Orexin system: Network multi-tasking

Abstract

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 hypocretin 2). The Majority of the central nervous system orexin peptides are synthesized in neurons located in the lateral and back hypothalamus and send projections throughout the brain regions Orexin neurons are "multi-tasking" hence regulating also energy homeostasis, 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 emotions. All the studies conducted confirm that orexin system regulates vigilance states, energy homeostasis, reward system, and emotions. These crucial role might be the target to develope treatments of narcolepsy, obesity, emotional stress, and drug addiction.