THE EFFECT OF NICOTINE ON THE DAMAGE OF SPINAL CORD

用原代培养的神经细胞研究烟碱乙酰胆碱受体刺激对神经组织的影响。烟碱受体激动剂甲基氨甲酰胆碱可增加培养的大鼠星形胶质细胞内钙离子水平。这种升高被同时加入烟碱受体拮抗剂六甲双铵完全阻断。在无钙培养基中也观察到甲基氨甲酰胆碱引起的细胞内钙升高，表明甲基氨甲酰胆碱诱导的钙升高是由尼古丁受体刺激介导的，钙的来源似乎是细胞内钙储存。我们还研究了甲基氨基甲酰胆碱对大鼠培养的小胶质细胞的影响。LPS诱导的小胶质细胞NO和TNF-α的释放不受甲基氨基甲酰胆碱的影响。在我们培养的小胶质细胞中，通过加入Cl-腺苷（一种非选择性腺苷受体激动剂）诱导DNA片段化。甲基氨基甲酰胆碱本身并不诱导培养的小胶质细胞凋亡，但是，甲基氨基甲酰胆碱的加入增强了由Cl-腺苷诱导的细胞凋亡。这些结果表明，神经胶质细胞通过烟碱受体对尼古丁产生反应，并且烟碱受体刺激可抑制活化的小胶质细胞介导的炎症反应。

The effects of nicotinic acethylcholice receptor stimulation on neuronal tissue were investigated using primary cultured cells. The addition of methylcarbamylcholine, a nicotinic receptor agonist, increased intracellular calcium level in rat cultured astrocytes. This elevation was completely blocked by the simultaneous addition of hexamethonium, a nicotinic receptor antagonist. Intracellular calcium elevation by methylcarbamylcholine was also observed in calcium-free medium, indicating that the methylcarbamylcholine-induced calcium elevation was mediated by nicotinic receptor stimulation and the source of calcium seems to be intracellular calcium storage. We also investigated the effect of methylcarbamylcholine on rat cultured microglia. The LPS-induced NO and TNF-α release from microglia was not altered by the addition of methylcarbamylcholine. In our cultured microglia, DNA fragmentation was induced by the addition of Cl-adenosine, an unselective adenosine receptor agonists. Methylcarbamylcholine did not induce apoptosis in cultured microglia by itself, however, the addition of methylcarbamylcholine enhanced apoptosis induced by Cl-adenosine. These results suggest that glial cells responds to nicotine via nicotinic receptors and the inflammatory response mediated by activated microglia may be inhibited by nicotinic receptor stimulation.