Miyano Kanako, Minami Kouichiro, Yokoyama Toru, Ohbuchi Katsuya, Yamaguchi Takuhiro, Murakami Satoshi, Shiraishi Seiji, Yamamoto Masahiro, Matoba Motohiro, Uezono Yasuhito
From the *Division of Cancer Pathophysiology, National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan; †Department of Anesthesiology and Critical Care Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan; ‡Tsumura Research Labs, Tumura & Co., Inashiki-gun, Ibaraki, Japan; §Division of Biostatistics, Tohoku University Graduate School of Medicine, Clinical Research Data Center, Tohoku University Hospital, Sendai, Miyagi, Japan; ∥Department of Palliative Medicine, Seirei Sakura Citizen Hospital, Sakura-shi, Chiba, Japan; and ¶Department of Palliative Medicine, Aomori Prefectural Central Hospital, Aomori-city, Aomori, Japan.
Anesth Analg. 2015 Apr;120(4):790-8. doi: 10.1213/ANE.0000000000000625.
The transient receptor potential vanilloid 1 (TRPV1) and the transient receptor potential ankyrin 1 (TRPA1), which are expressed in sensory neurons, are polymodal nonselective cation channels that sense noxious stimuli. Recent reports showed that these channels play important roles in inflammatory, neuropathic, or cancer pain, suggesting that they may serve as attractive analgesic pharmacological targets. Tramadol is an effective analgesic that is widely used in clinical practice. Reportedly, tramadol and its metabolite (M1) bind to μ-opioid receptors and/or inhibit reuptake of monoamines in the central nervous system, resulting in the activation of the descending inhibitory system. However, the fundamental mechanisms of tramadol in pain control remain unclear. TRPV1 and TRPA1 may be targets of tramadol; however, they have not been studied extensively.
We examined whether and how tramadol and M1 act on human embryonic kidney 293 (HEK293) cells expressing human TRPV1 (hTRPV1) or hTRPA1 by using a Ca imaging assay and whole-cell patch-clamp recording.
Tramadol and M1 (0.01-10 μM) alone did not increase in intracellular Ca concentration ([Ca]i) in HEK293 cells expressing hTRPV1 or hTRPA1 compared with capsaicin (a TRPV1 agonist) or the allyl isothiocyanate (AITC, a TRPA1 agonist), respectively. Furthermore, in HEK293 cells expressing hTRPV1, pretreatment with tramadol or M1 for 5 minutes did not change the increase in [Ca]i induced by capsaicin. Conversely, pretreatment with tramadol (0.1-10 μM) and M1 (1-10 μM) significantly suppressed the AITC-induced [Ca]i increases in HEK293 cells expressing hTRPA1. In addition, the patch-clamp study showed that pretreatment with tramadol and M1 (10 μM) decreased the inward currents induced by AITC.
These data indicate that tramadol and M1 selectively inhibit the function of hTRPA1, but not that of hTRPV1, and that hTRPA1 may play a role in the analgesic effects of these compounds.
瞬时受体电位香草酸亚型1（TRPV1）和瞬时受体电位锚蛋白1（TRPA1）在感觉神经元中表达，它们是感受有害刺激的多模态非选择性阳离子通道。最近的报道表明，这些通道在炎性疼痛、神经性疼痛或癌痛中起重要作用，提示它们可能是有吸引力的镇痛药理学靶点。曲马多是一种有效的镇痛药，广泛应用于临床实践。据报道，曲马多及其代谢产物（M1）与μ-阿片受体结合和/或抑制中枢神经系统中单胺的再摄取，从而激活下行抑制系统。然而，曲马多控制疼痛的基本机制仍不清楚。TRPV1和TRPA1可能是曲马多的靶点；然而，尚未对它们进行广泛研究。
我们通过钙成像测定和全细胞膜片钳记录，研究曲马多和M1是否以及如何作用于表达人TRPV1（hTRPV1）或hTRPA1的人胚肾293（HEK293）细胞。
与辣椒素（一种TRPV1激动剂）或异硫氰酸烯丙酯（AITC，一种TRPA1激动剂）相比，单独使用曲马多和M1（0.01 - 10 μM）不会增加表达hTRPV1或hTRPA1的HEK293细胞内的钙浓度（[Ca]i）。此外，在表达hTRPV1的HEK293细胞中，用曲马多或M1预处理5分钟不会改变辣椒素诱导的[Ca]i增加。相反，用曲马多（0.1 - 10 μM）和M1（1 - 10 μM）预处理可显著抑制AITC诱导的表达hTRPA1的HEK293细胞中[Ca]i的增加。此外，膜片钳研究表明，用曲马多和M1（10 μM）预处理可减少AITC诱导的内向电流。
这些数据表明，曲马多和M1选择性抑制hTRPA1的功能，而不抑制hTRPV1的功能，并且hTRPA1可能在这些化合物的镇痛作用中发挥作用。
Zotero 插件