Abstract: Objective To evaluate the effects of different concentrations of follicle stimulating hormone receptor binding inhibitor (FRBI) on ovarian development, reproductive hormone secretion and protein expression in mice. Methods The mice of FRBI groups were intramuscularly injected with 20, 30 and 40 mg/kg FRBI, respectively. Mice of FSH group were intramuscularly injected with 10IU/mL FSH. Mice of the control group were injected with 0.20 mL normal saline. Each group was injected for 5 days. The body weight and ovarian weights of five groups mice were accurately weighed. Ovarian cortex thickness（OCT）and secondary follicles were observed and measured under the light microscope. ELISA was used to determine the serum concentrations of FSH. Expression levels of FSH receptor (FSHR) in the ovarian tissues were detected using Western blot. Results There were no significant differences of body weights between all groups. Ovarian weights of FRBI groups were significantly lower than that of control group (P <0.05) after day 15 on, with the least value of FRBI-30 mg group. The OCT，maximum longitudinal diameter (MLD) and maximum transverse diameter (MTD) of three experiment groups were less than those of CG and FSH group (P <0.05). The smallest values of MLD and MTD were found in the FRBI-40 mg group. Serum concentration of FSH FRBI-20 mg group was the lowest. Expression levels of FSHR proteins in the ovaries were gradually reduced along with the increase of FRBI doses. They were significantly less than that of FSH group (P <0.01). Conclusions FRBI could dose-dependently inhibit the growth and development of mice ovaries, and reduce serum FSH concentration, additionally attenuate expression levels of FSHR protein in ovaries.

Key words: Key words: follicle stimulating hormone, follicle stimulating hormone receptor, FRBI, reproductive hormone, protein expression