THE ACTIVITY OF THE PITUITARY-ADRENAL CORTEX AXIS DURING PREGNANCY AND LACTATION1

Abstract

The activity of the anterior pituitary-adrenal cortex axis was studied in the laboratory rat during diestrus, pregnancy, and lactation. Adrenal cortical activity was assessed by measuring the concentration of total and free cholesterol in the adrenal gland. Pituitary ACTH potency was determined by the ascorbic acid depletion technique. The concentration of total adrenal cholesterol was: 2.79 mg/100 mg of adrenal tissue in the diestrous rat; 1.81 mg on the 15th day of pregnancy; 2.79 mg on the 21 day of pregnancy; 1.38 mg one hour after parturition; and 0.81 mg on the 10th day of lactation. The milliunits of ACTH per 200 [mu]g of anterior pituitary tissue were: 0.90 in the diestrous rat; 0.77 on the 15th day of pregnancy; 1.20 on the 21 day of pregnancy; 0.73 one hour after parturition; and 0.95 on the 10th day of lactation.