deGroot J F, Coggeshall R E, Carlton S M
Department of Anatomy and Neurosciences, Marine Biomedical Institute, Galveston, TX 77555-1069, USA.
Neurosci Lett. 1997 Sep 19;233(2-3):113-6. doi: 10.1016/s0304-3940(97)00642-3.
The mu opioid receptor is concentrated in laminae I and II (LI and LII, respectively) of the normal rat dorsal horn. Fourteen days after transection of the L4-L6 segmental peripheral nerves, image analysis demonstrates a 49, 34 and 17% decrease in mu opioid staining density in the medial, middle and lateral thirds of the superficial dorsal horn, respectively, when comparing the operated to the unoperated side. Intralaminar analysis demonstrates that the greatest change in density occurs in LI and LII outer, compared to LII inner. By 31 days post-surgery, staining has returned to normal with side to side differences no longer present. These results imply that mu opioid ligands such as morphine might be less effective in ameliorating pain 2 weeks after a peripheral nerve lesion than they are in the normal condition, but that this effectiveness should return as the receptors are restored to their normal levels. Thus, the time following a lesion may be an important variable in assessing the effectiveness of mu opioid ligands in alleviating neuropathic pain. Furthermore, this study shows that the organization of opioid receptors in the superficial dorsal horn is malleable and could lead to changes in drug efficacy.
μ阿片受体集中在正常大鼠背角的Ⅰ层和Ⅱ层（分别为LI和LII）。切断L4-L6节段性周围神经14天后，图像分析显示，与未手术侧相比，手术侧浅背角内侧、中间和外侧三分之一区域的μ阿片染色密度分别降低了49%、34%和17%。层内分析表明，与LII内层相比，密度变化最大的是LI和LII外层。术后31天，染色恢复正常，两侧差异不再存在。这些结果表明，μ阿片配体如吗啡在周围神经损伤2周后缓解疼痛的效果可能不如正常情况下，但其效果应会随着受体恢复到正常水平而恢复。因此，损伤后的时间可能是评估μ阿片配体缓解神经性疼痛有效性的一个重要变量。此外，本研究表明，浅背角阿片受体的组织具有可塑性，可能导致药物疗效的变化。
