Neuroexcitatory effects of morphine-3-glucuronide are dependent on Toll-like receptor 4 signaling.
Neuroexcitatory effects of morphine-3-glucuronide are dependent on Toll-like receptor 4 signaling.
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DOI：
10.1186/1742-2094-9-200
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发表时间：
2012-08-16
影响因子：
9.3
通讯作者：
White FA
中科院分区：
文献类型：
--
作者：
Due MR;Piekarz AD;Wilson N;Feldman P;Ripsch MS;Chavez S;Yin H;Khanna R;White FA
多种不良事件与使用吗啡治疗慢性非癌性疼痛相关，包括阿片类药物诱导的痛觉过敏（OIH）。OIH的机制与阿片耐受无关，可能与吗啡代谢产物吗啡-3-葡萄糖醛酸苷（M3 G）有关。M3 G对阿片受体的亲和力有限，无镇痛作用。先前的报道表明，M3 G可以通过Toll样受体4（TLR 4）/髓样分化蛋白-2（MD-2）异二聚体在中枢神经系统中起作用以引起疼痛。采用免疫印迹和免疫细胞化学方法检测大鼠腰段背根神经节（DRG）中TLR 4的表达。使用体外细胞内钙离子和电流钳技术，我们确定是否TLR 4激活引起的TLR 4，脂多糖（LPS）和M3 G的原型激动剂，导致细胞内钙离子的变化和增加兴奋。啮齿类动物也注射M3 G，以确定在大鼠或TLR 4敲除小鼠中使用MD-2/TLR 4复合物的小分子抑制剂可以减少M3 G诱导的触觉痛觉过敏的程度。对对照和M3 G处理的神经元的小直径和中等直径DRG神经元（25 μm < DRG直径<45 μm）进行全细胞电压钳记录，以确定对电压门控钠通道（NaVs）的潜在影响。我们观察到，TLR 4免疫反应存在于肽能和非肽能感觉神经元的DRG。DRG中的非神经元细胞缺乏TLR 4表达的证据。大约15%的测定的小直径和中等直径的感觉神经元表现出细胞内钙的变化后，LPS管理。观察到伤害性和非伤害性神经元都有反应，并且这些细胞中约40%是辣椒素不敏感的。在LPS或M3 G后在感觉神经元中观察到的增加的兴奋性可以使用化合物15（TLR 4/MD-2复合物的小分子抑制剂）消除。同样地，全身注射M3 G在大鼠中诱导快速的触觉而非热的伤害性行为变化，这通过用化合物15预处理动物来防止。与TLR 4野生型小鼠不同，TLR 4敲除小鼠没有表现出M3 G诱导的痛觉过敏。由于异常的疼痛敏感性通常与NaVs相关，我们预测M3 G通过MD-2/TLR 4复合物起作用可能会影响感觉神经元中NaVs的密度和门控。我们发现，M3 G增加河豚毒素敏感和河豚毒素抗性（NaV1.9）电流密度。这些结果提供了证据表明，M3 G可能通过TLR 4/MD-2异二聚体复合物和河豚毒素敏感和河豚毒素抗性NaV电流的生物物理特性在OIH中发挥作用。
Multiple adverse events are associated with the use of morphine for the treatment of chronic non-cancer pain, including opioid-induced hyperalgesia (OIH). Mechanisms of OIH are independent of opioid tolerance and may involve the morphine metabolite morphine-3-glucuronide (M3G). M3G exhibits limited affinity for opioid receptors and no analgesic effect. Previous reports suggest that M3G can act via the Toll-like receptor 4 (TLR4)/myeloid differentiation protein-2 (MD-2) heterodimer in the central nervous system to elicit pain. Immunoblot and immunocytochemistry methods were used to characterize the protein expression of TLR4 present in lumbar dorsal root ganglion (DRG). Using in vitro intracellular calcium and current clamp techniques, we determined whether TLR4 activation as elicited by the prototypical agonists of TLR4, lipopolysaccharide (LPS) and M3G, contributed to changes in intracellular calcium and increased excitation. Rodents were also injected with M3G to determine the degree to which M3G-induced tactile hyperalgesia could be diminished using either a small molecule inhibitor of the MD-2/TLR4 complex in rats or TLR4 knockout mice. Whole cell voltage-clamp recordings were made from small- and medium-diameter DRG neurons (25 μm < DRG diameter <45 μm) for both control and M3G-treated neurons to determine the potential influence on voltage-gated sodium channels (NaVs). We observed that TLR4 immunoreactivity was present in peptidergic and non-peptidergic sensory neurons in the DRG. Non-neuronal cells in the DRG lacked evidence of TLR4 expression. Approximately 15% of assayed small- and medium-diameter sensory neurons exhibited a change in intracellular calcium following LPS administration. Both nociceptive and non-nociceptive neurons were observed to respond, and approximately 40% of these cells were capsaicin-insensitive. Increased excitability observed in sensory neurons following LPS or M3G could be eliminated using Compound 15, a small molecule inhibitor of the TLR4/MD-2 complex. Likewise, systemic injection of M3G induced rapid tactile, but not thermal, nociceptive behavioral changes in the rat, which were prevented by pre-treating animals with Compound 15. Unlike TLR4 wild-type mice, TLR4 knockout mice did not exhibit M3G-induced hyperalgesia. As abnormal pain sensitivity is often associated with NaVs, we predicted that M3G acting via the MD-2/TLR4 complex may affect the density and gating of NaVs in sensory neurons. We show that M3G increases tetrodotoxin-sensitive and tetrodotoxin-resistant (NaV1.9) current densities. These outcomes provide evidence that M3G may play a role in OIH via the TLR4/MD-2 heterodimer complex and biophysical properties of tetrodotoxin-sensitive and tetrodotoxin-resistant NaV currents.
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影响因子：
4.2
作者：
Hou, LF;Wang, X
通讯作者：
Wang, X
影响因子：
4.8
作者：
Chiang, Chih-Yuan;Veckman, Ville;David, Michael
通讯作者：
David, Michael
影响因子：
15.1
作者：
Hutchinson, Mark R.;Zhang, Yingning;Shridhar, Mitesh;Evans, John H.;Buchanan, Madison M.;Zhao, Tina X.;Slivka, Peter F.;Coats, Benjamen D.;Rezvani, Niloofar;Wieseler, Julie;Hughes, Travis S.;Landgraf, Kyle E.;Chan, Stefanie;Fong, Stephanie;Phipps, Simon;Falke, Joseph J.;Leinwand, Leslie A.;Maier, Steven F.;Yin, Hang;Rice, Kenner C.;Watkins, Linda R.
通讯作者：
Watkins, Linda R.
DOI：
10.1523/jneurosci.3795-08.2008
发表时间：
2008-12-24
期刊：
The Journal of neuroscience : the official journal of the Society for Neuroscience
影响因子：
--
作者：
Binshtok AM;Wang H;Zimmermann K;Amaya F;Vardeh D;Shi L;Brenner GJ;Ji RR;Bean BP;Woolf CJ;Samad TA
通讯作者：
Samad TA
影响因子：
7.6
作者：
Diogenes, A.;Ferraz, C. C. R.;Hargreaves, K. M.
通讯作者：
Hargreaves, K. M.