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Hypocretin/orexin and energy expenditure |
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| Authors: | J A Teske C J Billington C M Kotz |
| Institution: | 1. Veterans Affairs Medical Center, Minneapolis, MN, USA
Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA;2. Veterans Affairs Medical Center, Minneapolis, MN, USA Minnesota Obesity Center, Minneapolis, MN, USA Department of Medicine, University of Minnesota, Saint Paul, MN, USA;3. Veterans Affairs Medical Center, Minneapolis, MN, USA Food Science and Nutrition, University of Minnesota, Saint Paul, MN, USA Minnesota Obesity Center, Minneapolis, MN, USA |
| Abstract: | The hypocretins or orexins are endogenous neuropeptides synthesized in discrete lateral, perifornical and dorsal hypothalamic neurones. These multi-functional neuropeptides modulate energy homeostasis, arousal, stress, reward, reproduction and cardiovascular function. This review summarizes the role of hypocretins in modulating non-sleep-related energy expenditure with specific focus on the augmentation of whole body energy expenditure as well as hypocretin-induced physical activity and sympathetic outflow. We compare the efficacy of hypocretin-1 and 2 on energy expenditure and evaluate whether the literature implicates hypocretin signalling though the hypocretin-1 and -2 receptor as having shared and or functionally specific physiological effects. Thus far data suggest that hypocretin-1 has a more robust stimulatory effect relative to hypocretin-2. Furthermore, hypocretin-1 receptor predominantly mediates behaviours known to influence energy expenditure. Further studies on the hypocretin-2 receptor are needed. |
| Keywords: | diet-induced obesity neuropeptide spontaneous physical activity |