In Vitro Sterol and Steroid Synthesis by Ovaries of Hypophysectomized Immature Rats Treated With Human Gonadotrophins

Abstract

The in vitro conversion of sodium [ 1,2- 14C] acetate into sterols and steroids was studied following the incubation of groups of ovaries from hypophysectomized immature rats with human gonadotrophins. Tritium labelled internal standards were used to monitor procedural losses and sterols and steroids were isolated in a radiochemically homogeneous form. The gonadotrophin preparations studied included a highly purified human urinary LH preparation (with no detectable FSH activity) as well as human urinary FSH and HCG preparations in which the LH and FSH-like activity, respectively, was selectively neutralized by the addition of appropriate antigonadotrophic sera. The ovaries of saline-treated control animals converted considerable quantities of labelled acetate into cholesterol and small amounts into cholesterol esters. Little, if any, acetate was converted by these ovaries into steroids. The injection of a human urinary LH-free FSH preparation or of a highly purified human urinary LH preparation resulted in a marked increase in the incorporation of labelled acetate into cholesterol, which was accompanied by a slightly increased incorporation into cholesteryl esters. Small amounts of carbon-14 labelled androstenedione and testosterone were also isolated but no pregnenolone or progesterone was found.

The Effects of Hcg, Indomethacin, Flufenamic Acid and Aspirin in the Immature Female Rat

“…In hypophysectomized immature female rats, HCG produces a limited increase in ovarian weight which is confined to the ovarian interstitial tissue (Urna Bai et al, 1973). In intact immature female rats the increase in ovarian weight produced by HCG appears to be due to a synergism with endogenous FSH, the secretion of which may be stimulated by HCG (Evans & Simpson, 1950).…”

Quantitation of meiosis activating sterols in human follicular fluid using HPLC and photodiode array detection

“…Most cholesterol utilized for this purpose is generally believed to be derived from lipoproteins (Christie et al, 1979;Gwynne andStrauss, 1982, Grummer andCarroll, 1988). However, cholesterol synthesis de novo has been reported in ovine (Douglas et al, 1978), porcine (Barañao and Hammond, 1986) and bovine (Spicer et al, 1996) granulosa cells, rat ovaries (Bai et al, 1973) or luteal cells (Christie et al, 1979;Azhar et al, 1985), and isolated rabbit follicles (Mills and Savard, 1972), and it appears that steroidogenesis can proceed to some extent by the de novo pathway alone (Schuler et al, 1981).…”