Growth hormone releasing activity of small peptides: effect of pyroglutamyl-seryl-glycinamide and thyrotropin releasing hormone on rat pituitaries.
Growth hormone (GH) releasing activity of pyroglutamyl-seryl-glycinamide (PSG) and of thyrotropin-releasing hormone (TRH) was assayed on rat pituitaries in vitro, by radioimmunoassay of the GH released into the incubation media. TRH was found to be a partial agonist, producing maximal effects (at ca. 600 ng/ml) that were below the maximum response of the system to hypothalamic extract. The responses to a higher TRH concentration (1500 ng/ml) were smaller than that obtained at 600 ng/ml. PSG also behaved as a partial agonist producing maximum response at 150 ng/ml. The results are discussed in relation to possible structural similarities between the physiological GHRF and the tripeptides TRH, PSG and MIF (MSH release inhibiting hormone).
D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D004305:Dose-Response Relationship, Drug; D013007:Growth Hormone-Releasing Hormone / Q000378:metabolism / Q000494:pharmacology*; D007028:Hypothalamic Hormones / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects* / Q000502:physiology; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D011863:Radioimmunoassay; D051381:Rats; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism / Q000494:pharmacology*
D007028:Hypothalamic Hormones; D009842:Oligopeptides; C019070:pyroglutamyl-seryl-glycinamide; D013973:Thyrotropin-Releasing Hormone; D013007:Growth Hormone-Releasing Hormone; D011761:Pyrrolidonecarboxylic Acid