Localization of insulin-like growth factor (IGF-I) and IGF-I receptor expression in human corpora lutea: role on estradiol secretion.

OBJECTIVE

To determine whether insulin-like growth factor (IGF-I) and its receptors are expressed by human corpus luteum (CL) and to establish the effect of IGF-I on E2 biosynthesis in human luteal cell cultures.

DESIGN

Middle corpora lutea were obtained from women undergoing surgical sterilization. The tissue was frozen for binding and in situ studies or dispersed for cell cultures.

SETTING

Procedures were performed at the San Borja-Arriarán Hospital, National Health Service, and Institute of Maternal and Child Research, Faculty of Medicine, University of Chile.

PATIENTS

Twelve patients aged 30 to 40 years requesting surgical sterilization in our institution. The laparotomy was scheduled 6 to 8 days after ovulation.

MAIN OUTCOME MEASURES

Expression of IGF-I and IGF-I receptor messenger RNAs (mRNAs) by in situ hybridization. Concentration of IGF-I receptor and binding characteristics. Production of E2 by luteal cells.

RESULTS

The binding of IGF-I was detected in middle human CL membranes. In addition, this tissue expressed the mRNAs of IGF-I and its receptor. In culture, IGF-I caused a progressive increase on E2 production.

CONCLUSION

These data suggest that the IGF-I system is present in middle human CL. The topographic distribution of IGF-I and its receptors and the ability of IGF-I to stimulate E2 secretion strongly suggest that IGF-I has a role as a paracrine or autocrine regulator of the human luteal function.