Phospholipase C and protein kinase A mediate bradykinin sensitization of TRPA1: a molecular mechanism of inflammatory pain.
Phospholipase C and protein kinase A mediate bradykinin sensitization of TRPA1: a molecular mechanism of inflammatory pain.
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DOI：
10.1093/brain/awn060
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发表时间：
2008-05
期刊：
影响因子：
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通讯作者：
Shenglan Wang;Yi Dai;T. Fukuoka;H. Yamanaka;Kimiko Kobayashi;K. Obata;Xiu-Yu Cui;M. Tominaga;K. Noguchi
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文献类型：
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作者：
Shenglan Wang;Yi Dai;T. Fukuoka;H. Yamanaka;Kimiko Kobayashi;K. Obata;Xiu-Yu Cui;M. Tominaga;K. Noguchi
缓激肽是一种炎症介质，通过兴奋和/或敏化伤害感受器在炎症组织的疼痛和痛觉过敏中起关键作用。TRPA 1是环境刺激物和内源性痛觉原介导伤害性感受器引起炎性疼痛的传导机制的重要组成部分。在这里，使用电生理学，免疫细胞化学和行为分析，我们显示了这两个炎症相关分子在异源表达系统和初级感觉神经元的功能相互作用。我们发现，缓激肽增加由异硫氰酸烯丙酯（AITC）或肉桂醛在HEK 293细胞表达TRPA 1和缓激肽受体2（B2 R）诱发的TRPA 1电流。这种增强作用可被磷脂酶C（PLC）抑制剂或蛋白激酶A（PKA）抑制剂抑制，并被PLC或PKA激活剂模拟。在大鼠背根神经节神经元中也观察到B2 R和TRPA 1之间的功能相互作用及其调节机制。在闭塞实验中，PLC激活剂可以进一步增强AITC诱导的TRPA 1电流，即使在饱和的PKA介导的增强，表明PLC和PKA途径的加性增强作用。这些数据第一次表明，cAMP-PKA信号转导参与下游的B2受体在背根神经节神经元除了PLC。最后，皮下预注射亚炎症剂量的缓激肽到大鼠后爪增强AITC诱导的疼痛行为，这与体外观察结果一致。总的来说，这些结果代表了一种新的机制，通过这种机制，组织炎症反应中释放的缓激肽可能通过TRPA 1激活引发疼痛感。
Bradykinin is an inflammatory mediator that plays a pivotal role in pain and hyperalgesia in inflamed tissues by exciting and/or sensitizing nociceptors. TRPA1 is an important component of the transduction machinery through which environmental irritants and endogenous proalgesic agents depolarize nociceptors to elicit inflammatory pain. Here, using electrophysiological, immunocytochemical and behavioural analyses, we showed a functional interaction of these two inflammation-related molecules in both heterologous expressing systems and primary sensory neurons. We found that bradykinin increased the TRPA1 currents evoked by allyl isothiocyanate (AITC) or cinnamaldehyde in HEK293 cells expressing TRPA1 and bradykinin receptor 2 (B2R). This potentiation was inhibited by phospholipase C (PLC) inhibitor or protein kinase A (PKA) inhibitor, and mimicked by PLC or PKA activator. The functional interaction between B2R and TRPA1, as well as the modulation mechanism, was also observed in rat dorsal root ganglia neurons. In an occlusion experiment, the PLC activator could enhance AITC-induced TRPA1 current further even in saturated PKA-mediated potentiation, indicating the additive potentiating effects of the PLC and PKA pathways. These data for the first time indicate that a cAMP-PKA signalling is involved in the downstream from B2R in dorsal root ganglia neurons in addition to PLC. Finally, subcutaneous pre-injection of a sub-inflammatory dose of bradykinin into rat hind paw enhanced AITC-induced pain behaviours, which was consistent with the observations in vitro. Collectively, these results represent a novel mechanism through which bradykinin released in response to tissue inflammation might trigger the sensation of pain by TRPA1 activation.