Functional changes in luteinizing hormone-secreting cells from pre- and postpartum ewes
Wise, M.E.; Sawyer, H.R.; Nett, T.M.
American Journal of Physiology 250(3 Pt 1): E282-E287
1986
ISSN/ISBN: 0002-9513 PMID: 3513614 Document Number: 284312
Pituitaries collected from ewes on days 50 and 140 of gestation and on days 2, 13, 22 and 35 after parturition were enzymatically dissociated and the resulting cells were cultured in media containing oestradiol (12 pg/ml), cortisol (12 ng/ml) or no steroid (controls). After 4, 7 or 10 days of culture, cells were washed and basal LH, GnRH-stimulated release of LH, and cellular content of LH were determined. The content of LH (ng per 106 cells) was lowest on day 140 of gestation (2.7+or-0.3) and day 2 post partum (2.2+or-0.6), and then increased (P<0.05) to 36.6+or-8.3, 59.9+or-14.4 and 54.6+or-19.3 on days 13, 22 and 35 post partum resp. The percentage of pituitary cells containing immunoreactive LH nearly doubled (P<0.05) between days 2 (5.6+or-0.2%) and 35 (10.6+or-1.1%) post partum. Moreover, LH-containing cells were smaller, and the percent total cellular volume occupied by secretory granules was less on day 2 than on days 22 and 35 after parturition. Secretion of LH after 4, 7 or 10 days of culture reflected the cellular content of LH, and was not influenced by the presence of steroids in the media. These data indicate that decreased synthesis of LH during gestation is associated with hypoplasia of the LH-secreting cells. These cells are reactivated during the postpartum period, and their capacity to synthesise LH gradually returns to normal.