In vitro responses of rainbow trout (Oncorhynchus mykiss) somatotrophs to carp growth hormone-releasing factor (GRF) and somatostatin.
To study the hypothalamic control of growth hormone (GH) release in lower vertebrates, we employed an in vitro technique using a monolayer cell culture system of rainbow trout pituitary glands. Two newly purified carp brain growth hormone-releasing factors, carp GRF(1-45) and carp GRF(1-29), and synthetic somatostatin-14 (SST-14) were applied to the cultured pituitary cells. The results indicate that: (1) The carp GRFs had a dose-related potency in stimulating growth hormone release. The dose of half maximum effect (ED50) for carp GRF(1-45) was 0.107 nM, and an equal potency for carp GRF(1-29) was 0.388 nM. (2) SST-14 inhibited GH release having a dose-dependent potency with an ED50 of 0.186 nM. (3) Osmotic pressure did not influence SST-14 inhibited GH secretion but did affect spontaneous GH release. (4) The response of cultured cells was not affected by length of incubation period with SST-14 or carp GRF but was affected by cell density.
Luo
D S
DS
Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
McKeown
B A
BA
Rivier
J
J
Vale
W
W
D000818:Animals; D002347:Carps; D002452:Cell Count; D002478:Cells, Cultured; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000031:analogs & derivatives / Q000494:pharmacology*; D009997:Osmotic Pressure; D010446:Peptide Fragments / Q000494:pharmacology; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013004:Somatostatin / Q000494:pharmacology*; D014337:Trout / Q000502:physiology*
D010446:Peptide Fragments; C062925:somatotropin releasing hormone (1-45); D013004:Somatostatin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; C059148:somatotropin releasing hormone (1-29)