Changes in FSH, LH and prolactin secretion during estrous cycle in rats.

Abstract

Serum and pituitary follicle-stimulating hormone (FSH) luteinizing hormone (LH) and prolactin contents during the normal rat estrous cycles were assayed every 2 hours in adult female rats of Holtzman strain (lights on 5 a.m. to 7 p.m.). NIAMD rat FSH LH and prolactin radioimmunoassay kits were used. Previously bioassay methods were used but they were not satisfactory in assaying the blood FSH and LH levels because of their low sensitivity. The serum LH surge was observed from 6 p.m. to 7 p.m. on the proestrus day. The serum FSH surge was observed from 7 p.m. on the proestrous day to 5 p.m. on the estrous day. The serum prolactin concentrations began to rise at 1 p.m. on the proestrous day and remained at high levels until 10 a.m. on the estrous day. The reduction in pituitary FSH LH and prolactin content was simultaneously observed from 7 p.m. to 11 p.m. on the proestrous day. These results confirm the data reported by Daane and Parlow (1971). They also demonstrate no diurnal rhythm on the first and second diestrous day as reported by Gay et al (1970).