摘要
目的:观察和比较多巴胺(DA)对新生大鼠离体脊髓运动神经元(MN)下行激活和外周传入通路的兴奋性突触后电位(EPSP)的影响。方法:选取新生SD大鼠(8~14日龄)制备脊髓横切片,对其MN进行细胞内记录,观察DA对电刺激同侧背根(iDR)、同侧腹外侧索(iVLF)在MN诱发的EPSP(iDR-EPSP、iVLF-EPSP)的影响。结果:①在17个稳定记录的MN,灌流6.25μmol/L DA 15 min,不仅增大MN膜电阻(P<0.01),还可减小动作电位(AP)幅度和超射(P<0.05)等。②在11个MN,灌流6.25μmol/L DA 15 min后同细胞iDR-EPSPs和iVLF-EPSPs的幅度、曲线下面积均减小并伴时程缩短(P<0.05)。③表观受体动力学分析显示,6.25μmol/L DA可减小iVLF-EPSPs的表观解离速率常数K 2和表观平衡解离常数K_(T)(P<0.05),但仅减小iDR-EPSPs表观结合速率常数K_(1)(P<0.05)。④给予6.25、25、100μmol/L DA累积灌流各15 min,DA可浓度依赖性(P<0.01)减小iVLF-EPSPs的幅度、曲线下面积、半幅时程和衰减时间(P<0.01),并同时减小同细胞iDR-EPSPs的幅度、时程和衰减时间(P<0.01)。且DA在同细胞对iVLF-EPSP的抑制作用比iDR-EPSP强(P<0.01)。结论:DA对MN外周传入和下行激活性兴奋性突触传递具有抑制作用,但对下行激活通路的抑制更强。
Objective:To observe the distinct effects of dopamine(DA)on afferent and descending synaptic transmission of motoneurons(MNs)in neonatal rat spinal cord slices.Methods:In spinal cord slices isolated from neonatal Sprague-Dawley rats(8-14 d),the intracellular recording technique was used to observe the effects of DA on excitatory postsynaptic potential(EPSP)of MNs evoked by electrical stimulation of ipsilateral dorsal root(iDR,iDR-EPSP)and ipsilateral ventrolateral funiculus(iVLF,iVLF-EPSP).Results:In 17 MNs,bathing DA(6.25μmol/L)for 15 min not only increased membrane resistance(P<0.01),but also reduced amplitude and overshoot of action potential(P<0.05).In 11 steadily recorded MNs,DA(6.25μmol/L)perfusion for 15 min decreased the amplitude,area under curve(AUC)and duration of iDR-EPSPs and iVLF-EPSPs in the same MNs(P<0.05).The apparent dissociation rate constant(K 2)and apparent equilibrium dissociation constant(K_(T))of iVLF-EPSPs were decreased significantly by bathing DA(6.25μmol/L)for 15 min(P<0.05),while only the apparent association rate constant(K_(1))of iDR-EPSPs reduced(P<0.05).Moreover,in 6 MNs with both iDR-EPSP and iVLF-EPSP,bath of DA(6.25,25,100μmol/L)for 15 min with each concentration not only reversibly and concentration-dependently(P<0.01)depressed the amplitude,AUC,half-width and decay time of iVLF-EPSPs(P<0.01),but also decreased the amplitude,AUC and decay time of iDR-EPSPs(P<0.01),respectively.The inhibitory effect of DA on iVLF-EPSPs was more potent than that on iDR-EPSPs(P<0.01).Conclusion:These results suggest that DA may inhibit the afferent and descending excitatory synaptic transmission in MNs,and present a more potent depression on descending activation than that on afferent pathway.
作者
吴金蓉
汪萌芽
WU Jinrong;WANG Mengya(Cell Electrophysiology Laboratory,Wannan Medical College,Wuhu 241002,China)
出处
《皖南医学院学报》
CAS
2023年第1期4-8,共5页
Journal of Wannan Medical College
基金
国家自然科学基金项目(31271155)。
关键词
脊髓
运动神经元
突触传递
多巴胺
spinal cord
motoneuron
synaptic transmission
dopamine