Role of neuropeptide Y in diet-, chemical- and genetic-induced obesity of mice

OBJECTIVE: The goal of this study was to ascertain whether neuropeptide Y (NPY) is required in mice for the development of obesity induced by a high-fat diet (HFD), chemical lesions of the hypothalamus caused by monosodium glutamate (MSG) or gold thioglucose (GTG), impaired brown adipose tissue (BAT) due to a diphtheria toxin transgene driven by the uncoupling protein 1 promoter (UCP-DTA) or the lethal yellow agouti mutation (A(Y)). BACKGROUND: The obesity syndrome of the leptin-deficient (ob/ob) mouse can be partially reversed by the genetic removal of NPY. In the murine models of obesity examined in this study, the animals become obese despite increased serum leptin levels, indicating that they are resistant to the weight-limiting actions of leptin. The role of NPY in these obesity models with elevated leptin levels is unknown. EXPERIMENTAL DESIGN: Mice lacking NPY due to genetic disruption of the gene and wildtype littermates were made obese by allowing them access to a highly palatable HFD, by treatment with MSG, or GTG, or by inheriting the dominant UCP-DTA or A(Y) alleles. Food consumption, body weight and dissectable fat pad weights were measured and compared to values obtained from non-obese littermates. RESULTS: In each model of obesity tested, NPY-deficient mice achieved the same food intake, body weight and fat content as wildtype littermates. CONCLUSION: NPY is not necessary for the progressive development of obesity exhibited by multiple murine models with leptin resistance.