and Kirstein, 2007). These data support similar reports in the adult literature (Weiss et al., 1996); however, a recent adolescent alcohol report (Sahr, Thielen, Lumeng, Li and McBride, 2004) suggested there were no differences in DA for rats selectively bred to drink alcohol during adolescence. Differences between the previous adolescent report and the present study may certainly be attributable to differences in route of administration whereas the previous report incorporated voluntary self-administration and the present study incorporated passive experimenter administration of alcohol injections. Voluntary self-administration of alcohol produces different neurochemical responses than involuntary or passive administration of alcohol (Ericson et al., 1998; Weiss et al., 1993; Imperato and Di Chiara, 1986; Kiianmaa, Nurmi, Nykanen and Sinclair, 1995; Yoshimoto, McBride, Lumen and Li, 1992). DA results may have differed had rats in the present study been allowed to voluntarily drink alcohol during adolescence. Further, differences between the previous report and the present study may be attributable to genetic differences between rodent strains particularly because rats used in the previous report were selectively bred for high ethanol consumption while rats in the present study were out-bred rats.
