冲击波重复暴露对大鼠抑郁样行为和海马病理变化的影响

目的 探究冲击波重复暴露下大鼠抑郁样行为及海马病理组织学的变化情况, 为轻度爆炸性脑损伤(mild blast induced traumatic brain injury, mbTBI) 致抑郁样行为的损伤机制研究提供模型及病理基础。方法 选择 SD大鼠 80 只, 随机分为对照组和冲击波重复暴露组。按暴露后观察时间每组分 7、 14、21 和 28 d 4 个亚组。 采用生物激波管 (压力峰值 120 kPa, 正压持续时间 11 ms, 重复 3 次, 每次间隔 24 h) 构建模型。利用旷场实验、 明暗箱穿梭实验和强迫游泳实验评价大鼠神经行为变化, 采用 HE 染色观察大鼠海马组织病理改变。 结果 冲击波重复暴露组大鼠均存活。 3 次冲击波暴露后 24 h 出现呆滞、麻痹、反应迟钝、食欲不振等表现, 72 h 后上述表现逐步缓解。与对照组相比, 冲击波重复暴露组大鼠旷场实验 14、21 和 28 d 移动总距离明显下降, 休息时间明显上升 (P<0. 05); 明暗箱穿梭实验 14、21 和 28 d 进入明箱的时间明显下降, 潜伏期明显上升 (P<0. 05); 强迫游泳实验 28 d 时不动时间明显上升 (P<0. 05)。病理组织学检测显示, 冲击波重复暴露后 14 d 大鼠海马齿状回( dentate gyrus, DG)区的部分神经细胞排列紊乱; 21 d DG 区神经细胞排列松散, 部分细胞核固缩; 28 d 海马 DG 区神经细胞体积缩小, 数量减少且排列松散。 结论 冲击波重复暴露后可引起大鼠产生持续性抑郁样行为, 其严重程度随时间的推移逐渐加重, 这种行为改变可能与大鼠海马 DG 区神经细胞的损伤进展有关。

Effects of repeated exposure to shock waves on depressive like behavior and hippocampal pathological changes in rats

Objective To explore the depression-like behavior and pathological changes in hippocampus of rats repeatedly exposed to shock waves, thereby provide a model and pathological basis for the study of the damage mechanism of depression-like behavior induced by mild blast induced traumatic brain injury (mbTBI). Methods 80 SD rats were randomly divided into a control group and a shock wave repeated exposure group, and the exposed group was divided into four subgroups of 7, 14, 21 and 28 days according to the observation time after exposure. The biological shock tube (with peak pressure of 120 kPa, positive pressure duration of 11 ms, repeated 3 times in 24 h of interval) was used to construct the model, the open-field test, light-dark test and forced swimming test were used for assessing the behavioral changes of rats, the histopathologic changes of hippocampus were observed as well by LM with HE staining. Results All the rats in exposure group survived, the symptoms such as dull-ness, paralysis, delayed response and loss of appetite appeared at 24th hour after three exposures, the symptoms were gradually relieved 72 h later after three exposures; compared with control group, the total moving distance of rats in open-field experiment were decreased significantly on the 14th, 21st and 28th day after exposure, while the rest time significantly increased ( P <0. 05); the subtle experiment of light and dark boxes showed that the time of entering the light box decreased significantly on the 14th, 21st and 28th day of experiment, the incubation time increased significantly (P<0. 05); and the immobility time of the forced swimming on the 28th day of experiment was increased significantly, too (P<0. 05); additionally, the pathological exami-nation showed that some nerve cells in hippocampal dentate gyrus (DG) area of rats were disordered on the 14th day after repeated exposure to shock wave, the arrangement of nerve cells in DG region of hippocampus became loose on the 21st day, some nuclei were shrinking, while on the 28th day after experiment, the reduce in volume and quantity of nerve cells in DG region of the hippocampus were appeared and loosely arranged. Conclusion The study shows that the repeated exposure to shock wave could cause persistent depression-like behavior in rats, and its severity of depression-like behavior gradually increases with time; this change of behavior may be related to the progression of nerve cell damage in hippocampal DG region of rats.