MC1R and Impaired glucose tolerance: The results obtained by us indicate that the agouti-mice with the “yellow” mutation at the mouse agouti locus (Ay) associated with the overexpression of ASIP1, the endogenous antagonist of the MC1R and MC4R had the increased body weight and fat mass, the elevated levels of glucose, insulin and leptin, the impaired glucose tolerance and the altered lipid metabolism (Fig 8).