Follicle-stimulating hormone regulates steroidogenic enzymes in cultured cells of the chick embryo ovary

This investigation addresses the potential regulation of enzymes involved i n the biosynthesis of steroid hormones during early stages of gonadal devel opment by follicle-stimulating hormone (FSH). Gonadal cells of 10-day-old c hick embryo and cells of the left ovary of 18-day-old chick embryo were cul tured for 60 h in a defined medium with or without the addition of FSH (2.0 IU/ml). At the end of the culture, cells were recovered and evaluated by b iotransformation of tritiated steroid precursors and mRNA levels were evalu ated by RT-PCR. The production of estrone from androstenedione was increase d in the FSH-treated cells, both human FSH (hFSH) and recombinant human FSH (rhFSH), indicating a stimulatory effect on aromatase (P450arom). Similarl y, the intensity of the band corresponding to P450arom mRNA was higher in h FSH and rhFSH than in control and chorionic gonadotropin (hCG) groups. The P450arom stimulation was observed in the ovary of 10- and 18-day-old chick embryo. The transformation of dehydroepiandrosterone to androstenedione was taken as evidence of 3 beta -hydroxysteroid dehydrogenase function. This e nzyme was stimulated in the cultured ovarian cells of 18-day-old chick embr yos treated with hFSH and rhFSH compared with controls. The production of p regnenolone in the mitocondrial fraction of 18-day-old chick embryo ovary w as increased when cultured with hFSH and rhFSH. This observation together w ith the increase in the band intensity corresponding to mRNA of P450 choles terol sidechain cleavage indicates stimulation by FSH treatment; hCG produc ed a similar effect. Somatic cells of the medullary cords are proposed to b e FSH target cells in the ovary of the chick embryo. (C) 2001 Academic Pres s.