Phenotyping the function of TRPV1-expressing sensory neurons by targeted axonal silencing.
Phenotyping the function of TRPV1-expressing sensory neurons by targeted axonal silencing.
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DOI：
10.1523/jneurosci.2804-12.2013
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发表时间：
2013-01-02
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影响因子：
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通讯作者：
Woolf CJ
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作者：
Brenneis C;Kistner K;Puopolo M;Segal D;Roberson D;Sisignano M;Labocha S;Ferreirós N;Strominger A;Cobos EJ;Ghasemlou N;Geisslinger G;Reeh PW;Bean BP;Woolf CJ
特定的躯体感觉可以由初级传入的不同子集处理。例如，提出表达热敏TRPV 1通道的C纤维是热而不是机械疼痛检测器。为了在大鼠中表现TRPV 1+传入神经的感觉功能，我们通过将膜不渗透性钠通道阻断剂QX-314经由TRPV 1通道孔引入这些轴突中，快速地和选择性地仅沉默它们的活性。使用串联质谱，我们表明，在激活辣椒素，QX-314选择性地积累在胞质溶胶中的TRPV 1表达细胞，而不是在控制细胞。暴露于QX-314和辣椒素诱导小DRG神经元在30秒内产生强烈的钠电流阻滞。在坐骨神经中，细胞外QX-314与辣椒素的应用持续降低C-纤维而不是A-纤维复合动作电位，并且这种效应在TRPV 1 −/−小鼠中不发生。通过神经周注射QX-314和辣椒素选择性沉默TRPV 1+坐骨神经轴突后的行为表型显示热和机械压力的缺陷，但不是针刺或轻触感知。正如预期的那样，对足底辣椒素的反应大大降低。在炎症过程中，沉默TRPV 1+轴突消除热，机械和冷痛觉过敏，但触觉和冷异常性疼痛仍然在周围神经损伤后。这些结果表明，TRPV 1表达的感觉神经元处理特定的热和机械体感，并且由机械和冷刺激激活的感觉通道在幼稚/发炎大鼠中产生疼痛不同于外周神经损伤后的动物。
Specific somatosensations may be processed by different subsets of primary afferents. C-fibers expressing heat-sensitive TRPV1 channels are proposed, for example, to be heat but not mechanical pain detectors. To phenotype in rats the sensory function of TRPV1+ afferents, we rapidly and selectively silenced only their activity, by introducing the membrane-impermeant sodium channel blocker QX-314 into these axons via the TRPV1 channel pore. Using tandem mass spectrometry we show that upon activation with capsaicin, QX-314 selectively accumulates in the cytosol only of TRPV1-expressing cells, and not in control cells. Exposure to QX-314 and capsaicin induces in small DRG neurons a robust sodium current block within 30 s. In sciatic nerves, application of extracellular QX-314 with capsaicin persistently reduces C-fiber but not A-fiber compound action potentials and this effect does not occur in TRPV1−/− mice. Behavioral phenotyping after selectively silencing TRPV1+ sciatic nerve axons by perineural injections of QX-314 and capsaicin reveals deficits in heat and mechanical pressure but not pinprick or light touch perception. The response to intraplantar capsaicin is substantially reduced, as expected. During inflammation, silencing TRPV1+ axons abolishes heat, mechanical, and cold hyperalgesia but tactile and cold allodynia remain following peripheral nerve injury. These results indicate that TRPV1-expressing sensory neurons process particular thermal and mechanical somatosensations, and that the sensory channels activated by mechanical and cold stimuli to produce pain in naive/inflamed rats differ from those in animals after peripheral nerve injury.