Concentrations of insulin-like growth factor (IGF)-I and IGF binding protein-3 in the follicular fluid of women undergoing ovarian hyperstimulation with different gonadotropin preparations

Abstract

Insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) have an important regulatory role in follicular development and oocyte maturation. The aim of this prospective ,randomized ,double-blindstudy was to measure the concentrations of IGF-I and IGFBP-3 in follicular fluids collected from infertile women undergoing ovarian hyperstimulation using three different gonadotropin preparations. Twentyinfertile women (mean age 33 years ,range 28-40) undergoing in vitro fertilization (IVF) programs were recruited. After a written informed consent ,each woman randomly underwent a long-protocolfor ovarian hyperstimulation using gonadotropin-releasing hormone (GnRH)-analog and one of the following recombinant- and urinary-gonadotropins - α-follitropin ,β-follitropin oruro-follitropin. Serum 17β-estradiol (E2) levels and follicle growth were assessed during the follicular phase. The concentrations of IGF-I and IGFBP-3 in the follicular fluid ofaspirated dominant follicles were measured directly. Women treated with α-follitropin needed significantly lower doses of follicle-stimulating hormone (FSH) compared to those receiving β-follitropin(p < 0.05). No other statistically significant differences were detected between groups. Serum E2 levels increased in the three groups from early to late follicular phase. Follicularfluid IGF-I and IGFBP-3 concentrations did not differ significantly in the three groups of women. A statistically significant relationship was observed between follicular fluid IGF-I and IGFBP-3 levels(r = 0.41 ,p = 0.001). Oocyte maturation correlated in a positive manner with IGF-I (r = 0.34 ,p = 0.01) and IGFBP-3 (r = 0.29 ,p = 0.03). These findings show thatboth recombinant- and urinary-gonadotropin preparations were equally effective in releasing IGF-I and IGFBP-3 in the follicular fluid of dominant follicles ,and confirmed the role of these compounds onoocyte maturation.