电刺激坐骨神经对新生期大鼠脊髓背角浅层及海马CAl区突触可塑性及c—fos蛋白表达的影响

Effects of electrical stimulation of sciatic nerve on synaptic plasticity of spinal dorsal horn, hippocampal CA1 region and spinal e-fos, hippocampal CA1 region expression in neonatal rats

目的观察电刺激坐骨神经对新生期大鼠脊髓背角浅层、海马CAl区突触可塑性及O—fos蛋白表达的影响。方法（1）将大鼠分为新生组及成年期组，记录左侧胸13-腰I脊髓背角浅层及右侧海马CAl区诱发场电位，予条件电刺激后，记录电位幅度，潜伏期变化至120min，再在脊髓表面加D．AP5，继续观察场电位的幅度及潜伏期变化至175min。（2）大鼠分为新生组、成年期组，每组数字随机法随机分为3组：空白对照、单刺激、条件电刺激后组，其中，条件电刺激后组分为条件电刺激后60、120和175min组，实验后动物脊髓和海马做免疫组织化学染色，观察c．fos蛋白表达。结果（1）电刺激坐骨神经在新生期组大鼠脊髓背角浅层及海马CAl区诱发产生NMDA受体依赖的长时程增强（LTP），主要由脊髓A类神经纤维诱发；成年期组大鼠以C类神经纤维诱发产生LTP。（2）条件电刺激后，在新生期大鼠脊髓（L1组由阳的10±8上升至T3的45±14；L2组由11D的13±10上升至r13的41±10；L3组由哟的19±7上升至T3的41±9）及海马CAl区c—los蛋白（由110的25±7上升为49±8）表达都增加，成年期大鼠脊髓背角浅层海马CAl区c-fos蛋白表达增加。结论条件电刺激在新生期组大鼠脊髓背角诱发A类神经纤维特征，NMDA受体依赖的TJTP，同时c—fos蛋白在脊髓不同层和海马表达，说明痛觉信号随发育而变化。

Objective To explore the response to nociceptive stimuli in spinal cord of neonatal rat and observe the electrical stimulation of sciatic nerve on synaptic plasticity of spinal dorsal horn, hippocampal CA1 region and spinal c-fos, hippocampal CA1 region expression in neonatal rats. Methods The rats were divided into neonatal and adult groups. The evoked potentials of left spinal dorsal horn from T13-L1 and right hippocampal CA1 region were recorded. After conditional electric stimulations, the potential amplitudes were recorded. When the incubation period reached 120 min, D-AP5 was added to spinal cord of rats and resulting changes in field potential and e-fos expression were recorded. Results Long-term potentiation （LTP） in neonatal rats was mainly evoked by A-type nerve fibers whereas LTP in adult rats was mainly evoked by C-type nerve fibers. C-fos expression was significantly increased in superficial, deep layers of spinal dorsal horn, ventral horn and hippocampal CA1 region in neonatal rats. Conclusion Pain signals change with age.