Various in vivo and in vitro pituitary lactotropic and gonadotropic functions were measured in mature (6-7 mo, normally cycling) and old (24 mo, constant diestrus) female Wistar rats. Serum prolactin (PRL) levels were higher (P < 0.001), whereas luteinizing hormone (LH) values were similar (P > 0.05) in old versus mature rats both before and 3 days after ovariectomy. Serum PRL levels decreased significantly (P < 0.005) postovariectomy only in the mature rats. The in vitro release of PRL and LH was measured for 4 days in primary adenohypophyseal cell cultures from the ovariectomized rats. Both basal and 17β-estradiol (E2)-stimulated PRL release (P < 0.001) and production (P < 0.005) were greater by cells from old rats. In contrast, both basal release and E2-stimulated LH release were greater (P < 0.001) by cells from mature rats. Peak PRL release by cells from both old and mature rats occurred after exposure to E2 doses 1/100th of those required for peak LH release. These data support the hypothesis that intrinsic derangements in anterior pituitary function contribute to the reproductive decline in aging female rats and that different pituitary cell types exhibit discordant age changes in estrogenic sensitivity.
|Original language||English (US)|
|Journal||American Journal of Physiology - Endocrinology and Metabolism|
|State||Published - Jan 1 1984|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Physiology (medical)