Follicular growth and development under continuous gonadotropin-releasing hormone antagonist administration

Effects of gonadotropin on Fas and/or FasL expression and proliferation in rat ovary

Although gonadotropin is a dominant hormone involved in promoting ovarian follicle development in females, the mechanism by which gonadotropin regulates follicular development is still unknown. To systematically evaluate the effectiveness of the gonadotropin on apoptosis and proliferation of ovarian cells in vivo, rats were injected subcutaneously with eCG and/or anti-eCG antiserum. Equine chorionic gonadotropin treatment increased ovarian cell proliferation and expression of FSH receptors (FSHR) as revealed by increased immunostaining of proliferating cell nuclear antigen and FSHR in rat ovary. These effects did not occur in a follicular stage-dependent manner. Moreover, these actions were abolished by anti-eCG antiserum. However, granulosa cells exhibited more intense Fas- and FasL-positive immunostaining during all follicular stages in the anti-eCG antiserum group. We used Western blot analysis to confirm these results; Fas and FasL protein contents in rat ovaries were decreased by eCG. Meanwhile, proliferating cell nuclear antigen and FSHR expression were upregulated by eCG. However, all these eCG-induced regulations were reversed by anti-eCG antiserum treatment. Furthermore, there were no significant differences between the anti-eCG antiserum and control groups. These results indicate that eCG promotes follicular development via downregulation of death-inducer Fas/FasL expression and promotion of ovarian cell proliferation, which is partially mediated by FSHR.

Controlled ovarian stimulation using a long gonadotropin-releasing hormone antagonist protocol: a proof of concept and feasibility study

BACKGROUND/AIMS

To evaluate the feasibility of a long protocol of controlled ovarian stimulation prior to in vitro fertilization (IVF) and embryo transfer with a gonadotropin-releasing hormone (GnRH) antagonist used for pituitary and ovarian suppression.

METHODS

Thirty patients undergoing IVF/intracytoplasmic sperm injection were randomized into two groups. The control group (n = 16) received a standard flexible GnRH antagonist protocol. Ovarian stimulation consisted of 225 IU/day of recombinant follicle-stimulating hormone for 5 days, followed by 225 IU/day of human menopausal gonadotropin until human chorionic gonadotropin (hCG) administration. The study group (n = 14) received 0.25 mg of GnRH antagonist daily for 7 days, thereafter, upon confirmation of pituitary and ovarian suppression, ovarian stimulation was commenced with the same protocol as used in the control group. Hormone and follicle dynamics, as well as laboratory characteristics and cycle outcome, were compared for both groups.

RESULTS

Both groups were comparable in baseline characteristics. Pituitary and ovarian suppression were effectively achieved in 12/14 patients in the study group. The duration of ovarian stimulation and gonadotropin consumption were similar in both groups, as was also the number and size of follicles on hCG day.

CONCLUSION

The results of our study confirm the feasibility of a long GnRH antagonist protocol. This regimen could become another option to optimize GnRH antagonist protocols, and should thus be further explored.

The effect of gonadotropin on glucose transport and apoptosis in rat ovary

Although the effects of Gonadotropin on ovarian physiology have been known for many decades, its action on glucose uptake in the rat ovary remained poorly understood. Evidence also suggests that glucose uptake is mediated by a number of glucose transporter proteins (Glut). Therefore, we examined the rat ovary for the presence of Glut1–4 and blood glucose level after eCG (equine chorionic gonadotropin) and anti-eCG antiserum treatment. All of the glucose transports were present in the ovarian oocyte, granulosa cells and theca cells in different stage follicles. The expression of Glut in ovary was up-regulated by eCG, however, anti-eCG antiserum reversed eCG action. Western blot analysis also demonstrated the content of Glut1 was higher in eCG treatment group compared with anti-eCG antiserum and control group. The same tendency was shown in other glut isoforms. Moreover, there were no significant difference between the anti-eCG antiserum and control group. In additional, the level of serum glucose in eCG treatment group was significantly higher than others, which is similar with glut expression pattern. High glucose level in blood is correlated with increased expression of glucose transporter proteins in rat ovary. Meanwhile, anti-eCG antiserum increased granulosa cell apoptosis in antral follicle compared with those in eCG group. Our observations provide potential explanation for the effects of Glut on follicular development in rat ovary and a role for eCG in the regulation of ovarian glucose uptake.

GnRH antagonist cetrorelix inhibits mitochondria-dependent apoptosis triggered by chemotherapy in granulosa cells of rats

OBJECTIVE

Exposure to chemotherapy causes various adverse effects on the ovaries including premature ovarian failure and infertility. GnRH antagonist cetrorelix could reverse the ovarian damage during chemotherapy, but the mechanism remains unclear. The objectives of this study were to examine the role of the cetrorelix for prevention of mitochondria-dependent apoptosis in granulosa cells of rats during the treatment with cyclophosphamide(Cy), if the mitochondria-dependent apoptotic process was involved.

METHODS

Female SD rats were injected with cetrorelix before and after administration of saline, or Cy. Main outcome measures were the apoptotic indexes, serum hormones, ultrastructure of granulosa cells, mitochondrial membrane potential, the kinetics of cytochrome c (Cyt-c) processing in cells, and apoptotic markers.

RESULTS

The ovarian apoptotic indexes as shown by TUNEL assay were reduced by cetrorelix pretreatment and the rats regained normal hormonal profile. The ultrastructure and JC-1 fluorescence intensity assessments showed cetrorelix pretreatment inhibited mitochondrial dysfunction in granulosa cells induced by chemotherapy. Western blot analysis showed that cetrorelix suppressed the release of Cyt-c from mitochondria to cytoplasm. Meanwhile, cetrorelix pretreatment expressed less Bax, caspase-3 and Cyt-c in granulosa cells compared with chemotherapy alone.

CONCLUSION

Cetrorelix could reduce the apoptosis in granulosa cells through inhibiting mitochondria-dependent apoptosis triggered by chemotherapy.