Department of Physiology, Gannan Medical University, Ganzhou, P.R. China.
Pain Medicine Research Institute, Gannan Medical University, Ganzhou, P.R. China.
Acupunct Med. 2021 Aug;39(4):358-366. doi: 10.1177/0964528420938376. Epub 2020 Aug 2.
Evidence shows that the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway participates in the pathogenesis of neuropathic pain. Our previous study revealed that electroacupuncture (EA) attenuated neuropathic pain via activation of alpha-7 nicotinic acetylcholine receptor (α7nAChR) in the spinal cord. However, whether 2 Hz EA alleviates neuropathic pain by regulating the downstream molecules JAK2/STAT3 has not been fully clarified.
Paw withdrawal threshold (PWT) was used as a marker of mechanical allodynia in rats with spared nerve injury (SNI). After applying 2 Hz EA on day 3, 7, 14 and 21 post-surgery, spinal expression of JAK2, STAT3 and pro-inflammatory cytokine interleukin (IL)-6 was examined using quantitative reverse transcription and real-time polymerase chain reaction (qRT-PCR) and Western blot analysis. Intrathecal injection of the α7nAChR antagonist alpha-bungarotoxin (α-Bgtx) was used to further explore the mechanism underlying the effects of 2 Hz EA on expression of JAK2/STAT3 in SNI rats.
It was found that levels of spinal STAT3 and IL-6 mRNA, as well as levels of phosphorylated (p)-JAK2, p-STAT3 and IL-6 protein, were markedly increased in SNI rats. 2 Hz EA attenuated the SNI-induced up-regulation of p-JAK2, p-STAT3 and IL-6 expression in the spinal cord. Furthermore, intrathecal injection of α-Bgtx (1.0 μg/kg) not only inhibited the effect of 2 Hz EA on mechanical hypersensitivity but also ameliorated the down-regulation of p-JAK2, p-STAT3 and IL-6 expression induced by 2 Hz EA.
This study revealed that 2 Hz EA attenuated SNI-induced mechanical hypersensitivity and the concomitant up-regulation of spinal JAK2, STAT3 and IL-6 in SNI rats, suggesting that suppression of the JAK2/STAT3 signaling pathway might be the mechanism underlying the therapeutic effect of 2 Hz EA on neuropathic pain.
有证据表明，Janus 激酶 2（JAK2）/信号转导和转录激活因子 3（STAT3）信号通路参与了神经性疼痛的发病机制。我们之前的研究表明，电针（EA）通过激活脊髓中的α7 烟碱型乙酰胆碱受体（α7nAChR）来减轻神经性疼痛。然而，2Hz EA 是否通过调节下游分子 JAK2/STAT3 来缓解神经性疼痛尚未完全阐明。
在 spared nerve injury（SNI）手术后第 3、7、14 和 21 天，用 paw withdrawal threshold（PWT）作为大鼠机械性痛觉过敏的标志物。手术后第 3 天开始应用 2Hz EA，连续应用 3、7、14 和 21 天，采用定量逆转录实时聚合酶链反应（qRT-PCR）和 Western blot 分析检测脊髓 JAK2、STAT3 和促炎细胞因子白细胞介素（IL）-6 的表达。鞘内注射α7nAChR 拮抗剂α-银环蛇毒素（α-Bgtx）进一步探讨 2Hz EA 对 SNI 大鼠 JAK2/STAT3 表达的影响机制。
结果发现，SNI 大鼠脊髓 STAT3 和 IL-6 mRNA 水平以及磷酸化 JAK2（p-JAK2）、磷酸化 STAT3（p-STAT3）和 IL-6 蛋白水平均显著升高。2Hz EA 可减弱 SNI 诱导的脊髓 p-JAK2、p-STAT3 和 IL-6 表达上调。此外，鞘内注射 1.0μg/kg 的α-Bgtx 不仅抑制了 2Hz EA 对机械性痛觉过敏的作用，还改善了 2Hz EA 诱导的 p-JAK2、p-STAT3 和 IL-6 表达下调。
本研究表明，2Hz EA 可减轻 SNI 诱导的机械性痛觉过敏及同时伴有的脊髓 JAK2、STAT3 和 IL-6 上调，提示抑制 JAK2/STAT3 信号通路可能是 2Hz EA 治疗神经性疼痛的机制。
