光学成像甘氨酸对蜗核和前庭核神经元兴奋的抑制作用

The spatiotemporal characteristic of glycinergic inhibition in cochlear nucleus and vestibular nucleus by optical imaging

目的 从神经细胞群的水平研究甘氨酸是否对蜗核(cochlear nucleus,CN)与前庭核(vestibular nucleus,VN)神经元核团的兴奋起抑制作用以及其作用方式。方法 从新生小鼠(1-3天)制备活体(in vitro)脑干组织切片,并用电压敏感染料(voltage-sensitive dye)进行染色,采用多位点光学记录系统(optical imaging)观察电刺激位听神经(第8颅神经,nⅧth)后传入兴奋的传导。结果 光学成像显示电刺激nⅧth后兴奋传导至脑干的CN核团和VN核团,并且光学方法可同步记录256个记录单元(elements)中神经兴奋传导的二维动态过程(n=35)。用甘氨酸受体桔抗剂-马钱子碱(50μM)浸泡组织切片后,在CN和VN中的光学信号与脑片在标准人工脑脊液中相比较有明显的增强(n=10)。马钱子碱对峰样快反应信号与慢反应信号的增强效应不同,在CN和VN的不同核团之间也有差异。在CN核团,快反应信号与慢反应信号增强幅度分别为154±34％(n=23,elements)和271±91％(n=23,elements),马钱子碱的增强效应与标准ACSF相比有显著性统计学差异(P<0.05)。在VN核团,慢反应信号增强幅度为149±56％(n=17,elements),也有显著性统计学差异(P<0.05)。但是,在VN核团,快反应信号增强幅度仅为102±14％(n=17,elements),与对照组相比较无显著性统计学差异(P>0.05)。另外,?

Objective To study the role of glycinergic inhibition in cochlear nucleus and vestibular nucleus. Methods Using multiple - site optical recording technique coupled with a voltage - sensitive dye (RH 155), the spatiotemporal activity was observed in both cochlear and vestibular nucleus in newborn mouse after electrical stimulation of the vestibu-locochlear nerve. Results In both CN and VN, the optical responses were enhanced obviously by the bath - applied strychnine (50 μM,STR), a glycine receptor antagonist. After application of STR, the amplitude of the spike and slow -signal (at the 10 ms point after the spike) in CN was increased to 154 ±34% (n = 23, elements), 271±91% (n =23, elements), respectively. On the contrary, the amplitude of the slow - signal in VN was increased to 149±56% (n = 17, elements). These amplitude values were significantly (P <0. 05) higher than the control ones. The amplitude of the spike in VN, however, was increased to 102 ± 14% . This increase was no significant (P> 0. 05) . The excitatory enhancements were occurred in the central areas of the responses in CN and VN as well as in the edges areas of the responses. Conclusion Glycine is identified as an inhibitory neurotransmitter in cochlear nucleus (CN) and vestibular nucleus (VN) in newborn mice. Glycine primarily sharpens the lateral edges of the excitatory response area as well as modulates excitation within central portions of the excitatory response area of CN and VN.