离体脊髓运动神经元兴奋性突触传递的双脉冲易化和抑制

Paired-pulse facilitation and depression of excitatory synaptic transmission in spinal cord motoneurons in vitro

目的:探讨同侧背根(iDR)和腹外侧索(iVLF)双脉冲电刺激(PPS)对脊髓运动神经元(MN)兴奋性突触后电位(EPSP)的影响。方法:应用新生大鼠(7～14天龄)脊髓切片MN细胞内记录技术,对iDR和iVLF施加不同刺激间隔(ISI)的PPS,在MN观察iDR-EPSP和iVLF-EPSP的变化。结果:在69个记录到iDR-EPSP和(或)iVLF-EPSP的MN,对iDR或(和)iVLF给予ISI为30～150ms的PPS,主要诱发iDR-EPSP和iVLF-EPSP的双脉冲易化(PPF,P<0.01),也可在少数MN产生双脉冲抑制(PPD,P<0.01)。比较分析还显示iVLF-EPSP的PPF出现率高于iDR-EPSP(P<0.01),其PPF的双脉冲比值随ISI的延长而降低(P<0.01)。结论:通过给予iDR和iVLF不同脉冲间隔的PPS,MN的外周传入性和下行激活性突触传递均出现以PPF为主的短时程可塑性变化。

Objective：To study the short-term synaptic plasticity of excit- atogy postsynaptie potential （EPSP） elicited by paired-pulse stimulation （PPS） of ipsilateral dorsal rootlet （iDR） and ventrolateral funiculus （ iVLF） in motoneurons （MNs） of the spinal cord slices. Methods： The intraeellular recordings were kept in MNs of neonatal rat spinal cord slices, with observation of iDR-EPSPs and iVLF-EPSPs evoked by PPS with different interstimulus intervals （ISis）. Results： In the 69 MNs with iDREPSPs and/or iVLF-EPSPs, two successive stimuli with different ISis （30,50,100,150 ms） induced paired-pulse facilitation （PPF） in most of the tested cells （ P 〈 0.01 ） , whereas paired-pulse depression （ PPD ） were found in a smaller number of cells （P 〈0.01 ）. By comparison with iDR-EPSPs,iVLF-EPSPs not only showed a higher incidence of PPF （ P 〈 0. 01 ）, but also had a negative relationship between its paired-pulse ratio and ISI （P 〈0. 01l ）. Conclusion： The prominent paired-pulse facilitation of the afferent or descending activation to MNs is induced by PIPS of iDR or iVLF with differerat ISis in the spinal cord slices.