ARC and obesity due to melanocortin 4 receptor deficiency: Since ganglioside depletion coincides with the start of the obesity development, Ugcgf/f//CamKCreERT2 mice that were weight-matched to control littermates were analyzed 3–4 wk p.i. Decreased leptin responsiveness could already be observed in the Arc of these mice (Figure 6B) as well as in the Arc of obese mice 6 wk p.i. (Figure 6C).