Particularly, after the development of hyperprolactinemia-induced obesity in these mice, a significant increase in mRNA levels of the orexigenic hormones agouti-related peptide (AGRP) and neuropeptide Y (NPY) were observed in the hypothalamic arcuate and dorsomedial nuclei, respectively (56). Here, NPY is linked to obesity due to melanocortin 4 receptor deficiency.