In vivo effects of recombinant human growth differentiation factor-9 protein on ovulation induction in mice

Objective To explore the effect of recombinant protein growth differentiation factor-9 (GDF-9) on follicular development in mice. Methods Thirty eugamic KM mice were divided into three groups, which received human menopausal gonadotropin (hMG) 10 IU, hMG 10 IU with recombinant protein GDF-9 10 μg (combination group) and normal saline (0.5 mL) i.p. (control group), respectively; 48 h later, human chorionic gonadotropin (hCG) 10 IU was injected into each mouse, 16-20 h later 30 mice were killed, their ovary weight and the number of follicles were compared. Enzyme linked immunosorbent assay (ELISA) was used to examine the level of serum estrogen (E2), their oocytes were fertilized in vitro, and fertilization information was observed. Results The number of follicles (28.9±10.2, 36.5±13.0), ovary index [(32.26±6.33) mg/100 g, (38.80±8.90) mg/100 g] and the level of serum E2 [(45.64±14.19) ng/L, (52.02±16.08) ng/L] after ovulation induction in hMG group and combination group were higher than those of control group [11.4±5.4, (26.11± 7.16) mg/100 g, (25.03±13.62) ng/L], with statistical significances (P=0.001, P=0.034, P=0.029; P=0.000, P=0.028, P=0.014), especially, and they were significantly higher in combination group than in hMG group (P=0.025, P=0.031, P=0.043). There were no significant differences in fertilization rate among different groups (P>0.05). Conclusion Recombinant protein GDF-9 combined with gonadotropin (Gn) could effectively increase oocyte retrieval rate in mice, while had no influence on mouse oocytes fertilizability. Utilizing recombinant protein GDF-9 combined with Gn provide a new clinical idea for improving ovarian response to ovulation stimulation. Key words: Ovulation induction; Growth differentiation factor-9 (GDF-9); Gonadotropin (Gn); Ovarian response (OR)