全脑照射后对小鼠血脑屏障通透性和室管膜下区细胞增殖的影响

目的:探讨60Co-γ射线(Gy)全脑照射后对小鼠血脑屏障通透性和室管膜下区神经干细胞增殖的影响。方法:112只健康小鼠随机分成0 Gy组(对照组),5 Gy照射组(小剂量照射组),15 Gy照射组(中等剂量照射组)和30 Gy照射组(大剂量照射组),每组28只。各组随机取出7只分别于照射后1周和4周测定各组小鼠脑组织伊文思蓝的含量,7只观察室管膜下区的BrdU+细胞形态和数量。结果:(1)照射后1周,15 Gy组和30Gy组脑组织伊文思蓝含量明显升高(P<0.05),室管膜下区的BrdU+细胞数明显降低(P<0.05);(2)照射后4周,15 Gy剂量照射组脑组织伊文思蓝含量和室管膜下区的BrdU+细胞数均恢复到对照组水平(P>0.05),而30Gy剂量照射组脑组织伊文思蓝含量仍明显升高(P<0.05),BrdU+细胞数也未见恢复(P<0.05)。结论:全脑照射后血脑屏障破坏可能对室管膜下区的细胞增殖有进一步抑制作用。

Effects of changes of blood-brain barrier permeability and proliferation of cells in subependymal zone following whole brain irradiation in mouse

Objective:To investigate the effect of spinal cord stimulation(SCS) on pain behavior and activition of microglia in spinal dorsal horn of rats with neuropathic pain(NP).Methods: 20 adult rats were randomly divided into 4 groups:(1) control group;(2) SCS group: normal rats with SCS;(3) SNL+shamSCS group:the SCS device was implanted but without SCS;(4) SNL+SCS group: SNL rats with SCS.Mechanical withdrawal threshold(MWT) was detected for 3 consecutive days pre-operation and on the 5 d post-operation.Rats in SCS and SNL+SCS groups received SCS during 2-5 d after the operation,8 hours each day.Besides,both of SCS group and SNL+SCS group were given a 90 min test before 8 hours SCS,which meant that SCS was applied for 30 min and the withdrawl thresholds of the ipsilateral hind paw were assessed at time of 0,15,30,45,60 and 90 min.After SCS on the 5 d of post-operation,rats were sacrificed.Immunohistochemistry combined with average optical density(AOD) analysis was performed to examine the expression of OX-42(marker of microglia) in the L5 segment spinal dorsal horn of rats of all 4 groups.Result:(1) The behavior results showed that the MWT in SNL+shamSCS group and SNL+SCS group reduced significantly from 26.00±0.0 g pre-operation to 5.50±0.96 g and 6.40±0.40 g respectively on the 5 d of post-operation(P<0.05).Significantly elevation of MWT,from 6.40±0.40 g pre-SCS to 16.20±2.60 g,was observed after 30 min SCS for the SNL+SCS group(P<0.05).What ’ s more,30 min after cessation of SCS,the MWT decreased obviously to the pre-SCS level.(2)Immunohistochemical results demonstrated that on the 5 d of postoperation,the expression of OX-42-immunoreactivity in SNL+SCS group was more lower than SNL+shamSCS group,but both of them showed more immunoreactivity than control group and SCS group.The results of AOD analysis also showed that the spinal dorsl horn AOD of SNL+SCS group(1.29±0.28)was remarkably lower than SNL+shamSCS group(2.66±0.38,P<0.05),but still higher than control group(0.14±0.21)and SCS group(0.24±0.08).Conclusion: SCS had remarkable analgesic effect on SNL induced NP of rats;the underlying mechanism for the effect might be closely related to the inhibition of the acivition of the microglia in spinal dorsal horn.