Histofluorescence studies of monoamine neurons in the rat brain after cobaltous acetate intoxication.

The aim was to study changes in brain monoamine neurons in an experimental animal model with an extrapyramidal motor syndrome of the parkinsonian type. The neurological signs were observed in rats after acute cobaltous acetate intoxication under mild ischemic conditions. Histofluorescence studies showed a decrease in catecholamine fluorescence (which signifies a decrease in the amine content) in the hypothalamus and mesencephalic reticular formation, but not in the substantia nigra or basal ganglia. Serotonin fluorescence was increased in nerve cell bodies of the dorsal and median raphe nuclei and in nerve terminals in some thalamic and preoptic regions. Histological staining of sections adjacent to the fluorescent ones showed no neuronal loss and some pathology of myelin. The disturbing effect of cobaltous ions on the neuronal transmission, and/or the imbalance between dopamine and serotonin in the extrapyramidal motor syndrome observed in poisoned rats have been discussed.