Stimulation of estrogen synthesis in rabbit follicles by luteinizing hormone.

Abstract

The response of isolated ovarian follicles to gonadotropic stimulation in vitro has been investigated. Large follicles (1–2 mm diameter) dissected from estrous rabbit ovaries were cleared of interstitium and then incubated in Krebs-Ringer bicarbonate buffer containing 100 μCi sodium acetate-l-14C plus gonadotropin or an equivalent concentration of bovine serum albumin as control. Incorporation of radioactivity into estrone and 17β-estradiol was assessed by reverse isotope dilution analysis with recrystallization of radioactive products to constant specific activity. Luteinizing hormone (LH) at concentrations of 2.5, 0.25, 0.025 or 0.0025 μg/ml caused 5-to 13-fold increases in incorporation of radioactivity into estrogens; LH at 0.001 μg/ml caused a doubling of incorporation. Prolactin (100 μg/ml) was without stimulatory activity in the follicular system. The following FSH preparations caused increases in incorporation which could be related to the LH content: i) follicle stimulating hormone (FSH) at conce...