In addition to their similar effects on TG levels, ethanol and fat are also found to have similar effects on specific hypothalamic, orexigenic peptides (Leibowitz, 2007). Recent studies have focused on opioid peptides (Chang et al., 2007a; Chang et al., 2007b) and on the peptide orexin (OX), which is believed to have a role in processes of arousal and reward (Harris and Aston-Jones, 2006). Chronic and acute consumption of a HFD, along with raising TG, stimulates the expression of OX (Wortley et al., 2003), and similar effects on TG and OX are seen with peripheral injection of the fat emulsion, Intralipid (Chang et al., 2004). These results, suggesting that TG are involved in the effect of dietary fat on OX, are substantiated by evidence showing Intralipid to increase c-Fos-like immunoreactivity in specific neurons of the perifornical lateral hypothalamus (PFLH) that synthesize OX (Chang et al., 2004; Lo et al., 2007). Further investigations reveal a similar relationship of ethanol to OX. Studies in rats chronically consuming ethanol, which increases circulating TG (Chang et al., 2007a), demonstrate an analogous increase in OX
