MPTP-induced parkinsonian model in mice: biochemistry, pharmacology and behavior.

The effects of MPTP administered to mice were examined biochemically and pharmacologically. The dopamine level in the striatum of the mice injected with MPTP decreased markedly, but recovered to 50% of the control level 6 weeks later. Amine fluorescence showed a decrease in the amount of amine especially in the lateral part of the striatum. Of the four neuropeptides, only the concentration of somatostatin changed with time. These findings indicate that the time elapsed after MPTP treatment should be taken into consideration when MPTP-treated mice are used as a parkinsonism model. Six weeks after MPTP treatment, the concentration of the striatal muscarinic cholinergic receptor decreased significantly but recovered to the normal level after the administration of L-dopa. Such a change was not detected with the dopamine D2-receptor. The therapeutic efficacy of medication in MPTP-treated mice as examined by the pole test showed that L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS), which is considered to be the precursor of norepinephrine, enhances the effect of L-dopa.