FSH receptor binding inhibitor restrains follicular development and possibly attenuates carcinogenesis of ovarian cancer through down-regulating expression levels of FSHR and ERß in normal ovarian tissues.

OBJECTIVES: The current study aimed to investigate FSH receptor binding inhibitor (FRBI) effects in the expressions of FSH receptor (FSHR) and estrogen receptor-beta (ERß) in the mice ovaries at the gene and protein levels, also to find the potential efficacy of FRBI on suppressing ovarian cancer through down-regulating over-expression of FSHR and ERß in the normal ovarian tissues. METHODS: 180 female mice were randomized into six groups (n = 30). Mice of FRBI-1, FRBI-2 and FRBI-3, FRBI-4 were intramuscularly injected with FRBI of 10, 20, 30 and 40 mg/kg, respectively, for five consecutive days. The qPCR and Western blotting were used to determine expression levels of FSHR and ERß mRNAs and proteins in mouse ovaries. RESULTS: The ovarian cortex thickness (OCT) of the FRBI-4 group were less than that FSH group on day 30 (P < 0.05). The numbers of secondary follicles (SF) and the maximum transverse diameters (MTD) of secondary follicles of FRBI-3 and FRBI-4 groups were decreased as compared to FSH group (P < 0.05 or P < 0.01) by 24.11% and 27.47% on day 20 based on the control group (CG) levels. On day 15, the reductions of FSHR mRNA levels in FRBI-2, FRBI-3 and FRBI-4 were 27.78%, 29.37% and 43.65% (P < 0.05 or P < 0.01), respectively in comparison with CG. ERß and FSHR protein levels of FRBI-treated mice were gradually decreased as compared to and CG and FSH group. ERß protein level of FRBI-4 was less than that of CG on day 20 (P < 0.05). On days 15 and 20, estradiol (E2) concentrations of FRBI-2, FRBI-3 and FRBI-4 groups were lower than those of the CG and FSH group (P < 0.05 or P < 0.01). CONCLUSIONS: FRBI could reduce OCT and follicle numbers. A high dose of FRBI (30 mg/kg to 40 mg/kg) could suppress ovarian and follicular development, and attenuate expression levels of ERß and FSHR mRNAs and proteins in the ovaries, additionally inhibit E2 production. Therefore, FRBI will possibly be utilized to restrain the carcinogenesis of ovarian cancer by down-regulating overexpression of FSHR and ERß in the ovaries.

FSH receptor binding inhibitor influences estrogen production, receptor expression and signal pathway during in vitro maturation of sheep COCs.

Follicle-stimulating hormone (FSH) promotes secretion of follicle fluid and follicle development. FSH acts via cognate FSH receptor (FSHR). It remains unknown whether the supplement of FSH-receptor binding inhibitor (FRBI) into the in vitro maturation (IVM)medium influence the estrogen receptor expression and signal pathway of oocytes in sheep. The present study aimed to investigate FRBI effects on inositol trisphosphate (IP3) of oocytes and protein kinase A (PKA) of sheep granulosa cells, further to elucidate the signal pathway of FRBI effects. Cumulus-oocyte complexes (COCs) were recovered from antral follicles. COCs were cultured for 24 h in the IVM medium supplemented with varying concentrations of FRBI (0, 10, 20, 30 and 40 µg/mL) and FSH (10IU/mL). ELISA was used to measure the concentrations of estradiol (E2) and IP3 in the IVM medium. Western blotting was utilized to detect protein expression of ERß of COCs and protein kinase A (PKA) of granulosa cells. The results showed IP3 concentrations of FRBI-3 and FRBI-4 groups were less than that of CG and FSH groups at 22 h and 24 h (P < 0.05). PKA levels of FRBI-3 and FRBI-4 groups were significantly less than that of CG and FSH group (P < 0.05 or P < 0.01). Expression levels of ERß mRNA and protein of FRBI-treated groups were gradually decreased in comparison to CG and FSH group. The minimum value was detected in the FRBI-4 group. ERß protein level of the FRBI-4 group was significantly less than that of FSH group (P < 0.05). E2 concentrations of FRBI-treated groups were elevated as compared to CG, with the highest increment of FRBI-2 group (P < 0.05). Our results revealed a higher dose of FRBI reduced IP3 production. FRBI could suppress slightly expression levels of ERß mRNA and protein of COCs and PKA of granulosa cells, additionally increased E2 production of sheep COCs.