Orexin system: Network multi-tasking

Orexin system regulates sleep/wake states and its deficiency result in narcolepsy thus indicating the crucial role of orexins in maintaining wakefulness. There are two types of orexin peptides: the orexin-A (OXA or hypocretin 1) and orexin-B (OXB or hypocre- tin 2). The Majority of the central nervous system orexin peptides are synthesized in neurons located in the lateral and back hypotha- lamus and send projections throughout the brain regions Orexin neurons are “multi-tasking” hence regulating also energy homeosta- sis, reward systems and feeding behaviour through connection with hypothalamic nuclei and through responsiveness to leptine and glucose. It has recently been found a connection with lymbic system suggesting a further possible role of orexins in regulating emo- tions. All the studies conducted confirm that orexin system regulates vigilance states, energy homeostasis, reward system, and emo- tions. These crucial role might be the target to develope treatments of narcolepsy, obesity, emotional stress, and drug addiction.