Yamada T, Murayama T, Nomura Y
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
Jpn J Pharmacol. 1997 Apr;73(4):311-6. doi: 10.1254/jjp.73.311.
Several studies have shown that the nervous (and hormonal) system controls immune functions. In the present study, we examined the presence of muscarinic acetylcholine receptors and the effect of carbachol on DNA fragmentation in adult rat thymocytes. Rat thymocytes possessed high affinity binding sites for the muscarinic antagonist [3H]3-quinuclidinyl benzilate (QNB). The average number of binding sites per cells was 3000, and the equilibrium dissociation constant of [3H]QNB on intact cell was approximately 80 nM. The binding was inhibited by an M1- and M3-selective antagonist, 4-diphenylacetoxy-N-methylpiperidine methiodine (4-DAMP). Hydrocortisone (100 mg/kg, s.c.) treatment of rats for 2 days prior to sacrifice increased the average number of [3H]QNB binding sites on thymocytes by 82 +/- 33%. The gel electrophoresis of DNA extracted from carbachol-treated thymocytes revealed a ladder pattern typical of intranucleosomal fragmentation. The addition of oxotremorine-M also induced DNA fragmentation and the effects of muscarinic agonists were inhibited by the addition of atropine or 4-DAMP. The results suggest the existence of muscarinic receptors and the possible involvement in apoptosis in thymocytes.
多项研究表明，神经（及激素）系统控制免疫功能。在本研究中，我们检测了成年大鼠胸腺细胞中毒蕈碱型乙酰胆碱受体的存在情况以及卡巴胆碱对DNA片段化的影响。大鼠胸腺细胞具有毒蕈碱拮抗剂[3H]3-喹核醇基苯甲酸酯（QNB）的高亲和力结合位点。每个细胞结合位点的平均数为3000，完整细胞上[3H]QNB的平衡解离常数约为80 nM。该结合被M1和M3选择性拮抗剂4-二苯基乙酰氧基-N-甲基哌啶甲碘化物（4-DAMP）抑制。在处死前2天，给大鼠皮下注射氢化可的松（100 mg/kg），可使胸腺细胞上[3H]QNB结合位点的平均数增加82±33%。从经卡巴胆碱处理的胸腺细胞中提取的DNA进行凝胶电泳，显示出典型的核小体间片段化梯形图谱。加入氧化震颤素-M也诱导了DNA片段化，毒蕈碱激动剂的作用可被加入阿托品或4-DAMP抑制。结果提示毒蕈碱受体的存在以及可能参与胸腺细胞凋亡。
