Effect of substance P/bombesin antagonists on the release of growth hormone by GHRP and GHRH.
The substance P(SP)/bombesin (Bn) antagonists [DArg1DTrp7,9Leu11] SP(P-7482), [DArg1-DPro2DTrp7,9Leu11]SP (P-7483), [DArg1DPhe5DTrp7,9Leu11]SP(P-7492), and the growth hormone releasing hormone (GHRH) antagonist [DArg2Ala8,9,15]GHRH(1-29)(DC21-366) were tested for their in vitro effects on the release of growth hormone (GH) in the presence of GHRH and growth hormone releasing peptide, HisDTrpAlaTrpDPheLysNH2(GHRP). P-7492, P-7483, and P-7482 decreased, dose-dependently, the release of GH by GHRP (IC50 = 0.2 microM, 0.85 microM, and 6 microM, respectively). These antagonists had only a 10-15% inhibitory effect on the stimulated GH release of GHRH even at high dosage. DC21-366 decreased the stimulated release of GH by GHRH (IC50 = 0.16 microM) but not by GHRP. Neither SP nor Bn had GH releasing or inhibitory effects in this system.
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Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112.
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D000595:Amino Acid Sequence; D000818:Animals; D001839:Bombesin / Q000037:antagonists & inhibitors*; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006728:Hormones / Q000494:pharmacology*; D008297:Male; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors* / Q000494:pharmacology
D006728:Hormones; D009842:Oligopeptides; D013373:Substance P; C041048:growth hormone releasing hexapeptide; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D001839:Bombesin