神经保护肽预处理对氯胺酮所致幼龄大鼠记忆损伤的影响

The Study of NAP on Ketamine-induced Memory Impairment in Young Rats

目的研究神经保护肽(NAP)预处理对氯胺酮所致幼龄大鼠神经毒性及学习记忆能力损伤的影响。方法80只1周龄SD大鼠随机分4组:氯胺酮单独注射组(K组)、NAP单独注射组(NAP组)、NAP预处理后再行氯胺酮注射组(N+K组)、生理盐水注射组(NS组),均腹腔注射给药,1次/d,连续3d。最后一次给药后24h,每组随机取6只大鼠行免疫印迹法,另取6只用于TUNEL染色,最后8只饲养至27日龄行水迷宫试验。通过水迷宫试验测试大鼠的空间学习和记忆能力;TUNEL染色检测海马神经细胞凋亡情况;免疫印迹检测海马tau蛋白ser404位点的磷酸化程度。结果与NS组比较,K组大鼠逃避潜伏期增加(P<0.01)、穿越平台次数减少(P<0.01)、原平台停留时间减少(P<0.01),大鼠海马神经细胞凋亡率增加(P<0.01),tau蛋白ser404位点磷酸化水平增加(P<0.01);而N+K组大鼠较K组大鼠逃避潜伏期减少(P<0.05)、穿越平台次数和在原平台停留时间增加(P均<0.05),大鼠海马神经细胞凋亡率降低(P<0.01),tau蛋白ser404位点磷酸化水平降低(P<0.01)。结论神经保护肽预处理可减轻早期氯胺酮暴露对幼鼠成年后学习和记忆能力损害,其作用可能与降低海马区tau蛋白ser404位点异常磷酸化水平及神经细胞凋亡程度有关。

Objective To study the effect of neuroprotective peptide(NAP)on neurotoxicity and the damages of learning and memory in young rats induced by ketamine.Methods Eighty seven-day-old SD rats were randomly divided into four groups:ketamine intraperitoneal injection group(K group),NAP intraperitoneal injection group(NAP group),NAP pretreatment and ketamine intraperitoneal injection group(N+K group),saline intraperitoneal injection group(NS group),once a day for three consecutive days.At 24 hours after the last treatment,six rats were subjected to immune-blotting,and another 6 rats were used for TUNEL staining,the last 8 rats fed to 27-day-old were subjected to water maze test.Spatial learning and memory ability of rats was tested by water maze navigation and space exploration test.The apoptosis of hippocampal neurons was detected by TUNEL staining and phosphorylation of tau ser404 site was detected by immune-blotting.Results Compared with NS group,the escape latency of rats in K group increased(P<0.01),the number of times crossing plateau decreased(P<0.01),the length of stay of original plateau decreased(P<0.01),the apoptotic rate of hippocampal neurons increased(P<0.01),the phosphorylation level of tau protein ser404 increased(P<0.01).Compared with K grong,the escape latency of rats in N+K group decreased(P<0.05),the number of times crossing plateau and the residence time on the original platform increased(P all<0.05),the apoptotic rate of hippocampal neurons decreased(P<0.01),and the phosphorylation level of tau ser404 site decreased(P<0.01).Conclusion NAP can reduce learning and memory ability damage caused by ketamine,which may be related to the reduction of abnormal phosphorylation of tau ser404 site in hippocampus and the degree of neuronal apoptosis.