Inasmuch as leptin and insulin are potent inhibitors of arcuate neuronal AgRP and NPY expression and activity under normal metabolic conditions [89,90,91,92], and these neurons lose their responsiveness to such leptin and insulin actions during high fat feeding and obesity [93,94,95,96,97], these present findings strongly imply an improvement in AgRP/NPY neuronal leptin and insulin sensitivity to reduce AgRP and NPY expression, even during prolonged high fat diet feeding by ZT 13 bromocriptine treatment. Here, NPY is linked to obesity due to melanocortin 4 receptor deficiency.