Differences in the rat uterine weight-stimulating capacity of rat luteinizing hormone and other LH's: the non-physiologic nature of bovine and ovine LH in the rat.

Abstract

Previous observations on an apparent causal relationship between species differences in the circulatory half—time of LH' in the rat and differences in certain aspects of the biological activity of these LH' have been extended, in this study, to the intact, immature female rat uterine weight assay. LH preparations (specifically, hCG, and human (hLH), simian (rhLH), rat (rLH), bovine (bLH), and ovine (oLH) LH'), largely devoid of FSH activity, were standardized in terms of one reference preparation (NIH—LH—Sl, ovine), and one bioassay (OAAD). On this basis, the activities of these preparations were then compared in another type of bioassay, the rat uterine weight method. Bovine and ovine LH', even in doses as high as 400–1000 μgEq of NIH—LH—Sl (OAAD assay) were ineffective in stimulating rat uterine weight increase. However, all other LH' were highly active in this regard. Relative potencies decreased in the order hCG, hLH, rLH, rhLH, bLH, oLH. Quantitative assessment, by simultaneous testing, of the potenc...