Infusion of insulin in the hypothalamic could briefly enhance 5-HT release in rostromedial hypothalamus (89), and systemic administration of 5-HTR2C agonist mCPP by osmotic minipumps could reduce fasting plasma insulin level through POMC neurons in diet-induced obesity (DIO) mice without altering blood glucose (90). Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.