组胺对新生大鼠离体脊髓运动神经元下行激活的影响

Effects of histamine on descending activation of rat spinal motoneurons in vitro

目的:观察组胺对新生大鼠离体脊髓运动神经元下行激活所诱发的兴奋性突触后电位(EPSP)的影响。方法:选用8~14日龄的新生SD大鼠的脊髓腰骶膨大处横切片,运用细胞内记录技术,通过同芯双极电极刺激同侧腹外侧索(iVLF)诱发iVLF-EPSP,观察组胺(100μmol/L)灌流后iVLF-EPSP的变化。结果:①记录到54个稳定的MN,检测到其静息电位为(-64.71±4.23)mV,动作电位幅值为(75.68±7.44)mV、超射值为(11.77±5.65)mV;②记录到上述54个MN阈刺激诱发的iVLF-EPSP,其幅值为(4.60±2.88)mV、时程为(52.87±29.32)ms、曲线下面积为(98.77±90.03)mV·ms;③组胺(100μmol/L)灌流14个稳定记录的MN,在11个细胞诱导出膜去极化(P<0.05),且膜电阻有增大趋势;④组胺灌流使5个MN的自发放电频率增加,冲洗后可恢复;⑤对上述14个MN灌流组胺(100μmol/L),其中11个有去极化反应的细胞表现出iVLF-EPSP的幅度、曲线下面积、时程增加(均P<0.05)。结论:组胺可能是通过增强大鼠下行激活而调节脊髓运动控制的输出。

Objective:To observe the effects of histamine on excitatory postsynaptic potential(EPSP)evoked by descending activation in newborn rats spinal cord motoneurons(MN)in vitro.Methods:By using intracellular recording techniques and 8-14-day-old neonatal SD rat spinal cord slices,cell electrophysiological parameters of excitatory postsynaptic potentials(EPSP)evoked by ipsilateral ventrolateral funiculus(iVLF)stimulation were observed from MN,then the effects of histamine(100μmol/L)bath on MN were evaluated.Results:①We recorded 54 stable and healthy MNs,in which the resting potential of(-64.71±4.23)mV,amplitude of(75.68±7.44)mV and overshoot of(11.77±5.65)mV were measured;②Amplitude of iVLF-EPSPs evoked by iVLF threshold stimulation was observed to be(4.60±2.88)mV,duration(52.87±29.32)ms,and area under curve(98.77±90.03)mV·ms in 54 MN;③In 11 cells of 14 tested MNs,histamine(100μmol/L)bath induced a membrane depolarization(P<0.05);④After histamine(100μmol/L)bathing,5 MNs with spontaneous firing increased the neuronal repetitive firing frequency;⑤In 11 MNs of 14 tested cells with iVLF-EPSPs,histamine(100μmol/L)bath increased amplitude,area under curve and duration of iVLF-EPSPs(all P<0.05).Conclusion:These results suggest that histamine may modulate final motor outputs by enhancing the descending activation in the rat spinal cord.