Tokunaga A, Doi M, Senba E
Department of Anatomy and Neurobiology, Wakayama Medical College, Japan.
Neuroreport. 1995 Nov 27;6(17):2301-4. doi: 10.1097/00001756-199511270-00008.
A subcutaneous injection of formalin into foot pad of the rat produces a bimodal nociceptive response including an early intense response in the first 5 min and a later moderate response that is exhibited from 20 to 60 min after injection. In this study, we investigated the effects of blocking the early phase and late phase input, respectively, on Fos-like immunoreactivity (Fos-LI) expression in dorsal horn neurones. Rats of the early phase block (EB) group were injected with 5% formalin (0.05 ml) into the footpad 5 min after a s.c. injection of 4% lidocaine (0.15 ml) into the angle. The rats of the late phase block (LB) group were injected with 5% formalin into the footpad 10 min before the s.c. injection of 3% prilocaine (0.20 ml) containing felypressin into the ankle. The rats of the control group were given the formalin injection alone. Fos-LI was detected in the dorsal horn 2 h after the formalin injection. The numbers of Fos-LI neurones in the dorsal horn of both EB and LB group were markedly decreased compared with the control group, being 31.3% (laminae I-III of EB), 37.1% (laminae I-III of LB), 13.9% (laminae IV-VI of EB) and 16.2% (laminae IV-VI of LB) of the control values. No significant difference was observed between EB and LB group. These findings suggested that the early and late phase contribute in concert to the induction of genetic changes in dorsal horn neurones after formalin injection.
将福尔马林皮下注射到大鼠足垫会产生双峰伤害性反应，包括注射后最初5分钟内的早期强烈反应以及注射后20至60分钟出现的后期中度反应。在本研究中，我们分别研究了阻断早期和后期输入对背角神经元中Fos样免疫反应性（Fos-LI）表达的影响。早期阻断（EB）组大鼠在向腹股沟皮下注射4%利多卡因（0.15 ml）5分钟后，向足垫注射5%福尔马林（0.05 ml）。后期阻断（LB）组大鼠在向踝关节皮下注射含去甲肾上腺素的3%丙胺卡因（0.20 ml）前10分钟，向足垫注射5%福尔马林。对照组大鼠仅给予福尔马林注射。福尔马林注射2小时后在背角检测Fos-LI。与对照组相比，EB组和LB组背角中Fos-LI神经元数量均显著减少，分别为对照组值的31.3%（EB组I-III层）、37.1%（LB组I-III层）、13.9%（EB组IV-VI层）和16.2%（LB组IV-VI层）。EB组和LB组之间未观察到显著差异。这些发现表明，早期和后期共同促成了福尔马林注射后背角神经元基因变化的诱导。
