Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/Center for Drug Research, Development and Safety (ZAFES), University Hospital, Goethe-University, D-60590 Frankfurt am Main, Germany.
J Neurosci. 2012 May 2;32(18):6364-72. doi: 10.1523/JNEUROSCI.5793-11.2012.
Epoxyeicosatrienoic acids (EETs) are cytochrome P450-epoxygenase-derived metabolites of arachidonic acid that act as endogenous signaling molecules in multiple biological systems. Here we have investigated the specific contribution of 5,6-EET to transient receptor potential (TRP) channel activation in nociceptor neurons and its consequence for nociceptive processing. We found that, during capsaicin-induced nociception, 5,6-EET levels increased in dorsal root ganglia (DRGs) and the dorsal spinal cord, and 5,6-EET is released from activated sensory neurons in vitro. 5,6-EET potently induced a calcium flux (100 nm) in cultured DRG neurons that was completely abolished when TRPA1 was deleted or inhibited. In spinal cord slices, 5,6-EET dose dependently enhanced the frequency, but not the amplitude, of spontaneous EPSCs (sEPSCs) in lamina II neurons that also responded to mustard oil (allyl isothiocyanate), indicating a presynaptic action. Furthermore, 5,6-EET-induced enhancement of sEPSC frequency was abolished in TRPA1-null mice, suggesting that 5,6-EET presynaptically facilitated spinal cord synaptic transmission by TRPA1. Finally, in vivo intrathecal injection of 5,6-EET caused mechanical allodynia in wild-type but not TRPA1-null mice. We conclude that 5,6-EET is synthesized on the acute activation of nociceptors and can produce mechanical hypersensitivity via TRPA1 at central afferent terminals in the spinal cord.
环氧二十碳三烯酸（EETs）是花生四烯酸的细胞色素 P450-加氧酶衍生代谢物，作为内源性信号分子在多种生物系统中发挥作用。在这里，我们研究了 5,6-EET 对伤害感受器神经元中瞬时受体电位（TRP）通道激活的特定贡献及其对伤害感受处理的后果。我们发现，在辣椒素诱导的伤害感受期间，5,6-EET 水平在背根神经节（DRG）和背侧脊髓中增加，并且 5,6-EET 从体外激活的感觉神经元中释放。5,6-EET 强烈诱导培养的 DRG 神经元中的钙流（100nm），当 TRPA1 缺失或抑制时完全消除。在脊髓切片中，5,6-EET 剂量依赖性地增强了 II 层神经元中自发性 EPSC（sEPSC）的频率，但不增强幅度，这些神经元对芥末油（丙烯基异硫氰酸酯）也有反应，表明存在突触前作用。此外，在 TRPA1 缺失小鼠中，5,6-EET 诱导的 sEPSC 频率增强被消除，表明 5,6-EET 通过 TRPA1 突触前促进脊髓突触传递。最后，体内鞘内注射 5,6-EET 导致野生型小鼠但不是 TRPA1 缺失型小鼠产生机械性痛觉过敏。我们得出结论，5,6-EET 在伤害感受器的急性激活时合成，并可以通过脊髓中的 TRPA1 在中枢传入末端产生机械性超敏反应。
