热应激预适应对小鼠学习记忆的影响

目的观察热应激对脑缺血处理的小鼠空间学习记忆能力、海马CA1区神经元CREB的影响。方法采用Morris水迷宫筛选空间学习记忆能力正常的昆明小鼠60只,体重(40±5)g,雌雄不限。将实验动物分为4组:正常对照组(Normal)、热应激预处理后缺血再灌注组(HS/IR)、缺血再灌注组(IR)、单纯热应激组(HS);处理后存活时间分别为3h、24h、72h,每个时间点6只,动物处死前再作水迷宫检测。用免疫组织化学方法检测CREB的表达。常规尼氏染色法镜下计数海马CA1区存活神经元。结果水迷宫检测IR组小鼠潜伏期增加,其搜索策略以边缘式和限制式为主,与其它3组比较有显著的统计学意义(P<0.01)。尼氏染色证实IR组锥体细胞神经元减少;24h的HS/IR组的CREB的表达高于IR组。结论热应激预处理可以改善动物因脑缺血引起的学习记忆功能下降。其机制可能涉及到热应激对CREB表达的上调。

The pretreatment of heat stress influences the memory and learning of mice

Objective To investigate heat stress influence the expression of CREB in CA1 region of hippocampus and behavior, and its relation to spatial learning and memory function in mice. Methods Sixty Kunming mice with normal learning and memory tested by Morris water maze before pretreatment were used in this study. The mice were divided into four groups by random:①Normal control group; ②Ischemia and Reperfusion after pretreated by heat stress group (HS/IR) ③Ischemia and Reperfusion group (IR) ④heat stress group(HS). The later three groups were subdivided into 3 groups,3, 24 and 72hour. There were 6 mice each group. These mice were tested in Morris water maze before sacrificed. The expression of CREB were detected by immunohistochemistry (ABC methods) and the intensity of immunostaining was measured using MedHPIAS pathologic imaging analysis system. Coronal slices with Nissl's staining were used to count neurons in hippocampus CA1 regions. Results Compared to groups, normal, HS, HS/IR, IR, escape latency of IR group became longer following elongation of reperfusion (P< 0.01). In Hippocampus CA1 regions the number of neurons was not reduced in groups Normal, HS and HS/IR, but decreased in IR groups (P< 0.01). Compared to normal group, the expressions of CREB in Hippocampal CA1 region obviously increased in HS and HS/IR groups (P< 0.05),but in groups IR 24h and 96h their expressions had no significant change (P >0.05). Conclusion Heat stress can promote CREB's excretion and may protect the spatial learning and memory function .