Influence of cortisol on insulin- and insulin-like growth factor 1 (IGF-1)-induced steroid production and on IGF-1 receptors in cultured bovine granulosa cells and thecal cells.

During stress, hyperactivity of the adrenal gland can directly and indirectly inhibit ovarian function. However, little evidence existed to support the notion that glucocorticoids could influence insulin-like growth factor 1 (IGF-1) action within the ovary. Therefore, the effect of cortisol on IGF-1-induced granulosa and thecal cell function was evaluated. Granulosa and thecal cells from bovine ovarian follicles were cultured for 2 d in the presence of 10% fetal calf serum and then cultured for an additional 2 d in serum-free medium with added hormones. Cortisol had little or no effect (p > 0.05) on IGF-1-induced progesterone production by granulosa cells from both small (1-5 mm) or large (> or =8 mm) follicles. Also, cortisol had little or no effect (p > 0.05) on basal, insulin-, or IGF-1-induced estradiol production by granulosa cells from small or large follicles, or on the number of IGF-1 receptors in granulosa cells from small follicles. Cortisol had no effect (p > 0.10) on insulin-induced granulosa cell numbers, but increased IGF-1-induced granulosa cell numbers. In thecal cells, doses of 1-100 ng/mL of cortisol increased (p< 0.05) insulin- and IGF-1-induced thecal cell numbers by 10-20%, progesterone production by 18-36%, and androstenedione production by two- to fourfold. The estimated dose of cortisol necessary to stimulate 50% of the maximum androstenedione production in the presence of IGF-1 was 7 ng/mL. In contrast, cortisol decreased (p < 0.05) the number of IGF-1 receptors in thecal cells by 45%. In conclusion, cortisol at physiological levels can directly influence ovarian follicular function in cattle, especially thecal androstenedione production.