High corticosterone levels in prenatally stressed rats predict persistent paradoxical sleep alterations

Prenatal stress predisposes rats to long-lasting disturbances that persist throughout adulthood (e.g., high anxiety, dysfunction of the hypothalamo-pi tuitary-adrenal axis, and abnormal circadian timing). These disturbances pa rallel to a large extent those found in depressed patients, in which hyperc ortisolemia and sleep alterations may be related to stress-inducing events. We studied sleep-wake parameters in control and prenatally stressed adult rats (3-4 months old) and examined possible relationships with their cortic osterone levels (determined at 2 months of age). Under baseline conditions, prenatally stressed rats showed increased amounts of paradoxical sleep, po sitively correlated to plasma corticosterone levels. Other changes include increased sleep fragmentation, total light slow-wave sleep time, and a slig ht decrease in the percentage of deep slow-wave sleep relative to total sle ep time. During recovery sleep from acute restraint stress, all sleep chang es persisted and were correlated with stress-induced corticosterone secreti on. High corticosterone levels under baseline conditions as well as an acut e stress challenge may thus predict long-term sleep-wake alterations in rat s. Taken together with other behavioral and hormonal abnormalities in prena tally stressed animals, the pronounced changes in sleep-wake parameters tha t are similar to those found in depressed patients suggest that prenatal st ress may be a useful animal model of depression.