Radioimmunoassay of inhibin in the serum of male monkeys
ABSTRACT A heterologous inhibin radioimmunoassay method to measure inhibin in serum of male cynomolgus (Macaca fascicularis) and rhesus (Macaca mulatta) monkeys has been validated using a specific antibody against bovine 31 kDa inhibin and 125I-labelled 31 kDa inhibin as tracer. A serum pool from male monkeys was used as standard. Serial dilutions of normal monkey serum showed parallel logit–log dose–response curves to purified porcine and bovine inhibin as well as to a female human serum pool. The intra-assay coefficient of variation was 4·2% (n=10) and the interassay coefficient of variation 5·1% (n=10). No loss of inhibin immunoactivity was noted after storage at 23 °C for 5 days or repeated thawing and freezing of the serum samples. Serum from castrated monkeys showed undetectable levels of inhibin. Treatment with a gonadotrophin-releasing hormone agonist for 15 weeks led to a marked suppression of peripheral serum inhibin to concentrations similar to those after hypophysectomy or pituitary stalk section. Journal of Endocrinology (1989) 122, 477–483