Growth hormone stimulates follicular development by stimulating ovarian production of insulin-like growth factor-I.

The present study was undertaken to investigate the effects of GH on follicular growth, oocyte maturation, ovulation, and production of insulin-like growth factor-I (IGF-I) in the in vitro perfused rabbit ovaries. Ovulation did not occur in any ovaries perfused with GH at a concentration of 1, 10, 100, or 200 ng/ml, but the addition of GH to the perfusate increased the follicle diameter in a dose-dependent manner. The production of IGF-I by ovaries perfused with medium alone was very low throughout the perfusion period. The addition of 100 ng/ml GH to the perfusate significantly increased ovarian production of IGF-I at 4, 6, 8, and 12 h compared with the contralateral control ovaries. Changes in the tissue concentrations of IGF-I in ovaries perfused with 100 ng/ml GH paralleled those triggered by exposure to 50 IU human CG (hCG). When the effect of GH on the tissue concentration of IGF-I was determined at 4 h, GH stimulated the tissue concentration of IGF-I in perfused rabbit ovaries in a dose-dependent m...