To study whether in this situation the endogenous NP/GC-A system modulates β-cell proliferation and function, control and β GC-A KO littermates were fed a HFD, a condition known to provoke obesity, arterial hypertension, insulin resistance and enhanced β-cell proliferation in mice [8, 35, 36]. Here, GCA is linked to obesity due to melanocortin 4 receptor deficiency.