The Chemokine CCL2 Increases Nav1.8 Sodium Channel Activity in Primary Sensory Neurons through a Gβγ-Dependent Mechanism
The Chemokine CCL2 Increases Nav1.8 Sodium Channel Activity in Primary Sensory Neurons through a Gβγ-Dependent Mechanism
复制标题
DOI：
10.1523/jneurosci.3386-11.2011
复制
发表时间：
2011-12-14
影响因子：
5.3
通讯作者：
Sarret, Philippe
中科院分区：
文献类型：
--
作者：
Belkouch, Mounir;Dansereau, Marc-Andre;Sarret, Philippe
伤害性初级感觉神经元中电压门控钠通道功能的变化参与了神经性和炎症性慢性疼痛病症中发生的外周过度兴奋的发展。其中，抗河豚毒素（TTX-R）钠通道Na(v)1.8主要由中小型背根神经节（DRG）神经元表达，对这些神经元动作电位的上升有很大贡献。令人信服的证据还表明，趋化因子 CCL2 通过与 CCR2 受体结合，在促进慢性疼痛中发挥着关键作用。因此，在这项研究中，我们研究了 CCL2 对幼稚成年大鼠急性小/中分离腰椎 DRG 神经元中 TTX-R Na(v)1.8 电流密度和动力学特性的影响。全细胞膜片钳记录表明，CCL2 浓度依赖性地增加中小直径感觉神经元中 TTX 抗性 Na(v)1.8 电流密度。与 CCL2 一起孵育还使小感觉神经元中 Na(v)1.8 的激活和稳态失活曲线向超极化方向移动。然而，在中等大小的伤害性神经元中没有观察到激活和失活动力学的变化。我们的电生理记录还表明，选择性 CCR2 拮抗剂 INCB3344 [N-[2-[[(3S， 4S)-1-E4-(1,3-苯并间二氧杂环己烷-5-基)-4-羟基环己基]-4-乙氧基-3-吡咯烷基]氨基]-2-氧代乙基]-3-(三氟甲基)苯甲酰胺]以浓度依赖性方式阻断CCL2对Na(v)1.8电流的增强。此外，用百日咳毒素（PTX）或gallein（一种G beta gamma抑制剂）预处理可以防止Na（v）1.8电流的增强，这表明从PTX敏感的G（i/o）蛋白释放的G beta gamma参与了CCR2和Na（v）1.8之间的串扰。总之，我们的数据清楚地表明，CCL2 可能通过 CCR2/G β γ 依赖性机制作用于 Na(v)1.8 电流的生物物理特性，从而激发初级感觉神经元。
Changes in function of voltage-gated sodium channels in nociceptive primary sensory neurons participate in the development of peripheral hyperexcitability that occurs in neuropathic and inflammatory chronic pain conditions. Among them, the tetrodotoxin-resistant (TTX-R) sodium channel Na(v)1.8, primarily expressed by small-and medium-sized dorsal root ganglion (DRG) neurons, substantially contributes to the upstroke of action potential in these neurons. Compelling evidence also revealed that the chemokine CCL2 plays a critical role in chronic pain facilitation via its binding to CCR2 receptors. In this study, we therefore investigated the effects of CCL2 on the density and kinetic properties of TTX-R Na(v)1.8 currents in acutely small/medium dissociated lumbar DRG neurons from naive adult rats. Whole-cell patch-clamp recordings demonstrated that CCL2 concentration-dependently increased TTX-resistant Na(v)1.8 current densities in both small-and medium-diameter sensory neurons. Incubation with CCL2 also shifted the activation and steady-state inactivation curves of Na(v)1.8 in a hyperpolarizing direction in small sensory neurons. No change in the activation and inactivation kinetics was, however, observed in medium-sized nociceptive neurons. Our electrophysiological recordings also demonstrated that the selective CCR2 antagonist INCB3344 [N-[2-[[(3S, 4S)-1-E4-(1,3-benzodioxol-5-yl)-4-hydroxycyclohexyl]-4-ethoxy-3-pyrrolidinyl]amino]-2-oxoethyl]-3-(trifluoromethyl)benzamide] blocks the potentiation of Na(v)1.8 currents by CCL2 in a concentration-dependent manner. Furthermore, the enhancement in Na(v)1.8 currents was prevented by pretreatment with pertussis toxin (PTX) or gallein (a G beta gamma inhibitor), indicating the involvement of G beta gamma released from PTX-sensitive G(i/o)-proteins in the cross talk between CCR2 and Na(v)1.8. Together, our data clearly demonstrate that CCL2 may excite primary sensory neurons by acting on the biophysical properties of Na(v)1.8 currents via a CCR2/G beta gamma-dependent mechanism.