neuropeptide-y and Sclerosis

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

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

Detailed neuropathological studies of the extent of hippocampal sclerosis (HS) in epilepsy along the longitudinal axis of the hippocampus are lacking. Neuroimaging studies of patients with temporal lobe epilepsy support that sclerosis is not always localised. The extent of HS is of relevance to surgical planning and poor outcomes may relate to residual HS in the posterior remnant. In 10 post mortems from patients with long histories of drug refractory epilepsy and 3 controls we systematically sampled the left and right hippocampus at seven coronal anatomical levels along the body to the tail. We quantified neuronal densities in CA1 and CA4 subfields at each level using Cresyl Violet (CV), calretinin (CR), calbindin (CB) and Neuropeptide Y (NPY) immunohistochemistry. In the dentate gyrus we graded the extent of granule cell dispersion, patterns of CB expression, and synaptic reorganisation with CR and NPY at each level. We identified four patterns of HS based on patterns of pyramidal and interneuronal loss and dentate gyrus reorganisation between sides and levels as follows: (1) symmetrical HS with anterior-posterior (AP) gradient, (2) symmetrical HS without AP gradient, (3) asymmetrical HS with AP gradient and (4) asymmetrical cases without AP gradient. We confirmed in this series that HS can extend into the tail. The patterns of sclerosis (classical versus atypical or none) were consistent between all levels in less than a third of cases. In conclusion, this series highlights the variability of HS along the longitudinal axis. Further studies are required to identify factors that lead to focal versus diffuse HS.

Topics: Adult; Aged; Aged, 80 and over; Benzoxazines; CA1 Region, Hippocampal; Calbindin 2; Calbindins; Cell Count; Coloring Agents; Dentate Gyrus; Epilepsy, Temporal Lobe; Female; Humans; Interneurons; Male; Middle Aged; Neuropeptide Y; Oxazines; Pyramidal Cells; S100 Calcium Binding Protein G; Sclerosis

In this study, we performed immunohistochemistry for somatostatin (SS), neuropeptide Y (NPY), and parvalbumin (PV) in LiCl-pilocarpine-treated rats to observe quantitative changes and axonal sprouting of GABAergic interneurons in the hippocampus, especially in the sclerotic hippocampus. Fluoro-Jade B (FJB) was performed to detect the specific degeneration of GABAergic interneurons. Compared with age-matched control rats, there were fewer SS/NPY/PV-immunoreactive (IR) interneurons in the hilus of the sclerotic hippocampus in pilocarpine-treated rats; hilar dentritic inhibitory interneurons were most vulnerable. FJB stain revealed degeneration was evident at 2 months after status epilepticus. Some SS-IR and NPY-IR interneurons were also stained for FJB, but there was no evidence of degeneration of PV-IR interneurons. Axonal sprouting of GABAergic interneurons was present in the hippocampus of epileptic rats, and a dramatic increase of SS-IR fibers was observed throughout all layers of CA1 region in the sclerotic hippocampus. These results confirm selective loss and degeneration of a specific subset of GABAergic interneurons in specific subfields of the hippocampus. Axonal sprouting of inhibitory GABAergic interneurons, especially numerous increase of SS-IR neutrophils within CA1 region of the sclerotic hippocampus, may constitute the aberrant inhibitory circum and play a significant role in the generation and compensation of temporal lobe epilepsy.

Topics: Animals; Axons; Disease Models, Animal; gamma-Aminobutyric Acid; Hippocampus; Interneurons; Lithium Chloride; Male; Nerve Degeneration; Neuropeptide Y; Parvalbumins; Pilocarpine; Rats; Rats, Sprague-Dawley; Sclerosis; Somatostatin; Status Epilepticus

Hippocampal sclerosis is a common pathological finding in patients with temporal lobe epilepsy, including children, but a causal relationship to early-life seizures remains in question. Neonatal status epilepticus in animals can result in neuronal death within the hippocampus, although macroscopic features of hippocampal shrinkage are not evident at adulthood. Here, we examined electrophysiological and pathological consequences of focally evoked status epilepticus triggered by intra-amygdala microinjection of kainic acid in postnatal day 10 rat pups. Neonatal status epilepticus resulted in extensive neuronal death in the ipsilateral hippocampal CA1 and CA3 subfields and hilus, as assessed by DNA fragmentation and Fluoro-Jade B staining 72 hours later. The contralateral hippocampus was not significantly damaged. Histopathology at P55/P65 revealed unilateral hippocampal sclerosis (grade IV, modified Wyler/Watson scale) comprising >50% CA1 and CA3 neuron loss and astrogliosis. Additional features included hydrocephalus ex vacuo, modest dentate granule cell layer widening, and altered neuropeptide Y immunoreactivity indicative of synaptic rearrangement. Hippocampal atrophy was also evident on magnetic resonance imaging. Depth electrode recordings at adulthood detected spontaneous seizures that involved the ipsilateral hippocampus and amygdala. A significant positive correlation was found between hippocampal pathology grade and both frequency and duration of epileptic seizures at adulthood. The current study demonstrates that experimental neonatal status epilepticus can result in classical unilateral hippocampal sclerosis and temporal lobe epilepsy.

Topics: Aging; Amygdala; Animals; Animals, Newborn; Cell Death; Cell Shape; Electroencephalography; Epilepsy, Temporal Lobe; Female; Hippocampus; Magnetic Resonance Imaging; Male; Neurons; Neuropeptide Y; Phenotype; Rats; Rats, Sprague-Dawley; Sclerosis; Status Epilepticus

Vesicular glutamate transporters (VGLUTs) are responsible for loading synaptic vesicles with glutamate, determining the phenotype of glutamatergic neurons, and have been implicated in the regulation of quantal size and presynaptic plasticity. We analyzed VGLUT subtype expression in normal human hippocampus and tested the hypothesis that alterations in VGLUT expression may contribute to long-term changes in glutamatergic transmission reported in patients with temporal lobe epilepsy (TLE).. VGLUT immunohistochemistry, immunofluorescence, in situ hybridization, Western blotting, and quantitative polymerase chain reaction (qPCR) were performed on biopsies from TLE patients without (non-HS) and with hippocampal sclerosis (HS) and compared to autopsy controls and rat hippocampus. VGLUT1 expression was compared with synaptophysin, neuropeptide Y (NPY), and Timm's staining.. VGLUT1 was the predominant VGLUT in human hippocampus and appeared to be localized to presynaptic glutamatergic terminals. In non-HS hippocampi, VGLUT1 protein levels were increased compared to control and HS hippocampi in all subfields. In HS hippocampi VGLUT1 expression was decreased in subfields with severe neuronal loss, but strongly up-regulated in the dentate gyrus, characterized by mossy fiber sprouting.. VGLUT1 is used as marker for glutamatergic synapses in the human hippocampus. In HS hippocampi VGLUT1 up-regulation in the dentate gyrus probably marks new glutamatergic synapses formed by mossy fiber sprouting. Our data indicate that non-HS patients have an increased capacity to store glutamate in vesicles, most likely due to an increase in translational processes or upregulation of VGLUT1 in synapses from afferent neurons outside the hippocampus. This up-regulation may increase glutamatergic transmission, and thus contribute to increased extracellular glutamate levels and hyperexcitability.

Topics: Animals; Dentate Gyrus; Epilepsy, Temporal Lobe; Glutamic Acid; Hippocampus; Humans; Immunohistochemistry; Mossy Fibers, Hippocampal; Neurons; Neuropeptide Y; Rats; Sclerosis; Synapses; Synaptic Vesicles; Synaptophysin; Tissue Distribution; Vesicular Glutamate Transport Protein 1

Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry.. Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21-96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death.. Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients.. Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon.

Topics: Adult; Aged; Aged, 80 and over; Cell Count; Dentate Gyrus; Dynorphins; Epilepsy, Temporal Lobe; Functional Laterality; Humans; Immunohistochemistry; Middle Aged; Mossy Fibers, Hippocampal; Neuropeptide Y; Sclerosis; Young Adult

This study is a retrospective analysis of the pathology of the hippocampus from patients with medically intractable temporal lobe epilepsy. We attempted to relate neuronal density, immunohistochemistry, electrophysiologic data, and surgical outcome.. Immunostaining patterns for neuropeptide Y, somatostatin, substance P, and dynorphin defined the immunohistochemical characteristics of the hippocampi. Neuronal densities were determined by microscopic cell counts. Sharp electrode recordings from dentate granule cells determined measures of inhibition and excitation.. Patient hippocampi without evidence of sclerosis generally resembled autopsy controls on the basis of neuronal densities of hippocampal subfields and patterns of immunostaining. The nonsclerotic hippocampi were divisible into two subgroups on the basis of neuronal density correlations between hippocampal subfields, the excitability of dentate granule cells, etiology, and surgical outcome. Hippocampi with sclerosis were divisible into those with significant neuronal loss confined to area CA1 and those with neuronal loss throughout the hippocampus and dentate gyrus. In the former, the dentate gyrus resembled in morphology the nonsclerotic hippocampi but with slightly increased excitability of the dentate granule cells. The hippocampi with more extensive neuronal loss had changes in immunostaining patterns associated with the dentate gyrus, correlated with significant hyperexcitability of dentate granule cells. The surgical outcome, with the exception of one group, was good in approximately 70-90%.. Hippocampi from patients with intractable temporal lobe epilepsy can be assigned to several groups on the basis of pathophysiology. Different pathologies may represent differing causative mechanisms of intractable temporal lobe epilepsy and be predictive of surgical outcome.

Topics: Adult; Apoptosis; Cell Count; Culture Techniques; Dentate Gyrus; Dynorphins; Electroencephalography; Epilepsy, Temporal Lobe; Evoked Potentials; Female; Follow-Up Studies; Hippocampus; Humans; Immunoenzyme Techniques; Interneurons; Male; Neurons; Neuropeptide Y; Reference Values; Retrospective Studies; Sclerosis; Somatostatin; Substance P; Treatment Outcome

This study determined differences of fascia dentata (FD) peptide and inhibitory neuroanatomy between patients with epileptogenic hippocampal sclerosis (HS), those with extrahippocampal seizure pathologies, and autopsy comparisons. Surgically treated temporal lobe epilepsy patients were clinically classified into two pathogenic categories: (1) HS with focal mesial temporal neuroimaging and histories of initial precipitating injuries to the brain (n = 18) and (2) non-HS patients with extrahippocampal mass lesions or idiopathic seizures (i.e., without lesions or HS; mass lesion/idiopathic; n = 9). The hippocampal sections were studied for (1) granule cell, hilar, CA4, and CA3 neuron densities; (2) hilar densities and the percentage of neurons immunoreactive (IR) for neuropeptide Y (NPY), somatostatin (SS), and glutamate decarboxylase (GAD); (3) densities of GAD neurons in the lower granule cell and infragranular zone (basket-like cells); (4) the semiquantitative pattern of IR peptides/GAD FD molecular layer axon sprouting; (5) IR gray values (GV) of the FD molecular layers; and (6) the thickness of the supragranular molecular layer. Results showed the following. (1) Compared to autopsies, both HS and mass lesion/idiopathic patients showed less granule cell and CA3 neuron densities, but there were no statistical differences between the latter two pathogenic categories. (2) By contrast, compared to autopsies and mass lesion/idiopathic cases, HS patients showed less hilar and CA4 neuron densities, and there were no differences between autopsies and mass lesion/idiopathic. (3) Compared to autopsies, the NPY and SS hilar neuron densities in HS patients, but not mass lesion/idiopathic cases, were less. (4) Compared to autopsies, the hilar GAD neuron densities for HS and mass lesion/idiopathic patients were not less. (5) In HS patients the averaged percentages of hilar SS neurons were less than autopsies, and no other differences of IR hilar percentages were found. (6) The densities of GAD basket-like neurons and the thickness of the supragranular molecular layer were not different between any combination of pathogenic categories and autopsies. (7) By semiquantitative visual assessments, peptides/GAD axon sprouting into the FD was greater in HS compared to mass lesion/idiopathic or autopsies. (8) Compared to mass lesion/idiopathic cases, in HS NPY outer molecular layer GVs were lower, SS GVs were not different, and GAD inner molecular layer GVs were higher. (9) Ana

Topics: Analysis of Variance; Autopsy; Axons; Epilepsy, Complex Partial; Epilepsy, Temporal Lobe; Glutamate Decarboxylase; Hippocampus; Humans; Models, Neurological; Nerve Net; Neurons; Neuropeptide Y; Pyramidal Cells; Reference Values; Sclerosis; Somatostatin; Synapses