Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The toxin N-methyl-1,2,3,6-tetrahydropyridine produces a model of neural degeneration very similar to idiopathic Parkinson disease. To understand the cellular mechanisms that modulate susceptibility to its active metabolite N-methyl-4-phenylpyridinium (MPP+), we have transfected a cDNA expression library from the relatively MPP(+)-resistant rat pheochromocytoma PC12 cells into MPP(+)-sensitive Chinese hamster ovary (CHO) fibroblasts. Selection of the stable transformants in high concentrations of MPP+ has yielded a clone extremely resistant to the toxin. Reserpine reverses the resistance to MPP+, suggesting that a transport activity protects against this form of toxicity, perhaps by sequestering the toxin within an intracellular compartment. In support of this hypothesis, dopamine loaded into the CHO transformant shows a localized distribution that is distinct from the pattern observed in wild-type cells and is also reversed by reserpine.
 ...
PMID:Gene transfer of a reserpine-sensitive mechanism of resistance to N-methyl-4-phenylpyridinium. 140 4

Epinephrine and norepinephrine-containing chromaffin cells proliferate in the adrenal glands of normal adult rats throughout life. Moreover, their rate of proliferation is markedly increased by short-term administration of reserpine, one of many agents which in long-term experiments are associated with the development of adrenal medullary tumors. Current data suggest that chromaffin cell proliferation in the adult rat adrenal is mediated by the interaction of neurogenic and hormonal signals. Reserpine is known to directly deplete catecholamine stores, and to reflexively increase the activity of the splanchnic nerve endings innervating the adrenal medulla to stimulate both secretion and synthesis of catecholamines and other secretory granule constituents. Its effect on chromaffin cell proliferation suggests that the same signals may regulate chromaffin cell number to meet physiological needs. The reserpine model might shed light on signal transduction mechanisms which normally promote or prevent proliferation of chromaffin cells and of other neuroendocrine cells during development or in adult life, and on ways in which such mechanisms are altered in the course of the development and progression of tumors. It also suggests the possibility that chromaffin cells might be propagated in vitro for use in basic biological studies or in transplants for the treatment of Parkinson's disease.
 ...
PMID:Chromaffin cell proliferation in the adult rat adrenal medulla. 281 83

Delta-9-tetrahydrocannabinol (THC), a substance in marihuana, was found to produce a profound potentiation of reserpine-induced hypokinesia in rats as measured with a bar test. In these experiments, THC had no hypokinetic effect by itself but produced a more than 20-fold increase in the hypokinesia produced by reserpine. Reserpine-induced hypokinesia has been viewed as animal model of Parkinson's Disease. THC potentiation of reserpine-induced hypokinesia was observed to be both time- and dose-dependent (1 to 10 mg/kg THC). When administered by gavage to reserpine-pretreated subjects (7.5 mg/kg IP, 24 hours before), THC produced a potentiation of hypokinesia that developed fully within 1 hour, lasted at least 5 hours, and was absent by 12 hours after THC administration. This THC effect was slightly increased by physostigmine, a cholinesterase inhibitor, relatively unaffected by scopolamine, a muscarinic antagonist, and almost completely blocked by ethopropazine, an anticholinergic antiparkinson drug. The effect was completely unaffected by naloxone. Insofar as reserpine has been used with some clinical efficacy in hyperkinetic movement disorders such as Huntington's disease and tardive dyskinesia, it may be that potentiation of reserpine's hypokinetic effect by a drug such as THC could greatly increase the clinical value of reserpine or related drugs in the treatment of these disorders.
 ...
PMID:Tetrahydrocannabinol potentiates reserpine-induced hypokinesia. 627 40

Though depletion of CSF homovanillic acid (HVA) concentration has often been regarded as a direct indicator of dopamine (DA) deficiency in Parkinson's Disease (PD), CSF HVA is normal in mildly affected patients. To explore why, we measured DA and its metabolites in striatum and CSF in rabbits receiving reserpine for 5 days. Reserpine, which depletes striatal DA by disrupting vesicular storage of the neurotransmitter, results in a compensatory increase of DA turnover. In response to a 96% depletion of striatal DA, its catabolic intermediates 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxytyramine (3-MT) decreased 64% and 92% in striatum, although the endproduct, HVA, was unchanged. In contrast, CSF concentrations of HVA and DOPAC increased significantly, though 3-MT and levodopa (LD) were unaltered. A 5-fold rise in striatal LD concentration after reserpine-induced DA depletion provided evidence for enhanced DA synthesis. As in PD, the compensatory increase of DA synthesis after reserpine administration confounds the ability of CSF HVA to reflect DA depletion.
 ...
PMID:Markers of dopamine depletion and compensatory response in striatum and cerebrospinal fluid. 760 89

MK-801, a non-competitive antagonist of NMDA receptors, is known to exhibit a beneficial action in many animal models of Parkinson's disease. The aim of this study was to examine the influence of MK-801 on the reserpine-induced muscle rigidity. The rigidity was estimated by a direct mechanomyographic method. This method consists in successive bending and straightening of a rat's hind foot in the ankle joint and measuring the resistance of the foot to passive movements. Reserpine in doses of 5-10 mg/kg ip, given alone or in combination with alpha-methyl-p-tyrosine (alpha MT, 250 mg/kg ip), induced rigidity. The strongest muscle rigidity was induced by 10 mg/kg of reserpine 1 hour after administration. MK-801 (0.32-1.28 mg/kg sc) injected 70 min after reserpine (10 mg/kg ip) decreased the rigidity induced by the latter compound. Similarly, MK-801 (1.28 mg/kg sc), administered 27 h 40' after joint treatment with reserpine (10 mg/kg ip) and alpha MT (250 mg/kg ip), strongly inhibited the reserpine-induced muscle rigidity. The obtained results show that the glutamatergic hyperactivity plays a significant role in the reserpine-induced rigidity. As the reserpine-induced motor disturbances are commonly accepted to be an animal model of parkinsonian symptoms, it may be assumed that the NMDA receptor blocking component may contribute substantially to the therapeutic action of antiparkinsonian drugs.
 ...
PMID:Antiparkinsonian action of MK-801 on the reserpine-induced rigidity: a mechanomyographic analysis. 771 Jun 66

The effects of amantadine, its dimethyl derivative, memantine and the chemically unrelated compound bifemelane were tested for antidepressant activity. Reserpine-induced hypothermia and the forced swim test (Porsolt test) were selected for this purpose. In the former test amantadine and bifemelane but not memantine were effective. In the forced swim test all three agents produced antidepressive-like activity (decreased immobility time), but in case of bifemelane it was less pronounced. The effect in the forced swim test was specific i.e. it was apparently not the result of an increase in general activity as evidenced by control experiments in the open field. The mechanism of amantadine and memantine action may involve indirect dopaminomimetic activity resulting from the blockade of NMDA receptors. However in reserpine-induced hypothermia this explanation is not valid considering the lack of effect of memantine and positive action of amantadine. Hence, amantadine may have an additional central sympathomimetic action that memantine is lacking. Bifemelane antidepressant-like activity might be attributed to an enhancement of noradrenergic transmission. We suggested that amantadine and bifemelane could be particularly useful therapeutically when depressive symptoms are present in patients suffering from Parkinson's disease and dementia.
 ...
PMID:Potential antidepressive properties of amantadine, memantine and bifemelane. 836 50

The substantia nigra has one of the highest levels of ATP-sensitive K+ channel in the brain. Since this channel is controlled by cell metabolism, the aim of this study was to see how closely it is associated with nigral dopamine systems, which are decreased in Parkinson's disease. In a sub-population of neurons within the rostral substantia nigra pars compacta of the guinea-pig, a brief period of hypoxia resulted in a tolbutamide (100-500 microM) sensitive hyperpolarisation [input resistance (IR) decrease from 144.88 +/- 14.04 M omega pre-hypoxia to 105.91 +/- 13.25 M omega during hypoxia]. Maximal blockade of this decrease was seen in presence of 500 microns tolbutamide [IR decrease only from 161.35 +/- 32.82 M omega to 155.02 +/- 34.29 M omega]. Reserpine (which depletes dopamine stores) but not alpha-methyl-para-tyrosine (which decreases de novo synthesis of dopamine) caused a marked attenuation of this hyperpolarisation [IR decrease only from 163.32 +/- 44.42 M omega pre-hypoxia to 154.42 +/- 50.97 M omega during hypoxia]. This observation suggests that blockade of dopamine storage, but not of de novo synthesis, leads to a loss of responsiveness of certain mid-brain neurons to hypoxia, rendering them potentially more susceptible to subsequent degeneration. The possible link between nigral dopamine systems and ATP-sensitive K+ channels is discussed.
 ...
PMID:Blockade of dopamine storage, but not of dopamine synthesis, prevents activation of a tolbutamide-sensitive K+ channel in the guinea-pig substantia nigra. 887 Oct 95

The ability of anticholinergic agents microinjected into the subthalamic nucleus to reduce reserpine-induced muscular rigidity was assessed in rats. The electromyographical activity of the gastrocnemius-soleus muscle was used as a parameter of muscular rigidity. Reserpine (5 mg/kg i.p.) produced the appearance of electromyographical activity. The muscarinic antagonists M3 (1.27 nmol of 4-DAMP) and M1 (2.36 nmol of pirenzepine) markedly reduced the reserpine-induced electromyographical activity, whereas the M2 antagonist AFDX-116 (2.37 nmol) had no effect. These results suggest that a high cholinergic tone in the subthalamic nucleus is associated with the reserpine-induced muscular rigidity. Moreover, the M3 muscarinic antagonist is more effective than the M1 muscarinic antagonist in reducing the muscular rigidity in reserpinized rats, a model of Parkinson's disease, by blocking the high cholinergic tone in the subthalamic nucleus.
 ...
PMID:Muscarinic antagonists microinjected into the subthalamic nucleus decrease muscular rigidity in reserpinized rats. 887 38

The significance of guanine nucleotides and nucleosides in neurodegenerative disorders is suggested by recent reports that these molecules enhance neurite branching and astrocyte proliferation. The objective of this study was to investigate the influence of increased dopamine metabolism, produced by 5-day treatment of rabbits with reserpine (2 mg/kg) or levodopa (LD) (50 mg/kg), on striatal concentrations of guanosine, guanine, and their metabolites. Reserpine treatment decreased striatal guanosine by 41% and increased guanine by 50%, while LD decreased guanosine by 48% (all p < 0.01 vs. vehicle-treated controls). LD also increased guanine by 22% (not statistically significant). Xanthine and uric acid concentrations were unchanged. Because of the neurotrophic properties of guanosine and guanine, changes in striatal concentrations of these purines secondary to increased dopamine (DA) turnover may have relevance for survival of remaining dopaminergic neurons in Parkinson's disease (PD).
 ...
PMID:Altered guanosine and guanine concentrations in rabbit striatum following increased dopamine turnover. 951 Apr 22

We studied effects of L-dihydroxyphenylalanine (L-DOPA) treatment in rats following reserpine treatment or unilateral 6-hydroxydopamine (6-OHDA) injections into medial forebrain bundle. Quantitative in situ hybridization for mRNA's coding for the zinc finger immediate early gene (IEG) zif/268 or Jun family IEG jun b revealed that single L-DOPA injections accentuated IEG expression 3- to 7-fold in the dopamine (DA)-depleted striatum. This increased IEG response did not derive from any alterations in DA receptor-G protein coupling, assayed by DA stimulation of 35S-guanosine-5' (gamma-thio) triphosphate (35S-GTP-gamma-S) binding to striatal sections. Reserpine treatment increased both basal and maximal striatal DA-stimulated 35S-GTP-gamma-S binding. The augmented IEG responses to single L-DOPA treatments involved dependency on both D1 and D2 receptors and acutely to N-methyl-D-aspartate (NMDA) channels. Repetitive L-DOPA treatments yielded persistently elevated (zif/268) or additionally up-regulated (jun b) IEG response in the denervated striatum and down-regulated IEG responses in the control striatum. Degraded L-DOPA responses and appearance of involuntary movements after chronic L-DOPA use in advanced Parkinson's disease may derive from these IEG changes.
 ...
PMID:Effects of single and multiple treatments with L-dihydroxyphenylalanine (L-DOPA) on dopamine receptor-G protein interactions and supersensitive immediate early gene responses in striata of rats after reserpine treatment or with unilateral nigrostriatal lesions. 989 Apr 35


1 2 3 Next >>