DEVELOPMENT AND CHARACTERIZATION OF A HOMOLOGOUS RADIOIMMUNOASSAY FOR BOVINE FOLLICLE-STIMULATING HORMONE

Abstract

SUMMARY A radioimmunoassay for bovine FSH has been developed using a rabbit antiserum against highly purified bovine FSH (160 × NIH-FSH-S1) and a ¹²⁵I-labelled tracer of the same preparation. The sensitivity was 0·25 ng/ml for purified bovine FSH or 25 ng/ml with reference to a crude bovine FSH (NIH-FSH-B1) standard. Purified bovine LH and TSH showed cross-reactivities of less than 1%, while their subunits and other purified protein hormones showed no significant inhibition at concentrations up to 100 ng/ml. Ovine FSH cross-reacted significantly but in a non-parallel manner; human and rat FSH cross-reacted only slightly. The concentrations of FSH (means ± s.e.m.) in the sera of cows (n = 12), cows at oestrus (4), bulls (7) and steers (9) were measured as 25·4 ± 4·7, 58·4 ± 12·6, 45·7 ± 9·5 and 120·2 ± 36·0 ng/ml respectively. The FSH content of bovine pituitary glands varied greatly between individuals, from 2 to 25 μg/mg tissue. The inhibition curves of pituitary and serum FSH were parallel to that of the bovine FSH standard.