Chemogenetic Regulation of CX3CR1-Expressing Microglia Using Gi-DREADD Exerts Sex-Dependent Anti-Allodynic Effects in Mouse Models of Neuropathic Pain
Chemogenetic Regulation of CX3CR1-Expressing Microglia Using Gi-DREADD Exerts Sex-Dependent Anti-Allodynic Effects in Mouse Models of Neuropathic Pain
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DOI：
10.3389/fphar.2020.00925
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发表时间：
2020-06-19
影响因子：
5.6
通讯作者：
Kiguchi, Norikazu
中科院分区：
文献类型：
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作者：
Saika, Fumihiro;Matsuzaki, Shinsuke;Kiguchi, Norikazu
尽管越来越多的证据表明，脊髓小胶质细胞在雄性啮齿动物实验性神经性疼痛（NP）的分子机制中起着重要作用，但有关这些小胶质细胞在NP中的性别依赖性作用的证据还不够。在这项研究中，我们评估了小胶质细胞调节NP使用设计师药物（Gi-DREADD）驱动的小胶质细胞特异性Cx 3cr 1启动子专门激活的Gi-designer受体的影响。为了在表达CX 3C趋化因子受体1（CX 3CR 1（+））的细胞中人Gi偶联的M4毒蕈碱受体（hM 4Di）的Cre依赖性表达，将R26-LSL-hM 4Di-DREADD小鼠与CX 3CR 1-Cre小鼠杂交。通过部分坐骨神经结扎（PSL）和用抗癌剂紫杉醇（PTX）或奥沙利铂（OXA）治疗来产生NP的小鼠模型，并且使用von Frey测试来评估机械异常性疼痛。免疫组化结果显示，hM 4Di在CX 3CR 1-hM 4Di小鼠脊髓背角的Iba 1（+）小胶质细胞上特异性表达，而在星形胶质细胞和神经元上不表达。通过全身（腹膜内，i. p.）在雄性CX 3CR 1-hM 4Di小鼠中给予10 mg/kg的氯氮平N-氧化物（CNO）（一种hM 4Di-选择性配体）。CNO的腹腔内给药并未改变未处理CX 3CR 1-hM 4Di小鼠的机械阈值。一致性，局部（鞘内，i.t.）CNO（20 nmol）的给药显著减轻了雄性CX 3CR 1-hM 4Di小鼠中PSL诱导的机械异常性疼痛。然而，无论是IP还是I.T. CNO的给药影响雌性CX 3CR 1-hM 4Di小鼠中的PSM诱导的机械异常性疼痛。ip和i.t. CNO的给药减轻了雄性CX 3CR 1-hM 4Di小鼠中PTX诱导的机械性异常性疼痛，并且在雌性CX 3CR 1-hM 4Di小鼠中观察到腹膜内CNO的有限作用。与PTX诱导的异常性疼痛不同，通过在雄性和雌性CX 3CR 1-hM 4Di小鼠中腹膜内给予CNO，OXA诱导的机械性异常性疼痛略有改善，但没有显著缓解。这些结果表明脊髓小胶质细胞可以受到Gi-DREADD的调节，并支持CX 3 CR 1（+）脊髓小胶质细胞在神经损伤诱导的NP中发挥性别依赖性作用的观点;然而，它们的作用可能因NP的不同模型而异。
Despite growing evidence suggesting that spinal microglia play an important role in the molecular mechanism underlying experimental neuropathic pain (NP) in male rodents, evidence regarding the sex-dependent role of these microglia in NP is insufficient. In this study, we evaluated the effects of microglial regulation on NP using Gi-designer receptors exclusively activated by designer drugs (Gi-DREADD) driven by the microglia-specificCx3cr1promoter. For the Cre-dependent expression of human Gi-coupled M4 muscarinic receptors (hM4Di) in CX3C chemokine receptor 1-expressing (CX3CR1(+)) cells, R26-LSL-hM4Di-DREADD mice were crossed with CX3CR1-Cre mice. Mouse models of NP were generated by partial sciatic nerve ligation (PSL) and treatment with anti-cancer agent paclitaxel (PTX) or oxaliplatin (OXA), and mechanical allodynia was evaluated using the von Frey test. Immunohistochemistry revealed that hM4Di was specifically expressed on Iba1(+)microglia, but not on astrocytes or neurons in the spinal dorsal horn of CX3CR1-hM4Di mice. PSL-induced mechanical allodynia was significantly attenuated by systemic (intraperitoneal, i.p.) administration of 10 mg/kg of clozapine N-oxide (CNO), a hM4Di-selective ligand, in male CX3CR1-hM4Di mice. The mechanical threshold in naive CX3CR1-hM4Di mice was not altered by i.p. administration of CNO. Consistently, local (intrathecal, i.t.) administration of CNO (20 nmol) significantly relieved PSL-induced mechanical allodynia in male CX3CR1-hM4Di mice. However, neither i.p. nor i.t. administration of CNO affected PSL-induced mechanical allodynia in female CX3CR1-hM4Di mice. Both i.p. and i.t. administration of CNO relieved PTX-induced mechanical allodynia in male CX3CR1-hM4Di mice, and a limited effect of i.p. CNO was observed in female CX3CR1-hM4Di mice. Unlike PTX-induced allodynia, OXA-induced mechanical allodynia was slightly improved, but not significantly relieved, by i.p. administration of CNO in both male and female CX3CR1-hM4Di mice. These results suggest that spinal microglia can be regulated by Gi-DREADD and support the notion that CX3CR1(+)spinal microglia play sex-dependent roles in nerve injury-induced NP; however, their roles may vary among different models of NP.