic models. In SR gerbils, most NPY(+) cells were located at the dentate hilus (DH) and the subiculum (SC). In the pre-seizure group of SS gerbils, neurons in the DH and SC were nearly devoid of NPY immunoreactivity. Interestingly, the acute NPY expressions were observed in these areas of the post-seizure group at 30 min, and its immunoreactivity was declined at 12 h after the onset of seizure. These findings suggest that in seizure, the deficiency of NPY in DH and SC may be one of the factors, and that the acute expression of NPY after seizure in these areas may be the compensatory response for reduction of seizure activity in this animal.

Topics: Animals; Dentate Gyrus; Entorhinal Cortex; Epilepsy; Gerbillinae; Hippocampus; Immunohistochemistry; Neuropeptide Y; Seizures

Seizures increase the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus. Because this neurotrophin exerts modulatory effects on hippocampal neuronal excitability, it may play an important role in epileptogenesis initiated in this structure. Moreover BDNF is known to regulate the expression of neuropeptide Y (NPY), which displays modulatory properties on seizure activity. This suggests that the effects of BDNF on epileptogenesis may be mediated by NPY.. Adult male rats received a 7-day chronic intrahippocampal infusion of BDNF, BDNF antisense oligodeoxynucleotides, NPY, or anti-NPY immunoglobulin G during kindling of the hippocampus. The long-term regulation of NPY expression by BDNF was also studied by immunohistochemistry and radioimmunoassay.. BDNF applied during the first week of hippocampal stimulation significantly delayed the progression of kindling, an effect that outlasted the end of the infusion by at least 7 days. Conversely, infusion of BDNF antisense oligodeoxynucleotides to reduce the expression of endogenous BDNF in the hippocampus aggravated the electroencephalographic expression of seizures. Chronic infusion of BDNF increased the expression of NPY in the hippocampus, with a time course similar to that of the protective effect of the neurotrophin on kindling. Finally, chronic infusion of NPY in the hippocampus delayed the progression of hippocampal kindling, whereas anti-NPY antibodies had an aggravating effect.. Our results suggest that the seizure-induced increase in BDNF expression in the hippocampus may constitute an endogenous protective mechanism able to counteract hippocampal epileptogenesis. This protective effect appears to be mediated at least in part through the regulation of NPY expression.

Topics: Animals; Brain-Derived Neurotrophic Factor; Epilepsy; Hippocampus; Immunohistochemistry; Kindling, Neurologic; Male; Neuronal Plasticity; Neuropeptide Y; Radioimmunoassay; Rats

Neuronal heterotopia are seen in various pathologies and are associated with intractable epilepsy. We examined brain tissue from four children with subcortical or periventricular nodular heterotopia of different aetiologies: one with severe epilepsy following focal brain trauma at 17 weeks gestation, one with hemimegalencephaly and intractable epilepsy, one with focal cortical dysplasia and intractable epilepsy, and one dysmorphic term infant with associated hydrocephalus and polymicrogyria. The connectivity of nodules was investigated using histological and carbocyanine dye (DiI) tracing techniques. DiI crystal placement adjacent to heterotopic nodules revealed numerous DiI-labelled fibres within a 2-3 mm radius of the crystals. Although we observed labelled fibres closely surrounding nodules, the majority did not penetrate them. Placement of DiI crystals within nodules also identified a limited number of projections out of the nodules and in one case there was evidence for connectivity between adjacent nodules. The cellular and neurochemical composition of nodules was also examined using immunohistochemistry for calretinin and neuropeptide Y (NPY), which are normally expressed in GABAergic cortical interneurons. Within heterotopic nodules from all cases, numerous calretinin-positive neurons were identified, along with a few cell bodies and many processes positive for NPY. Calretinin-positive neurons within nodules were less morphologically complex than those in the cortex, which may reflect incomplete differentiation into an inhibitory neuronal phenotype. There were also abnormal clusters of calretinin-positive cells in the overlying cortical plate, indicating that the migratory defect which produces heterotopic nodules also affects development of the cortex itself. Thus, heterotopic nodules consisting of multiple neuronal cell types are associated with malformation in the overlying cortical plate, and have limited connectivity with other brain regions. This abnormal development of connectivity may affect neuronal maturation and consequently the balance of excitation and inhibition in neuronal circuits, leading to their epileptogenic potential.

Topics: Brain Chemistry; Calbindin 2; Carbocyanines; Cell Size; Cerebral Cortex; Child; Choristoma; Epilepsy; Fatal Outcome; Female; Fluorescent Antibody Technique; Fluorescent Dyes; gamma-Aminobutyric Acid; Humans; Infant, Newborn; Interneurons; Magnetic Resonance Imaging; Male; Neuropeptide Y; S100 Calcium Binding Protein G

Seizures increase the synthesis of brain-derived neurotrophic factor in forebrain areas, suggesting this neurotrophin has biological actions in epileptic tissue. The understanding of these actions requires information on the sites and extent of brain-derived neurotrophic factor production in areas involved in seizures onset and their spread. In this study, we investigated by immunocytochemistry the changes in brain-derived neurotrophic factor in the hippocampus, entorhinal and perirhinal cortices of rats at increasing times after acute seizures eventually leading to spontaneous convulsions. We also tested the hypothesis that seizure-induced changes in brain-derived neurotrophic factor induce later modifications in neuropeptide Y expression by comparing, in each instance, their immunoreactive patterns. As early as 100 min after seizure induction, brain-derived neurotrophic factor immunoreactivity increased in CA1 pyramidal and granule neurons and in cells of layers II-III of the entorhinal cortex. At later times, immunoreactivity progressively decreased in somata while increasing in fibres in the hippocampus, the subicular complex and in specific layers of the entorhinal and perirhinal cortices. Changes in neuropeptide Y immunoreactivity were superimposed upon and closely followed those of brain-derived neurotrophic factor. One week after seizure induction, brain-derived neurotrophic factor and neuropeptide Y immunoreactivities were similar to controls in 50% of rats. In rats experiencing spontaneous convulsions, brain-derived neurotrophic factor and neuropeptide Y immunoreactivity was strongly enhanced in fibres in the hippocampus/parahippocampal gyrus and in the temporal cortex. In the dentate gyrus, changes in immunoreactivity depended on sprouting of mossy fibres as assessed by growth-associated protein-43-immunoreactivity. These modifications were inhibited by repeated anticonvulsant treatment with phenobarbital. The dynamic and temporally-linked alterations in brain-derived neurotrophic factor and neuropeptide Y in brain regions critically involved in epileptogenesis suggest a functional link between these two substances in the regulation of network excitability.

Topics: Acute Disease; Animals; Anticonvulsants; Brain; Brain-Derived Neurotrophic Factor; Colchicine; Electroencephalography; Epilepsy; Immunohistochemistry; Limbic System; Male; Neuropeptide Y; Phenobarbital; Rats; Rats, Sprague-Dawley; Status Epilepticus; Time Factors

Noda epileptic rat (NER) is a new epileptic rat strain, which was developed by inbreeding rats with spontaneous tonic-clonic seizures in a stock of Crj:Wistar. In the present study, possible changes of two neuropeptides, neuropeptide Y (NPY) and corticotropin-releasing factor (CRF), in the brains of NER were investigated. Increased contents of immunoreactive (IR) NPY were found in the striatum and amygdala of 8-week NERs with partial seizure, while these changes extended to the limbic region including hippocampus in 16-week NERs with fully developed generalized tonic-clonic seizure. IR-CRF were elevated only in the entorhinal and pyriform cortex of both 8-week and 16-week NERs. Generalized tonic-clonic seizure in NERs induced a transient increase of NPY mRNA in the granular layer of dentate gyrus. These results suggest that NPY metabolism in the limbic brain contributes to the seizure susceptibility in this model of epilepsy.

Topics: Animals; Brain Chemistry; Corpus Striatum; Corticotropin-Releasing Hormone; DNA Probes; Entorhinal Cortex; Epilepsy; Hippocampus; Hypothalamus; In Situ Hybridization; Male; Neuropeptide Y; Protein Precursors; Radioimmunoassay; Rats; Rats, Mutant Strains; RNA, Messenger

This study examined the acute actions of brain-derived neurotrophic factor (BDNF) in the rat dentate gyrus after seizures, because previous studies have shown that BDNF has acute effects on dentate granule cell synaptic transmission, and other studies have demonstrated that BDNF expression increases in granule cells after seizures. Pilocarpine-treated rats were studied because they not only have seizures and increased BDNF expression in granule cells, but they also have reorganization of granule cell "mossy fiber" axons. This reorganization, referred to as "sprouting," involves collaterals that grow into novel areas, i.e., the inner molecular layer, where granule cell and interneuron dendrites are located. Thus, this animal model allowed us to address the effects of BDNF in the dentate gyrus after seizures, as well as the actions of BDNF on mossy fiber transmission after reorganization. In slices with sprouting, BDNF bath application enhanced responses recorded in the inner molecular layer to mossy fiber stimulation. Spontaneous bursts of granule cells occurred, and these were apparently generated at the site of the sprouted axon plexus. These effects were not accompanied by major changes in perforant path-evoked responses or paired-pulse inhibition, occurred only after prolonged (30-60 min) exposure to BDNF, and were blocked by K252a. The results suggest a preferential action of BDNF at mossy fiber synapses, even after substantial changes in the dentate gyrus network. Moreover, the results suggest that activation of trkB receptors could contribute to the hyperexcitability observed in animals with sprouting. Because human granule cells also express increased BDNF mRNA after seizures, and sprouting can occur in temporal lobe epileptics, the results may have implications for understanding temporal lobe epilepsy.

Topics: Action Potentials; Animals; Brain-Derived Neurotrophic Factor; Cell Size; Epilepsy; Excitatory Postsynaptic Potentials; GABA Antagonists; In Vitro Techniques; Male; Mossy Fibers, Hippocampal; Neuropeptide Y; Pilocarpine; Rats; Rats, Sprague-Dawley; Receptor Protein-Tyrosine Kinases; Receptor, Ciliary Neurotrophic Factor; Receptors, GABA; Receptors, N-Methyl-D-Aspartate; Receptors, Nerve Growth Factor; Seizures; Status Epilepticus; Synapses; Synaptic Transmission

Changes occurring in neuropeptide-Y immunoreactivity after kainic acid injection in rats and their possible consequences on seizure-brain damage were studied.. First, an intra-hippocampal kainic acid injection was performed (n = 7), inducing an ectopic and bilateral neuropeptide-Y immunoreactivity in mossy fibers. On the side of the injection, this neuropeptide-Y staining was associated with dramatic neuronal loss whereas, in the contralateral hippocampus staining was observed without associated neuronal loss. The CA3 a-b pyramidal cell loss induced by an intra-ventricular kainic acid injection was then compared between a control group (n = 6) and a pre-conditioned group (n = 6) characterized by neuropeptide-Y staining in the mossy fibers obtained by a previous contralateral intra-hippocampal kainic acid injection as described.. In the pre-conditioned group, the CA3 a-b pyramidal cell loss was significantly lower (m = 33.5%) than in the control group (m = 86.6%). The neuropeptide-Y inhibiting the pre-synaptic release of glutamate, glutamate-related epileptic-brain damage could be reduced when neuropeptide-Y is expressed by granulated cells.. Seizure-linked plasticity could induce a self-protection phenomenon against excitotoxic lesions possibly partially mediated by de novo neuropeptide-Y mossy fiber expression.

Topics: Animals; Cell Count; Epilepsy; Hippocampus; Immunohistochemistry; Kainic Acid; Mossy Fibers, Hippocampal; Neuronal Plasticity; Neuropeptide Y; Pyramidal Cells; Rats; Rats, Wistar

Topics: Animals; Anticonvulsants; Brain; Drug Design; Epilepsy; Humans; Neuropeptide Y; Obesity; Proto-Oncogene Proteins c-fos; Receptors, Neuropeptide Y

Neuropeptide Y (NPY) potently inhibits glutamate-mediated synaptic transmission in areas CA1 and CA3 of the rat hippocampus without affecting other synaptic inputs onto principal cells of the hippocampal formation, suggesting that its biological role may include the regulation of excitability within the hippocampus. Here we examine NPY's actions in three in vitro models of epilepsy [0 Mg2+-, picrotoxin-, and stimulus-train-induced bursting (STIB)] with the use of extracellular and whole cell patch-clamp recordings from rat hippocampal-entorhinal cortex slices. Perfusion of the slice with saline that had Mg2+ omitted (0 Mg2+) or that had picrotoxin (100 microM) added resulted in brief spontaneous bursts (SBs) resembling interictal discharges. SB frequency is significantly reduced in both models by 1 microM NPY and by the Y2-preferring agonists peptide (P)YY(3-36) (1 microM) and 1-4-(6-aminohexanoic acid)-25-36 ([ahx(5-24)] NPY; 3 microM). The Y1-preferring agonist Leu31-Pro34NPY (1 microM) is considerably less potent, but also reduces burst frequency, even in the presence of the selective Y1 receptor antagonist GR231118, suggesting the involvement of a different receptor. In STIB, high-frequency stimulus trains to stratum radiatum of area CA2/CA3 result in clonic or tonic-clonic ictaform primary afterdischarges (primary ADs) as well as longer, spontaneous secondary ictaform discharges and SBs similar to those in the other models. Primary AD duration is greatly reduced or abolished by Y2- but not Y1-preferring agonists. SBs, although variable, were inhibited by both Y1 and Y2 agonists. In single and dual whole cell recordings from CA3 pyramidal cells, we frequently observed spontaneous, rhythmic synchronous events (SRSEs) arising after several STIB stimuli. Once established, SRSEs persist in the absence of further stimuli and are insensitive to the application of NPY. SRSEs in pyramidal cells typically occur at 2-4 Hz, are outward currents when cells are clamped near rest (>100 pA at a holding potential of -55 mV), reverse between -60 and -70 mV, and are inhibited by 100 microM picrotoxin, indicating involvement of gamma-aminobutyric acid-A receptors. They are inhibited by blockers of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) but not N-methyl-D-aspartate receptors. Whole cell patch-clamp recordings from interneurons in CA3 after STIB reveal NPY-insensitive, rhythmic, inward AMPA-receptor-mediated currents that are similar in frequency

Topics: Animals; Anticonvulsants; Electric Stimulation; Epilepsy; Hippocampus; Magnesium Deficiency; Male; Membrane Potentials; Neuropeptide Y; Patch-Clamp Techniques; Picrotoxin; Rats; Rats, Sprague-Dawley; Receptors, Neuropeptide Y

Neuropeptide Y (NPY) inhibits excitatory synaptic transmission in the hippocampus and is implicated in control of limbic seizures. In the present study, we examined hippocampal function and the response to pharmacologically induced seizures in mutant mice lacking this peptide. In slice electrophysiology studies, no change in normal hippocampal function was observed in NPY-deficient mice compared with normal wild-type littermates. Kainic acid (KA) produced limbic seizures at a comparable latency and concentration in NPY-deficient mice compared with littermates. However, KA-induced seizures progressed uncontrollably and ultimately produced death in 93% of NPY-deficient mice, whereas death was rarely observed in wild-type littermates. Intracerebroventricular NPY infusion, before KA administration, prevented death in NPY-deficient mice. These results suggest a critical role for endogenous NPY in seizure control.

Topics: Action Potentials; Animals; Convulsants; Electroencephalography; Epilepsy; Gene Expression Regulation; Genotype; Hippocampus; Kainic Acid; Mice; Mice, Knockout; Neuropeptide Y; Perforant Pathway; Seizures; Synaptic Transmission

Repetitive electroconvulsive stimulations (ECSs) increase neuropeptide Y (NPY) synthesis in hippocampal neurons, but whether NPY release and the density of NPY receptors are affected is unknown. In rats exposed to 14 daily ECSs, the concentration of NPY specific binding sites in hippocampal membranes was reduced by about 75% compared with sham, but was unchanged in membranes isolated from the cerebral cortex and the thalamus. In accordance with this, in vitro autoradiography revealed a similar reduction in binding in the dentate gyrus and the CA1 and CA3 regions, but not in the parietal cortex, the entorhinal cortex or the thalamus. These results show significant changes in NPY receptor binding after repeated ECSs, suggesting that NPYergic neurotransmission, most likely within the hippocampus, is strongly affected by ECSs.

Topics: Animals; Autoradiography; Binding Sites; Cell Membrane; Electroshock; Epilepsy; Hippocampus; Male; Neuronal Plasticity; Neuropeptide Y; Peptide YY; Rats; Rats, Wistar; Receptors, Neuropeptide Y

Ihara's genetically epileptic rat (IGER) is a rat mutant with genetically scheduled spontaneous convulsions mimicking human limbic seizures. In the present study, the possible changes of three neuropeptides, neuropeptide Y (NPY), somatostatin (SRIF) and corticotropin-releasing factor (CRF), in the brains of IGER were investigated. Increased contents of immunoreactive (IR) NPY were found only in the hippocampus of 2-month IGERs before developing convulsive seizures, while similar increases of IR-NPY were discovered in the striatum and pyriform and entorhinal cortex as well as hippocampus in 8-month IGERs with repetitive seizures. There were no significant differences in the brain contents of IR-SRIF and IR-CRF between IGERs and the controls at both ages. These findings indicate an enhanced rate of NPY synthesis in this experimental model of epilepsy which may play a critical role in the development of epileptogenesis.

Topics: Animals; Antibody Specificity; Brain Chemistry; Corticotropin-Releasing Hormone; Disease Models, Animal; Epilepsy; Female; Male; Neuropeptide Y; Rats; Rats, Mutant Strains; Rats, Wistar; Somatostatin

The effect of neuropeptide Y (NPY) on the picrotoxin-induced activity was studied in rat brain hippocampal slices in vitro and after intrahippocampal injection in vivo. In the hippocampal slices, NPY (0.1-0.5 microM) inhibited the picrotoxin-induced epileptiform activity recorded extracellularly in CA1 and CA3 hippocampal pyramidal cells. Similar inhibition was induced by the Y2 receptor agonist NPY13-36, which indicates that the effect of NPY was due to activation of Y2 receptors. In behavioural studies, rats with chronically implanted cannulae were injected unilaterally into the CA1 hippocampal region with a 1 ml volume of the studied substances. Picrotoxin in a dose of 1 mg (1.6 nmol) induced behavioural excitation, shakes and weak signs of epileptic behaviour. NPY in a dose of 2 mg (470 pmol), but not 1 mg, inhibited some excitatory effects of picrotoxin, but did not change the epileptic symptoms. The obtained results suggest that NPY has an inhibitory action in the hippocampus, which can be observed in vitro and also in a behavioural study.

Topics: Animals; Anticonvulsants; Behavior, Animal; Central Nervous System Stimulants; Electrophysiology; Epilepsy; Hippocampus; In Vitro Techniques; Injections; Male; Neuropeptide Y; Picrotoxin; Pyramidal Cells; Rats; Rats, Wistar

Granule cells of the dentate gyrus can express neuropeptide-Y (NPY) in several models of epilepsy involving limbic seizures, however, the nature of this ectopic expression is not well understood at present. We have studied the expression of NPY-immunoreactivity in mossy fibres contralateral to a unilateral intrahippocampal injection of kainic acid and report that ectopic mossy fibre NPY-immunoreactivity is observed throughout the contralateral hippocampus.

Topics: Animals; Antibody Specificity; Epilepsy; Excitatory Amino Acid Agonists; Hippocampus; Immunohistochemistry; Kainic Acid; Male; Microinjections; Neuropeptide Y; Rats; Rats, Wistar

The in vitro release of somatostatin and neuropeptide Y, their tissue concentration and immunocytochemical pattern were examined in the entorhinal cortex of chronically epileptic rats. A systemic administration of 12 mg/kg kainic acid causing generalized tonic-clonic seizures for at least 3 h after injection was used to induce, 60 days later, a chronically enhanced susceptibility to seizures in the rats. The release of both peptides under depolarizing conditions was significantly reduced by 15% on average from slices of the entorhinal cortex two days after kainic acid-induced status epilepticus. At 60 days, the spontaneous and 30 mM KCl-induced release of somatostatin was significantly enhanced by 30% on average. The release induced by 100 mM KCl was raised by 70%. The spontaneous, 30 mM and 100 mM KCl-induced release of neuropeptide Y from the same slices was increased, respectively, by 120%, 76% and 36%. The late changes were associated with an increased tissue concentration of neuropeptide Y but not of somatostatin. This was confirmed by immunocytochemical evidence showing that neuropeptide Y-, but not somatostatin-immunoreactive neurons were increased in the entorhinal cortex of kainic acid-treated rats. These results indicate that neurotransmission mediated by somatostatin and neuropeptide Y, two peptides previously shown to play a role in limbic epileptogenesis, is enhanced in the entorhinal cortex of chronically epileptic rats.

Topics: Animals; Cell Count; Entorhinal Cortex; Epilepsy; Excitatory Amino Acid Agonists; Immunohistochemistry; Kainic Acid; Male; Neurons; Neuropeptide Y; Rats; Rats, Sprague-Dawley; Somatostatin; Synaptic Transmission

Topics: Animals; Brain Damage, Chronic; Brain Mapping; Dentate Gyrus; Dominance, Cerebral; Epilepsy; gamma-Aminobutyric Acid; Hippocampus; Interneurons; Kindling, Neurologic; Male; Nerve Regeneration; Neural Inhibition; Neural Pathways; Neuropeptide Y; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Somatostatin

Immunoreactive- (IR-) somatostatin (SRIF), neuropeptide Y (NPY) and corticotropin-releasing factor (CRF) contents were investigated in the brain of tremor rats with absence-like seizure and spontaneously epileptic rats (SER), which is a genetically defined double-mutant (zi/zi, tm/tm) obtained by mating zitter homozygote (zi/zi) with tremor heterozygote (tm/+) and shows both absence-like seizure and tonic convulsions. Increased levels of IR-NPY and IR-CRF were observed in several regions including the amygdala and hippocampus in homozygous SER compared to heterozygous SER (zi/zi, tm/+ or +/+). Homozygous tremor rats (tm/tm) showed lower levels of IR-NPY and IR-CRF contents mainly in the hippocampus and mesolimbic system (entorhinal and pyriform cortex and nucleus accumbens) than heterozygous tremor rats. IR-SRIF contents of homozygous SER were higher in frontal cortex than heterozygous SER and in amygdala than homozygous tremor rats. No change of IR-SRIF between groups was noted in the hippocampus among brain structures underlying epileptogenicity. The results suggest that the change of neuropeptide levels, most conspicuous in NPY among three peptides tested, may be involved in the phenotypical manifestation of seizures in SER and tremor rats, and that the development of tonic convulsion and absence seizures may be differently associated with the change of brain neuropeptide levels.

Topics: Animals; Brain; Corticotropin-Releasing Hormone; Epilepsy; Epilepsy, Absence; Male; Neuropeptide Y; Rats; Rats, Mutant Strains; Somatostatin; Tremor

Interruption of a chronic GABA infusion into the rat somatosensory cortex induces the appearance of focal epileptic manifestations, known as the 'GABA withdrawal syndrome' (GWS). The aim of the present study was to determine, by immunocytochemistry, if neurotransmitters other than GABA are involved in GWS, namely: noradrenaline (NA), serotonin, choline acetyltransferase (CAT), cholecystokinin, neuropeptide Y, somatostatin and glial fibrillary acid protein (GFAP). Immunocytochemical data were compared in three animal groups: GABA-, saline- and L-aspartate (L-Asp)-infused rats. Only GABA-infused rats presented epileptic manifestations after interruption of the infusion. Saline- and L-Asp-infused rats served as controls. Observations were limited to the region surrounding the cortical infusion site. GABA-infused rats showed in the zone of the epileptic focus a number of cell bodies strongly immunoreactive to NA antibodies much larger than control rats. In addition, NA-immunoreactive fibers formed a dense plexus and some of them were observed around perikarya. In saline- and L-Asp-infused rats, the NA-immunolabelled fibers were sparse and NA immunolabelling was rarely observed in cell bodies. These results contrast to those obtained for the serotonergic system, where no significant difference was observed among the three groups of rats. CAT immunolabelling was observed in cell bodies, but not in nerve terminals in rats of the three groups. The number of CAT-immunoreactive cell bodies was much greater in GABA-infused rats than in the control animals. GFAP immunolabelling showed an important number of astrocytes throughout the cortex of the GABA-infused hemisphere, whereas, astrocytic reaction was limited to the infusion site in controls. Immunocytochemical data concerning peptides revealed cortical neuronal elements labelled similarly in the three groups of rats. Noradrenergic, cholinergic and glial modifications observed mainly in GABA-infused rats can result from lesion and from a specific action of GABA in chronic infusion. These modifications may contribute to the epileptogenesis of GWS, as recently demonstrated by electrophysiological recordings that show a modulating action of NA on firing activity of neurons involved in the epileptic focus.

Topics: Animals; Cholecystokinin; Choline O-Acetyltransferase; Epilepsy; gamma-Aminobutyric Acid; Glial Fibrillary Acidic Protein; Gliosis; Immunohistochemistry; Male; Neuropeptide Y; Norepinephrine; Rats; Rats, Wistar; Serotonin; Somatosensory Cortex; Somatostatin

Topics: Animals; Brain; Corticotropin-Releasing Hormone; Epilepsy; Male; Neuropeptide Y; Radioimmunoassay; Rats; Rats, Mutant Strains; Somatostatin

The neuropeptides somatostatin and neuropeptide Y and the activity of glutamate decarboxylase were determined in the frontal cortex of rats subjected to experimental epilepsy. Two different animal models, (1) rats kindled for 4 weeks by daily injection of pentylenetetrazole, and (2) rats which had undergone strong limbic seizures induced by kainic acid, were used. Decreased seizure threshold, as shown by injection of a subconvulsive dose of pentylenetetrazole, was observed 10 days after the last kindling session and 1 month after injection of kainic acid, respectively. Significantly increased levels of somatostatin (by 60%), neuropeptide Y (135%) and increased activity of glutamate decarboxylase (22%) were found in the frontal cortex of rats previously treated with kainic acid. Separation of somatostatin-like immunoreactivity by size exclusion high-performance liquid chromatography showed a marked increase of immunoreactivity in fractions containing the somatostatin precursor (by 200%) and less prominently of somatostatin-14 and somatostatin-28 (by 60 and 80%, respectively). Michaelis-Menten kinetics of glutamate decarboxylase revealed an increased maximal velocity (Vmax) in the frontal cortex of kainic acid-treated rats, but no change in the Km value was found. Similar results were also obtained in pentylenetetrazole-kindled rats. Injection of cysteamine (100 mg/kg, i.p.) resulting in a 30% decrease of cortical somatostatin in kainic acid-pretreated rats markedly suppressed seizures induced by an otherwise subconvulsive dose of pentylenetetrazole.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Cysteamine; Dose-Response Relationship, Drug; Epilepsy; Frontal Lobe; Glutamate Decarboxylase; Kainic Acid; Kindling, Neurologic; Male; Neuropeptide Y; Pentylenetetrazole; Rats; Rats, Inbred Strains; Somatostatin; Time Factors