Radioimmunoassays for Rat Follicle Stimulating and Luteinizing Hormones

Abstract

Radioimmunoassays for rat FSH and LH have been studied taking advantage of rat FSH and LH radioimmunoassay kits supplied by the NIAMD. Separation of free and antibody bound labeled hormone was accomplished by the double antibody method with pre-precipitation technique. Although rat GH and prolactin did not react in the FSH assay, LH crossreacted slightly to a negligible extent. Hypophysectomized rat serum inhibited the reaction between labeled rat FSH and anti-rat FSH serum. To eliminate the nonspecific interference by serum, hypophysectomized rat serum was added to the diluent for reference preparations in the FSH assay. Rat GH and prolactin did not react in the LH assay. However, FSH crossreacted in the LH assay to a greater degree than LH in the FSH assay. This indicates that LH concentrations may be overestimated when samples with extraordinary large amounts of FSH are measured. Hypophysectomized rat serum did not influence the LH assay. The FSH activity of pituitary extracts determined by bioassay and that by radioimmunoassay agreed well. And there was also a good correlation between LH values obtained both by bioassay and by radioimmunoassay. Although a marked decrease in pituitary FSH and LH levels was found between proestrus and estrus, serum FSH and LH levels were elevated only slightly at 2:00 PM of the proestrus day. Serum and pituitary FSH and LH levels increased after ovariectomy.