GABA_A和GABA_B受体介导的成年动物背根神经节神经元的电活动  

ELECTRICAL ACTIVITY MEDIATED BY GABA_A AND GABA_B RECEPTORS ON DORSAL ROOT GANGLION NEURONS IN ADULT ANIMALS

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,上海200031

出　　处：《神经解剖学杂志》1997年第2期95-101,共7页Chinese Journal of Neuroanatomy

摘　　要：许多药理学研究表明，哺乳动物脊髓背角中的GABA受体亚型（GABAA和GABAB）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GABAB受体激活对背根神经节细胞膜电特性的作用。实验标本取自SD成年大鼠L4～6后根节和猫在体L6～7后根节。当灌流液加入GABAB受体激动剂baclofen时，后根节的98个细胞中，约58％的细胞无反应。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GABAS受体选择性拮抗剂saclofen阻断。一些对baclofen反应的细胞也可被GABAA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GABAB受体介导细胞膜电位去极化和超级化反应。GABAA和GABAB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, GABAA and GABAB receptors, may exist inthe mammalian dorsal root ganglion (DRG) neurons and mediate presynaptic inhibition of the nociceptive primary afferentterminals in the spinal cord. This study was to determine further the effects of GABAB receptor on the electrical activities ofDRG neurons. The experiments were performed on DRG neurons in SD rats (120~ 190g, n=58) in vitro and cats (n= 8)in vivo. The DRG of L4~L5 from rats and L6~L7 in cats were prepared and recorded intracellularly. The membrane poten-tial and action potential of neurons were observed. Ninety-eight DRG neurons were recorded. in which 71 and 27 respondedto the excitation of A and C afferent fibers, respectively. Following transient superfusion of GABAB receptor agonist baclQlen (10-4~10-6mol/L), both hyperpolarization (n= 37)and depolarization (n=14) of membrane potential were recorded.These responses could be blocked by selective GABAB receptor antagonist 2-hydroxy-saclofen (10-3 ~ 10-5mol/L). Therewas no difference betwpen the resPonses of A- and C-afferent sensitive neurons. No alteration in the duration of action potertials was induced by stimulation of the sciatic and tibial nerve. other tested neurons(n= 57)failed to respond to baclofen.Muscimol. a GABAA receptor agonist,only produced the depolarizing responses. The present study not only provided futhercvidence fOr coexistence of GABAA and GABAB receptors in the slow conduction velocity A8 and C neurons, but also showedthat they might co-exist on the fast conduction velocity A. and Al neurons. It is suggested that GABAB receptor may be in-volvcd in processing presynaptic event in the first synapse of the spinal dorsal horn.

关 键 词：神经电生理学 背根神经节 Γ氨基丁酸 受体 

分 类 号：Q424[生物学—神经生物学] R338.8[生物学—生理学]