2 Hz与100 Hz刺激在诱导大鼠视皮层长持续长时程增强中的不同作用

在哺乳动物的视皮层,多种不同参数的刺激可诱导出长时程增强(long-term potentiation,LTP)现象。但关于刺激参数与持续时间长于3h的长持续LTP(long lasting LTP,L-LTP)之间关系的研究较少。本研究用3周龄的大鼠视皮层脑片标本,在Ⅳ层刺激而在Ⅱ／Ⅲ层记录场电位,待场电位稳定后施加强直刺激诱导LTP,探讨2Hz与100Hz的强直刺激在诱发持续时间长于3h的L-LTP中的作用。结果表明,多于300个脉冲不同频率的刺激可稳定地诱导出L-LTP;2Hz与100Hz的刺激诱发的L-LTP有明显不同的表达形式,100Hz刺激可诱导出较大的L-LTP;频率相同而脉冲数不同的强直刺激诱发的L-LTP有相同的表达形式。以上结果提示,不同频率的强直刺激诱发的L-LTP机制可能不同;相同频率的刺激(脉冲数不同)诱发的L-LTP可能有相同的机制。

Different effects of 2 and 100 Hz tetanus on the expression of long-lasting long-term potentiation in rat visual cortical slices

Long-term potentiation (LTP) can be induced by various tetanic parameters in the mammalian visual cortex. However, little researches have been done on the relationship between the expression of the long-lasting LTP (late phase LTP or L-LTP) lasting more than 3 h and the tetanic parameters. In the present study, the effects of 2 Hz and 100 Hz tetanic parameters on L-LTP of the field potentials were recorded from the layer II/III of the rat visual cortical slices in response to stimulation of the layer IV. As a result, tetanic parameters that had more than 300 pulses reliably induced L-LTP in the postnatal day 15-21 rats. Obviously different L-LTP expressions were induced by 2 Hz and 100 Hz tetani. There was no difference in L-LTP expression induced by the parameters with the same frequency and different total pulses. These data suggest that L-LTPs induced by different frequency parameters may have different induction and maintenance mechanisms; L-LTPs induced by the parameters with the same frequency may have the same mechanisms.