Abstract
Orexins, also called as hypocretins, are peptides produced by the lateral hypothalamus revealed in 1998. These hormones were originally described as orexigenic as they increase food intake.
However, further research demonstrated an important role of orexin signaling in regulations of multiple physiological functions. Orexin-A increases spontaneous physical activity and thus promotes obesity resistance in spite of its orexinergic effects.
Orexin-A also favorably affects insulin sensitivity. Orexins are also engaged in regulation of sympathetic nervous activity, sleep/wake states, cognitive functions, reward systems, mood, response to stress, nociception and pain.
In addition, antitumor effects of orexin-A have recently been demonstrated in experimental studies. Modulation of orexinergic pathways was proposed as a novel treatment approach in obesity, sleep disorders, addiction and cognitive and mood impairments.