Abstract
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.
Published Version
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