[Hypothalamic monoamines in the postnatal ontogeny of rats]

The purpose of the paper is to study sex differences in the level of monoamines in the nuclei of the preoptic area and in the mediobasal hypothalamus during pubescence of rats, and the influence of female neonatal androgenization and castration of male animals on the monoaminergic cerebral system. Experiments were staged on males and females aged 3, 5, 7, 10, 20, 30, and 60 days. The histochemical technique was used to reveal sex differences in the fluorescence of monoamines on the 5th day of the life. The intensity of monoamine fluorescence in neonatally castrated males was lower than that in controls. Neonatal androgenization of females caused a sharp rise of the intensity of monoamine fluorescence in all the investigated nuclei on days 3, 5, 7, and in the arcuate nucleus on day 10. The rise was followed by a decrease in monoamine fluorescence in all the nuclei below the control level. It was only on day 60 that a repeated rise of the intensity of monoamine fluorescence was noted in the preoptic medial and arcuate nucleus; differences in the preoptic lateral nucleus were not statistically significant.