Which of the following inhibits appetite by counteracting the effects of neuropeptide Y?

Leptin acts on receptors in the hypothalamus of the brain where it inhibits appetite by (1) counteracting the effects of neuropeptide Y (a potent feeding stimulant secreted by cells in the gut and in the hypothalamus); (2) counteracting the effects of anandamide (another potent feeding stimulant that binds to the same receptors as THC), and (3) promoting the synthesis of a-MSH, an appetite suppressant. Ghrelin is a hormone produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas that stimulates hunger. Neuropeptide Y is a natural substance that acts on the brain to stimulate eating.Leptin reduces the output of NPY from the hypothalamus, a major production center. Orexins (hypocretins) are neuropeptides primarily localized in the hypothalamus and are implicated in the regulation of a variety of activities, including feeding behavior and energy balance.