Hypocretins and primary headaches: neurobiology and clinical implications.
Hypocretins (or orexins) are two neuropeptides synthesized by neurons located exclusively in the hypothalamus. Hypocretin-containing neurons have widespread projections throughout the CNS; with particularly dense excitatory projections to monoaminergic and serotonergic brainstem centers. The hypocretin system influences a wide range of physiological processes in mammals, such as feeding, arousal, rewards and drug addiction. Recently, a number of studies in experimental animals showed that hypocretins are involved in pain modulation within the CNS, and suggested the presence of a link between these peptides and nociceptive phenomena observed in primary headaches. The aim of this review is to describe and discuss recent studies in humans suggesting a role for the hypocretin neuronal system in cluster headache and chronic migraine.
Rainero
Innocenzo
I
Neurology II - Headache Centre, Department of Neuroscience, University of Turin, Via Cherasco 15-10126, Torino, Italy. irainero@molinette.piemonte.it
De Martino
Paola
P
Pinessi
Lorenzo
L
D000818:Animals; D001933:Brain Stem / Q000502:physiology; D003027:Cluster Headache / Q000503:physiopathology; D006261:Headache / Q000503:physiopathology*; D006801:Humans; D007031:Hypothalamus / Q000503:physiopathology; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008881:Migraine Disorders / Q000503:physiopathology; D009474:Neurons / Q000502:physiology; D009479:Neuropeptides / Q000502:physiology*; D000068797:Orexins; D017288:Pain Threshold / Q000502:physiology
D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins