Hypocretins and primary headaches: neurobiology and clinical implications

Abstract

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.

Keywords::

• cluster headache
• G1246A polymorphism
• HCRTR2 gene
• hypocretin
• migraine
• pain

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.