Xu Xingshun, Chua Chu C, Gao Jinping, Hamdy Ronald C, Chua Balvin H L
Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.
Stroke. 2006 Oct;37(10):2613-9. doi: 10.1161/01.STR.0000242772.94277.1f. Epub 2006 Sep 7.
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.
Mice underwent middle cerebral artery occlusion for 75 minutes followed by 24-hour reperfusion. Mice were pretreated with 0.1 microg HNG (intracerebroventricularly) 30 minutes before ischemia; posttreated at 0, 2, 4, and 6 hours after ischemia; or pretreated with 1 microg 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.
Pretreatment with 0.1 microg 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 microg 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.
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.
人胰岛素（HN）是一种由24个氨基酸组成的肽，以其保护神经元免受阿尔茨海默病相关蛋白损伤的能力而闻名。本研究探讨了HNG（HN的一种有效形式）对小鼠局灶性脑缺血/再灌注损伤的神经保护作用。
小鼠大脑中动脉闭塞75分钟，随后再灌注24小时。在缺血前30分钟用0.1微克HNG（脑室内注射）对小鼠进行预处理；在缺血后0、2、4和6小时进行后处理；或在缺血前1小时用1微克HNG（腹腔注射）进行预处理。评估神经功能缺损和脑梗死体积。分别通过TUNEL和蛋白质印迹分析测量神经元凋亡和活化的聚（ADP - 核糖）聚合酶表达。通过蛋白质印迹分析检测活化的细胞外信号调节激酶（ERK）。
缺血前30分钟用0.1微克HNG（脑室内注射）预处理可使脑梗死体积从56.2±3.0%降至26.1±1.4%（P<0.01）。再灌注4小时后用HNG进行后处理可使脑梗死体积降至45.6±2.6%（P<0.05）。缺血前1小时用1微克HNG（腹腔注射）预处理或再灌注2小时后进行后处理可显著降低脑梗死体积。HNG还显著改善神经功能，并抑制神经元凋亡以及聚（ADP - 核糖）聚合酶活化。在用HNG处理的小鼠中观察到磷酸化ERK显著降低，而磷酸化JNK和磷酸化p38水平未改变。
我们的结果表明，HNG可保护小鼠免受脑缺血/再灌注损伤。HNG至少部分通过抑制ERK活化在体内提供神经保护作用。这些发现提示HNG在中风治疗中具有潜在的治疗作用。
