Regulation of brain aromatase activity in rats.

We studied the distribution and regulation of aromatase activity in the adult rat brain with a sensitive in vitro assay that measures the amount of 3H2O formed during the conversion of [1 beta-3H]androstenedione to estrone. The rate of aromatase activity in the hypothalamus-preoptic area (HPOA) was linear with time up to 1 h, and with tissue concentrations up to 5 mgeq/200 microliters incubation mixture. The enzyme demonstrated a pH optimum of 7.

Cytoplasmic progesterone receptors in the hypothalamus-preoptic area of the mouse: effect of estrogen priming.

A synthetic progestin, R5020, was used to identify cytoplasmic progestin receptors in the hypothalamuspreoptic area (HPOA) of ovariectomized mice. These high-affinity receptors exhibited an apparent dissociation constant of approx. 1 nM.