Institute of Neurobiology, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an, 710061, Shaanxi, People's Republic of China.
Department of Anatomy and Histology, Patuakhali Science and Technology University, Dhaka, Bangladesh.
Neurochem Res. 2020 May;45(5):1230-1243. doi: 10.1007/s11064-020-03006-1. Epub 2020 Mar 5.
The activation of microglia in response to intracerebral hemorrhagic stroke is one of the principal components of the progression of this disease. It results in the formation of pro-inflammatory cytokines that lead to neuronal death, a structural deterioration that, in turn interferes with functional recovery. Metabotropic glutamate receptor 5 (mGluR5) is highly expressed in reactive microglia and is involved in the pathological processes of brain disorders, but its role in intracerebral hemorrhage (ICH) remains unknown. We hypothesized that mGluR5 regulates microglial activation and ICH maintenance. In this study, collagenase-induced ICH mice received a single intraperitoneal injection of the mGluR5 antagonist-, MTEP, or vehicle 2 h after injury. We found that acute ICH upregulated mGluR5 and microglial activation. mGluR5 was highly localized in reactive microglia in the peri-hematomal cortex and striatum on days 3 and 7 post-ICH. The MTEP-mediated pharmacological inhibition of mGluR5 in vivo resulted in the substantial attenuation of acute microglial activation and IL-6, and TNF-α release. We also showed that the blockade of mGluR5 markedly reduced cell apoptosis, and neurodegeneration and markedly elevated neuroprotection. Furthermore, the MTEP-mediated inhibition of mGluR5 significantly reduced the lesion volume and improved functional recovery. Taken together, our results demonstrate that ICH injury enhances mGluR5 expression in the acute and subacute stages and that mGluR5 is highly localized in reactive microglia. The blockade of mGluR5 reduces ICH-induced acute microglial activation, provides neuroprotection and promotes neurofunctional recovery after ICH. The inhibition of mGluR5 may be a relevant therapeutic target for intracerebral hemorrhagic stroke.
脑内出血性中风后小胶质细胞的激活是该疾病进展的主要组成部分之一。它导致促炎细胞因子的形成,导致神经元死亡,结构恶化,进而干扰功能恢复。代谢型谷氨酸受体 5(mGluR5)在反应性小胶质细胞中高度表达,参与脑疾病的病理过程,但它在脑内出血(ICH)中的作用尚不清楚。我们假设 mGluR5 调节小胶质细胞激活和 ICH 维持。在这项研究中,胶原酶诱导的 ICH 小鼠在损伤后 2 小时接受单次腹腔注射 mGluR5 拮抗剂 MTEP 或载体。我们发现急性 ICH 上调了 mGluR5 和小胶质细胞的激活。mGluR5 在急性 ICH 后第 3 天和第 7 天的血肿周围皮质和纹状体中高度定位于反应性小胶质细胞。体内 MTEP 介导的 mGluR5 药理学抑制导致急性小胶质细胞激活和 IL-6、TNF-α释放显著减弱。我们还表明,mGluR5 的阻断显著减少细胞凋亡和神经退行性变,并显著提高神经保护作用。此外,MTEP 介导的 mGluR5 抑制显著降低损伤体积并改善功能恢复。总之,我们的结果表明,ICH 损伤在急性期和亚急性期增强 mGluR5 的表达,mGluR5 高度定位于反应性小胶质细胞。mGluR5 阻断减少 ICH 诱导的急性小胶质细胞激活,提供神经保护并促进 ICH 后的神经功能恢复。抑制 mGluR5 可能是脑内出血性中风的一个相关治疗靶点。