In the female mice lacking dopamine D2 receptors in lactotropes, long-term chronic hyperprolactinemia was found to increase the expression of the orexigenic genes, such as neuropeptide Y, in the hypothalamic arcuate nucleus and ventromedial nucleus, resulting in obvious weight gain and leptin resistance from the age of 5-10 months (10). The gene discussed is DRD2; the disease is hyperprolactinemia.