Pituitary-adrenal responses to morphine and footshock stress are enhanced following prenatal alcohol exposure.

The effect of prenatal ethanol exposure on pituitary-adrenal function in adult offspring was assessed by measuring corticosterone (CS) levels in plasma following exposure to two forms of footshock stress, intermittent and continuous, and after administration of 20 mg/kg of morphine. The footshock experiments were conducted at two time points in the circadian pituitary-adrenal cycle. Prenatally ethanol-exposed (E) rats had higher levels of CS than pair-fed and normal controls following intermittent footshock when tested at the crest of the CS circadian rhythm. However, this difference was not present when intermittent footshock was presented at the trough of the circadian cycle. At either time of day, there were no differences among the prenatal treatment groups in the basal condition or following continuous footshock. In addition, E rats had significantly higher levels of plasma CS than controls following morphine. Plasma adrenocorticotropin (ACTH) levels were measured after intermittent footshock at the crest of the circadian rhythm and were significantly higher in E rats than in controls. These results extend our previous reports of enhanced activation of the hypothalamo-pituitary-adrenal axis in response to other stressors as well as to ethanol in adult rats exposed to ethanol in utero. They also confirm that E rats are differentially hyperresponsive only to intermittent footshock stress, not to continuous footshock, as we had found to be the case when the analgesia induced by these two stressors was the dependent measure.