@@ IntroductionThe melanocortin-4 receptor (MC4R) is expressed primarily in the central nervous system, and is a part of melanocortinergic pathway that regulates food intake and controls energy homeostasis[1]. The MC4R homozygous knock-out mice had maturity-onset obesity, hyperphagia, increased linear growth, hyperinsulinemia, and hyperglycemia [2] The heterozygous mice had intermediate bodyweights compared with the wild-type and homozygous mice, suggesting the gene dosage effect. In addition, MC4R-knockout mice had reduced metabolic rate.