Adrenergic activity in hypothalamus and ovulation.

PIP: The turnover of norepinephrine (NE) and its synthesis in the hypothalamus in rats just prior to and subsequent to ovulation was studied. Hypothalamic NE concentration in proestrus (preovulatory) was higher than in estrus rats (3.48 plus or minus) .09 mcg/gm vs. 2.13 plus or minus .04 mcg/gm). When methylester hydrochloride (MPT), a blocker of catecholamine biosynthesis, was injected, proestrus rats NE dropped 62% vs. estrus rats' drop of 28.6%. Tritiated NE injected to show synthesis rates showed a higher rate of NE synthesis produced in the hypothalamus during proestrus vs. estrus. In addition there was an increase in NE levels between diestrus Day 2 and proestrus localized to the anterior and middle hypothalamus.^ieng