Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, 1st You Yi Road, Yuzhong District, Chongqing, 400016, China.
Department of Neurology, Nanchong Central Hospital, The Second Clinical Medical College, North Sichuan Medical College, Nanchong, China.
J Headache Pain. 2022 Feb 10;23(1):25. doi: 10.1186/s10194-022-01397-w.
Central sensitization is an important pathophysiological mechanism of chronic migraine (CM), and microglia activation in trigeminocervical complex (TCC) contributes to the development of central sensitization. Emerging evidence implicates that blocking sphingosine-1-phosphate receptor 1 (S1PR1) can relieve the development of chronic pain and inhibit the activation of microglia. However, it is unclear whether S1PR1 is involved in the central sensitization of CM. Therefore, the purpose of this study is to explore the role of S1PR1 and its downstream signal transducers and activators of transcription 3 (STAT3) signaling pathway in the CM, mainly in inflammation.
Chronic intermittent intraperitoneal injection of nitroglycerin (NTG) established a mouse model of CM. First, we observed the changes and subcellular localization of S1PR1 in the trigeminocervical complex (TCC). Then, W146, a S1PR1 antagonist; SEW2871, a S1PR1 agonist; AG490, a STAT3 inhibitor were applied by intraperitoneal injection to investigate the related molecular mechanism. The changes in the number of microglia and the expression of calcitonin gene-related peptide (CGRP) and c-fos in the TCC site were explored by immunofluorescence. In addition, we studied the effect of S1PR1 inhibitors on STAT3 in lipopolysaccharide-treated BV-2 microglia.
Our results showed that the expression of S1PR1 was increased after NTG injection and S1PR1 was colocalized with in neurons and glial cells in the TCC. The S1PR1 antagonist W146 alleviated NTG-induced hyperalgesia and suppressed the upregulation of CGRP, c-fos and pSTAT3 in the TCC. Importantly, blocking S1PR1 reduced activation of microglia. In addition, we found that inhibiting STAT3 signal also attenuated NTG-induced basal mechanical and thermal hyperalgesia.
Our results indicate that inhibiting S1PR1 signal could alleviate central sensitization and inhibit microglia activity caused by chronic NTG administration via STAT3 signal pathway, which provide a new clue for the clinical treatment of CM.
中枢敏化是慢性偏头痛（CM）的一个重要病理生理机制，三叉颈复合体（TCC）中的小胶质细胞激活有助于中枢敏化的发展。新出现的证据表明，阻断鞘氨醇-1-磷酸受体 1（S1PR1）可以缓解慢性疼痛的发展并抑制小胶质细胞的激活。然而，S1PR1 是否参与 CM 的中枢敏化尚不清楚。因此，本研究旨在探讨 S1PR1 及其下游信号转导和转录激活因子 3（STAT3）信号通路在 CM 中的作用，主要是在炎症方面。
慢性间歇性腹腔内注射硝酸甘油（NTG）建立了 CM 小鼠模型。首先，我们观察了 S1PR1 在三叉颈复合体（TCC）中的变化和亚细胞定位。然后，通过腹腔注射 S1PR1 拮抗剂 W146、S1PR1 激动剂 SEW2871 和 STAT3 抑制剂 AG490，研究相关的分子机制。通过免疫荧光法研究 TCC 部位小胶质细胞数量的变化以及降钙素基因相关肽（CGRP）和 c-fos 的表达。此外，我们研究了 S1PR1 抑制剂对脂多糖处理的 BV-2 小胶质细胞中 STAT3 的影响。
我们的结果表明，NTG 注射后 S1PR1 的表达增加，S1PR1 与 TCC 中的神经元和神经胶质细胞共定位。S1PR1 拮抗剂 W146 缓解了 NTG 诱导的痛觉过敏，并抑制了 TCC 中 CGRP、c-fos 和 pSTAT3 的上调。重要的是，阻断 S1PR1 减少了小胶质细胞的激活。此外，我们发现抑制 STAT3 信号也减弱了 NTG 诱导的基础机械和热痛觉过敏。
我们的结果表明，抑制 S1PR1 信号可以通过 STAT3 信号通路缓解慢性 NTG 给药引起的中枢敏化和抑制小胶质细胞活性，为 CM 的临床治疗提供了新的线索。
