Endocrine Changes during 48 Hours of Food Withdrawal in the Pregnant Rhesus Monkey in the Last Third of Gestation*

Abstract

We studied the hormonal responses in four pregnant rhesus monkeys between 112 and 149 days gestation. After 2 days, during which the monkeys were fed ad libitum, their food was withdrawn at 1500 h for 48 h while allowing free access to water. The food then was returned, and the animals were studied for a further 2 days. The mean maternal whole blood glucose concentration significantly decreased, and plasma cortisol and dehydroepiandrosterone sulfate (DHEAS) concentrations significantly increased within 30 h of food withdrawal (P less than 0.05). The maternal plasma estradiol concentration increased significantly at 1000 h on the second day of food withdrawal (P less than 0.05), whereas the plasma progesterone concentration did not change. The maternal blood glucose and plasma cortisol, DHEAS and estradiol concentrations returned to baseline by the second day of food replacement. We conclude that the stress of hypoglycemia and/or the attendant inability to eat, together or separately, stimulate maternal adrenal glucocorticoid and androgen secretion during the period of food withdrawal. The increased maternal DHEAS and perhaps other adrenal androgen concentrations result in increased maternal estrogen production.