Effects of growth hormone on follicle growth, oocyte maturation, and ovarian steroidogenesis.

OBJECTIVES

To assess the effects of GH on follicle growth, oocyte maturation, ovulation, and ovarian steroidogenesis.

DESIGN

In vitro perfused rabbit ovary.

INTERVENTIONS

The rabbit ovaries were perfused with medium alone, with GH at 1, 10, 100, or 200 ng/mL, or with 50 IU hCG for 12 hours.

MAIN OUTCOME MEASURES

The follicle diameter, the percent change in follicle diameter, the percentage of oocytes achieving germinal vesicle breakdown, and the production of P and E2 by the perfused rabbit ovaries.

RESULTS

The addition of GH to the perfusate increased the follicle diameter at 12 hours after perfusion in a dose-dependent manner. The percent change in follicle diameter in GH-treated ovaries did not differ significantly from that in hCG-treated ovaries at each time point of perfusion. However, ovulation did not occur in either the control ovaries or the experimental ovaries treated with GH. Exposure to GH at a concentration of > 10 ng/mL significantly stimulated the resumption of meiosis, as compared with the contralateral control ovaries. Although the concentration of P in the perfusate did not differ significantly between GH-treated and control ovaries, GH stimulated E2 production by the perfused rabbit ovaries in a dose-dependent manner.

CONCLUSIONS

Growth hormone acts on the rabbit ovary to stimulate follicle growth, oocyte maturation, and ovarian E2 production.