脑震荡鼠大脑多巴胺转运体变化研究

A study on the changes of dopamine transporters after cerebral concussion in rats

为了进一步探讨脑震荡(cerebral concussion,CC)大鼠认知行为障碍的神经生物学基础,本实验观察了CC大鼠多巴胺转运体(dopamine transporters,DAT)的变化规律。用自制金属单摆式闭合性脑损伤打击装置复制脑震荡大鼠模型48只,随机分为伤后1、2、4、8、16、24d六个实验组,另设一正常对照组(n=8)。运用抗DAT抗体SP法行免疫组化染色,并测定大脑前额叶皮质(PFC)、尾壳核(CPu)、伏隔核(Acbc)、内侧隔核(MS)、斜角带垂直臂核(VDB)、斜角带水平臂核(HDB)、梨形皮质(Pir)、顶叶皮质(CPL)、海马CA1-3、丘脑中央背内侧核(MD)、丘脑背外侧核(LD)、下丘脑腹内侧核(VMH)和杏仁核等16个脑区DAT阳性表达物的光密度值。结果表明,与正常对照组相比脑震荡后大鼠多个脑区DAT阳性表达物呈下调变化。PFC、CPu-2、MS、LD、MD的DAT阳性表达物在伤后第2d表达最低;CPu-1、VDB、HDB、CPL、CA1、CA2、CA3、VMH和杏仁核的DAT阳性表达物在伤后第4d表达最低;Pir的DAT阳性表达物在伤后第8d表达最低;Acbc的DAT阳性表达物在伤后第16d表达最低。各脑区恢复时间各不相同,至24d基本恢复正常。以上结果提示DAT可在大鼠不同脑区广泛表达;脑震荡后其在多个脑区呈下调性改变,提示多巴胺转运体的伤后变化可能参与了脑震荡后的认知障碍。

To understand the neurobiology mechanisms of cognitive behavioral deficits after injury the changes of dopamine transporters （DAT） following cerebral concussion （CC） in rats were examined. The brain concussion rats were induced by a metallic pendulum - striker concussive device. Animals （n =48） subjected CC were randomized into six injured groups, 1 d, 2 d, 4 d, 8 d, 16 d and 24 d post- concussive groups. One control group （n =48） was used. The immunostaining of DAT by streptavidin -peroxidase （SP） method and image analysis of optical density were conducted in the following areas, cortex of prefrontal lobe （PFC） , caudate putamen （ CPu）, ac- cumbens nucleus （ Acbc）, medial septal nucleus （ MS）, nucleus of the vertical limb of the diagonal band （ VDB）, nucleus of the horizontal limb of the diagonal band （ HDB ） , piriform cortex （ Pir）, cortex of parietal lobe （CPL） , CAI - 3, mediodorsal thalamic nucleus （MD） , laterodorsal thalamie nucleus （LD） , ventromedial thalamic nucleus （VMH） and amygdaloid nucleus. The expression of DAT in the brain regions mentioned above declined comparing with the control after CC and began to recover in different time. The lowest expression for DAT occurred as follows： PFC, CPU-2, MS, MD and LD in the 2nd day, CPu-1, VDB, HDB, CPL, CA1, CA2, CA3, VMH and amygdaloid nucleus in the 4th day, Pir in the 8th day and Acbc in the 16th day. By the 24 days after injury, the DAT expressions were nearly recovered to the normal. These results suggest that DAT can be extensively expressed in many brain regions and it declined after CC, suggesting that DAT may play critical role on cognitive behavioral deficits after CC.