Abstract
The modulation of ovarian steroidogenesis by epidermal growth factor (EGF) was investigated in cultured rat granulosa cells. Granulosa cells, obtained from ovaries of immature, hypophysectomized, estrogen-treated rats, were incubated for 2 days with EGF, follicle-stimulating hormone (FSH), or EGF plus FSH. Treatment with EGF did not affect estrogen production, but stimulated progestin (i.e. progesterone and 20 alpha-hydroxy-pregn-4-en-3-one) production in a dose-dependent manner. Stimulation of progestin production by EGF appears to be the result of an increase in pregnenolone biosynthesis as well as increases in the activities of 20 alpha-hydroxysteroid dehydrogenase and 3 beta-hydroxysteroid dehydrogenase/isomerase. Treatment with FSH increased both estrogen and progestin production by cultured granulosa cells. When cells were treated concomitantly with EGF, FSH-stimulated estrogen production was inhibited, while progestin production was further enhanced. The EGF enhancement of FSH-stimulated progestin production appears to be the result of synergistic increases in pregnenolone biosynthesis and 20 alpha-hydroxysteroid dehydrogenase activity, resulting in substantial increases in 20 alpha-hydroxypregn-4-en-3-one but not progesterone production. The effects of EGF were shown to be time-dependent. The concept of a direct action of EGF on rat granulosa cells is reinforced by the demonstration of high affinity (Kd approximately 3 X 10(-10) M), low capacity (approximately 5,000 sites/cell) EGF binding sites in these cells. Thus, EGF interacts with specific granulosa cell receptors to stimulate progestin but to inhibit estrogen biosynthesis.
Highlights
Mal growth factor (EGF) was investigated in cultured induced increase in luteinizing hormone receptor content of rat granulosa cells
Stimulation of progestin production by EGF appears to be the result of an increase in pregnenolone biosynthesis as well as increases in the activities of 20a-hydroxysteroid dehydrogenase and 3jLhydroxysteroid dehydrogenase/isomerase
The reaction was stopped in of EGF on ovarian steroidogenesis, granulosa cells were incubated in medium alone,or withincreasing concentrations of EGF, follicle-stimulating hormone (FSH) (10 ng/ml), or EGF plus FSH
Summary
Effects of EGF and FSH Ponrogestin and Estrogen Pronenolone to progesterone. Our modification of this procedure has duction by Cultured Granulosa CeZls-To examine the effect been described elsewhere [16]. The medium concentration of 20a-OH-P was low in control cells while FSH treatment stimulated 20a-OH-Pproduction from 40 s by the addition of40pgof sodium metabisulfite in 10 p1 of
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