[Effects of insulin-like growth factor-I and insulin-like growth factor binding-protein 1 on development of ovarian...

To investigate the effects of insulin-like growth factor I (IGF-I) and insulin-like growth factor binding-protein 1 (IGFBP-1) on development of ovarian follicles during gonadotropin stimulation in in-vitro fertilization (IVF) program.

Enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay were used to determine the levels of IGF-I, IGFBP-1 and estradiol (E2) in serum and follicular fluid obtained during oocyte pick-up (OPU) in 32 IVF-embryo transfer cycles.

(1) Serum IGFBP-1 levels increased with growth of follicles [(3.5 +/- 1.0) micrograms/L during OPU, (2.1 +/- 0.5) micrograms/L before stimulation, P < 0.05]; follicular fluid (FF) IGFBP-1 levels were significantly higher than those of matched serum levels [(77.7 +/- 26.7) micrograms/L, (3.5 +/- 1.0) micrograms/L respectively P < 0.001]; Serum IGFBP-1 levels were positively correlated with developing of follicle numbers (r = 0.48, P < 0.05). (2) There were no significant changes of serum IGF-I levels before and after superovulation, neither was there between serum and follicle fluid [(103.7 +/- 39.2) micrograms/L, (105.9 +/- 36.8) micrograms/L, (108.9 +/- 19.1) micrograms/L respectively P > 0.05]. Significant positive correlation was found between serum IGFBP-1 and serum E2[(3.5 +/- 1.0) micrograms/L, (3,293 +/- 1,361) pmol/L, r = 0.41, P < 0.05).

During superovulation serum total IGF-I levels do not change. However changes of serum IGFBP-1 levels may play a complementary role in regulation of follicular development by altering free IGF-I levels.