Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran.
Brain Res. 2012 Oct 10;1478:16-23. doi: 10.1016/j.brainres.2012.08.013. Epub 2012 Aug 14.
In the present study, the effect of orexin-A (ORXA) microinjection into the paragigantocellularis lateralis (LPGI) on nociceptive behaviors, using hot-plate and formalin tests as thermal and chemical models of pain in rat, was examined. Also, we determined whether the pretreatment with SB-334867, a selective OX1-receptor antagonist, would prevent the antinociceptive effect of orexin-A. ORXA (0.1-100 nM/0.5 μL) microinjected into the LPGi nucleus, dose-dependently decreased the formalin induced nociceptive behaviors and also produced a dose-dependent antinociceptive effect in the hot-plate test. Pretreatment with a selective orexin receptor 1 (OX1R) antagonist, SB-334867, also inhibited the effect of ORXA on formalin induced nociceptive behaviors while the SB-334867 (100 μM) alone had no effect on formalin test. These data demonstrated that the ORXA-induced antinociception in formalin test is mainly mediated through the OX1R in LPGi which might play a potential role in processing the pain information associated with descending pain modulation.
在本研究中，我们通过热板和福尔马林测试（作为疼痛的热和化学模型）研究了将orexin-A（ORXA）注射到外侧巨细胞旁核（LPGI）中对伤害性行为的影响，以确定预先给予选择性 OX1 受体拮抗剂 SB-334867 是否会阻止 orexin-A 的镇痛作用。ORXA（0.1-100 nM/0.5 μL）注射到 LPGi 核中，剂量依赖性地减少了福尔马林引起的伤害性行为，并且在热板测试中也产生了剂量依赖性的镇痛作用。预先给予选择性 orexin 受体 1（OX1R）拮抗剂 SB-334867 也抑制了 ORXA 对福尔马林引起的伤害性行为的作用，而单独使用 SB-334867（100 μM）对福尔马林测试没有影响。这些数据表明，ORXA 诱导的福尔马林测试中的镇痛作用主要是通过 LPGi 中的 OX1R 介导的，这可能在处理与下行疼痛调节相关的疼痛信息中发挥潜在作用。
