Afarinesh Mohammad Reza, Sheibani Vahid, Arabzadeh Somaye, Shamsizadeh Ali
Kerman Neuroscience Research Center, Kerman University of Medical Sciences, Kerman, Iran.
Addict Biol. 2008 Mar;13(1):31-9. doi: 10.1111/j.1369-1600.2007.00087.x. Epub 2008 Jan 14.
Chronic exposure to morphine can impair performance in tasks which need sensory processing. Using single unit recordings we investigate the effect of chronic morphine exposure on the firing properties of neurons in layers IV and V of the whisker-related area of rat primary somatosensory cortex. In urethane-anesthetized animals, neuronal activity was recorded in response to principal and adjacent whisker deflections either stimulated independently or in a conditioning test paradigm. A condition test ratio (CTR) was calculated for assessing the inhibitory receptive field. In layer IV, chronic morphine treatment did not change the spontaneous discharge activity. On responses to principal and adjacent whisker deflections did not show any significant changes following chronic morphine exposure. The magnitude Off responses to adjacent whisker deflection decreased while its response latency increased. In addition, there was a significant increase in the latency of Off responses to principal whisker deflection. CTR did not change significantly following morphine exposure. Layer V neurons, on the other hand, did not show any significant changes in their spontaneous activity or their evoked responses following morphine exposure. Our results suggest that chronic morphine exposure has a subtle modulatory effect on response properties of neurons in barrel cortex.
长期接触吗啡会损害需要感官处理的任务表现。我们使用单神经元记录技术，研究了长期接触吗啡对大鼠初级体感皮层与触须相关区域IV层和V层神经元放电特性的影响。在乌拉坦麻醉的动物中，记录神经元活动以响应独立刺激或在条件测试范式下的主要和相邻触须偏转。计算条件测试比率（CTR）以评估抑制性感受野。在IV层，长期吗啡治疗并未改变自发放电活动。长期接触吗啡后，对主要和相邻触须偏转的反应未显示出任何显著变化。对相邻触须偏转的Off反应幅度减小，而其反应潜伏期增加。此外，对主要触须偏转的Off反应潜伏期显著增加。吗啡暴露后CTR没有显著变化。另一方面，V层神经元在吗啡暴露后的自发放电活动或诱发反应中未显示出任何显著变化。我们的结果表明，长期接触吗啡对桶状皮层神经元的反应特性具有微妙的调节作用。
