title: Radioimmunoassay for GH-release inhibiting hormone.
abstract: The synthetic growth hormone release inhibiting hormone (GH-RIH) was conjugated with human serum globulin using glutaraldehyde and administered to rabbits. An antiserum thus generated 70% of 125I-Tyr1-GH-RIH. The binding was inhibited by unlabelled GH-RIH and the inhibition was dose-related, enabling us to establish a radioimmunoassay method for GH-RIH. The minimum detectable dose was 4 pg. A linearity was demonstrated for immunoreactive GH-RIH of extracts of rat and pig hypothalami, indicating that they contained substance(s) indistinguishable from GH-RIH. Various hypothalamic and pituitary hormones did not interfere with the radioimmunoassay, but considerable cross-reaction was observed for linear GH-RIH and the ring portion of GIH-RIH, suggesting that the antigenic determinant involved the amino acid sequence from position 3-14 of GH-RIH or part of it. Plasma protein appears to contain substance(s) immunologically indistinguishable from GH-RIH or to interfere, in a nonspecific manner, with the radioimmunoassay system for GH-RIH.
mesh_terms: D000818:Animals; D000937:Antigen-Antibody Reactions; D002845:Chromatography; D003429:Cross Reactions; D004305:Dose-Response Relationship, Drug; D006493:Heparin; D006801:Humans; D007030:Hypothalamo-Hypophyseal System; D007031:Hypothalamus / Q000032:analysis / Q000276:immunology; D007457:Iodine Radioisotopes; D008297:Male; D010455:Peptides; D010907:Pituitary Hormones; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D012756:Sheep; D013004:Somatostatin / Q000032:analysis / Q000276:immunology*; D013552:Swine; D014020:Tissue Extracts / Q000032:analysis / Q000276:immunology
chemical_list: D007457:Iodine Radioisotopes; D010455:Peptides; D010907:Pituitary Hormones; D014020:Tissue Extracts; D013004:Somatostatin; D006493:Heparin