Effects of growth hormone-releasing factor and somatostatin on growth hormone secretion and cellular cyclic AMP levels. Cultured ovine and rat anterior pituitary cells show markedly different responses.
Human pancreatic growth hormone-releasing factor (GRF-44-NH2) stimulated growth hormone (GH) secretion and intracellular cyclic AMP levels in cultured pituitary cells from both sheep and rat. Somatostatin (SRIF), over a wide range of doses and time, showed no significant effect on the elevated cyclic AMP levels in sheep cells, but did block the GH release in a dose-dependent manner. In rat cells, however, SRIF inhibited GRF-stimulated cyclic AMP levels by 75% maximum (still 8-fold greater than the basal levels) and GH release to almost half the basal value. We conclude that somatostatin inhibits GRF-elevated cyclic AMP levels in rat pituitary cells but not in sheep cells.
Law
G J
GJ
Ray
K P
KP
Wallis
M
M
D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012756:Sheep; D013004:Somatostatin / Q000494:pharmacology*; D013045:Species Specificity
D013004:Somatostatin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D000242:Cyclic AMP