双脉冲低频刺激诱导成年大鼠海马CA1区NMDA受体依赖性长时程压抑

目的：研究诱导成年大鼠海马CA1区长时程压抑（long-term depression,LTD）的有效刺激参数及其受体机制.方法：成年雄性SD大鼠断头取脑制作海马脑薄片,采用细胞外场电位记录技术,用不同刺激参数刺激海马CA1区Schaffer传入纤维,记录海马CA1区LTD,寻找有效探讨诱导成年大鼠海马CA1区LTD的刺激参数及其受体机制.结果：双脉冲间隔（paired-pulse interval,PPI）为200 ms,频率1 Hz,900对双脉冲为1组,共2组,组间隔10 min的双脉冲低频刺激（paired-pulse low frequency stimulation,PP-LFS）能够有效诱导海马CA1区LTD,60 min和120 min测定其细胞外场兴奋性突触后电位（fEPSP）斜率,结果分别为前对照的（72.33±3.19）％和（69.11±2.80）％;与PP-LFS相同、仅仅刺激强度增加1倍的高强度的双脉冲低频刺激（high-intensity paired-pulse low frequency stimulation,HI-PP-LFS）也能有效诱导海马CA1区LTD,60 min和120m in测定其细胞外场兴奋性突角后电位（fEPSP）斜率,结果分别为前对照的（50.75±2.10）％和（50.90±5.52）％;NMDA受体拮抗剂APV能有效阻断PP-LFS和HI-PP-LFS诱导的LTD.结论：PP-LFS可有效诱导成年大鼠海马CAI区LTD,HI-PP-LFS可诱导产生更大幅度的LTD,且这种LTD是NMDAR依赖性的.

Paired-pulse Low Frequency Stimulation Inducted NMDA Receptors-dependent Long-term Depression in Hippocampal CA1 Region of Adult Rat

Objective：To investigate the induction protocol and receptor mechanism of long-term depression （LTD） in hippocampal CA1 in adult rat.Methods：Standard extracellular recording technique was used.Field EPSP （fEPSP） evoked by Schaffer collateral stimulation were recorded from the CA1 subfield of adult rat hippocampal slices.Results：LTD was induced by 2 groups of paired-pulse low frequency stimulation （PP-LFS）,which consisted of 900 paired-pulses （200 ms interval） at 1 Hz for 10 min.The percentage of depotentiation of slope of field EPSP （fEPSP） was （72.33 ± 3.19）％ and （69.11 ±2.80）％ in 60 min and 120 min after the induction.Then higher intensity PP-LFS was tested （HI-PP-LFS,twice the intensity as test stimulation）,which induced significant LTD.The percentage of depotentiation of slope of field EPSP （fEPSP） was （50.75 ±-2.10）％ and （50.90 ± 5.52） ％.NMDA receptor antagonist APV can effectively block the PP-LFS and HI-PP-LFS induced LTD.Conclusions：PP-LFS can effectively induct adult rat hippocampal CA1 region LTD,and HI-PPLFS can effectively induct significant LTD,which is NMDARs dependent.