INS and obesity due to melanocortin 4 receptor deficiency: Specifically, in genetically (db/db) and diet-induced obese mice, α7nAChR activation by nicotine, at doses not involving changes in food intake or body weight, reduces adipose tissue inflammation and improves body glucose homeostasis and insulin sensitivity [22], whereas activation of α2nAChR in mouse subcutaneous fat promotes the development of energy-dissipating beige adipocytes, increases non-shivering thermogenesis, and ameliorates diet-induced obesity [23].