NPY and obesity due to melanocortin 4 receptor deficiency: Administration of NPY into different brain regions, including the hypothalamus, frontal cortex, hindbrain, and hippocampus, induces hyperphagia (even in a satiated state), decreased sympathetic activity and thermogenesis, increased fat deposition, and promotion of weight gain and obesity (Clark et al., 1984; Billington et al., 1991; Egawa et al., 1991; Raposinho et al., 2001).