INTERACTION BETWEEN ALCOHOL AND INTERLEUKIN-1-BETA ON ACTH-SECRETION AND THE EXPRESSION OF IMMEDIATE-EARLY GENES IN THE HYPOTHALAMUS

We have observed that alcohol does not alter adrenocorticotropin (ACTH) released in response to the iv injection of interleukin-1 beta(IL-1 beta). In contrast, prior (-30 to -90 min) administration of moderate doses of alcohol (0.5-2.0 g/kg) significantly blunts ACTH secretion following the intracerebroventricular (icv) injection of the cytokine. We explored two possible mechanisms responsible for this phenomenon: Corticosteroid feedback and alcohol-induced inhibition of hypothalamic neuronal activation (measured through changes in c-fos and NGFI-B mRNA levels). Increasing plasma corticosterone levels by exposing rats to mild electroshocks or injecting them with corticosterone did not alter ACTH released by rats administered with IL-1 beta into the brain ventricles. Alcohol, which by itself did not stimulate c-fos or NGFI-B mRNA levels in the paraventricular nucleus of the hypothalamus, significantly blunted the ability of icv IL-1 beta to increase the expression of these immediate early genes. We conclude that the inhibitory influence exerted by prior alcohol treatment on ACTH released by icv administered IL-1 beta may reflect an interference with the stimulatory influence of the cytokine on hypothalamic neurons involved in the activation of the hypothalamic-pituitary-adrenal axis. (C) 1994 Academic Press, Inc.