Modulation of growth hormone-releasing factor-induced release of growth hormone from bovine pituitary cells.
Growth hormone (GH)-releasing factor (GRF) at concentrations of 10(-12) through 10(-7) M for 6 hr linearly increased GH release (b1 = 10.4 +/- .3) from bovine anterior pituitary cells in culture. Maximum release of GH (262% above controls) occurred at 10(-7) M GRF. In contrast, GH release-inhibiting factor (SRIF) at 10(-12) through 10(-5) M had no effect on basal concentrations of GH. In a second experiment, as the proportion of SRIF relative to GRF increased, SRIF suppression of GRF-induced GH release from anterior pituitary cells increased. In a third experiment, anterior pituitary cells cultured in media containing fetal calf serum (FCS) were treated with cortisol (0 or 10 ng/ml media) for 24 hr before exposure to 10(-13) through 10(-7) M GRF. GRF linearly increased GH secretion (b1 = 7.4 +/- .3) and cortisol augmented this response (b1 = 10.5 +/- .6). However, when cells were cultured in media containing dextran-charcoal treated FCS, cortisol did not alter GRF-induced GH release. Our results demonstrate that GH response of bovine anterior pituitary cells to GRF was modulated negatively by SRIF. However, augmentation of GRF-induced GH release by cortisol was evident only when cells were cultured in media supplemented with untreated FCS.
Padmanabhan
V
V
Department of Animal Science, Michigan State University, East Lansing 48824.
Enright
W J
WJ
Zinn
S A
SA
Convey
E M
EM
Tucker
H A
HA
D000818:Animals; D002417:Cattle / Q000502:physiology*; D002478:Cells, Cultured; D003470:Culture Media; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006854:Hydrocortisone / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013004:Somatostatin / Q000494:pharmacology
D003470:Culture Media; D013004:Somatostatin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D006854:Hydrocortisone