Prenatal ethanol exposure alters adrenocortical response to predictable and unpredictable stressors

In the present study, effects of psychological stressors and stressor predictability on the adreno-cortical responses of animals exposed to ethanol in utero were examined. Male and female offspring from ethanol-exposed (E), pair-fed (PF), and ad lib-fed control (C) conditions were tested in adulthood. Separate sets of animals were exposed once daily for 5 consecutive days to either unpredictable (UNPRED) or predictable (PRED) restraint stress or to UNPRED novelty stress. On the fifth test day, blood samples for plasma corticosterone determination were taken either prior to stress (basal levels) or following stress. Males in all groups and C females had higher basal corticosterone levels if previously subjected to PRED restraint than if previously subjected to UNPRED restraint; E and PF females did not exhibit this differential responsiveness. Following restraint stress on the fifth test day, there were no significant differences in response to PRED and UNPRED restraint among E, PF, and C males. In contrast, C but not E or PF females exhibited a greater plasma corticosterone response to UNPRED than to PRED restraint. Following novelty stress, E males exhibited a significantly reduced plasma corticosterone response compared to PF and C males. For females, there was a trend for an increased corticoid response in E compared to PF females following novelty stress as well as a different pattern of response among groups from days 1 to 5 of testing. These data support and extend previous studies suggesting that, compared to PF and C animals, E animals may exhibit altered responses to stressors as well as deficits in the ability to use or respond to environmental cues.