脑震荡对大鼠多巴胺能神经元及神经纤维的影响

Influence of brain concussion on dopaminergic neuron and nerve fiber in rats

目的：探讨脑震荡(BC)鼠多巴胺能神经元和神经纤维内酪氨酸羟化酶(TH)含量的变化。方法：用金属单摆打击装置复制 BC 模型。动物随机分为对照组和伤后1～24 d 损伤组；用免疫组织化学结合图像分析方法研究 BC 后中脑黑质致密区(SNC)和腹侧被盖区(VTA)多巴胺能神经元及基底节尾壳核多巴胺能神经纤维 TH 含量的变化。结果：在 SNC 和 VTA 及基底节,BC 后1、4、8及16 d 组的 TH 免疫反应阳性明显高于对照组,其中以4d 组反应最强,24 d 组在 SNC 和基底节与对照组比较无显著性差异,但在 VTA,TH 免疫反应阳性仍高于对照组。结论：BC 后 TH 早期增高可能是脑损伤神经元过度兴奋的反应,随后持续增高一段时间可能是多巴胺能神经元上调其合成能力的一种代偿反应。

Objective： To explore the changes of Tyrosine hydroxylase （TH） in dopaminergic neurons and nerve fibers in brain concussion （BC） rats. Methods： Animal model of concussive brain injury in rats was duplicated with a metallic pendulum-striker concussive device. BC rats were equally divided into 6 groups （n=12） ： day 1,2, 4,8,16,and 24 post-concussive injury groups. There were 12 normal rats in control group. The changes of dopaminergic neurons in substantia nigra pars compact （SNC） and ventral tegmental area （VTA） of midbrain, dopaminergic nerve fibers in caudate putamen of basal ganglia were studied by immunohistochemistry and image analysis. Results： TH-immunoreaction（TH-IR） increased significantly in the SNC, VTA and basal ganglia on 1,4, 8,16 day post-concussive injury. The most significant change occured in 4 day group. The expression of TH-LR recovered in day 24 group in SNC and basal ganglia, but the TH-IR was still significantly higher as compared to the control group in VTA. Conclusion： The increased expression of TH-IR in dopaminergic neurons and nerve fibers in earlier period following BC may be caused by neuronal transient over excitation following post brain concussion. The increase in TH maintains for a period of time, which may reflect a compensatory response of dopaminergic neurons to upregulate their synthesizing capacity.