不同剂量美金胺对HIBD新生大鼠的脑保护作用及机制分析

目的 探讨不同剂量美金胺对缺氧缺血性脑损伤(HIBD)新生大鼠的脑保护作用及机制。方法 144只新生大鼠随机分为六组,假手术组大鼠仅将颈部皮肤切开,分离右侧颈总动脉,不进行结扎及缺氧处理。其余五组建立缺氧缺血性脑损伤新生大鼠模型。药物组四组分别腹腔注射不同剂量美金胺(13 mg/kg、26 mg/kg、39 mg/kg、52 mg/kg),模型对照组分别腹腔注射等量生理盐水。分析六组新生大鼠皮质、纹状体、海马及丘脑的脑损伤评分;六组新生大鼠皮质、海马区(海马CA1、海马CA3及齿状回)、纹状体及皮质下蛋白的TUNEL阳性细胞计数;六组新生大鼠皮质、海马区(海马CA1、海马CA3及齿状回)、纹状体及皮质下蛋白的Caspase-3阳性细胞计数;比较六组新生大鼠的神经功能及六组新生大鼠的缺氧缺血处理后的12 h、48 h、72 h的胶质细胞源性营养因子(GDNF)蛋白表达水平。结果 假手术组大鼠不同脑区域损伤评分、TUNEL及Caspase-3阳性细胞计数相比,差异均无统计学意义(P> 0. 05);在其余五组新生大鼠中,皮质、纹状体、海马及丘脑区域脑损伤评分比较差异均有统计学意义(P <0. 05),模型对照组、药物1组、药物2组、药物3组及药物4组的TUNEL阳性细胞计数均明显高于假手术组,表明造模成功。在海马CA1、皮质下蛋白中的的TUNEL阳性细胞计数差异有统计学意义,在海马CA3、齿状回及皮质下蛋白中的Caspase-3阳性细胞计数差异有统计学意义(P <0. 05),以上比较顺序均为模型对照组>药物1组>药物2组>药物3组>药物4组;六组新生大鼠的神经功能比较差异有统计学意义(P <0. 05),术后12 h、48 h、72 h时,六组新生大鼠的GDNF蛋白表达水平具有统计学意义,神经功能及GDNF蛋白表达水平顺序均为模型对照组<药物1组<药物2组<药物3组<药物4组<假手术组,以上各项指标中除药物3组与药物4组间比较差异无统计学意义(P> 0. 05)外,其余组间比较差异均有统计学意义(P <0. 05)。结论 随着美金胺剂量的增加,其对HIBD新生大鼠的脑保护作用逐渐增加,最佳剂量为39 mg/kg,可能美金胺可提高HIBD大鼠的GDNF蛋白表达水平有关。

Brain protective effects and mechanism of memantine in HIBD newborn rats

Objective To investigate the cerebral protective effect and mechanism of memantine in HIBD newborn rats.Methods 144 newborn rats were randomly divided into six groups.In the sham operation group,only the skin of the neck was cut and the right common carotid artery was isolated.A neonatal rat model of hypoxic-ischemic brain injury was established and divided into 5 groups.The 4 drug groups were injected intraperitoneally with different doses of memantine(13 mg/kg,26 mg/kg,39 mg/kg,52 mg/kg),and the sham operation group and the model control group were injected intraperitoneally with the same amount of normal saline.The brain injury scores of cortex,striatum,hippocampus and thalamus in the six groups of newborn rats were analyzed,and the TUNEL positive cell counts of cortex,hippocampus(hippocampal CA1,hippocampal CA3 and dentate gyrus),striatum and subcortical protein in the six groups of newborn rats were analyzed,the neurological function scores of newborn rats in the six groups were compared with the expression levels of GDNF protein at 12 h,24 h and 72 h after hypoxic-ischemia treatment in newborn rats in the six groups.Results There were no significant differences in the scores,TUNEL and Caspase-3 positive cell count of different brain regions in the sham operation group(P>0.05).In the other 5 groups,the cerebral injury scores in cortex,striatum,hippocampus and thalamus were statistically significant.The TUNEL positive cells number in blank control group,drug group 1,drug group 2,drug group 3 and drug group 4 were all significantly higher than that in sham operation group,indicating that the model was successfully constructed.The number of TUNEL positive cells in hippocampal CA1 and subcortical proteins was statistically significant,and the number of caspase-3 positive cells in hippocampal CA3,dentate gyrus and subcortical proteins was statistically significant(P<0.05).The above comparison sequence was blank control group>drugs 1 group>drugs 2 groups>drugs 3 groups>drugs 4 groups.The neurological function scores of newborn rats in the six groups were statistically significant(P<0.05),and GDNF protein expression levels of newborn rats in the six groups were statistically significant at 12 h,48 h and 72 h after surgery,the score and the sequence of GDNF protein expression level were blank control group0.05),while the other groups showed statistical significance(P<0.05).Conclusion With the increase of memantine dose,its cerebral protective effect on HIBD newborn rats gradually increases,and the optimal dose is 39 mg/kg.Memantine can improve the expression level of GDNF protein in HIBD rats.