The effect of orexin-A on the pathological mechanism in the rat focal cerebral ischemia.

Orexin-A is a neuropeptide involved in the control feeding, arousal or sleep behavior in the hypothalamus. In the present study, the cortex and lateral hypothalamus of rats subjected to middle cerebral artery occlusion (MCAO)-reperfusion brain injury were examined by double immunofluorescence staining. The number of orexin-A-expressing neurons in the non-ischemic side was significantly lower than the ischemic side. Next, orexin-A was administered intracerebroventricularly followed by the induction of MCAO-reperfusion injury. Administration of orexin-A at 0.3nmol significantly reduced the brain infarct area. The results suggested that orexin-A alters the pathological mechanisms involved in brain ischemia and has a neuroprotective effect.