Terms Of Steroidogenesis Research Articles

Corticosterone stage-dependently inhibits progesterone production presumably via impeding the cAMP-StAR cascade in granulosa cells of chicken preovulatory follicles

Stress can suppress reproduction capacity in either wild or domestic animals, but the exact mechanism behind it, especially in terms of steroidogenesis, remains under-investigated so far. Considering the important roles of progesterone in avian breeding, we investigated the modulation of corticosterone on progesterone production in cultured granulosa cells of chicken follicles at different developmental stages. Using enzyme immunoassays, our study showed that corticosterone could only inhibit progesterone synthesis in granulosa cells from F5-6, F4, and F3 follicles, but not F2 and F1 follicles. Coincidentally, both quantitative real-time PCR and western blotting revealed that corticosterone could downregulate steroidogenic acute regulatory protein (StAR) expression, suggesting the importance of StAR in corticosterone-related actions. Using the dual-luciferase reporter system, we found that corticosterone can potentially enhance, rather than inhibit, the activity of StAR promoter. Of note, combining high-throughput transcriptomic analysis and quantitative real-time PCR, phosphodiesterase 10A (PDE10A), protein kinase cAMP-dependent type II regulatory subunit alpha (PRKAR2A) and cAMP responsive element modulator (CREM) were identified to exhibit the differential expression patterns consistent with cAMP blocking in granulosa cells from F5-6, F4, and F3, but not F2 and F1 follicles. Afterward, the expression profiles of these genes in granulosa cells of distinct developmental-stage follicles were examined by quantitative real-time PCR, in which all of them expressed correspondingly with progesterone levels of granulosa cells during development. Collectively, these findings indicate that corticosterone can stage-dependently inhibit progesterone production in granulosa cells of chicken preovulatory follicles, through impeding cAMP-induced StAR activity presumptively.

GATA6, SF1, NGFIB and DAX1 in the remodeled subcapsular zones in primary aldosteronism

The majority of the cases diagnosed as primary aldosteronism (PA) are caused by aldosterone-producing adenoma (APA) or idiopathic hyperaldosteronism (IHA). Histopathologically, both IHA and adjacent adrenal glands of APA demonstrate remodeled subcapsular zone (RSZ) but these zones in two disorders are markedly different in terms of steroidogenesis. 3β-Hydroxysteroid dehydrogenase/Δ⁵-Δ⁴ isomerase (3β-HSD) expression has been known to be activated synergistically by GATA6 and SF1, and repressed by DAX1 through abolishing the activation. Nerve growth factor-induced clone B (NGFIB) is also known as one of the transcription factors to bind to and activate 3β-HSD promoter. The results of our immunohistochemical analysis demonstrated the expression levels of 3β-HSD in RSZ of IHA were higher than in RSZ of adjacent adrenals of APA, while those in the zona glomerulosa (ZG) of normal adrenal gland (NA) were in between these two RSZs. The expression levels of GATA6, SF1 and DAX1 did not prominently differ among these three types of adrenals, especially between in RSZs of IHA and APA cases, indicating the marked difference of 3β-HSD expression was unlikely to be explained by the levels of these three factors. However, the levels of NGFIB expression were significantly higher in RSZ of IHA than in RSZ of adjacent adrenals of APA and the ZG of NA (P<0.05), which may partly account for the expression levels of 3β-HSD among the three groups of adrenals. These results may imply NGFIB plays important roles in the marked differences in steroidogenic functions in the two distinct types of RSZ of PA cases.

Does Atorvastatin Affect Androgen Levels in Men in the Era of Very-low LDL Targeting Therapy?

An adequate pool of free intracellular cholesterol is essential for steroidogenesis in gonads and LDL is the major source of cholesterol used in this pathway. Effect of peripheral LDL on the synthesis of steroids is dose dependent and although LDL levels around 100 mg/dl is demonstrated to be safe in terms of steroidogenesis, effect of LDL levels <70 mg/dl with higher doses of statins on steroidogenesis remains controversial. Androgen and gonadotropin levels are prospectively evaluated at baseline and after 12 weeks of treatment in 77 male coronary heart disease patients receiving high doses of atorvastatin (40-80 mg daily) targeting serum LDL levels <70 mg/dl and in 83 male coronary heart disease patients receiving regular doses of atorvastatin (10-20 mg daily) targeting serum LDL levels <100 mg/dl. At the end of the study, mean LDL levels of the high and regular dose atorvastatin groups were 77+/-9 mg/dl and 98+/-10 mg/dl respectively. After twelve weeks of treatment, there were no significant alterations in serum total testosterone, free testosterone, sex hormone binding globulin, luteinizing hormone and follicle stimulating hormone levels between two groups. High dose atorvastatin in order to reach serum LDL levels around 70 mg/dl seems to be as safe as regular doses in order to reach serum LDL levels around 100 mg/dl, in terms of gonadal steroidogenesis in men with coronary heart disease.

BMP-2 and -6 modulate porcine theca cell function alone and co-cultured with granulosa cells

Bone morphogenetic proteins (BMPs) are emerging as a family of proteins crucial in the regulation of fertility and ovulation rate. We have shown that porcine theca cells express BMP receptors, however, there is a paucity of information regarding the effect(s) of BMPs on theca cell function. The purpose of this study was to investigate the effects of BMP-2 and -6 on theca cells cultured under serum-free conditions in terms of steroidogenesis, cAMP release and proliferation. The study was further extended to determine whether BMP responses in theca cells are affected by the addition of granulosa cells to the culture system. Both BMPs suppressed progesterone and androstenedione synthesis by theca cells ( P < 0.05) after 144 h in culture. Oestradiol synthesis was suppressed ( P < 0.05) by BMP-2, but not BMP-6, and theca cell proliferation was stimulated ( P < 0.05) by BMP-6, but not BMP-2, after 144 h in culture. Both BMP-2 and -6 inhibited cAMP release ( P < 0.05) by theca cells. Furthermore, progesterone and androstenedione synthesis by co-cultured theca and granulosa cells were suppressed ( P < 0.05) whereas cell proliferation was stimulated ( P < 0.05). These results provide strong evidence for a functional BMP system in the porcine ovary and that theca cells are responsive to BMPs in terms of steroidogenesis and proliferation. BMP-2 and -6 may have a role as luteinisation inhibitors in this polyovular species.

Oocyte-mediated suppression of follicle-stimulating hormone- and insulin-like growth factor-induced secretion of steroids and inhibin-related proteins by bovine granulosa cells in vitro: possible role of transforming growth factor alpha.

The objective was to investigate the potential role of the oocyte in modulating proliferation and basal, FSH-induced and insulin-like growth factor (IGF)-induced secretion of inhibin A (inh A), activin A (act A), follistatin (FS), estradiol (E(2)), and progesterone (P(4)) by mural bovine granulosa cells. Cells from 4- to 6-mm follicles were cultured in serum-free medium containing insulin and androstenedione, and the effects of ovine FSH and IGF analogue (LR3-IGF-1) were tested alone and in the presence of denuded bovine oocytes (2, 8, or 20 per well). Medium was changed every 48 h, cultures were terminated after 144 h, and viable cell number was determined. Results are based on combined data from four independent cultures and are presented for the last time period only when responses were maximal. Both FSH and IGF increased (P < 0.001) secretion of inh A, act A, FS, E(2), and P(4) and raised cell number. In the absence of FSH or IGF, coculture with oocytes had no effect on any of the measured hormones, although cell number was increased up to 1.8-fold (P < 0.0001). Addition of oocytes to FSH-stimulated cells dose-dependently suppressed (P < 0.0001) inh A (6-fold maximum suppression), act A (5.5-fold), FS (3.6-fold), E(2) (4.6-fold), and P(4) (2.4-fold), with suppression increasing with FSH dose. Likewise, oocytes suppressed (P < 0.001) IGF-induced secretion of inh A, act A, FS, and E(2) (P < 0.05) but enhanced IGF-induced P(4) secretion (1.7-fold; P < 0.05). Given the similarity of these oocyte-mediated actions to those we observed previously following epidermal growth factor (EGF) treatment, we used immunocytochemistry to determine whether bovine oocytes express EGF or transforming growth factor (TGF) alpha. Intense staining with TGFalpha antibody (but not with EGF antibody) was detected in oocytes both before and after coculture. Experiments involving addition of TGFalpha to granulosa cells confirmed that the peptide mimicked the effects of oocytes on cell proliferation and on FSH- and IGF-induced hormone secretion. These experiments indicate that bovine oocytes secrete a factor(s) capable of modulating granulosa cell proliferation and responsiveness to FSH and IGF in terms of steroidogenesis and production of inhibin-related peptides, bovine oocytes express TGFalpha but not EGF, and TGFalpha is a prime candidate for mediating the actions of oocytes on bovine granulosa cells.

Pharmacodynamics and pharmacokinetics after subcutaneous and intramuscular injection of human chorionic gonadotropin

The pharmacokinetics and efficiency of human chorionic gonadotropin (hCG) after subcutaneous (SC) injection was to clarify in comparison with the intramuscular (IM) mode of administration. In a prospective study, the pharmacokinetics of hCG and the response of serum testosterone (T), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) after an IM and SC injection of 5,000 IU hCG were evaluated up to 144 hours in two randomized groups. The study was carried out in a clinical dermatology department providing tertiary care. Twenty-four healthy male volunteers with a mean age of 22.7 +/- 4.3 years were divided into two groups. Human chorionic gonadotropin (5,000 IU) was injected IM or SC. Serum concentration of /b-hCG, T, LH, and FSH were evaluated after IM and SC administration of hCG. Differences between the two groups were determined by t-test. Compared with IM administration of hCG, peak serum drug concentration was significantly delayed (P = 0.01) and serum half-life was prolonged (P = 0.01) after SC injection; however, T, LH, and FSH responses were identical. Subcutaneous application of 5,000 IU hCG is as effective as IM administration in terms of steroidogenesis.