多重脑震荡大鼠脑干中缝核团内5-羟色胺免疫阳性表达变化的研究

为了探讨多重脑震荡(multiple cerebral concussion,MCC)后大鼠中缝核团内5-羟色胺(5-HT)能神经元的变化规律,本实验采用自制单摆式机械打击装置复制MCC大鼠模型,研究伤后大鼠脑干中缝核团内5-HT及5-HT合成过程中的限速酶-色胺酸羟化酶(TPH)的表达。将56只大鼠随机分为7组:对照组、伤后1、2、4、8、16和24d组(n=8)。用免疫组织化学染色技术及图像分析法定量分析伤后大鼠脑干中缝核团内5-HT和TPH的表达变化。结果显示:(1)TPH免疫反应阳性产物在中缝背核、正中中缝核的表达在伤后2d时达到高峰,与正常对照组相比有显著性差异(P<0.05);中缝大核和中缝苍白核分别以伤后1d组和4d组阳性反应最强;(2)5-HT免疫反应阳性产物在中缝背核、正中中缝核的表达也在伤后2d时达到高峰,16、24d组基本恢复至正常水平;而中缝大核和中缝苍白核内5-HT的免疫反应性在各损伤组与正常对照组之间均无显著性差异(P>0.05)。以上结果表明,多重脑震荡后中缝核团内TPH和5-HT的表达增高,这为研究5-HT对MCC后认知障碍的影响提供了形态学依据。

A study on expressional changes of serotonin-immunoreactivity in the raphe nuclei of rats brainstem after multiple cerebral concussions

To investigate the changes of the serotoninergic neurons in raphe nuclei after multiple cerebral concussions (MCC), MCC model rats were duplicated by using a metallic pendulum-striker concussive device and the expression of 5-HT and its rate-limiting enzyme, tryptophan hydroxylase (TPH) was studied in the present study. Fifty-six rats were randomly divided into seven groups: control group, post-injury for 1, 2, 4, 8, 16 and 24 d groups (n=8 for each group). The changes of 5-HT and TPH in serotoninergic neurons of raphe nuclei of brainstem were observed via immunohistochemical staining and quantitative methods by image analysis system. The results showed that: (1) The expression of TPH reached peak at 2 d group in the dorsal raphe nucleus and median raphe nucleus, and there were significantly different compared with the control group (P<0.05). Moreover, TPH immunoreactivity in the raphe magnus nucleus and raphe pallidus nucleus was the highest at 1 d and 4 d group, respectively; (2) 5-HT immunoreactivities in the dorsal raphe nucleus and median raphe nucleus also reached peak at 2 d group, then recovered to normal level at 16 d and 24 d. No significant difference of 5-HT immunoreactivities was observed in the raphe magnus nucleus and raphe pallidus nucleus between injury and control rats (P>0.05). These results indicate that the expression of 5-HT and TPH in the raphe nuclei of the brainstem is up-regulation following MCC in rats, which supply a morphologic base of serotonin on cognitive deficits post MCC.