Three groups of 2-3 months old alcohol preferring rats were used for long-term alcohol consumption and gene expression profiling: male P rats (n = 15; IndianaUniversity, Indianapolis), male HAD rats (n = 13; IndianaUniversity, Indianapolis) and male AA rats (n=14; National Public Health Institute, Helsinki). The rats were kindly provided by T.K. Li (Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis)and D. Sinclair (Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki). Each rat strain shows alcohol preference due to various neurochemical alterations, as indicated by the abbreviations P (preference), HAD (high alcohol drinking), AA (alcohol addicted).43,44 All experimental procedures were approved by the Committee on Animal Care and Use (Regierungspräsidium Karlsruhe), and carried out in accordance with the local Animal Welfare Act and the European Communities Council Directive of 24 November 1986 (86/609/EEC).
