Evidence for a single glucocorticoid regulated pool of adrenocorticotropin in sheep anterior pituitary.
The goal of this study was to determine whether separate glucocorticoid-sensitive releasable pools of adrenocorticotropic hormone (ACTH) could be distinguished in sheep anterior pituitary cells. Isolated cells were cultured in serum-free medium containing 0-10 nM cortisol (F) for 7-11 days to determine whether variation in the glucocorticoid environment selectively affected ACTH release stimulated by corticotropin-releasing hormone (CRH) or arginine vasopressin (AVP). Secretion was studied using a microperifusion system. The results indicated that while the concentration of F in the medium bathing the cells profoundly influenced the magnitude of ACTH released in response to either peptide, the fractional release of total ACTH was unchanged. F concentration in culture medium similarly did not alter the negative-feedback effectiveness of a larger dose of F applied to cells 45 min before treatment with CRH or AVP. These results support the existence of a single glucocorticoid-sensitive pool of ACTH in corticotrophs.
Kemppainen
R J
RJ
Department of Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Alabama 36849.
Clark
T P
TP
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002478:Cells, Cultured; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D016895:Culture Media, Serum-Free; D005246:Feedback; D005938:Glucocorticoids / Q000494:pharmacology*; D006854:Hydrocortisone / Q000494:pharmacology; D008297:Male; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D012756:Sheep
D016895:Culture Media, Serum-Free; D005938:Glucocorticoids; D001127:Arginine Vasopressin; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D006854:Hydrocortisone