Prog Brain Res. 2012;198:65-77. doi: 10.1016/B978-0-444-59489-1.00006-9.
Orexin, also known as hypocretin, is a hypothalamic neuropeptide important for mediation of arousal and sleep as well as feeding and energy homeostasis. Recent studies have indicated that orexin also plays a key role regulating motivation and reward associated with food intake and with drugs of abuse. Based on those findings, it has been hypothesized that orexin is involved in control of other natural reward behaviors. This review will summarize studies that examine the role of orexin in motivation and reward associated with food intake, maternal behavior, and male sexual behavior. In particular for sexual behavior in male rats, we have recently shown that orexin cell-specific lesions do not impair sexual performance and motivation but disrupt conditioned responses associated with sexual reward.