双眼形觉剥夺对成年大鼠视皮层兴奋性突触后电流的影响

Effects of binocular form deprivation on neuron excitory postsynaptic currents in adult visual cortex

目的探讨双眼形觉剥夺(FD)对成年大鼠视皮层神经元兴奋性突触传递特性的影响。方法采用视皮层脑片膜片钳全细胞记录和电流分离技术,分别记录9周龄正常大鼠和7周龄大鼠双眼FD后14d的视皮层神经元膜学特性、突触后电流(PSCs)与NMDA兴奋性突触后电流(EPSCs)。结果双眼FD不改变成年大鼠视皮层神经元的膜学特性和PSCs电学指标。双眼FD对成年大鼠视皮层神经元EPSCs、NMDA-EPSCs的峰值以及NMDA-EPSCs在总EPSCs中所占比例,NMDA-EPSCs的复极化时间无明显影响。结论双眼FD不影响成年大鼠视皮层神经元兴奋性神经传递功能。

Objective Our previous study demonstrated that binocular form deprivation （FD） in critical period visual cortex of rats can inhibit the development of N-mehyl-D-aspartate （NMDA） receptor and prolong the plasticity stage. Present study was to investigate the excitory synaptic transmission of layer Ⅱ -Ⅲ neurons from visual cortex of adult rats manipulated by binocular FD. Methods The visual cortex slices were prepared from Long-Evans rats aged from postnatal weeks （9-week-old rats and 7-week-old rats） after 14-day binocular FD. Patch-clamp whole cell recording techniques were adopted to observe the postsynaptic current. Presynaptic stimulation was given at 0.5 mA through bipolar stimulating electrodes placed in layer Ⅳ. Postsynaptic currents of layer Ⅱ -Ⅲ neurons were recorded with recording electrodes. Excitory postsynaptic currents （EPSCs） were isolated by holding the membrane potential at -60 mV, which was close to the reversal potential for inhibitory postsynaptic currents. Then NMDA-EPSCs were isolated by adding CNQX into artificial cerebrospinal fluid after EPSCs were obtained. Above current isolations were confirmed by pharmacological method. Results Input resistance, resting membrane potential and the peak value of postsynaptic currents（PSCs）were unchanged in adult visual cortex treated with binocular FD in comparison with 9-week-old rats （P = 0. 336,0. 976,0. 983）. No significant differences were found in peak value and 10%--90% decay time of EPSCs and NMDA-EPSCs as well as the NMDA-EPSCs/EPSCs ratio between 9-week-old rats and binocular FD rats （P = 0. 951, 0. 773,0. 827,0. 901 ）. Conclusion This study indicates that binocular FD has no effect on excitory synaptic transmission in the adult visual cortex.