MPTP decreases MT-I mRNA in mouse striatum.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a drug that induces parkinsonism in humans and non-human primates. Free radicals are thought to be involved in its mechanism of action. Recently, metallothionein has been proposed to play a role as a scavenger of free radicals. In the present work, we studied the effect of MPTP neurotoxicity on brain metallothionein-I (MT-I) mRNA expression. Male C-57 black mice were treated with MPTP (30 mg/kg, i.p., daily) for 3 or 5 days. All animals were killed by cervical dislocation 7 days after the last MPTP dose. The brains were removed quickly and immediately frozen, and quantitative in situ hybridization was performed using MT-I cDNA probe. MT-I mRNA content in striatum, a region which is known to be highly predisposed and sensitive to MPTP-induced oxidative stress, decreased by 30% (3 days) and 39% (5 days) respectively, after the last MPTP administration. These results suggest that MT-I gene expression is decreased in MPTP neurotoxicity. It is suggested that the reduction of MT, an anti-oxidant and a free radical scavenger, in the striatum by MPTP enables the neurotoxin to exert maximal oxidative damage to the striatum.