LEP and obesity due to melanocortin 4 receptor deficiency: To address whether the underlying cause of the obesity in female Kiss1r KO mice was at the level of the hypothalamus, De Bond et al. used quantitative PCR and in situ hybridization histochemistry to examine the expression of key genes in the hypothalamic appetite-regulating system, including Pomc and Npy as well as the genes expressing the receptors for leptin, ghrelin, and the melanocortins (79).