PROGENY OF MOTHERS DRINKING CORTICOSTERONE DURING LACTATION HAS LOWER STRESS-INDUCED CORTICOSTERONE SECRETION AND BETTER COGNITIVE PERFORMANCE

In order to test the hypothesis that maternal corticosterone influences hypothalamus-pituitary-adrenal (HPA) system activity in the adult rat and behaviors related to it, we induced a moderate increase in maternal plasma level of corticosterone by adding the hormone to the drinking water of the dams (200 mug/ml) from the day after delivery to weaning. Our previous experiments have shown that this procedure produces plasma levels of the hormone in the range of those following a mild psychic stress (from 4.3+/-0.5 to 9.5+/-1.8 mug/100 ml in the dams, and from 0.7+/-0.1 to 1.2+/-0.2 mug/100 ml in the pups at 10 days of lactation). Adrenal weights were slightly and temporarily decreased by treatment in both mothers and offspring. Only the male progeny was investigated in this study. Corticosterone-nursed rats had significantly less corticosterone and ACTH in basal conditions and after a 2 min restraint stress at 3 months of age, and showed better performances at weaning and at 1, 2 and 3 months of life in the Morris water maze. Our results demonstrate that a moderate increase in maternal corticosterone during lactation influences the activity of HPA axis and improves spatial learning ability of the adult offspring.