The two major findings of these studies are that streptozotocin itself is not neurotoxic and that neutral endopeptidase deficient mice are protected from the slowing of nerve conduction velocity and thermal hypoalgesia that occur in streptozotocin-induced diabetic- or diet-induced obesity-C57Bl/6 mice. Here, MME is linked to obesity due to melanocortin 4 receptor deficiency.