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At least 199 records · Page 11Linked to original sources
PubMed2003

Synergistic action of growth hormone and insulin-like growth factor I (IGF-I) on proliferation and estradiol secretion in porcine granulosa and theca cells cultured alone or in coculture.

The effect of growth hormone (GH) on insulin-like growth factor I (IGF-I) secretion and the effects of GH and IGF-I on [(3)H] thymidine incorporation and estradiol (E2) secretion by theca interna (Tc) and granulosa cells (Gc) cultured alone and in coculture were studied in cultured porcine follicular cells, prepared from small (SF), medium (MF) and large (LF) preovulatory follicles. We demonstrated that both Tc and Gc secrete IGF-I and that GH had no effect on IGF-I secretion by Tc but, increased IGF-I secretion by Gc isolated from SF and cultured alone or in coculture. IGF-I stimulated secretion of E2 by all cells, except in Tc derived from SF in which the effect was not statistically significant. The only stimulatory effect of concurrent treatment with GH on E2 secretion was noted in Tc derived from MF. IGF-I increased the [(3)H] thymidine incorporation in all Tc cells but GH did not augment this effect. In Gc, IGF-I stimulated [(3)H] thymidine incorporation in cells derived from SF and MF but not from LF. GH had no stimulatory effect except on Gc derived from LF and grown alone. The highest stimulatory effect was observed in SF. This was smaller in MF and no effect was noted in LF. In conclusion, our work shows that both Gc and Tc are sites of IGF-I production and for the first time shows the stimulatory role of IGF-I in proliferation of Tc cells derived from all types of follicles and augmentation of E2 secretion in Tc derived from MF and LF. The promotion of the mitogenic activity in Tc by IGF-I during all stages of follicular development suggests an important role for theca cells in follicular growth.

Animals↗
PubMed1992

Localization of renin gene expression to monkey ovarian theca cells by in situ hybridization.

To investigate the sites of renin gene expression and localization of renin in primate ovaries, five cynomolgus (Macaca fascicularis) and one rhesus (Macaca mulatta) monkey were treated with gonadotropins to induce multiple follicle development. One ovary was removed before hCG injection (1200 IU) from three monkeys and one ovary was removed 36 h after hCG administration from three monkeys. In three monkeys, the remaining ovary was removed 3, 5, and 7 days after injection of hCG. To detect and localize renin messenger RNA, 35S-radiolabelled 1.1 kb length complementary DNA and RNA probes of human renin were used for in situ hybridization. To compare the synthesis with the presence and the storage of renin or prorenin, renin antigen was assessed by immunohistochemistry in the same tissues using a polyclonal antibody against human renin (R15). Renin mRNA was detected by in situ hybridization only in ovaries collected within 5 days of exposure to hCG. All such ovaries exhibited a positive signal. Renin mRNA was localized to the theca interna and theca lutein cells. Positive cells were observed in a few growing antral follicles, in occasional mature preovulatory follicles, in corpus luteum, and most strikingly in atretic follicles. No signal was detected in primordial, primary, or in small antral follicles of ovaries exposed to hCG. In contrast with the in situ hybridization data, no signal was detected by immunohistochemistry using antirenin antibodies which exhibited a positive signal in monkey kidney. These results indicate that hCG turns on renin gene expression. Renin is synthesized without significant intracellular storage in monkey ovarian theca interna cells and in corpus luteum. The absence of storage of renin is consistent with the high concentrations of prorenin found in ovarian follicular fluid of hCG stimulated primates and with our knowledge of cellular renin processing which indicate that prorenin is secreted constitutively as it is synthesized.

Animals↗
PubMed1996

Developmental and hormonal regulation of rat theca-cell differentiation factor secretion in ovarian follicles.

We have recently presented data demonstrating that preantral follicles secrete a peptide (or family of peptides) that stimulates ovarian theca-interstitial cell (TIC) androgen production by an LH-independent mechanism. The purpose of the study reported here was to study the gonadotropin and developmental regulation of this thecal differentiating factor(s) (TDF) and to determine whether follicle-conditioned medium (FCM) containing TDF bioactivity could stimulate LH receptor and steroidogenic enzyme mRNA expression in TIC. Preantral follicles devoid of theca were obtained by limited enzymatic dispersal of 26-day-old rat ovaries. Follicles were cultured (5 follicles/well) in 96-well plates containing serum-free medium to generate FCM containing bioactive TDF. To bioassay for TDF activity, isolated TIC were cultured (2 days) with 50% FCM; then androsterone production was measured by RIA. Recombinant FSH (rFSH, 0.3-100 mlU/ml) increased TDF bioactivity in a dose-dependent fashion, stimulating maximum androsterone production (20 ng/ml) at 30 mlU/ml. To determine the time course of the production of TDF bioactivity, FCM was collected from follicle cultures treated with and without rFSH at 1, 6, 12, 18, 24, 30, 36, 42, and 48 h. FCM from follicles cultured without rFSH caused a progressive increase in androsterone production to a peak (8 ng/ml) at 18 h followed by a decline to baseline by 48 h. A similar time course was observed for the first 18 h with the rFSH-treated FCM, but androsterone production continued to increase to a level twice that of the untreated FCM (18 ng/ml) at 36 h of culture. In the presence of 100 mlU/ml of rFSH, TDF bioactivity was produced by preantral follicles with > or = 2 layers of granulosa cells but not by small antral follicles, preovulatory follicles, or corpora lutea, demonstrating that production of TDF bioactivity is developmentally regulated. To determine whether FCM could stimulate mRNA expression in TIC, LH receptor, cholesterol side-chain cleavage (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), and 17 alpha-hydroxylase (P450(17) alpha) mRNAs were measured by reverse transcription polymerase chain reaction assays. FCM stimulated LH-receptor, P450scc, 3 beta-HSD, and P450(17) alpha mRNAs above controls. Our data demonstrate that the production of TDF bioactivity is increased by FSH during a specific stage in follicular development when the theca interna is rapidly differentiating, but its production stops when the follicle develops an antrum. Treatment of TIC with FCM stimulates the expression of the mRNAs coding for LH receptors and the steroidogenic enzymes P450scc, 3 beta-HSD, and P450(17) alpha, mimicking the events that occur during normal thecal differentiation. Thus, it seems likely that TDF is involved in the regulation of initial thecal differentiation in preantral follicles.

Androstenedione↗