[Insulin growth factor I in the development of ovarian follicles]

To investigate the role of insulin growth in factor-1 (IGF-1) in the development of ovarian follicles under the stimulation of gonadotropins in an in-vitro fertilization (IVF) program.

Radioimmuoasssy was used to determine the levels of sex hormones and IGF-1 in the serum and follicular fluid samples. In situ hybridyzation was used to detect the expression of IGF-1 and IGF-1 receptor (IGF-1R) in the granulosa cell obtained from follicular aspiration in women undergoing IVF egg retrieval procedures.

(1) Levels of plasma IGF-1 increased with the development of follicles (P < 0.001); follicular fluid (FF) IGF-1 levels were lower than those of matched plasma; FF-IGF-1 decreased with increase of follicle numbers (P < 0.01), e.g. in patients with less than 2 follicles (diameter > or = 15 mm) at the tine of ovum pick-up the FF-IGF-1 levels were much higher than patients with more than 2 follicles (P < 0.05). (2) Significant negative correlation was found between plasma IGF-1 and plasma E2 and also between FF-IGF-1 and FF-follicle-stimulating hormone (FSH) during ovum pick-up (P < 0.01). (3) IGF-1 mRNA was not, while IGF-1R mRNA was found to be present in the human granulosa cells taken at ovum pick-up.

Plasma IGF-1 production might be stimulated by gonadotropins and distributed into the ovarian follicles by diffusion from peripheral circulation, acting upon the granulosa cells and therefore plays a complementary role with the gonadotropins in the regulation of follicular development.