Ohta M
Department of Hygiene and Preventive Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Hokkaido Igaku Zasshi. 1998 Jul;73(4):365-78.
Spatio-temporal patterns of neuronal activity after the induction of long-term potentiation (LTP) in mouse hippocampal slices were studied with the use of a real-time high-resolution optical recording system. The slices were stained with voltage-sensitive dye and then high-frequency pulses (tetanus) were delivered to Schaffer collaterals of CA3 at the stratum radiatum of CA1. Optical signals as well as field potential in response to test pulses were potentiated after tetanus. The area of response measured by optical recording was slightly but significantly enlarged after tetanus, suggesting that the propagation of optical responses from CA1 towards the subiculum was enlarged. It was suggested that a great increase in neuronal activity was elicited at CA1 and the subiculum after LTP. These changes of spatio-temporal patterns of neuronal activity may contribute to learning and memory. The effect of trichloroethylene (TCE) on LTP was studied with the use of both electrical and optical and recording. The hippocampus from mice injected with 300 mg/kg or 1000 mg/kg TCE was sliced 24 hours after TCE-administration. Test pulses were delivered to Schaffer collaterals every 30 sec and the field potential from the stratum pyramidale of CA1 was recorded. At 40 min after the application of tetanus, population spikes (PS) were potentiated in all groups, but the post/pre ratio of PS was smaller in TCE groups than in the control. Optical recording was also carried out in 1000 mg/kg TCE-injected mice. At 40 min after tetanus, the optical signal response to the test pulse was potentiated in both TCE and control groups, but the post/pre ratio of the optical signals was smaller in TCE than in the control. No significant difference was detected in the increase in the neuronal response area between TCE and the control. It was suggested that TCE depressed the LTP, whereas the increase in the area after tetanus meant that a good amount of neuronal activity was still potentiated.
利用实时高分辨率光学记录系统，研究了小鼠海马切片中诱导长时程增强（LTP）后神经元活动的时空模式。将切片用电压敏感染料染色，然后向CA1辐射层的CA3区的Schaffer侧支施加高频脉冲（强直刺激）。强直刺激后，光学信号以及对测试脉冲的场电位均增强。光学记录测量的反应面积在强直刺激后略有但显著增大，表明从CA1向海马下脚的光学反应传播范围扩大。提示LTP后CA1和海马下脚的神经元活动大幅增加。这些神经元活动时空模式的变化可能有助于学习和记忆。利用电记录和光学记录研究了三氯乙烯（TCE）对LTP的影响。在给予300mg/kg或1000mg/kg TCE的小鼠给药24小时后，将海马切片。每隔30秒向Schaffer侧支施加测试脉冲，并记录CA1锥体细胞层的场电位。在施加强直刺激40分钟后，所有组的群体峰电位（PS）均增强，但TCE组的PS后/前比值低于对照组。对注射1000mg/kg TCE的小鼠也进行了光学记录。在强直刺激40分钟后，TCE组和对照组对测试脉冲的光学信号反应均增强，但TCE组的光学信号后/前比值低于对照组。TCE组和对照组在神经元反应面积增加方面未检测到显著差异。提示TCE抑制LTP，而强直刺激后面积增加意味着仍有大量神经元活动被增强。
