Sun Rui-Qing, Lawand Nada B, Lin Qing, Willis William D
Department of Neuroscience and Cell Biology, The University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-1069, USA.
J Neurophysiol. 2004 Jul;92(1):320-6. doi: 10.1152/jn.00086.2004.
This study was designed to assess the role of calcitonin gene-related peptide (CGRP) and its receptor in the sensitization of dorsal horn neurons induced by intradermal injection of capsaicin in rats. Extracellular recordings were made from wide dynamic range (WDR) dorsal horn neurons with receptive fields on the hindpaw in the lumbar enlargement of anesthetized rats. The background activity and responses to brushing, pressing, and pinching the skin were assessed. A postsuperfusion or a presuperfusion of CGRP(8-37) paradigm was followed. When tested 30 min after capsaicin injection, there was an increase in background activity and responses to brush, press, and pinch applied to the receptive field. Superfusion of CGRP(8-37) into the spinal cord at 45 min after capsaicin injection significantly reversed the increased background activity and responses to brush, press, and pinch applied to the receptive field. On the other hand, spinal superfusion of CGRP(8-37) prior to capsaicin injection prevented the increased background activity and responses to brush, press, and pinch of WDR neurons that occurred following capsaicin injection in control experiments. A sensitization of spinal dorsal horn neurons could also be induced by superfusion of the spinal cord with CGRP. The effect could be blocked by CGRP(8-37) dose-dependently. Collectively, these results suggest that CGRP and its receptors are involved in the spinal cord central sensitization induced by intradermal injection of capsaicin.
本研究旨在评估降钙素基因相关肽（CGRP）及其受体在大鼠皮内注射辣椒素诱导的背角神经元敏化中的作用。在麻醉大鼠腰膨大处，对后爪具有感受野的广动力范围（WDR）背角神经元进行细胞外记录。评估背景活动以及对刷擦、按压和捏皮肤的反应。采用CGRP（8 - 37）模式的后灌注或前灌注。在注射辣椒素30分钟后进行测试时，背景活动以及对施加于感受野的刷擦、按压和捏的反应均增加。在注射辣椒素45分钟后将CGRP（8 - 37）灌注到脊髓中，可显著逆转背景活动的增加以及对施加于感受野的刷擦、按压和捏的反应。另一方面，在注射辣椒素之前对脊髓进行CGRP（8 - 37）灌注，可防止在对照实验中注射辣椒素后出现的WDR神经元背景活动增加以及对刷擦、按压和捏的反应。脊髓灌注CGRP也可诱导脊髓背角神经元敏化。该效应可被CGRP（8 - 37）剂量依赖性阻断。总体而言，这些结果表明CGRP及其受体参与了皮内注射辣椒素诱导的脊髓中枢敏化。
