多重脑震荡大鼠5-羟色胺能神经纤维变化

目的:研究多重脑震荡(MCC)与大鼠认知记忆相关脑区5-羟色胺(5-HT)能神经纤维变化的规律,以探讨MCC大鼠认知行为障碍的神经生物学基础。方法:应用自制单摆式机械打击装置构建MCC大鼠模型,免疫组织化学及半定量方法研究MCC后大鼠5-HT能神经纤维的变化。结果:前额叶皮质、中隔区、丘脑、海马CA1和CA3区5-HT能神经纤维免疫反应阳性物在伤后2d组反应达高峰,杏仁体、海马CA2和CA4区在伤后4d组免疫反应了阳性最强;顶叶皮质、梨状皮质及伏隔核内侧在伤后8d组反应最强。5-HT纤维密度在中隔区和伏隔核内侧以伤后2d最高,杏仁体区以伤后1d最高,大脑皮质和丘脑5-HT纤维密度在伤后各损伤组与对照组相比无显著性差异。结论:MCC可引起与认知功能有关脑区的5-HT表达增高,5-HT的高表达可能由脑损伤后神经元过度兴奋所引起的神经递质紊乱造成,而这种紊乱可能影响大鼠的认知功能。

Changes of serotoninergic nerve fibers after multiple cerebral concussions in rat

Objective:To study serotoninergic nerve fiber changes in the regions related to cognition and memory and to explore the neurobiologic mechanisms of cognitive behavioral dysfunction after multiple cerebral concussions(MCC)in rats.Methods:A rat MCC model was firstly duplicated using a metallic pendulum-striker concussive device.Forty- eight injured male Sprague-Dawley rats were randomly divided into 6 groups:1 d,2 d,4 d,8 d,16 d and 24 d post-in- jury and 1 control group.The expression changes of serotonin in nerve fiber and the density of serotoninergic nerve fi- ber in cerebral cortex,septal area,accumbens nucleus,thalamus,amygdaloid body and hippocampus were observed by using immunochemistry S-P method with anti-5-hydroxytryptamine(5-HT)antibody and semiquantitative methods. Results:The intensity of the 5-HT nerve fiber immunoreaction increased in each brain region post injury,while differ- ent area showed different peak time.Compared with the control,the intensity of 5-HT nerve fiber immunoreaction reached a peak in prefront cortex,medial septal area,thalamus,hippocampal CA1 and CA3 at day 2 group.The most significant change in amygdaloid body,hippocampal CA2 and CA4 at day 4 group,and parietal cortex,piriform cortex and accumbens nucleus occured at day 8 group.The differences in the density of serotoninergic nerve fiber in medial septal area and accumbens nucleus were the most obvious at 2 days post MCC,and the most striking change in amygda- loid body was found at 1 day after MCC.However,there was no significant difference in cerebral cortex and thalamus compared with the control group.Conclusion:The intensity and density of 5-HT nerve fiber immunoreaction in differ- ent encephalic regions related to cognition and memory increased following MCC in rats.The neurotransmitter disorder caused by neuronal overexcitation postinjury may result in a increase of 5-HT immunoreaction,which influence cogni- tive disorder in MCC rats.