毁损大鼠中缝背核内触液神经元对吗啡依赖和戒断的影响

目的:探索脑内远位触液神经元在吗啡依赖和戒断形成过程中的作用。方法:化学性神经元毁损、侧脑室引入霍乱毒素亚单位B与辣根过氧化物酶复合物(CB-HRP)神经示踪、TMB-ST呈色反应,Western blot、nNOS免疫组织化学。结果:毁损大鼠中缝背核内远位触液神经元后,纳洛酮催促的戒断症状明显减弱,戒断症状评分较戒断未毁损组降低约38%(P<0.05);给予溶媒和毁损触液神经元旁侧的大鼠戒断症状与戒断组比较未见明显变化(P>0.05)。毁损组脑片触液神经元密集区局部细胞损坏明显,仅在其毁损区边缘观测到少量CB-HRP阳性细胞。未毁损组CB-HRP标记细胞位置及数量恒定,形态清晰。毁损触液神经元后,脊髓背角nNOS阳性神经元计数及nNOS蛋白表达较戒断未毁损组减少明显(P<0.05),而较正常组和依赖组增加仍显著(P<0.01)。结论:毁损大鼠中缝背核内部分远位触液神经元可减弱吗啡戒断症状和脊髓背角神经元型一氧化氮合酶的表达,提示中缝背核内部分远位触液神经元可能参与了吗啡依赖和戒断的形成,NO介导脑内触液神经元与脊髓水平对吗啡依赖和戒断的调节。

The lesion of CSF contacting neurons in rat brain parenchyma inhibits the development of morphine dependence and withdrawal

Aim:To investigate the effect of CSF contacting neurons(CSF-CNs)lesion in rat dorsal raphe nucleus(DRN)on the scores of morphine withdrawal symptoms precipitated by naloxone and the nNOS expression in dorsal horn of spinal cord,and study the relationship between the distal CSF-CNs in rat brain parenchyma and the development of morphine dependence and withdrawal.Me-thods:Chemical lesion of neurons the injection of cholera toxin subunit B with horseradish peroxidase(CB-HRP)into one of the rats' lateral ventricles,TMB-ST reaction,nNOS immunohistochemistry and Western blot were used in this study.Results:The withdra-wal sympotoms by the naloxone precipitated attenuated obviously after the lesion of CSF-CNs in rat DRN,scores of all signs were significantly decreased about 38% compared to that of withdrawal group without lesion(P<0.05).The withdrawal sympotoms scores of vehicle withdrawal group and side lesion withdrawal group were not changed significantly(P>0.05).Neurons in the location of CSF-CNs concentrated in the rat brain slices of lesion group were damaged obviously,there were only few CB-HRP positive neurons around the lesion location.But the location and the quantity of the CB-HRP positive neurons in the brain slices of the group without lesion was stable relatively,and their appearance was very clear.After the lesion,the nNOS expression and the quantity of the nNOS positive neurons in dorsal horn of spinal cord decreased significantly compared to that of withdrawal group without lesion(P<0.05),but it also increased significantly compared to that of normal group and dependence group(P<0.01).Conclution:The lesion of distal CSF contacting neurons attenuated the scores of morphine withdrawal symptoms precipitated by naloxone and the nNOS expression in dorsal horn of spinal cord.The distal CSF contacting neurons in rat brain parenchyma partly participated in the develoment of morphine dependence and naloxone precipitated withdrawal possibly by the modulation of NO(nitric oxide).