Npy deletion in an alcohol non-preferring rat model elicits differential effects on alcohol consumption and body weight

Abstract

<p class="first" id="P1">Neuropeptide Y (NPY) is widely expressed in the central nervous system and influences many physiological processes. It is located within the rat quantitative trait locus (QTL) for alcohol preference on chromosome 4. Alcohol-nonpreferring (NP) rats consume very little alcohol, but have significantly higher NPY expression in the brain than alcohol-preferring (P) rats. We capitalized on this phenotypic difference by creating an <i>Npy</i> knockout (KO) rat using the inbred NP background to evaluate NPY effects on alcohol consumption. Zinc finger nuclease (ZNF) technology was applied, resulting in a 26-bp deletion in the <i>Npy</i> gene. RT-PCR, Western blotting and immunohistochemistry confirmed the absence of <i>Npy</i> mRNA and protein in KO rats. Alcohol consumption was increased in <i>Npy</i> ^+/− but not <i>Npy</i> ^−/− rats, while <i>Npy</i> ^−/− rats displayed significantly lower body weight when compared to <i>Npy</i> ^+/+ rats. In whole brain tissue, expression levels of Npy-related and other alcohol-associated genes, <i>Npy1r</i>, <i>Npy2r</i>, <i>Npy5r</i>, <i>Agrp</i>, <i>Mc3r</i>, <i>Mc4r</i>, <i>Crh</i> and <i>Crh1r</i>, were significantly greater in <i>Npy</i> ^−/− rats, whereas <i>Pomc</i> and <i>Crhr2</i> expressions were highest in <i>Npy</i> ^+/− rats. These findings suggest that the NPY-system works in close coordination with the melanocortin (MC) and corticotropin-releasing hormone (CRH) systems to modulate alcohol intake and body weight. </p>