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Neuropharmacology. 2003 Sep;45(4):484-92.

Neuroprotective action of MPEP, a selective mGluR5 antagonist, in methamphetamine-induced dopaminergic neurotoxicity is associated with a decrease in dopamine outflow and inhibition of hyperthermia in rats.

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Department of Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Cracow, Poland.


The aim of this study was to examine the role of metabotropic glutamate receptor 5 (mGluR5) in the toxic action of methamphetamine on dopaminergic neurones in rats. Methamphetamine (10 mg/kg sc), administered five times, reduced the levels of dopamine and its metabolites in striatal tissue when measured 72 h after the last injection. A selective antagonist of mGluR5, 2-methyl-6-(phenylethynyl)pyridine (MPEP; 5 mg/kg ip), when administered five times immediately before each methamphetamine injection reversed the above-mentioned methamphetamine effects. A single MPEP (5 mg/kg ip) injection reduced the basal extracellular dopamine level in the striatum, as well as dopamine release stimulated either by methamphetamine (10 mg/kg sc) or by intrastriatally administered veratridine (100 microM). Moreover, it transiently diminished the methamphetamine (10 mg/kg sc)-induced hyperthermia and reduced basal body temperature. MPEP administered into the striatum at high concentrations (500 microM) increased extracellular dopamine levels, while lower concentrations (50-100 microM) were devoid of any effect. The results of this study suggest that the blockade of mGluR5 by MPEP may protect dopaminergic neurones against methamphetamine-induced toxicity. Neuroprotection rendered by MPEP may be associated with the reduction of the methamphetamine-induced dopamine efflux in the striatum due to the blockade of extrastriatal mGluR5, and with a decrease in hyperthermia.

[Indexed for MEDLINE]

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