Increased cytochrome oxidase activity of mesencephalic neurons in developing rats displaying methylmercury-induced movement and postural disorders.

Abstract

Subcutaneous administration of the neurotoxin methylmercuric chloride to developing rats produced movement and postural disorders during the 4th postnatal week. Cytochrome oxidase histochemistry revealed an increase in the oxidative metabolic activity of small neurons within the magnocellular red nucleus (RMC) and the interrubral mesencephalon. A concurrent suppression of cytochrome oxidase activity in the large neurons and neuropil of RMC was apparent relative to controls. Decortication on postnatal day 3 did not alter the course of motor impairment or the cytochrome oxidase histopathology, suggesting that the role of neocortex in the pathogenesis of methylmercury-induced movement and postural disorders is minimal.