The use of DA2R-agonist bromocriptine to improve glucose tolerance and cardiovascular functions in diabetic patients [210,212,215–223]; the use of leptin-derived peptide ([D-Leu-4]-OB-3) in experimental models of T2DM [198–200]; the use of the 5-HT2CR-agonists to improve glucose tolerance in experimental model of T2DM [40]; the use of the MC4R agonists (Nle4,D-Phe7-α-MSH, BIM-22493, AZD2820, etc.) to improve feeding behavior, insulin sensitivity and cognitive functions in experimental models of metabolic disorders [298,300,304,310,312–317]. The gene discussed is MC4R; the disease is metabolic disease.