A family of neuropeptides from the hypothalamus, named orexins, was recently discovered and characterized. Orexins stimulate appetite and food consumption. Their genes are expressed bilaterally and symmetrically in the lateral hypothalamus, which was earlier determined to be the "feeding center" of the hypothalamus. In contrast, the so-called satiety center is expressed in the ventromedial hypothalamus and is dominated by the leptin-regulated neuropeptide network.