Endometrial insulin-like growth factor II and type I receptor in unexplained infertility and its steroid regulation

Abstract

OBJECTIVE: To investigate the endometrial expression of insulin-like growth factor II(IGF-II) and type I receptor(IGF-1R) in unexplained infertility. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect and quantify endometrial IGF-II and IGF-I R mRNA experession in the mid-luteal phase. Serum concentrations of estradiol(E(2)) and progesterone (P) were measured by radioimmunoassays. Thirty-four women with unexplained infertility were included in the study group. Twenty-one women with normal fertility were selected as the control group. RESULTS: Endometrial IGF-II and IGF-I R mRNA experession during the midluteal phase were significantly lower in the study group than in the control group (0.662 +/- 0.371 compared with 0.961+/- 0.389, P< 0.05; 0.582 +/- 0.257 compared with 0.829 +/-0.341, P< 0.05 respectively). The average serum P level in the study group was significantly lower than in the control group (23.782 +/-15.459 compared with 43.142 +/- 16.549nmol/L, P< 0.005). IGF-II mRNA expression correlated positively with IGF-I R mRNA expression in the two groups. Serum P level correlated positively with IGF-II and IGF-I R mRNA expression in the two groups. CONCLUSION: IGF-II and IGF-I R may play an important role in the implantation process. Their decreased expression relating to decreased P level may be important in unexplained infertility.