Serum inhibin B correlates with successful ovulation in infertile women

Activin A Reduces Porcine Granulosa Cells Apoptosis via ERβ-Dependent ROS Modulation

Unfavorable conditions compromise animal reproduction by altering the ovarian granulosa cells' follicular dynamics and normal physiological function (GCs), eventually resulting in oxidative damage and cell apoptosis. Activin is produced in the GCs and plays a vital role in folliculogenesis. This study investigated the effects of activin A (ACT-A) treatment in vitro on the apoptosis of porcine GCs and the underlying molecular mechanism. We found that ACT-A could attenuate the apoptosis of the GCs and enhance the synthesis of estrogen (E2). ACT-A also enhanced FSH-induced estrogen receptor-β (ERβ) expression, inhibiting ERβ aggravated intracellular accumulation of the reactive oxygen species (ROS) and apoptosis. The E2 levels in the culture medium, the mRNA expression pattern of the apoptosis-related genes (CASPASE 3, BCL2, and BAX), steroidogenesis-related gene (CYP19A1), and cell viability were analyzed to confirm the results. In summary, this study indicated the protective role of ACT-A in apoptosis by attenuating the ROS accumulation through ERβ. These results aim to enhance the follicular functions and improve animal reproductive performance.

Activin and inhibin signaling: From regulation of physiology to involvement in the pathology of the female reproductive system

Activins and inhibins - comprising activin A, B, AB, C and E, and inhibin A and B isoforms - belong to the transforming growth factor beta (TGFβ) superfamily. They regulate several biological processes, including cellular proliferation, differentiation and invasiveness, to enhance the formation and functioning of many human tissues and organs. In this review, we have discussed the role of activin and inhibin signaling in the physiological and female-specific pathological events that occur in the female reproductive system. The up-to-date evidence indicates that these cytokines regulate germ cell development, follicular development, ovulation, uterine receptivity, decidualization and placentation through the activation of several signaling pathways; and that their dysregulated expression is involved in the pathogenesis and pathophysiology of the numerous diseases, including pregnancy complications, that disturb reproduction. Hence, some of the isoforms have been suggested as potential biomarkers and therapeutic targets for the management of some of these diseases. Tackling the research directions highlighted in this review will enhance a detailed comprehension and the clinical utility of these cytokines.

Activin A in Mammalian Physiology

Activins are dimeric glycoproteins belonging to the transforming growth factor beta superfamily and resulting from the assembly of two beta subunits, which may also be combined with alpha subunits to form inhibins. Activins were discovered in 1986 following the isolation of inhibins from porcine follicular fluid, and were characterized as ovarian hormones that stimulate follicle stimulating hormone (FSH) release by the pituitary gland. In particular, activin A was shown to be the isoform of greater physiological importance in humans. The current understanding of activin A surpasses the reproductive system and allows its classification as a hormone, a growth factor, and a cytokine. In more than 30 yr of intense research, activin A was localized in female and male reproductive organs but also in other organs and systems as diverse as the brain, liver, lung, bone, and gut. Moreover, its roles include embryonic differentiation, trophoblast invasion of the uterine wall in early pregnancy, and fetal/neonate brain protection in hypoxic conditions. It is now recognized that activin A overexpression may be either cytostatic or mitogenic, depending on the cell type, with important implications for tumor biology. Activin A also regulates bone formation and regeneration, enhances joint inflammation in rheumatoid arthritis, and triggers pathogenic mechanisms in the respiratory system. In this 30-yr review, we analyze the evidence for physiological roles of activin A and the potential use of activin agonists and antagonists as therapeutic agents.

Inhibin B response to testicular toxicants hexachlorophene, ethane dimethane sulfonate, di-(n-butyl)-phthalate, nitrofurazone, DL-ethionine, 17-alpha ethinylestradiol, 2,5-hexanedione, or carbendazim following short-term dosing in male rats

BACKGROUND

Inhibin B is a heterodimer glycoprotein that downregulates follicle-stimulating hormone and is produced predominantly by Sertoli cells. The potential correlation between changes in plasma Inhibin B and Sertoli cell toxicity was evaluated in male rats administered testicular toxicants in eight studies. Inhibin B fluctuations over 24 hr were also measured.

METHODS

Adult rats were administered one of eight testicular toxicants for 1 to 29 days. The toxicants were DL-ethionine, dibutyl phthalate, nitrofurazone, 2,5-hexanedione, 17-alpha ethinylestradiol, ethane dimethane sulfonate, hexachlorophene, and carbendazim. In a separate study plasma was collected throughout a 24-hr period via an automatic blood sampler.

RESULTS

Histomorphologic testicular findings included seminiferous tubule degeneration, round and elongate spermatid degeneration/necrosis, seminiferous tubule vacuolation, aspermatogenesis, and interstitial cell degeneration. There was a varying response of plasma Inhibin B levels to seminiferous tubule toxicity, with three studies showing high correlation, three studies with a response only at a certain time or dose, and two studies with no Inhibin B changes. In a receiver operating characteristics exclusion model analysis, where treated samples without histopathology were excluded, Inhibin B showed a sensitivity of 70% at 90% specificity in studies targeting seminiferous tubule toxicity.

CONCLUSION

Decreases in Inhibin B correlated with Sertoli cell toxicity in the majority of studies evaluated, demonstrating the value of Inhibin B as a potential biomarker of testicular toxicity. There was no correlation between decreases in Inhibin B and interstitial cell degeneration. In addition, a pattern of Inhibin B secretion could not be identified over 24 hr.

Comparisons of follicular levels of sex steroids, gonadotropins and insulin like growth factor-1 (IGF-1) and epidermal growth factor (EGF) in poor responder and normoresponder patients undergoing ovarian stimulation with GnRH antagonist

OBJECTIVE

To determine the serum and intrafollicular concentrations of sex steroids, epidermal growth factor (EGF) and insulin like growth factor-1 (IGF-1) in women demonstrating poor response to ovarian stimulation with gonadotropins and GnRH antagonists, and to compare the results with age-matched women displaying normal ovarian response.

STUDY DESIGN

This is a prospective cross-sectional study conducted in a private IVF center. Forty-eight age-matched women producing 5 or fewer oocytes (poor responders) or 10 or more oocytes (normoresponders) at the end of controlled ovarian stimulation for assisted conception participated in the experiment. Gonadotropins and GnRH antagonists were used for ovarian stimulation, while ICSI was employed for assisted fertilization. Serum and follicular concentrations of FSH, LH and sex steroids (estradiol, progesterone and testosterone), and follicular concentrations of EGF and IGF-1 were assayed in both groups.

RESULTS

Serum and follicular levels of E(2) and progesterone were significantly lower in the poor responder group compared to the normoresponder group. Follicular level of testosterone was also lower in poor responders, but not to a level of statistical significance. The serum FSH level was higher in the poor responder group, but follicular levels of gonadotropins did not differ between the two groups. The follicular level of IGF-1 was significantly lower in poor responders. In contrast, the EGF concentration did not differ between the two groups.

CONCLUSIONS

Decreased levels of sex steroids in poor responder patients undergoing COH with GnRH antagonist, suggests that reduced IGF-1 expression acts as a modulator of impaired ovarian steroidogenesis.

Predictive factors for embryo implantation potential

In spite of recent improvements in IVF, pregnancy rates have not increased significantly and one of the major problems remains the high multiple pregnancy rate. Better criteria are therefore necessary to establish the viability of a transferable embryo. Early prognosis of the developmental fate of the oocyte would help in selecting the best embryos to transfer, but non-invasive selection at the oocyte stage (extracytoplasmic and intracytoplasmic morphology) has proved to be of little prognostic value. Recently, it has been shown that follicular vascularization appears to be predictive of oocyte developmental fate, making it a good first-step approach for selection. Observation of pronuclei patterns at the zygote stage appears to offer an additional prognostic tool, correlating well with IVF outcome. Morphological evaluation of the embryo at days 2-3 remains the most used and valid method of selection, even though it is not sufficient to select embryos with the higher implantation potential. Blastocyst culture is another possible strategy for selecting the best embryos with reduced risk of aneuploidies, though not all major chromosomal aberrations are excluded by prolonged in-vitro culture. In summary, selecting the best embryo for transfer is a decision that should be based on choices made during the different stages of assisted reproductive technologies.

Perifollicular vascularity monitoring and scoring: a clinical tool for selecting the best oocyte

The aim of our study was to assess relationship between perifollicular vascularity and outcome of in vitro fertilization (IVF) cycles. In our study, women who received embryos originating from oocytes developed in well vascularized follicles had a statistically higher pregnancy rate than women who received embryos chosen without considering follicles of origin.