GLP1R and obesity due to melanocortin 4 receptor deficiency: Considering that treatment with the long-acting GLP-1R agonist, liraglutide, resulted in levels 6 to 10 times greater than endogenous GLP-1 levels, liraglutide is suggested to inhibit the obesity-induced enlargement of β-cell mass both directly through the systemic circulation and indirectly through its actions on hepatic afferent nerves.