Normal plasma levels of orexin A (hypocretin-1) in narcoleptic patients

Deficient orexin signaling has been shown to cause narcolepsy-like conditio ns in animals. In human narcolepsy, CSF levels of orexin A (hypocretin-1) w ere reported to be low in most cases. The authors measured CSF and plasma o rexin A levels in patients with narcolepsy and in controls. Confirming earl ier studies, they found CSF orexin A levels to be extremely low in patients with narcolepsy. However, plasma orexin A levels did not differ from those observed in controls. These results suggest that orexin deficiency in pati ents with narcolepsy is a phenomena restricted to the CNS.