It is noteworthy that an early study examined whether an inverse relationship between monoamine levels and excessive alcohol consumption would hold for N-Nih heterogeneous stock rats (Murphy et al., 1987a). These authors found that, after preference testing, the N/Nih rats consuming at least 5 g/kg/day of ethanol had lower levels of 5-HIAA and DA in the hypothalamus and thalamus than rats that consumed less than 0.5 g/kg/day of ethanol. While it is true that ethanol experience may have influenced the findings in the high alcohol-consuming rats, it is doubtful that the miniscule amount of ethanol consumed by the low alcohol-consuming rats would have affected their innate monoamine levels. Moreover, a study in P rats revealed that chronic access to ethanol increased DAergic levels, although 5-HT levels were decreased, in the Acb and the DA levels remained elevated after two weeks of ethanol deprivation (Thielen et al., 2004). It is also noteworthy that a selective breeding program for high alcohol consumption in Wistar rats, Warsaw high-preferring (WHP) vs. Warsaw low-preferring (WLP), has resulted in rat lines with similar phenotypes as those
