Physiology: In-vivo studies on ovarian insulin-like growth factor I concentrations in human preovulatory follicles and human ovarian circulation

Abstract

In some recent hypotheses, the ovary has been indicated as a source of insulin-like growth factor (IGF)-I, with synthesis regulated from local steroidal and non-steroidal substances. We measured IGF-I concentrations in both serum and follicular fluid of women undergoing in-vitro fertilization (IVF) and embryo transfer, in both induced and spontaneous cycles. It was found that serum and follicular IGF-I concentrations were correlated with follicular morphology, oocyte maturity, steroid concentrations and clinical characteristics of IVF cycles. In addition, we measured IGF-I concentrations in both peripheral and ovarian circulation to gain further detailed information on the contribution of the ovary to IGF-I production. The results of our study support the hypothesis that follicular IGF-I is probably derived by diffusion from peripheral circulation and that local production appears unlikely.

Serum insulin-like growth factor I (IGF-I) and IGF-binding protein 3 (IGFBP-3) in IVF patients with polycystic ovary syndrome: correlations with outcome

“…The association of a fall in IGF-I levels with a higher number of immature oocytes in PCOS patients suggests that the bioavailability of IGF-I is integral to the mature oocyte in these patients. Several authors have found that in normally ovulating patients, follicular fluid IGF-I concentrations correlated with the degree of oocyte maturity (8,9,29) We did detect significantly different levels of IGFBP-3 and discrepant trends of serum IGFBP-3 levels during stimulation in PCOS and control patients. Serum IGFBP-3 levels decrease during FSH stimulation in normally ovulating patients (16,17,30).…”

Insulin-like growth factor-II (IGF-II), IGF-binding protein-3 (IGFBP-3), and IGFBP-4 in follicular fluid are associated with oocyte maturation and embryo development

“…Moreover, in vitro studies have shown that IGF-II increases the release of E 2 from cultured human GCs in a dose-dependent manner (28). In contrast, FF levels of IGF-I at the preovulatory stage are considerably lower than serum levels, indicating that IGF-I in FF is probably derived from peripheral circulation diffusion (17,29). Although IGF-I mRNA is not detected in GCs of the mature human ovary, IGF-I receptor mRNA is abundant in GCs of both Graafian and atretic follicles (15,16).…”

Association of in vitro fertilization outcome with circulating insulin-like growth factor components prior to cycle initiation

“…1,15 Moreover, serum levels of IGF-I are higher than follicular fluid levels in the preovulatory stage in women undergoing IVF. 18,19 This implies that IGF-I in follicular fluid is probably derived from the peripheral circulation. 20 Serum levels of IGF-I in women, therefore, may determine follicular levels of IGF-I, which subsequently affect oocyte maturation.…”