Relationship between GHRP-6 and TPA in the regulation of growth hormone secretion by human pituitary somatotrophinomas.
Growth hormone releasing peptide (GHRP-6) is a synthetic hexapeptide which specifically stimulates secretion of growth hormone (GH) by pituitary somatotrophs. Phorbel ester, 1, 2 tetradecanoylphorbol 13 acetate (TPA) can also stimulate releasing of GH. The precise intracellular mechanism has not been entirely deciphered. We used cell cultures of human pituitary somatotrophinomas to investigate the relation between GHRP-6 and TPA on membrane phosphatidylinositol (PI) turnover and GH secretion. The results showed that the working mechanisms of GHRP-6 and TPA are not identical, although they all can stimulate GH secretion in human pituitary somatotrophinomas. This indicates that PI-PKC signal transduction system may play a crucial role in the regulation of GH secretion.
Liu
Q
Q
Department of Pediatrics, Xiehe Hospital, Tongji Medical University, Wuhan.
Lei
T
T
Adams
E F
EF
Buchfedlder
M
M
Fahlbusch
R
R
D000236:Adenoma / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D009842:Oligopeptides; D018129:Phosphatidylinositol Phosphates; C041048:growth hormone releasing hexapeptide; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate