BDNF and obesity due to melanocortin 4 receptor deficiency: This notion is supported by data from McMurphy and colleagues that demonstrate that recombinant adeno-associated virus (AAV)-mediated hypothalamic BDNF gene transfer alleviates obesity and that BDNF gene transfer prevents aging-associated weight gain, improves glucose tolerance, and suppresses inflammatory genes in the hypothalamus and adipose tissues [19].