乙酰胆碱对视皮层诱发场电位及LTP形成的影响

Effects of acetylcholine on field potentials and LTP formation in primary visual cortex

采用幼年大鼠视皮层脑片标本，观察了乙酰胆碱对视皮层诱发场电位以及ＬＴＰ的影响。结果发现，１００μｍｏｌ·Ｌ－１及５μｍｏｌ·Ｌ－１两种浓度的乙酰胆碱均可使诱发场电位幅值增大；但对ＬＴＰ形成的作用不同。５μｍｏｌ·Ｌ－１的乙酰胆碱对ＬＴＰ的形成无负影响，甚至有轻度易化作用，当用人工脑脊液冲洗去除乙酰胆碱后，此组标本已形成的ＬＴＰ幅值无显著变化；浓度为１００μｍｏｌ·Ｌ－１的乙酰胆碱使所有实验标本在强直刺激后均不能记录出ＬＴＰ，当用人工脑脊液冲洗去除乙酰胆碱后，有半数标本显现出了ＬＴＰ现象。表明浓度为１００μｍｏｌ·Ｌ－１的乙酰胆碱并没有阻止ＬＴＰ的诱导过程，而是对ＬＴＰ的表达具有掩盖作用。

The effects of acetylcholine(Ach)on the field potentials and LTP produced in primary visual cortex of developing rats were observed in vitro.The results showed that Ach in 5μmol·L-1 or 100μmol·L-1 increased the amplitude of field potentials.However,different effects on LTP were found in different groups of Ach concentration:no LTP appearedafter tetanus in all the slices with 100 μmol·L-1 Ach perfusion and no influence on LTP production in the 5μmol·L-1 group.Washout of Ach with normal artificial cerebral spinal fluid(ACSF)produced the different results in different groups:no Significant change of the LTP amplitude could be found in 5pmol·L-1 group and notable increase of the responses appeared in 4 out of 8 slices of 100μmol·L-1group.The results suggest that 100μmol·L-1 Ach masks the expression of the induced LTP rather than prevents the induction of LTP in primary visual cortex.