Chung K M, Suh H W
Department of Pharmacology, Institute of Natural Medicine, Hallym University, Kangwon-do, South Korea.
Neuropeptides. 2001 Oct-Dec;35(5-6):197-203. doi: 10.1054/npep.2001.0862.
The present study was designed to examine the possible involvement of supraspinal CTX- and PTX-sensitive G-proteins in an opioid-induced antinociception in the formalin test. Morphine (1 microg) and beta-endorphin (1 microg) given i.c.v. displayed near-maximal inhibitory effects against the formalin response in the first (0-5 min) and the second (20-40 min) phases. CTX (0.1-0.5 microg) pretreated i.c.v. produced antinociceptive effects in both phases of the formalin responses. Its effect was more pronounced in the first phase. However, PTX (0.05-0.5 microg) injected i.c.v produced the antinociceptive effect only in the first, but not the second, phase. Both CTX (0.5 microg) and PTX (0.5 microg), at the dose which had no intrinsic effect, significantly reversed the beta-endorphin-induced antinociceptive effect observed during the second, but not the first, phase. However, the antinociceptive effect by morphine failed to be affected by the same dose of treatment with CTX or PTX. Our results indicate that, at the supraspinal level, CTX- and PTX-sensitive G-proteins appear to be involved in the modulation of antinociception induced by supraspinally administered beta-endorphin, but not morphine, in the formalin pain model.
本研究旨在检测脊髓上CTX和百日咳毒素（PTX）敏感的G蛋白在福尔马林试验中阿片类药物诱导的抗伤害感受中可能的参与情况。脑室内注射吗啡（1微克）和β-内啡肽（1微克）对福尔马林反应的第一阶段（0 - 5分钟）和第二阶段（20 - 40分钟）显示出近乎最大的抑制作用。脑室内预先注射CTX（0.1 - 0.5微克）在福尔马林反应的两个阶段均产生抗伤害感受作用。其作用在第一阶段更为明显。然而，脑室内注射PTX（0.05 - 0.5微克）仅在第一阶段而非第二阶段产生抗伤害感受作用。在无内在作用的剂量下，CTX（0.5微克）和PTX（0.5微克）均显著逆转了在第二阶段而非第一阶段观察到的β-内啡肽诱导的抗伤害感受作用。然而，吗啡诱导的抗伤害感受作用未受相同剂量的CTX或PTX处理影响。我们的结果表明，在脊髓上水平，CTX和PTX敏感的G蛋白似乎参与了在福尔马林疼痛模型中脊髓上给予β-内啡肽而非吗啡诱导的抗伤害感受的调节。
