Baclofen对成年大鼠和猫背根神经节神经元电活动的影响  

Effects of Baclofen on Electrical Activity of in Vitro Rat Drg Neurons and in Vivo Cat Ones

作　　者：王过渡[1] 周志上[1] 舒友生[1] 赵志奇[1] 

机构地区：[1]中国科学院上海脑研究所

出　　处：《三峡大学学报（人文社会科学版）》1997年第1期100-105,120,共7页Journal of China Three Gorges University(Humanities & Social Sciences)

摘　　要：药理学研究表明哺乳类动物脊髓背角中的GABA受体亚型（GABA_A和GABA_B）参与介导脊髓初级传入末梢的突触前抑制．本研究应用细胞内记录技术探讨GABA_B受体激活对背根神经节（dorsalrootganglion，DRG）细胞膜电特性的作用．实验标本取自SD成年大鼠（120-190g，n＝58）DRG（L₄-L₆）和猫（n＝8）在体L₆-L₇DRRG,当灌流液加入GABA_B受体激活剂baclofen（10-4-10-6mol／L）时，在DRG的98个细胞中，约58％的细胞（n＝57）无反应．部分A类和C类细胞的膜电位出现超极化（n＝37）和去极化（n＝14）反应．A传入（n＝71）和C传入（n＝27）激活的反应没有明显的差异．Baclofen引起的DRG细胞的去极化和超极化反应可被GABA_B受体选择性拮抗剂saclofen（10³-10⁵mo1／L）阻断．一些对baclofen反应的细胞也可被GABA_A受体激动剂muscimol去极化．在所记录的细胞中，baclofen对动作电位时程（APD₅0）没有明显的影响．上述结果提示，在部分细胞中，baclofen激活的GABA_B受体介导细胞膜电位去极化和超级化反应,GABA_A和GABA_B这二种受体不仅在慢传速的Aδ和C类细胞中共存，同样也共存于快传速的Aα和Aβ的细胞膜上．Pharmacological studies have shown that GABA receptor subtypes.GABA_A and GABA_B receptors may exist in the mammalian dorsal root ganglion (DRG)neurons and mediate presynaptic inhibition of the nociceptive primary afferent terminals inthe spinal cord. This study was further to determine the effects of GABA_B receptor on theelectrical activities of DRG neurons. The experments were performed on DRG neurons inSD rats(120-190g,n=58) in vitro and cats (n=8) in vivo. The DRG at L_4-L_5 of ratsand L_6-L_7 of cats were prepared and recorded intracellularly.The membrane potential and action potential of neurons were observed, Ninety-eightDRG neurons were recorded, in which 71 and 27 responded to the excitation of A and Cafferent fibers, respectively, Following transient superfusion of GABA_B receptor aganistBaclofen (10-4-10-6mol/L), both hyperpolarization (n=37) and depolarization (n=14 )of membrane potential were recorded. These responses could be blocked by selectiveGABA_B receptor antaganist 2-hydroxy-saclofen (10~3-10~5 mol/L ). There was nodifference between the responses of A-and C-afferent sensitive neurons. No alterationin the duration of action potentials was induced by stimulation of the sciate and tibialnerve. Other tested neurons (n=57) failed to respond to baclofen. Muscimol, a GABA_Areceptor agonist, only produced the depolarizing responses. The present study not onlyprovided further evidence for coexistence of GABA_A and GABA_B receptors in the slowconduction velocity A_δ and C neurons, but also showed that they might co-exist on thefast conduction velocity A_α and A_β neurons. It suggested that GABA_B receptor may beinvolved in processing presynaptic event in the first synapse of the spinal dorsal horn.

关 键 词：BACLOFEN 背根神经节 细胞内记录 膜电位 成年大鼠 猫 

分 类 号：R338.8[医药卫生—人体生理学]