Cheong M Y, Yun S H, Mook-Jung I, Joo I, Huh K, Jung M W
Neuroscience Laboratory, Institute for Medical Sciences, Ajou University School of Medicine, Suwon, Korea.
J Neurosci Res. 2001 Oct 1;66(1):117-21. doi: 10.1002/jnr.1203.
We have recently shown that cholinergic effects on synaptic transmission and plasticity in the superficial (II/III) layers of the rat medial entorhinal cortex (EC) are similar, but not identical, to those in the hippocampus (Yun et al. [2000] Neuroscience 97:671-676). Because the superficial and deep layers of the EC preferentially convey afferent and efferent hippocampal projections, respectively, it is of interest to compare cholinergic effects between the two regions. We therefore investigated the physiological effects of cholinergic agents in the layer V of medial EC slices under experimental conditions identical to those in the previous study. Bath application of carbachol (0.5 microM) induced transient depression of field potential responses in all cases tested (30 of 30; 18.5% +/- 2.3%) and rarely induced long-lasting potentiation (only 3 of 30; 20.4% +/- 3.2% in successful cases). At 5 microM, carbachol induced transient depression only (20 of 20, 48.9% +/- 2.8%), which was blocked by atropine (10 microM). Paired-pulse facilitation was enhanced during carbachol-induced depression, suggesting presynaptic action of carbachol. Long-term potentiation (LTP) could be induced in the presence of 10 microM atropine by theta burst stimulation, but its magnitude was significantly lower (9.1% +/- 4.7%, n = 15) compared to LTP in control slices (22.4% +/- 3.9%, n = 20). These results, combined with our previous findings, demonstrate remarkably similar cholinergic modulation of synaptic transmission and plasticity across the superficial and deep layers of EC.
我们最近发现，胆碱能对大鼠内侧内嗅皮质（EC）浅层（II/III层）突触传递和可塑性的影响与海马体中的相似，但并非完全相同（Yun等人，[2000]《神经科学》97:671 - 676）。由于EC的浅层和深层分别优先传递传入和传出海马体的投射，比较这两个区域的胆碱能效应很有意义。因此，我们在与先前研究相同的实验条件下，研究了胆碱能药物对内侧EC切片V层的生理效应。在所测试的所有情况下（30例中的30例；18.5%±2.3%），浴加卡巴胆碱（0.5微摩尔）均诱导场电位反应短暂抑制，很少诱导长时程增强（仅30例中的3例；成功案例中为20.4%±3.2%）。在5微摩尔时，卡巴胆碱仅诱导短暂抑制（20例中的20例，48.9%±2.8%），这被阿托品（10微摩尔）阻断。在卡巴胆碱诱导的抑制过程中，配对脉冲易化增强，表明卡巴胆碱的突触前作用。在存在10微摩尔阿托品时，可以通过θ波爆发刺激诱导长时程增强（LTP），但其幅度与对照切片中的LTP相比显著较低（9.1%±4.7%，n = 15）（22.4%±3.9%。n = 20）。这些结果与我们之前的发现相结合，表明EC浅层和深层在突触传递和可塑性方面存在显著相似的胆碱能调制。
