听皮层-内侧膝状体突触传递的长时程增强及其突触前机制的研究  

Presynaptic long-term potentiation of synaptic transmission in the pathway from auditory cortex to medial geniculate body

作　　者：赵明亮[1] 刘国龙[1] 万子兵[1] 隋建峰[1] 阮怀珍[2] 熊鹰[1] 

机构地区：[1]第三军医大学基础医学部生理学教研室,重庆400038 [2]第三军医大学基础医学部神经生物学教研室,重庆市神经科学研究所重庆400038

出　　处：《第三军医大学学报》2006年第2期147-150,共4页Journal of Third Military Medical University

基　　金：国家自然科学基金资助项目(30371532)~~

摘　　要：目的研究大鼠听皮层(AC)-内侧膝状体(MGB)突触传递的长时程增强(long-termpotentiation,LTP)及其突触前机制。方法刺激听辐射纤维,采用脑片膜片钳全细胞技术在MGB分离和记录兴奋性突触后电流(EPSCs);诱导LTP,并观察谷氨酸受体阻断剂对LTP的影响;采用配对脉冲实验对LTP的发生机制进行探讨。结果①AC-MGB突触的兴奋性传递主要由NMDA和AMAP/kainate受体介导,可在MGB成功诱导出LTP;②应用AP-5或KYN阻断突触后神经元的去极化后仍然可在MGB成功诱导出LTP;但用无Ca2+的ACSF替代正常ACSF后,在MGB难以诱导出LTP。③AC-MGB突触传递的LTP伴随着配对脉冲比率(paired-pulseratio,PPR)的下降。结论AC-MGB突触传递存在LTP机制,其诱导过程不依赖于突触后NMDA受体,但依赖于细胞外Ca2+的浓度;LTP的发生与突触前兴奋性神经递质释放概率增加有关。Objective To study thalamic pathway to medial geniculate the long-term potentiation （LTP） of synaptic transmission in the corticobody （MGB） and the mechanism underlying this synaptic potentiation. Methods After stimulating auditory thalamic radiation, excitatory postsynaptic currents （EPSCs） were recorded at MGB neurons using whole-cell patch clamp technique in AC-MGB slices. A brief 10 Hz conditioning stimulation was used to study whether LTP of synaptic transmission could be induced in MGB neurons. If there was LTP, its mechanism was further explored with paired-pulse test and by observing the effect of glutaminic acid receptors antagonist on it. Results ①Synaptic transmission from AC to MGB was predominantly mediated by ionotropic glutamate receptors and the LTP could be induced. ②Afier application AP-5 or KYN to block depolarization in the postsynaptic cells, conditioning stimulation still induced LTP. However, LTP could not be induced if using free-Ca^2＋ ACSF while giving conditioning stimulation. ③The induction of AC-MGB LTP was concomitantly with a decrease in paired-pulse ratio （PPR） of EPSCs. Conclusion Activation of ionotropic glutamate receptors and depolarization of postsynaptic cell are not required for the induction of this form of LTP while extracellular Ca^2＋ is indispensable. The induction of AC-MGB LTP maybe caused by an increase in the neurotransmitter release probability and should be presynaptic.

关 键 词：内侧膝状体 听皮层 长时程增强 膜片钳 

分 类 号：R338.13[医药卫生—人体生理学] R338.3[医药卫生—基础医学]