PARACRINE INTERACTIONS AMONG INSULIN-LIKE GROWTH FACTOR-I, INSULIN-LIKE GROWTH-FACTOR BINDING PROTEIN-1, AND STEROID-HORMONES IN FOLLICULAR-FLUID

Objective-To improve understanding of follicular paracrine interaction s. Patients and Methods-The levels of insulin-like growth factor I (IG F-I) and the IGF-binding protein-I (hIGFBP-1) in 28 follicular fluid s amples obtained from 10 in vitro fertilization patients were measured. Only samples containing mature oocytes which subsequently fertilized and cleaved were studied. These levels were then related to follicular fluid steroid levels in the individual follicle, pregnancy outcome, a nd the use of leuprolide acetate. Results-Linear regression analysis d emonstrated a positive relationship between individual follicular flui d levels of IGF-I and hIGFBP-1, as well as between levels of estradiol and hIGFBP-1. There was a negative relationship between follicular fl uid progesterone/estradiol ratios and the levels of both IGF-I and hIG FBP-1. Mean follicular fluid levels of IGF-I and hIGFBP-1 were not sta tistically related to pregnancy outcome or leuprolide use. Lower mean follicular fluid levels of estradiol and consequently higher follicula r fluid progesterone/estradiol ratios were found among patients who ac hieved pregnancy compared to nonpregnant patients. Conclusion-Our resu lts support the concept that critical interactions involving IGF-I, hI GFBP-1, and steroid hormones are necessary for the maintainence of an intrafollicular milieu favorable for optimal oocyte development.