Abstract
The role of the mechanism of the hypothalamus in the regulation of the reproductive function in rats has been investigated from the view point of the monoamine oxidase activity in the brain. Coincidentally with the estrous cycle, the enzyme activity in the hypothalamus, especially in its posterior part, showed cyclic fluctuation. Cyclic changes in the hypothalamus were characterized by the proestrous elevation in monoamine oxidase activity and the proestrous and estrous depression in choline acetylase activity. Following castration, the monoamine oxidase activity in the hypothalami of female rats showed a temporary decrease in the anterior part at the earlier stages after castration and, thereafter, a marked increase in both the anterior and posterior parts. The reciprocal relationship of the enzyme activities between monoamine oxidase and choline acetylase was also observed in the hypothalamus after castration. These data support the concept that acetylcholine and catecholamine or serotonin metabolism in the hypothalamus play an important role in the neural control of ovulation.
