双眼形觉剥夺对大鼠视皮层神经元电生理特性的影响

The electrophysiological properties of visual cortical neurons in binocular form-depri-vated rats

目的 研究形觉剥夺对发育过程中视皮层神经元突触电生理学影响,探索哺乳动物视觉发育可塑性的细胞水平机制。方法正常组和双眼形觉剥夺组Wistar大鼠61只,制作脑片并获得膜片钳全细胞记录。记录视皮层神经元的突触后电流(Postsynptre currents,PSCs)和诱发长时程增强(Lorg-term potentiation,LTP)。电生理记录结束后对所记细胞进行免疫组化染色。结果①双眼形觉剥夺组无反应型PSCs比例显著高于正常组(P<0.01);多突触反应型PSCs比例正常组显著高于双眼形觉剥夺组(P<0.01)。②双眼形觉剥夺组与正常组间相比,输入阻抗显著增高(P<0.01),静息电位较为去极化(P<0.01),EPSCs峰值显著降低(P<0.01)。③形觉剥夺组LTP诱发率显著低于正常组(P<0.05)。双眼形觉剥夺组组4周龄、5周龄的LTP增值显著高于正常组同周龄时(P<0.01,P<0.05)。结论①双眼形觉剥夺影响了静息突触向功能性突触的转化和神经网络的成熟。②双眼形觉剥夺可以在一定程度上影响神经元的突触传导功能。③双眼形觉剥夺在一定程度上降低视皮层神经元的可塑性,但可能保持了神经元对适宜刺激的反应能力。

Objective To investigate the electrophysiological properties of neurons in visual cortex of binocular form-deprivated rats during the developmental stages and to explore the synaptic and cellular mechanisms of plasticity in the visual cortex. Methods Whole cell patch clamp technique was applied to the visual cortex slices prepared from 61 Wistar rats of both genders, which were divided into two groups; control group and binocular form-deprivation (BFD) group. Excitatory postsynaptic currents (EPSCs) and long term potentiation (LTP) of the neurons were recorded. Results (1) The percentage of silent response in BFD group was significantly higher than that in the control group(P <0.01), but the percentage of polysynaptic EPSCs in BFD group was significantly lower than that in the control group( P < 0.01) .(2) Compared with those of the control group, significantly higher input resistance( P < 0.01) , lower peak value of EPSCs ( P < 0.01) and more depolarized resting membrane potentials ( P < 0.01) were found in neurons in BFD group. (3) The incidence of LTP induced in BFSD group was lower( P < 0.05), but the LTP magnitude was significantly higher than that in the control group( P < 0.01 or P < 0.05) . Conclusion (1)Binocular form-deprivation may influence the transformation from silent synapses to active ones and the maturation of synaptic circuits.(2)Binocular form-deprivation may influence the synaptic conduction of neurons in visual cortex at a certain degree. (3) The amplitude of LTP increased in BFSD group and the incidence of LTP induction decreased as compared with that in the control group, suggesting that binocular form-deprivation may decrease the plasticity of neurons in visual cortex at a certain degree but may protect the response capability of neurons to adequate stimulus.