Humana The Orexin/Hypocretin System: Physiology and Pathophysiology (Contemporary Clinical Neuroscience)

Orexin/hypocretin research began in 1998, as a result of the discovery of a new hypothalamic neuropeptide. In 1999, it was found that mutations in the orexin/ hypocretin-related genes caused a sleep disorder (narcolepsy) in dogs and mice. These findings were soon followed by the discoveries of orexin/hypocretin ligand deficiency in human narcolepsy. The finding of the major pathophysiological mechanisms of human narcolepsy resulted in its reclassification as a neurological, not a psychiatric, disorder. The - portance of early diagnosis and initiation of treatment for human narcolepsy has been repeatedly emphasized because the disease typically starts around puberty (when social and school influences become important). Orexin/hypocretin de- ciency in narcolepsy subjects can be detected clinically in cerebrospinal fluid (CSF) orexin/hypocretin measures (low CSF orexin/hypocretin levels are strongly asso- ated with narcolepsy-cataplexy among various neurologic and sleep disorders). Thus, the CSF orexin/hypocretin measurements are expected to be included as a diagnostic test for narcolepsy-cataplexy in the second revision of international di- nostic criteria (ICSD). This positive diagnostic test is very useful for establishing an early diagnosis for narcolepsy-cataplexy, and many patients will likely receive im- diate benefits. Cerebrospinal orexin/hypocretin measurements are also informative for the nosological classification of hypersomnia. Because orexin/hypocretin de- ciency is observed in most human narcolepsy-cataplexy, orexin/hypocretin repla- ment therapy is now a promising new choice for the treatment of human narcolepsy, and research in this area is actively in progress. From the Back Cover Impairment of orexin/hypocretin signaling causes narcolepsy-cataplexy in animals and humans. Most human narcolepsy-cataplexy cases are associated with orexin/hypocretin ligand deficiency, which can be detected clinically using cerebrospinal orexin/hypocretin measures and may lead to future treatments with orexin/hypocretin replacement therapy. In The Orexin/Hypocretin System: Physiology and Pathophysiology, leading researchers and clinicians review these exciting developments to set the stage for further research on the loss of orexin/hypocretin neurons in humans, regulation of sleep and wakefulness by the orexin/hypocretin system, and the role of the orexin/hypocretin system in many other physiological processes, including feeding, autonomic regulation, and neuroendocrine regulation. Topics of interest include an assessment of the functions and the physiology of orexin/hypocretin, its pathophysiology in human narcolepsy-cataplexy, and possible pharmacological treatments. The authors also introduce several experimental methods for orexin/hypocretin research, and, using multidisciplinary approaches, explain their uses and limitations. Authoritative and state-of-the-art, The Orexin/Hypocretin System: Physiology and Pathophysiology will aid scientists in the search for novel bioactive peptides and their receptors, as well as novel physiological insights and opportunities for the clinical treatment of not only narcolepsy, but also a broad range of diseases associated with endocrine, feeding, and body weight regulation.