Prenatal stress in rats: effects on plasma corticosterone, hippocampal glucocorticoid receptors, and maze performance

The present experiments were designed to investigate the effects of materna l stress on cognitive and endocrine parameters in the adult offspring. Preg nant rats were stressed daily during the last week of pregnancy (days 15-19 ) by restraint, and the performance of their offspring in the Morris water maze was recorded. Plasma corticosterone levels after swimming and the stat us of hippocampal glucocorticoid receptors (GRs) were determined. During ac quisition of the task, prenatally stressed (PS) males - but not females - s howed longer escape latencies than non-stressed controls when swimming in c old (10 degreesC) but not in warm (20 degreesC) water. This sex- and prenat al stress-specific difference was even more pronounced during reversal lear ning of the task. In contrast, PS females - but not males - had higher basa l corticosterone levels and a Lower density of hippocampal corticosteroid r eceptors than non-stressed controls. In all animals irrespective of treatme nt, swimming in the water maze causes an increase of corticosterone that wa s smaller on day 8 of swimming than on day 1. After swimming in cold water, the rise in corticosterone levels in females was steeper and returned fast er to baseline values than after swimming in warm water. A similar pattern could be seen in PS females when compared to their non-stressed controls. T he data suggest that prenatal stress impairs spatial learning in males but not in females. Basal and stress-induced increases in corticosterone levels , however, were altered in PS females and not in PS males; i.e., prenatal s tress-induced changes in corticosterone secretion were not paralleled by pr enatal stress-induced deficits in spatial learning. (C) 2000 Elsevier Scien ce Inc. All rights reserved.