preproenkephalin and Parkinson-Disease

Proenkephalin (PENK) and prodynorphin (PDYN) are peptides mainly produced by the striatal medium spiny projection neurons (MSNs) under dopaminergic signaling. Therefore, they may represent candidate biomarkers in Huntington's disease (HD) and Parkinson's disease (PD), two neurodegenerative diseases characterized by striatal atrophy and/or dysfunction.. Using an in-house established liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in multiple reaction monitoring mode (MRM) we measured cerebrospinal fluid (CSF) levels of PENK- and PDYN- derived peptides in patients with HD (n = 47), PD (n = 61), Alzheimer's disease (n = 11), amyotrophic lateral sclerosis (n = 14) and in 92 control subjects. Moreover, we investigated the possible associations between biomarkers and disease severity scales in HD and PD and the effect of dopaminergic therapy on biomarker levels in PD.. In HD, CSF PENK- and PDYN-derived peptide levels were significantly decreased compared to all other groups and were associated with disease severity scores. In PD, both biomarkers were within the normal range, but higher PDYN levels were found in dopamine-treated compared to untreated patients. In PD, both CSF PENK and PDYN did not correlate with clinical severity scales.. CSF PENK- and PDYN-derived peptides appeared to be promising pathogenetic and disease severity markers in HD, reflecting the ongoing striatal neurodegeneration along with the loss of MSNs. In PD patients, CSF PDYN showed a limitative role as a possible pharmacodynamic marker during dopaminergic therapy, but further investigations are needed.

Topics: Biomarkers; Chromatography, Liquid; Dopamine; Enkephalins; Humans; Huntington Disease; Parkinson Disease; Protein Precursors; Tandem Mass Spectrometry

The opioidergic neuropeptides dynorphin (DYN) and enkephalin (ENK) and the D1 and D2 dopaminergic receptors (D1R, D2R) are involved in the striatal control of motor and behavioral function. In Parkinson's disease, motor disturbances such as "on-off" motor fluctuations and involuntary movements (dyskinesia) are severe complications that often arise after chronic l-dihydroxyphenylalanine (l-DOPA) treatment. Changes in the striatal expression of preproENK (PPENK), proDYN (PDYN), D1R, and D2R mRNA have been observed in parkinsonian animals treated with l-DOPA. Enhanced opioidergic transmission has been found in association with l-DOPA-induced dyskinesia, but the connection of PPENK, PDYN, D1R, and D2R mRNA expression with locomotor activity remains unclear. In this study, we measured PPENK, PDYN, D1R and D2R mRNA levels by in situ hybridization in the striatum of 6-OHDA hemi-parkinsonian rats treated with l-DOPA (PD+l-DOPA group), along with two control groups (PD+saline and naive+l-DOPA). We found different levels of expression of PPENK, PDYN, D1R and D2R mRNA across the experimental groups and correlated the changes in mRNA expression with dyskinesia and locomotor variables assessed by open field test during several phases of l-DOPA treatment. Both PDYN and PPENK mRNA levels were correlated with the severity of dyskinesia, while PPENK mRNA levels were also correlated with the frequency of contralateral rotational movements and with locomotor variables. Moreover, a strong correlation was found between D1R mRNA expression and D2R mRNA expression in the PD+l-DOPA group. These findings suggest that, in parkinsonian animals treated with l-DOPA, high levels of PPENK are a prerequisite for a locomotor sensitization to l-DOPA treatment, while PDYN overexpression is responsible only for the development of dyskinesia.

Topics: Analysis of Variance; Animals; Antiparkinson Agents; Disease Models, Animal; Dynorphins; Dyskinesia, Drug-Induced; Enkephalins; Female; Gene Expression Regulation; Levodopa; Oxidopamine; Parkinson Disease; Protein Precursors; Rats; Rats, Sprague-Dawley; Receptors, Dopamine; RNA, Messenger; Statistics as Topic; Sympatholytics; Tyrosine 3-Monooxygenase

Adenosine A(₂A) receptor antagonism provides a promising approach to developing nondopaminergic therapy for Parkinson's disease (PD). Clinical trials of A(₂A) antagonists have targeted PD patients with L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID) in an effort to improve parkinsonian symptoms. The role of adenosine in the development of LID is little known, especially regarding its actions via A₁ receptors. We aimed to examine the effects of genetic deletion and pharmacological blockade of A₁ and/or A(₂A) receptors on the development of LID, on the induction of molecular markers of LID including striatal preprodynorphin and preproenkephalin (PPE), and on the integrity of dopaminergic nigrostriatal neurons in hemiparkinsonian mice. Following a unilateral 6-hydroxydopamine lesion A₁, A(₂A) and double A₁-A(₂A) knockout (KO) and wild-type littermate mice, and mice pretreated with caffeine (an antagonist of both A₁ and A(₂A) receptors) or saline were treated daily for 18-21 days with a low dose of L-DOPA. Total abnormal involuntary movements (AIMs, a measure of LID) were significantly attenuated (p<0.05) in A₁ and A(₂A) KOs, but not in A₁-A(₂A) KOs and caffeine-pretreated mice. An elevation of PPE mRNA ipsilateral to the lesion in WT mice was reduced in all KO mice. In addition, neuronal integrity assessed by striatal dopamine content was similar in all KOs and caffeine-pretreated mice following 6-hydroxydopamine lesioning. Our findings raise the possibility that A₁ or A(₂A) receptors blockade might also confer a disease-modifying benefit of reduced risk of disabling LID, whereas the effect of their combined inactivation is less clear.

Topics: Adrenergic Agents; Animals; Antiparkinson Agents; Caffeine; Corpus Striatum; Disease Models, Animal; Dynorphins; Dyskinesia, Drug-Induced; Enkephalins; Gene Expression Regulation; Levodopa; Mice; Mice, Inbred C57BL; Mice, Knockout; Oxidopamine; Parkinson Disease; Protein Precursors; Purinergic P1 Receptor Antagonists; Receptor, Adenosine A1; Receptor, Adenosine A2A; RNA, Messenger; Statistics, Nonparametric; Time Factors

Opioid peptides are involved in various pathophysiological processes, including algesia, epilepsy, and drug dependence. A strong association between L-DOPA-induced dyskinesia (LID) and elevated prodynorphin mRNA levels has been established in both patients and in animal models of Parkinson's disease, but to date the endogenous prodynorphin peptide products have not been determined. Here, matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) was used for characterization, localization, and relative quantification of striatal neuropeptides in a rat model of LID in Parkinson's disease. MALDI IMS has the unique advantage of high sensitivity and high molecular specificity, allowing comprehensive detection of multiple molecular species in a single tissue section. Indeed, several dynorphins and enkephalins could be detected in the present study, including dynorphin A(1-8), dynorphin B, α-neoendorphin, MetEnkRF, MetEnkRGL, PEnk (198-209, 219-229). IMS analysis revealed elevated levels of dynorphin B, α-neoendorphin, substance P, and PEnk (220-229) in the dorsolateral striatum of high-dyskinetic animals compared with low-dyskinetic and lesion-only control rats. Furthermore, the peak-intensities of the prodynorphin derived peptides, dynorphin B and α-neoendorphin, were strongly and positively correlated with LID severity. Interestingly, these LID associated dynorphin peptides are not those with high affinity to κ opioid receptors, but are known to bind and activate also μ- and Δ-opioid receptors. In addition, the peak intensities of a novel endogenous metabolite of α-neoendorphin lacking the N-terminal tyrosine correlated positively with dyskinesia severity. MALDI IMS of striatal sections from Pdyn knockout mice verified the identity of fully processed dynorphin peptides and the presence of endogenous des-tyrosine α-neoendorphin. Des-tyrosine dynorphins display reduced opioid receptor binding and this points to possible novel nonopioid receptor mediated changes in the striatum of dyskinetic rats. Because des-tyrosine dynorphins can only be detected by mass spectrometry, as no antibodies are available, these findings highlight the importance of MALDI IMS analysis for the study of molecular dynamics in neurological diseases.

Topics: Animals; Antiparkinson Agents; Disease Models, Animal; Dynorphins; Dyskinesia, Drug-Induced; Enkephalins; Female; Humans; Levodopa; Mice; Neostriatum; Parkinson Disease; Protein Precursors; Rats; Rats, Sprague-Dawley; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

L-DOPA-induced dyskinesia is a troublesome complication of L-DOPA pharmacotherapy of Parkinson's disease and has been associated with disturbed brain opioid transmission. However, so far the results of clinical and preclinical studies on the effects of opioids agonists and antagonists have been contradictory at best. Prodynorphin mRNA levels correlate well with the severity of dyskinesia in animal models of Parkinson's disease; however the identities of the actual neuroactive opioid effectors in their target basal ganglia output structures have not yet been determined. For the first time MALDI-TOF imaging mass spectrometry (IMS) was used for unbiased assessment and topographical elucidation of prodynorphin-derived peptides in the substantia nigra of a unilateral rat model of Parkinson's disease and L-DOPA induced dyskinesia. Nigral levels of dynorphin B and alpha-neoendorphin strongly correlated with the severity of dyskinesia. Even if dynorphin peptide levels were elevated in both the medial and lateral part of the substantia nigra, MALDI IMS analysis revealed that the most prominent changes were localized to the lateral part of the substantia nigra. MALDI IMS is advantageous compared with traditional molecular methods, such as radioimmunoassay, in that neither the molecular identity analyzed, nor the specific localization needs to be predetermined. Indeed, MALDI IMS revealed that the bioconverted metabolite leu-enkephalin-arg also correlated positively with severity of dyskinesia. Multiplexing DynB and leu-enkephalin-arg ion images revealed small (0.25 by 0.5 mm) nigral subregions with complementing ion intensities, indicating localized peptide release followed by bioconversion. The nigral dynorphins associated with L-DOPA-induced dyskinesia were not those with high affinity to kappa opioid receptors, but consisted of shorter peptides, mainly dynorphin B and alpha-neoendorphin that are known to bind and activate mu and delta opioid receptors. This suggests that mu and/or delta subtype-selective opioid receptor antagonists may be clinically relevant for reducing L-DOPA-induced dyskinesia in Parkinson's disease.

Topics: Animals; Dynorphins; Dyskinesias; Enkephalins; Female; Immunohistochemistry; Levodopa; Male; Mass Spectrometry; Mice; Mice, Knockout; Parkinson Disease; Protein Precursors; Rats; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Overactivity of striatal alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors is implicated in the pathophysiology of L-DOPA-induced dyskinesia (LID) in Parkinson's disease (PD). In this study, we evaluated the behavioural and molecular effects of acute and chronic blockade of Ca(2+)-permeable AMPA receptors in animal models of PD and LID. The acute effects of the Ca(2+)-permeable AMPA receptor antagonist 1-trimethylammonio-5-(1-adamantane-methylammoniopentane) dibromide hydrobromide (IEM 1460) on abnormal involuntary movements (AIMs) in the 6-hydroxydopamine (6-OHDA)-lesioned rat and LID in the MPTP-lesioned non-human primate were assessed. Subsequently, the effects of chronic treatment of 6-OHDA-lesioned rats with vehicle, L-DOPA/benserazide (6/15 mg/kg, i.p.) + vehicle or L-DOPA + IEM 1460 (3 mg/kg, i.p.) on behavioural and molecular correlates of priming for LID were evaluated. In the 6-OHDA-lesioned rat and MPTP-lesioned non-human primate, acute treatment with IEM 1460 (1-3 mg/kg) dose-dependently reduced LID without adverse effects on motor performance. Chronic co-treatment for 21 days with IEM 1460 reduced the induction of AIMs by L-DOPA in the 6-OHDA-lesioned rat without affecting peak rotarod performance, and attenuated AIMs score by 75% following l-DOPA challenge (p < 0.05). Chronic IEM 1460 treatment reversed L-DOPA-induced up-regulation of pre-proenkephalin-A, and normalised pre-proenkephalin-B mRNA expression in the lateral striatum, indicating an inhibition of both behavioural and molecular correlates of priming. These data suggest that Ca(2+)-permeable AMPA receptors are critically involved in both the induction and subsequent expression of LID, and represent a potential target for anti-dyskinetic therapies.

Topics: Adamantane; Animals; Antiparkinson Agents; Behavior, Animal; Benserazide; Brain; Calcium; Callithrix; Dyskinesia, Drug-Induced; Enkephalins; Levodopa; Male; Motor Activity; Oxidopamine; Parkinson Disease; Protein Precursors; Rats; Rats, Sprague-Dawley; Receptors, AMPA

The principal causative pathology of Parkinson disease is the progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta projecting to the striatum in the brain. The information regarding the expression of neuropeptides in parkinsonism is very limited. Here we have elucidated striatal neuropeptide mechanisms in experimental parkinsonism using the unilateral 6-hydroxydopamine model to degenerate dopamine neurons. A thoroughly controlled sample preparation technique together with a peptidomics approach and targeted neuropeptide sequence collections enabled sensitive detection, identification, and relative quantitation of a great number of endogenous neuropeptides. Previously not recognized alterations in neuropeptide levels were identified in the unilateral lesioned mice with or without subchronic 3,4-dihydroxy-L-phenylalanine administration, the conventional treatment of Parkinson disease. Several of these peptides originated from the same precursor such as secretogranin-1, somatostatin, prodynorphin, and cholecystokinin. Disease-related biotransformation of precursors into individual peptides was observed in the experimental model of Parkinson disease. Several previously unreported potentially biologically active peptides were also identified from the striatal samples. This study provides further evidence that neuropeptides take part in mediating the central nervous system failure associated with Parkinson disease.

Topics: Amino Acid Sequence; Animals; Cholecystokinin; Chromogranin B; Disease Models, Animal; Enkephalins; Mice; Molecular Sequence Data; Neostriatum; Oxidopamine; Parkinson Disease; Peptides; Postmortem Changes; Protein Precursors; Reproducibility of Results; Somatostatin; Tissue Extracts; Tyrosine 3-Monooxygenase

OFF-L-dopa dyskinesias have been a surprising side-effect of intrastriatal foetal ventral mesencephalic transplantation in patients with Parkinson's disease. It has been proposed that excessive and unregulated dopaminergic stimulation of host post-synaptic striatal neurons by the grafts could be responsible for these dyskinesias. To address this issue we transplanted foetal dopaminergic neurons from mice lacking the dopamine transporter (DATKO) or from wild-type mice, into a rat model of Parkinson's disease and L-dopa-induced dyskinesias. Both wild-type and DATKO grafts reinnervated the host striatum to a similar extent, but DATKO grafts produced a greater and more diffuse increase in extra-cellular striatal dopamine levels. Interestingly, grafts containing wild-type dopaminergic neurons improved parkinsonian signs to a similar extent as DATKO grafts, but provided a more complete reduction of L-dopa induced dyskinesias. Neither DATKO nor wild-type grafts induced OFF-L-dopa dyskinesias. Behavioural and receptor autoradiography analyses demonstrated that DATKO grafts induced a greater normalization of striatal dopaminergic receptor supersensitivity than wild-type grafts. Both graft types induced a similar downregulation and normalization of PEnk and fosb/Deltafosb in striatal neurons. In summary, DATKO grafts causing high and diffuse extra-cellular dompamine levels do not per se alter graft-induced recovery or produce OFF-L-dopa dyskinesias. Wild-type dopaminergic neurons appear to be the most effective neuronal type to restore function and reduce L-dopa-induced dyskinesias.

Topics: Animals; Antiparkinson Agents; Brain Tissue Transplantation; Corpus Striatum; Disease Models, Animal; Dopamine; Dopamine Plasma Membrane Transport Proteins; Dyskinesia, Drug-Induced; Enkephalins; Female; Fetal Tissue Transplantation; Gene Expression Regulation; Graft Survival; Levodopa; Mesencephalon; Microdialysis; Neurons; Parkinson Disease; Protein Precursors; Rats; Rats, Sprague-Dawley; Receptors, Dopamine D1; Receptors, Dopamine D2; Receptors, N-Methyl-D-Aspartate; RNA, Messenger

A real-time quantitative PCR approach was used to quantify mRNA levels corresponding to the neuropeptides enkephalin, dynorphin, and the 67-kDa isoform of glutamic acid decarboxylase (GAD67) in the human putamen from young and aged individuals as well as from aged patients affected by Parkinson's disease (PD). cDNA-specific primers were designed to amplify GAD67, proenkephalin (pENK), prodynorphin (pDYN), and the housekeeping genes glyceraldehydes-3-phosphate dehydrogenase (GAPDH) and guanine nucleotide binding protein, beta-peptide 2-like I (GNB2LI). GAPDH and GNB2LI mRNA levels were similarly expressed among the groups and were therefore used as endogenous reference genes. Normalized data showed that mRNA levels for both pENK and pDYN were reduced in the putamen of aged controls and aged individuals affected by PD, compared with young controls. In addition, we showed that GAD67 mRNA levels did not change during aging and PD. Further analyses showed no differences in mRNA levels, for pENK, pDYN, or GAD67 mRNA, between PD patients and aged matched controls. These findings contrast with animal models of parkinsonism, for which expression of pDYN, pENK, and GAD67 mRNA has been reported to change after striatal dopamine denervation. Compensatory mechanisms and regional differences within the human putamen as well as the severity index of the disease, clinical diagnosis, and response to phalmacological therapy are possible reasons for these results. The present study suggests that alteration of neuropeptide pathways in the human putamen may be involved in the functional deterioration of parts of the extrapyramidal system during aging.

Topics: Adult; Age Factors; Aged; Aged, 80 and over; Enkephalins; Female; Gene Expression Regulation; Glutamate Decarboxylase; Humans; Isoenzymes; Male; Middle Aged; Parkinson Disease; Postmortem Changes; Protein Precursors; Putamen; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

The effects of antisense FosB and CREB intra-striatum injection on the expression of prodynorphin (PDyn) gene in striatal neurons of Levodopa-induced dyskinesias (LID) rats with Parkinson disease (PD) were explored. PD model in rats was established by 6-OHDA microinjection stereotaxically. The rats were treated with chronic intermittent Levodopa celiac injection for 28 days to get the LID rats. Antisense FosB and cAMP response element-binding protein (CREB) were injected into striatum of all rats respectively. In situ hybridization was used to measure the changes in the expression of PDyn mRNA in striatum and behavior changes were observed. The results showed after administration of antisense FosB, abnormal involuntary movement (AIM) was decreased and the expression of PDyn mRNA in striatum was increased in LID rats as compared with sense FosB group (P<0.01, respectively). As compared with the control group, the expression of PDyn mRNA in striatum was decreased by antisense CREB-treated LID group (P<0.01) and compared with sense CREB treated LID group, antisense CREB-treated LID group showed no changes in AIM scores and the expressions of PDyn mRNA (both P>0.05). In conclusion, FosB protein, which replaced the CREG, could regulate the expression of PDyn mRNA and play critical role in the pathogenesis of LID.

Topics: Animals; Corpus Striatum; Cyclic AMP Response Element-Binding Protein; Dyskinesia, Drug-Induced; Enkephalins; Female; Levodopa; Neurons; Oligonucleotides, Antisense; Parkinson Disease; Protein Precursors; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; RNA, Messenger

Long-term treatment of Parkinson's disease with levodopa is compromised by the development of motor complications, including on-off fluctuations and involuntary movements termed dyskinesia. The neural mechanisms underlying treatment-related dyskinesias may involve underactivity of the output regions of the basal ganglia, i.e., the medial segment of the globus pallidus (GPm) and substantia nigra pars reticulata (SNR). Increased activity of GABAergic neurons of the "direct" striatopallidal pathway has been implicated in the suppression of the GPm and SNR and thus the development of dyskinesia. The direct pathway uses opioids as a co-neurotransmitter. These opioid peptides are products of the high-molecular weight opioid precursor pre-proenkephalin B (PPE-B). In situ hybridisation studies were employed to investigate PPE-B mRNA expression in postmortem striatal tissue from patients with a clinicopathological diagnosis of Parkinson's disease, all of whom displayed levodopa-induced motor complications, including dyskinesia prior to death and in the caudate-putamen (striatum) of the MPTP-lesioned macaque model of Parkinson's disease with treatment-related dyskinesia. Striatal PPE-B mRNA expression was significantly increased by 172% in dyskinetic Parkinson's disease patients compared to age-matched controls. This increase was heterogeneous with increased expression within the striosomes compared to matrix compartments of the striatum. Striatal PPE-B mRNA expression was significantly increased by 185% in the MPTP-lesioned macaque exhibiting dyskinesia, compared to parkinsonian, nondyskinetic MPTP-lesioned macaques, and by 146% compared to non-parkinsonian, nondyskinetic controls. Increased PPE-B mRNA expression, with subsequent elevations in opioid peptide transmission within the direct striatal output pathways, may underlie treatment-related dyskinesia in Parkinson's disease.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Aged; Aged, 80 and over; Animals; Antiparkinson Agents; Corpus Striatum; Disease Models, Animal; Dyskinesia, Drug-Induced; Enkephalins; Female; Humans; Macaca mulatta; Male; Parkinson Disease; Parkinsonian Disorders; Protein Precursors; RNA, Messenger

The expression of preproenkephalin messenger RNA was studied in the brain of Parkinson disease (PD) patients using in situ hybridization. All these patients were treated with levodopa (LD) and the development of motor complications was recorded. Eleven normal controls and 14 PD patients were used, of which 4 developed dyskinesias, 3 developed wearing-off, 3 developed both dyskinesias and wearing-off, and 4 developed no adverse effect following dopaminomimetic therapy. Nigrostriatal denervation was similar between the subgroups of PD patients as assessed using 125I-RTI-specific binding to the dopamine transporter and measures of catecholamine concentrations by HPLC. A significant increase of preproenkephalin messenger RNA levels was observed in the lateral putamen of dyskinetic patients in comparison to controls (+210%; p < 0.01) and in comparison to nondyskinetic patients (+112%; p < 0.05). No change was observed in medial parts of the putamen or in the caudate nucleus. No relationship between preproenkephalin messenger RNA levels and other clinical variables such as development of wearing-off, age of death, duration of disease, or duration of LD therapy was found. These findings suggest that increase synthesis of preproenkephalin in the medium spiny output neurons of the striatopallidal pathway play a role in the development of dyskinesias following long-term LD therapy in Parkinson disease.

Topics: Age Factors; Aged; Aged, 80 and over; Antiparkinson Agents; Caudate Nucleus; Dyskinesia, Drug-Induced; Enkephalins; Humans; In Situ Hybridization; Levodopa; Parkinson Disease; Protein Precursors; Putamen; RNA, Messenger; Statistics as Topic

The striatum is regulated by dopaminergic inputs from the substantia nigra. Several anatomical studies using in situ hybridization have demonstrated that in rodents, dopamine D1 and D2 receptors are segregated into distinct striatal efferent populations: dopamine D1 receptor into gamma-aminobutyric acid (GABA)/substance P striatonigral neurons, and dopamine D2 receptor into GABA/enkephalin striatopallidal neurons. The existence of such a segregation has not been investigated in primates. Therefore, to quantify the efferent striatal GABAergic neurons in the adult Cynomolgus monkey, we detected GAD67 mRNA expression while considering that only a minority of the GABAergic population is composed of interneurons. To characterize the peptidergic phenotype of the neurons expressing dopamine D1 or D2 receptors, we examined the mRNA coding for these receptors in the striatum at the cellular level using single- and double in situ hybridization with digoxigenin and 35S ribonucleotide probes. Double in situ hybridization demonstrated a high coexpression of dopamine D1 receptor and substance P mRNAs (91-99%) as well as dopamine D2 receptor and preproenkephalin A mRNAs (96-99%) in medium-sized neurons throughout the nucleus caudatus, putamen, and nucleus accumbens. Only a small subpopulation (2-5%) of the neurons that contained dopamine D1 receptor mRNA also expressed dopamine D2 receptor mRNA in all regions. Large-sized neurons known to be cholinergic expressed D2R mRNA. However, within the nucleus basalis of Meynert, the large cholinergic neurons expressed D2R mRNA, but the neurons producing enkephalin expressed neither D1R nor D2R mRNA. These results demonstrate that the striatal organizational pattern of D1 and D2 receptor segregation in distinct neuronal populations described in rodent also exists in primate.

Topics: Animals; Corpus Striatum; Enkephalins; Glutamate Decarboxylase; Isoenzymes; Macaca fascicularis; Neurons; Parkinson Disease; Phenotype; Protein Precursors; Receptors, Dopamine D1; Receptors, Dopamine D2; RNA, Messenger; Substance P

Loss of striatal dopamine has been associated with an increase in striatal enkephalin expression. However, the relationship between increased striatal enkephalin expression and the manifestation of parkinsonian motor deficits is not clear. Administration of MPTP to cats produces a severe parkinsonian condition from which the animals spontaneously recover. Using in situ hybridization histochemistry, preproenkephalin (PPE) mRNA expression was examined in the striatum of cats when normal, symptomatic for or spontaneously recovered from MPTP-induced parkinsonism. In all areas of the striatum, PPE mRNA levels were significantly elevated in animals exhibiting severe parkinsonian motor deficits and remained elevated even after recovery of gross motor functioning. These results show that striatal PPE gene expression and parkinsonian motor deficits are not directly correlated.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Behavior, Animal; Cats; Caudate Nucleus; Corpus Striatum; Dopamine Agents; Enkephalins; Female; Gene Expression; Male; Motor Activity; Parkinson Disease; Parkinson Disease, Secondary; Protein Precursors; Recovery of Function; RNA, Messenger

Common marmosets (Callithrix jacchus) with near-complete unilateral 6-hydroxydopamine denervation of the dopaminergic input received a single injection of saline or L-DOPA (15mg/kg plus 6.25mg/kg benserazide). Using in situ hybridization, the effects of these treatments on c-fos messenger RNA expression in the cerebral cortex, the striatal complex and the external layer of the pallidum were studied. Moreover, receptor autoradiography was used to determine the levels of dopamine D(1) and D(2) receptors in these areas. In the cerebral cortex, animals treated with L-DOPA displayed a high expression of c-fos messenger RNA restricted to the dopamine-denervated hemisphere. No changes in the levels of cortical D(1) and D(2) receptors were found in the dopamine-denervated hemisphere. L-DOPA treatment also induced a strong expression of c-fos messenger RNA in the striatal complex in the dopamine-denervated hemisphere. The levels of striatal D(2), but not D(1), receptors were increased in the dopamine-denervated hemisphere. In the external pallidum, the major terminal region for D(2) dopamine receptor-containing striatal projection neurons, L-DOPA treatment induced c-fos messenger RNA expression in both the intact and the dopamine-denervated hemispheres.Thus, using c-fos messenger RNA as a biochemical marker of postsynaptic neuronal activation, these results provide evidence that near-complete dopamine depletion causes a profound supersensitization to L-DOPA treatment in the cerebral cortex and in the striatal complex, but not in the external layer of the pallidum, of the primate brain. The cortical response may be unique to the primate brain, but c-fos messenger RNA activation within the striatum has also been reported in the rodent. The effects of L-DOPA probably depend both on a direct activation of supersensitized dopamine receptors by dopamine produced in the few remaining, but hyperactive, dopaminergic nerve terminals and in serotonergic nerve terminals, as well as on indirect actions of L-DOPA related to activation of circuitries connecting cerebral cortex and basal ganglia structures. These results provide novel information on the mechanisms underlying L-DOPA's action in the cerebral cortex, striatum and external pallidum in a primate model of Parkinson's disease.

Topics: Animals; Benzazepines; Blotting, Western; Callithrix; Cerebral Cortex; Corpus Striatum; Denervation; Disease Models, Animal; Dopamine; Dopamine Agents; Dopamine Antagonists; Enkephalins; Gene Expression; Genes, Immediate-Early; Levodopa; Nerve Degeneration; Oxidopamine; Parkinson Disease; Protein Precursors; Proto-Oncogene Proteins c-fos; Raclopride; Radioligand Assay; Receptors, Dopamine D1; Receptors, Dopamine D2; RNA, Messenger; Substance P; Substantia Nigra; Sympatholytics; Tritium

Many studies have previously described changes in preproenkephalin-A (PPE-A) and preproenkephalin-B (PPE-B) gene expression in the striatum of the 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (both with or without dopamine replacement treatment). To date, these studies have either taken the striatum as a whole or have focused on a single subregion of the striatum. However, the striatum is organized into anatomically discrete parallel circuits serving different functions (motor, associative, and limbic). We have therefore employed in situ hybridization to examine the detailed topography of changes in opioid precursor expression following dopamine depletion and subsequent treatment with apomorphine (5 mg/kg twice daily for 10 days). In the untreated 6-OHDA-lesioned striatum PPE-A expression was elevated only in the dorsal (sensorimotor) caudate-putamen. Following apomorphine treatment PPE-A mRNA levels were further raised in the sensorimotor striatum (

Topics: Animals; Apomorphine; Brain; Caudate Nucleus; Disease Models, Animal; Enkephalins; Gene Expression Regulation; In Situ Hybridization; Male; Motor Activity; Nucleus Accumbens; Organ Specificity; Oxidopamine; Parkinson Disease; Protein Precursors; Putamen; Rats; Rats, Sprague-Dawley; Reference Values; Time Factors

Gamma-aminobutyric acid (GABA)/substance P (SP) neurons and GABA/enkephalin (Enk) neurons in the striatum exert opposing influence on the regulation of movement. The loss of GABA/SP neurons results in hypokinetic disorders (parkinsonism), whereas the loss of GABA/Enk neurons results in hyperkinetic disorders (e.g. chorea). The present study determined age-related changes in the beta-preprotachykinin (the precursor of SP) and preproenkaphalin (the precursor of Enk) messenger RNA (mRNA) ratio in the postmortem human putamen using the reverse transcription-polymerase chain reaction (RT-PCR). The ratio of beta-preprotachykinin to preproenkephalin mRNA expression decreased with age. The reduction in the beta-preprotachykinin/preproenkephalin mRNA ratio was more marked in cases with multiple small infarcts (status lacunaris) in the putamen. These findings may in part explain the susceptibility of the elderly, particularly of those with ischemic changes in the striatum to hypokinetic disorders.

Topics: Adult; Aged; Aged, 80 and over; Aging; Cerebral Infarction; Disease Susceptibility; Enkephalins; Female; Humans; Linear Models; Male; Middle Aged; Parkinson Disease; Polymerase Chain Reaction; Protein Precursors; Putamen; RNA, Messenger; Tachykinins; Transcription, Genetic

Striatal expression of preproenkephalin and preprotachykinin messenger RNA was studied in normal controls and in patients with Parkinson's disease using in situ hybridization histochemistry. In controls, preproenkephalin messenger RNA was expressed in a population of medium-sized neurons of mean cross-sectional area 165 microns 2, accounting for 66% of striatal medium-sized neurons, whereas preprotachykinin messenger RNA was expressed in a population of medium-sized neurons of mean cross-sectional area 204 microns 2 (23% larger than those expressing enkephalin, P < 0.05), accounting for 58% of medium-sized striatal neurons. Much lower levels of both preproenkephalin messenger RNA and preprotachykinin messenger RNA were expressed by large neurons in the globus pallidus and substantia nigra reticulata. In addition, preproenkephalin messenger RNA was expressed at low levels by neurons in the subthalamic nucleus. In Parkinson's disease cases, there was a statistically significant increase in preproenkephalin messenger RNA expression in the body of the caudate (109% increase, P < 0.05) and in the intermediolateral putamen (55% increase, P < 0.05) due to an increase in the level of gene expression per neuron rather than an increase in the number of neurons expressing preproenkephalin messenger RNA. Similar increases were observed in other putaminal subregions and in the putamen as a whole, but these did not reach statistical significance. No change in preprotachykinin messenger RNA expression was detected. These findings demonstrate selective up-regulation of a striatal neuropeptide system in Parkinson's disease compatible with increased activity of the "indirect" striatopallidal pathway, which is thought to play a crucial role in the pathophysiology of akinesia and rigidity in this condition.

Topics: Adult; Aged; Aged, 80 and over; Autoradiography; Basal Ganglia; Dopamine Agents; Enkephalins; Female; Gene Expression; Humans; Levodopa; Male; Middle Aged; Neostriatum; Parkinson Disease; Protein Precursors; RNA, Messenger; Sensitivity and Specificity; Tachykinins

When measured in postmortem parkinsonian brains, dynorphin levels were unchanged, as compared to control brains, in mesencephalic, striatal and corticolimbic areas. A significant reduction in Leu5-enkephalin and Met5-enkephalin levels had been previously observed in the pallidum and putamen whereas only Met5-enkephalin concentrations were decreased in the substantia nigra of parkinsonian brains. These data suggest that L-Enk could be generated either from proenkephalin A in the striatal areas or from prodynorphin in the nigral areas.

Topics: Aged; Brain; Brain Chemistry; Dynorphins; Enkephalin, Leucine; Enkephalin, Methionine; Enkephalins; Humans; Parkinson Disease; Protein Precursors