Intra-Ovarian Actions of Steroids in Regulation of Follicular Steroid Biosynthesis

Armstrong, David T.; Daniel, Susan A.J.; Gore-Langton, Robert E.

doi:10.1007/978-1-4899-1971-7_15

Cited by 2 publications

(3 citation statements)

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“…As shown by Armstrong (1980), FSH activates the aromatase enzymes in granulosa cells and this effect of FSH is potentiated by T. Thus, it is possible that the marked increase in E2 at prooestrus is the result of a potentiation by the 'T peak' at late dioestrus of the aromatase stimulatory effect of FSH (as PMSG has mainly FSH effect in the rat).…”

Section: Discussionmentioning

confidence: 92%

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Steroidogenesis in isolated rat granulosa cells – changes during follicular maturation

Nordenström¹,

Johanson²

1985

Acta Endocrinologica

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Steroid release was investigated in granulosa cells isolated from rat ovarian follicles at different maturation stages. Immature rats were treated with 10 IU of pregnant mare's serum gonadotrophin (PMSG) to induce follicular growth and maturation. Granulosa cells were isolated and subsequently incubated for 4 h in the absence or presence of follicle stimulating hormone (FSH), luteinizing hormone (LH) or forskolin. The concentrations of progesterone (P), 20\g=a\-dihydroprogesterone (20\g=a\DHP), testosterone (T) and oestradiol (E2) in the media were determined by radioimmunoassay. During maturation, basal release of T increased markedly at late dioestrus. At pro-oestrus, concomitant with a sharp rise in E2 and P release, T release returned to previously low levels. Addition of FSH or LH stimulated P release at late dioestrus and pro-oestrus but had no effect on E2 or T levels. Basal 20\g=a\DHP levels remained low until a sharp rise at mid pro-oestrus. A stimulatory effect of gonadotrophins on 20\g=a\DHPwas first seen at this stage. The adenylate cyclase stimulator forskolin resembled FSH in all its effects.In summary, the present study demonstrates that maturing, but not preovulatory, granulosa cells have an increased capacity to release T during a relatively short period. It is suggested that this T peak could be of great importance for the further progress of follicular maturation.

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Section: Discussionmentioning

confidence: 92%

“…see Armstrong 1980;Hillensjö 1981). The quantitative contribution of steroids by theca and granulosa cells respectively is not so clear, due to the complicated interplay between these cells, varying with the dynamic changes in gonadotrophin levels during the repro¬ ductive cycle.…”

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confidence: 98%

Steroidogenesis in isolated rat granulosa cells – changes during follicular maturation

Nordenström¹,

Johanson²

1985

Acta Endocrinologica

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“…During thecal formation, the follicles begin steroid hormone synthesis [3,4], and then develop markedly. In later developmental stages, the follicles produce progestins, androgens and estrogens by gonadotropic stimulation [5,6], and these steroids are thought to regulate follicular development in ovaries [7][8][9].In organ-cultured mouse ovaries, oocyte growth proceeds normally, though proliferation of granulosa cells is severely retarded [10] unless stimulated by exogenous FSH [11, Ikeda et al, unpublished data], and the organ culture system of ovaries is thought to allow the effects of steroid hormones on the proliferation of granulosa cells to be examined in a highly controlled environment. In practise, the effects of estrogens on the early development of follicles have been examined in organ-cultured mouse ovaries and estrogens promoted proliferation of granulosa cells in follicles of ovaries from both 4-day-[12] and 8-day-old mice [11].…”

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confidence: 99%

Effects of Androgens on Early Development of Mouse Follicles in Organ-Cultured Ovaries.

Ikeda¹,

Hirao²,

Miyano³

1999

J.Mamm.Ova.Res.

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Abstract:Ovaries from 4-day-old mice were organ-cultured and the effects of progesterone, androstenedione and estradiol-17β on early follicular development were investigated. Both androstenedione (40-1,000 ng/ml) and estradiol-17β (8-1,000 ng/ml) promoted proliferation of granulosa cells in developing follicles, while progesterone showed no remarkable effect. Cyproterone acetate (4,000 ng/ml), an androgen receptor antagonist, partially inhibited the granulosa cell proliferation induced by androstenedione (40 ng/ml). Dihydrotestosterone (8-1,000 ng/ml), which is not converted to estrogens, also induced proliferation of granulosa cells. These results suggest that androgens directly promote proliferation of granulosa cells in early developing mouse follicles in vitro. Key words: Androstenedione, Granulosa cell, Mouse, Organ culture, Ovary.After birth, mouse oocytes increase in volume with an arrested nucleus at the diplotene stage of the first meiotic prophase, and ovarian follicles develop as granulosa cells proliferate within them. Oocyte growth is initially accompanied by a thickening of the flattened primitive granulosa cells to a cuboidal shape, and then by proliferation of granulosa cells. As the granulosa cells proliferate, a thecal layer appears on the surface of the follicle [1,2]. Before the follicles develop their thecal layer, negligible amounts of steroid hormones are produced in the ovaries. During thecal formation, the follicles begin steroid hormone synthesis [3,4], and then develop markedly. In later developmental stages, the follicles produce progestins, androgens and estrogens by gonadotropic stimulation [5,6], and these steroids are thought to regulate follicular development in ovaries [7][8][9].In organ-cultured mouse ovaries, oocyte growth proceeds normally, though proliferation of granulosa cells is severely retarded [10] unless stimulated by exogenous FSH [11, Ikeda et al., unpublished data], and the organ culture system of ovaries is thought to allow the effects of steroid hormones on the proliferation of granulosa cells to be examined in a highly controlled environment. In practise, the effects of estrogens on the early development of follicles have been examined in organ-cultured mouse ovaries and estrogens promoted proliferation of granulosa cells in follicles of ovaries from both 4-day-[12] and 8-day-old mice [11]. Kent [13] reported that pregnenolone, testosterone and estradiol-17β stimulated the growth of small follicles in organ-cultured ovaries from 15-day-old mice. In that experiment, however, follicular development was assessed without respect to the growth of oocytes which is one of the major factors determining follicular size in the early stages.Using the organ culture system of mouse ovaries, we examined the effect of steroid hormones on the proliferation of granulosa cells with respect to oocyte growth in early developing follicles. Ovaries from 4-day-old mice were cultured and the effects of three steroid hormones, progesterone, androstenedione and estradiol-17β, on follicul...

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Intra-Ovarian Actions of Steroids in Regulation of Follicular Steroid Biosynthesis

Cited by 2 publications

References 123 publications

Steroidogenesis in isolated rat granulosa cells – changes during follicular maturation

Steroidogenesis in isolated rat granulosa cells – changes during follicular maturation

Effects of Androgens on Early Development of Mouse Follicles in Organ-Cultured Ovaries.

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