Cortisol response and ovarian hormones in juvenile and cycling female Cebus monkeys: effect of stress and dexamethasone.
We examined cortisol profiles in relation to ovarian hormones and their response to a repeated composite stressor with and without dexamethasone suppression. To evaluate the day-to-day changes in circulating cortisol relative to ovarian hormones, we subjected five adult female Cebus apella monkeys daily to restraint, sedation, transport to a neighboring room for femoral venipuncture, and return to the cage throughout the menstrual cycle. The cortisol response to the repeated stressor for blood collection, its relationship with the ovarian function, and the effects of dexamethasone were evaluated in six juveniles (18-24 months old) and five adult females in the luteal phase. Blood was sampled at time 0; then the monkeys received the vehicle and their blood was sampled again at 1, 2, 4, and 24 hr. This experiment was repeated 3 weeks later, with dexamethasone (i.m. 2 mg/Kg) injected instead of vehicle. Plasma aliquots were assayed for cortisol, progesterone, and estradiol. The results revealed that from middle infancy and throughout adulthood, hypercortisolism is the norm in female Cebus monkeys. The high cortisol values remained unchanged across the cycle despite the cyclic changes in estradiol and progesterone levels. Juvenile monkeys exhibited a higher cortisol response to stress than adults, and both juvenile and adult monkeys exhibited the typical suppression by dexamethasone. A rapid suppression of progesterone co-occurred in parallel with cortisol after dexamethasone injection in juvenile monkeys, suggesting that most circulating progesterone originates in the adrenals. In contrast, adult females exhibited an overincrement of progesterone levels, in parallel with a rise in cortisol, in response to the stressor, and this effect was exacerbated by dexamethasone. The findings suggest that hypercortisolism is insufficient to disrupt ovarian development toward a normal cyclical function, and that ovarian steroids have no influence on day-to-day circulating cortisol levels. On the other hand, the overincrement of progesterone levels induced by stress and/or glucocorticoids during the early luteal phase is unlikely to interfere with the development of this phase and implantation in this monkey species.
Lahoz
Monica M
MM
Centro de Educacíon Medica e Investigaciones Clínicas (CEMIC) Aires, Argentina.
Nagle
Carlos A
CA
Porta
Margarita
M
Farinati
Zulema
Z
Manzur
Teresita D
TD
D000818:Animals; D002428:Cebus / Q000097:blood / Q000502:physiology*; D003907:Dexamethasone / Q000494:pharmacology*; D004958:Estradiol / Q000097:blood*; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology; D006854:Hydrocortisone / Q000097:blood*; D008597:Menstrual Cycle / Q000502:physiology*; D011374:Progesterone / Q000097:blood*; D013312:Stress, Physiological / Q000097:blood / Q000662:veterinary*
D005938:Glucocorticoids; D011374:Progesterone; D004958:Estradiol; D003907:Dexamethasone; D006854:Hydrocortisone