AP PSYCHOLOGY

Detailed explanation-1: -Orexins are also known as hypocretins, and were originally identified as appetite-stimulating peptides produced in the lateral hypothalamus (LH).

Detailed explanation-2: -Crucial evidence indicates that orexin-A increases food intake by delaying the onset of a behaviourally normal satiety sequence. In contrast, a selective orexin-1 receptor antagonist (SB-334867) suppresses food intake and advances the onset of a normal satiety sequence.

Detailed explanation-3: -Orexins (synonymous with hypocretins) are recently discovered neuropeptides made exclusively in hypothalamus. Behavioral, anatomical and neurophysiological studies show that a subset of these cells, specifically those in lateral hypothalamus (LH), are involved in reward processing and addictive behaviors.

Detailed explanation-4: -Ghrelin, a hormone produced by the stomach, triggers the release of orexin from the hypothalamus, signalling to the body that it is hungry.

Detailed explanation-5: -Orexin peptides are synthesized and secreted by a group of neurons mostly localized in the lateral hypothalamus including the perifornical area. Small groups of orexin neurons also found in the posterior hypothalamic area and dorsomedial hypothalamic nucleus.