demonstrate that ethanol injection preferentially stimulates consumption of a HFD compared to a LFD. This effect was observed with both the 2-h and 24-h access periods, indicating that ethanol has a significant effect on macronutrient selection in the course of a day. The mechanism underlying the effect of ethanol on fat preference is the matter under study. Ethanol injection, with the same paradigm used here, stimulates circulating TG levels 1.5 h after the injection (Chang et al., 2007a). One possibility is that ethanol, in elevating TG levels, works in concert with fat to stimulate the expression and production of the orexigenic peptides (Chang et al., 2007a) that, in turn, promote further consummatory behavior. This is supported by the findings that hypothalamic injection of OX in ethanol-drinking rats preferentially stimulates consumption of ethanol rather than chow (Schneider et al., 2007) and that ventricular injection of OX also stimulates intake of a HFD more than a LFD (Clegg et al., 2002). The possibility that calories themselves from the ethanol injection (approximately 14 kcal/day) are involved in stimulating this orexigenic peptide to promote further consummatory behavior is unlikely, given the finding that food intake, TG levels and OX are stimulated by a small
