LEP and obesity due to melanocortin 4 receptor deficiency: Interestingly, combiningobesity and age significantly attenuated phosphorylation of ERK and AMPK, theeffects of which were ablated and unaffected, respectively, by leptin treatment.Although we are unable to offer any precise explanation for the combined effectbetween age and obesity on ERK and AMPK at this time, our data do not favor asignificant role for ERK and AMPK in the reminiscent cardiac defects between agingand obesity as well as the disparity in the leptin cardiac responsiveness.