Studies on the release of follicle-stimulating hormone in vitro from rat pituitary glands stimulated by hypothalamic follicle-stimulating hormone-releasing factor.

Abstract

A specific and sensitive method for the assay of FSH-releasing factor (FRF) in vitro was developed. Pituitary halves of Wistar rats, ovariectomized and pretreated with estradiol i benzoate and progesterone, were incubated for 2 hr at 37 C in a Krebs-Ringer bicarbonate-glucose medium, in the presence or absence of FRF. At ithe end of the incubation period, the pituitary tissue and the supernatant were assayed for FSH using the Steelman-Pohley method. Control studies established that there was no evidence of inactivation of FSH under the conditions used for incubation and that hypothalamic extracts, injected directly into Steelman-Pohley rats, did ;not stimulate the ovaries, nor potentiate their response to FSH. Different substances such as pitressin, α- and β-MSH, serotonin, melatonin and cortical extract were shown not to act on the release of FSH from the pituitary. A graded response in release of FSH by pituitary tissue Stimulated with graded doses of a hypothalamic extract or purified FRF was observed....