Humanin Is a Novel Neuroprotective Agent Against Stroke

Document Type

Article

Publication Date

10-1-2006

Description

BACKGROUND AND PURPOSE - Humanin (HN) is a 24-amino acid peptide best known for its ability to protect neurons from damage caused by Alzheimer disease-related proteins. This study examines the neuroprotective effects of HNG (a potent form of HN) on focal cerebral ischemia/reperfusion injury in mice. METHODS - Mice underwent middle cerebral artery occlusion for 75 minutes followed by 24-hour reperfusion. Mice were pretreated with 0.1 μg HNG (intracerebroventricularly) 30 minutes before ischemia; posttreated at 0, 2, 4, and 6 hours after ischemia; or pretreated with 1 μg HNG (intraperitoneally) 1 hour before ischemia. Neurological deficits and cerebral infarct volume were evaluated. Neuronal apoptosis and activated poly(ADP-ribose) polymerase expression were measured by TUNEL and Western blot analysis, respectively. Activated ERKs were examined by Western blot analysis. RESULTS - Pretreatment with 0.1 μg HNG (intracerebroventricularly) 30 minutes before ischemia reduced cerebral infarct volume from 56.2±3.0% to 26.1±1.4% (P<0.01). HNG posttreatment after 4 hours of reperfusion reduced cerebral infarct volume to 45.6±2.6% (P<0.05). Pretreatment with 1 μg HNG (intraperitoneally) 1 hour before ischemia or posttreatment after 2 hours of reperfusion reduced cerebral infarct volume significantly. HNG also significantly improved neurological function and inhibited both neuronal apoptosis as well as poly(ADP-ribose) polymerase activation. A significant decrease of phospho-ERK was observed in mice treated with HNG, whereas phospho-JNK and phospho-p38 levels were not altered. CONCLUSIONS - Our results demonstrate that HNG protects against cerebral ischemia/reperfusion injury in mice. HNG offers neuroprotection in vivo at least in part by inhibiting ERK activation. These findings suggest a potential therapeutic role for HNG in the treatment of stroke.

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