[Tyrosine hydroxylase-immunohistochemical study in the midbrain of experimental MPTP parkinsonism]

We have performed tyrosine hydroxylase (TH)-immunohistochemical study in the midbrain of experimental MPTP parkinsonism. Eight female adult crab-eating monkeys (macaca fascicularis) were subjected to the experiment and divided into four groups. In the acute experimental parkinsonism (group A), a daily dose of 1.3 mg/kg MPTP was given intravenously for 7 days. Monkeys in the subacute group B were injected every other day a dose of 1.0 mg/kg MPTP intravenously for 7-14 days. Chronic experimental parkinsonism group C was induced by administration of a dose of 0.5 mg/kg twice a week intravenously for 120 days. Group D served as a control. TH-immunoreactive cells were counted in substantia nigra pars compacta (SNc: consisting of lateral, intermediate, medial regions) and paramedian region of midbrain. The remaining TH-immunoreactive cells in group A,B and C were approximately 65.1%, 46.6% and 32.1% of the control group D. The ratio of TH-immunoreactive cells in the lateral region of group A, B and C was lower than in group D. The TH-immunoreactive ratio in the intermediate and medial region of group B and C was lower than in group D. In the medial region of group C, the TH-immunoreactive ratio was increased than in group B. In the paramedian region of all groups, there was no significant differences in the ratio of TH-immunoreactive cells, but many more TH-immunoreactive nerve fibers were observed in group B and C than in group A and D. From the 90th day after MPTP treatment, monkeys in group C began to show a gradual recovery from the flexed posture and hypokinesia.(ABSTRACT TRUNCATED AT 250 WORDS)