Mansouri F A, Motamedi F, Fathollahi Y
Department of Physiology, School of Medicine, Shaheed Beheshti University of Medical Sciences, Tehran, Iran.
Brain Res. 1999 Jan 9;815(2):419-23. doi: 10.1016/s0006-8993(98)01148-2.
In this study, the effects of chronic morphine administration (20-30 days) on long-term potentiation (LTP) were investigated at the Schaffer collateral-CA1 pyramidal cell synapses of the rat hippocampal slices. Orthodromic population spike (OPS) amplitude and delay (peak latency) were measured as indices of increase in synaptic efficacy. The amounts of LTP of OPS delay and LTP of OPS amplitude were higher in slices from dependent rats. Perfusion of slices from control and dependent rats with morphine containing ACSF and delivering tetanic stimulation, showed that short-term presence of morphine could not mimic the LTP enhancing effects of chronic morphine administration, however, attenuated the amount of LTP of OPS amplitude in slices of dependent rats. This study supports the hypothesis that the susceptibility of CA1 synapses to plastic changes increases by chronic, not acute exposure to morphine and suggests that a withdrawal phenomenon might be an underlying mechanism for the observed augmented LTP of OPS amplitude in slices of dependent rats.
在本研究中，研究了慢性吗啡给药（20 - 30天）对大鼠海马切片中Schaffer侧支 - CA1锥体细胞突触处长期增强（LTP）的影响。测量了顺向群体峰电位（OPS）的幅度和延迟（峰潜伏期），作为突触效能增加的指标。依赖大鼠切片中OPS延迟的LTP量和OPS幅度的LTP量更高。用含吗啡的人工脑脊液（ACSF）灌注对照和依赖大鼠的切片并给予强直刺激，结果表明，吗啡的短期存在不能模拟慢性吗啡给药对LTP的增强作用，然而，却减弱了依赖大鼠切片中OPS幅度的LTP量。本研究支持以下假说：CA1突触对可塑性变化的易感性是通过慢性而非急性接触吗啡而增加的，并表明戒断现象可能是观察到的依赖大鼠切片中OPS幅度LTP增强的潜在机制。
