摘要目的 通过观察局部亚低温干预对大鼠脑缺血再灌注后缺血半暗带区内皮-单核细胞激活多肽Ⅱ(EMAPⅡ)、EMAPⅡ前蛋白(proEMAPⅡ)表达的影响,从而探讨局部亚低温干预的脑保护机制.方法 共选取雄性Wistar大鼠44只,采用随机数字表法将其分为假手术组、常温组及亚低温组.采用改良Longa线栓法将常温组及亚低温组大鼠制成大脑中动脉缺血再灌注模型,亚低温组于再灌注后立即给予亚低温干预(持续治疗6h).于脑缺血再灌注后6h、12h、24 h、48 h及72 h时处死大鼠并取脑,采用HE染色观察各组大鼠神经细胞受损情况,采用免疫组化染色法比较各组大鼠缺血脑组织EMAPⅡ、proEMAPⅡ阳性细胞表达情况.结果 常温组及亚低温组EMAPⅡ阳性细胞均于缺血再灌注6h时明显表达,于再灌注24 h时达到峰值,随后逐渐下降；2组大鼠proEMAPⅡ阳性细胞均于缺血再灌注6h时明显表达,之后亚低温组逐渐下降,常温组于再灌注12h达到峰值后开始下降,至再灌注72 h时2组大鼠proEMAPⅡ阳性表达均已接近假手术组水平.亚低温组EMAPⅡ阳性表达在脑缺血再灌注6h、12h、24 h、48 h及72 h时均较常温组显著减少(P＜0.05).常温组proEMAPⅡ阳性细胞数量在脑缺血再灌注6h、12h及24 h时均较亚低温组明显增多.结论 局部亚低温干预能减弱大鼠缺血半暗带区EMAPⅡ、proEMAPⅡ阳性表达,抑制缺血再灌注损伤导致的细胞凋亡及炎性反应,从而发挥神经保护作用.

abstractsObjective To investigate the effects of local mild hypothermia on the expression of EMAP-Ⅱ and proEMAP-Ⅱ after cerebral ischemia and reperfusion in rats and to explore the possible neuroprotection mechanism of mild hypothermia.Methods Forty-four male Wistar rats were divided randomly into a sham-operation group (Sham),a normothermia group (NT) and a hypothermia group (HT).Middle cerebral artery occlusion was performed using Longa's method,and reperfusion was allowed after 2 hours of occlusion.Mild hypothermia (33.0 ± 0.5)℃ for 6 hours was initiated at the start of reperfusion,followed by rewarming.Brains were harvested after 6,12,24,48 and 72 hours of reperfusion and used for HE staining to evaluate cellular apzoptosis and immunohistochemical staining for detecting the expression EMAP-Ⅱ and proEMAP-Ⅱ.Results The expression of EMAP-Ⅱ and proEMAP-Ⅱ in the ischemic penumbra was significant at 6 hours in the normothermia and hypothermia groups.It peaked at 12 hours in the normothermia group and 24 hours in the hypothermia group,and then decreased gradually.At 72 hours the expression of EMAP-Ⅱ and proEMAP-Ⅱ in the ischemic penumbras was very close to that in the sham group.EMAP-Ⅱ-positive cells were significantly fewer in the hypothermia group than in the normothermia group at all time points.ProEMAP-Ⅱ-positive cells were significantly more numerous in the normothermia group than in the hypothermia group at 6,12 and 24 hours.Conclusions Mild hypothermia (33.0 ± 0.5) ℃ has a valid neuroprotective effect which involves reducing EMAP-Ⅱ and proEMAP-Ⅱ expression in the ischemic penumbra and inhibiting apoptosis and inflammatory reactions after cerebral ischemia and reperfusion,at least in rats.