Acute ethanol induction of c-Fos immunoreactivity in pre-pro-enkephalin expressing neurons of the central nucleus of the amygdala

Previous studies have shown that acute ethanol administration induces expre ssion of c-Fos immunoreactivity in the central nucleus of the amygdala (CNA ) [S.L. Chang, N.A. Patel, A.A. Romero, Activation and desensitization of F os immunoreactivity in the rat brain following ethanol administration, Brai n Res., 679 (1995) 89-98; M. Morales, J.R. Criado, P.P. Sanna, S.J. Henriks en, F.E. Bloom, Acute ethanol induces c-fos immunoreactivity in GABAergic n eurons of the central nucleus of the amygdala, Brain Res., 798 (1998) 333-3 36; A.E. Ryabinin, J.R. Criado, S.J. Henriksen, F.E. Bloom, M.C. Wilson, Di fferential sensitivity of c-Fos expression in hippocampus and other brain r egions to moderate and low doses of alcohol, Mel. Psychiatry, 2 (1997) 32-4 3]. We recently showed that over 70% of these c-Fos immunoreactive neurons are GABAergic [M. Morales, J.R. Criado, P.P. Sanna, S.J. Henriksen, F.E. Bl oom, Acute ethanol induces c-fos immunoreactivity in GABAergic neurons of t he central nucleus of the amygdala, Brain Res, 798 (1998) 333-336]. In the present study, we report that ethanol-induced c-Fos immunoreactivity was ma inly confined to neurons that express pro-enkephalin (ENK). Ln contrast, a small number of c-Fos immunoreactive neurons express corticotrophin releasi ng factor (CRF). Our results thus provide anatomical evidence indicating th at within the amygdala, GABAergic neurons that contain ENK are responsive t o acute ethanol exposure. (C) 2000 Elsevier Science B.V, All rights reserve d.