Mitochondrial abnormalities in nigral neurons of the marmoset and Macaca fascicularis treated with MPTP.

In a previous study we observed the processes determining the cellular death in nigral neurons of Macaca fascicularis and common Marmoset treated with MPTP. The purpose of this study is to consider, in substantia nigra neurons of the same animals, mitochondrial abnormalities caused by neurotoxin. Three Macaca fascicularis and 5 common Marmosets, respectively treated with 3 and 4 mg/kg of MPTP dissolved in saline + 10% ethanol, were suppressed by means of an i.v. injection phenobarbital. The substantia nigra, isolated from the mesencephalon, has been examined under Electron Microscope. Different mitochondrial abnormalities have been observed in nigral neurons: crystal abnormalities occur more frequently than other alterations. They are correlated with various degrees of mitochondrial enlargement. Dissolution of the matrix induces formation of spherical highly electron-dense inclusions of various volume and in different number; they are probably lipoprotein. Laminar bodies and myelin-like figures are determined by alterations of the external membrane. Particular roundish organules, placed near normal mitochondria, are limited by fragments of membrane with a granular material, occasionally flowing in the cytoplasm. The biochemical hypothesis concerning the genesis of the observed abnormalities is discussed in the present study.