Circadian changes in norepinephrine turnover in rats following administration of estrogen

Abstract

1. Circadian changes in norepinephrine (NE) turnover were found in 4-month-old rats following administration of estrogen. 2. In the hypothalamus NE turnover occurred in the late-dark period only in mestranol-treated rats. 3. At the late-dark and early-light phases NE turnover was found to occur in the cerebellum of control rats, but was not found in mestranol-treated rats at these times nor in the mid-light period. 4. Following estrogen treatment adrenal NE turnover was discovered at early- and mid-light phases. 5. Cardiac NE turnover was not found to occur in mestranol-treated rats at any of the three times sampled.