Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania 15261, USA.
J Pharmacol Exp Ther. 2010 Jun;333(3):883-95. doi: 10.1124/jpet.109.163154. Epub 2010 Mar 19.
Nitro-oleic acid (OA-NO(2)), an electrophilic fatty acid by-product of nitric oxide and nitrite reactions, is present in normal and inflamed mammalian tissues at up to micromolar concentrations and exhibits anti-inflammatory signaling actions. The effects of OA-NO(2) on cultured dorsal root ganglion (DRG) neurons were examined using fura-2 Ca(2+) imaging and patch clamping. OA-NO(2) (3.5-35 microM) elicited Ca(2+) transients in 20 to 40% of DRG neurons, the majority (60-80%) of which also responded to allyl isothiocyanate (AITC; 1-50 microM), a TRPA1 agonist, and to capsaicin (CAPS; 0.5 microM), a TRPV1 agonist. The OA-NO(2)-evoked Ca(2+) transients were reduced by the TRPA1 antagonist 2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopropylphenyl) acetamide (HC-030031; 5-50 microM) and the TRPV1 antagonist capsazepine (10 microM). Patch-clamp recording revealed that OA-NO(2) depolarized and induced inward currents in 62% of neurons. The effects of OA-NO(2) were elicited by concentrations >or=5 nM and were blocked by 10 mM dithiothreitol. Concentrations of OA-NO(2) >or=5 nM reduced action potential (AP) overshoot, increased AP duration, inhibited firing induced by depolarizing current pulses, and inhibited Na(+) currents. The effects of OA-NO(2) were not prevented or reversed by the NO-scavenger carboxy-2-phenyl-4,4,5,5-tetramethylimidazolineoxyl-1-oxyl-3-oxide. A large percentage (46-57%) of OA-NO(2)-responsive neurons also responded to CAPS (0.5 microM) or AITC (0.5 microM). OA-NO(2) currents were reduced by TRPV1 (diarylpiperazine; 5 microM) or TRPA1 (HC-030031; 5 microM) antagonists. These data reveal that endogenous OA-NO(2) generated at sites of inflammation may initially activate transient receptor potential channels on nociceptive afferent nerves, contributing to the initiation of afferent nerve activity, and later suppresses afferent firing.
硝酰油酸（OA-NO（2））是一氧化氮和亚硝酸盐反应的亲电脂肪酸副产物，在正常和发炎的哺乳动物组织中以微摩尔浓度存在，并表现出抗炎信号作用。使用 fura-2 Ca（2+）成像和膜片钳技术研究了 OA-NO（2）对培养的背根神经节（DRG）神经元的影响。OA-NO（2）（3.5-35 microM）在 20-40%的 DRG 神经元中引发 Ca（2+）瞬变，其中 60-80%的神经元还对丙烯基异硫氰酸酯（AITC；1-50 microM）和辣椒素（CAPS；0.5 microM）做出反应，CAPS 是 TRPV1 激动剂。TRPA1 拮抗剂 2-（1,3-二甲基-2,6-二氧代-1,2,3,6-四氢-7H-嘌呤-7-基）-N-（4-异丙基苯基）乙酰胺（HC-030031；5-50 microM）和 TRPV1 拮抗剂辣椒素（10 microM）减少了 OA-NO（2）引起的 Ca（2+）瞬变。膜片钳记录显示，OA-NO（2）使 62%的神经元去极化并诱导内向电流。OA-NO（2）的作用是由浓度>或=5 nM 引发的，并被 10 mM 二硫苏糖醇阻断。浓度>或=5 nM 的 OA-NO（2）降低动作电位（AP）超射，增加 AP 持续时间，抑制去极化电流脉冲诱导的放电，并抑制 Na+电流。NO 清除剂羧基-2-苯基-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物不能预防或逆转 OA-NO（2）的作用。46-57%的 OA-NO（2）反应神经元也对 CAPS（0.5 microM）或 AITC（0.5 microM）有反应。OA-NO（2）电流被 TRPV1（二芳基哌嗪；5 microM）或 TRPA1（HC-030031；5 microM）拮抗剂减少。这些数据表明，炎症部位产生的内源性 OA-NO（2）可能最初激活伤害感受传入神经上的瞬时受体电位通道，有助于传入神经活动的启动，随后抑制传入神经放电。
