Expression of genes for some neuropeptides and their receptors was altered (Table 2); most (17/21) were expressed at lower levels after repeated binge drinking. The five genes in the opioid system, the 2 NPY receptors and the 2 galanin receptors that were altered by drinking all had decreased expression. The hypocretin (orexin) neuropeptide precursor (Hcrt) had increased expression but its receptor Hcrtr2 had reduced expression. The tachykinin precursor gene (Tac1) and the Tacr1 receptor had decreased expression, while Tacr3 had increased expression. Two of the 3 somatostatin receptor genes had decreased expression, whereas Sstr3 had increased expression.
