Physiological Role of Orexinergic System for Health

Orexins, or hypocretins, are excitatory neuropeptides involved in the regulation of feed- ing behavior and the sleep and wakefulness states. Since their discovery, several lines of evidence have highlighted that orexin neurons regulate a great range of physiological functions, giving it the definition of a multitasking system. In the present review, we firstly describe the mechanisms underlining the orexin system and their interactions with the central nervous system (CNS). Then, the system’s involvement in goal-directed behaviors, sleep/wakefulness state regulation, feeding behavior and energy homeostasis, reward system, and aging and neurodegenerative diseases are described. Advanced evidence suggests that the orexin system is crucial for regulating many physio- logical functions and could represent a promising target for therapeutical approaches to obesity, drug addiction, and emotional stress.