School of Nursing, Wei Fang Medical University, Weifang, Shandong, China.
Department II of Neurology, The Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China.
Brain Res Bull. 2023 Jul;199:110660. doi: 10.1016/j.brainresbull.2023.110660. Epub 2023 May 5.
In ischemia-reperfusion stroke, microglia play a dual role in brain injury as well as brain repair, and promoting their switch from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype is considered to be a potential therapeutic strategy. Docosahexaenoic acid (DHA) is an essential long-chain omega-3 polyunsaturated fatty acid that exhibits potent anti-inflammatory properties in the acute phase of ischemic stroke, but its effect on microglia polarization is unknown. Thus, the objective of this study was to investigate the neuroprotective effects of DHA on rat brain following ischemia-reperfusion injury, and to investigate the mechanism by which DHA regulates microglia polarization. We administered DHA 5 mg/kg intraperitoneally daily for 3 d following a transient middle cerebral artery occlusion reperfusion model in rats. The protective effects of DHA on cerebral ischemia-reperfusion injury were detected by TTC staining, HE staining, Nissler staining, and TUNEL staining. Quantitative real-time PCR, immunofluorescence, western blot, and enzyme-linked immunosorbent assay were used to detect the expression of M1 and M2 microglia-associated markers and PPARγ-mediated ERK/AKT signaling pathway proteins. We found that DHA significantly improved brain injury by decreasing the expression of the M1 phenotypic marker (iNOS, CD16) and increasing the expression of the M2 phenotypic marker (Arg-1, CD206). DHA also increased the expression of peroxisome proliferator-activated receptor gamma (PPARγ) mRNA and protein, increased the expression of the pathway protein AKT, and decreased the expression of ERK1/2. In addition, DHA promoted the expression of anti-inflammatory factor IL-10 and decreased the expression of pro-inflammatory factors TNF-α and IL-1β. However, the PPARγ antagonist GW9662 greatly blocked these beneficial effects. These results suggest that DHA may activate PPARγ to inhibit ERK and activate AKT signaling pathways to regulate microglia polarization, thereby reducing neuroinflammation and promoting neurological recovery to alleviate cerebral ischemia-reperfusion injury.
在缺血再灌注性脑卒中，小胶质细胞在脑损伤及脑修复中起双重作用，促进其由促炎 M1 表型向抗炎 M2 表型转变被认为是一种潜在的治疗策略。二十二碳六烯酸（DHA）是一种必需的长链ω-3 多不饱和脂肪酸，在缺血性脑卒中的急性期具有很强的抗炎作用，但它对小胶质细胞极化的影响尚不清楚。因此，本研究旨在探讨 DHA 对大鼠缺血再灌注损伤后脑的神经保护作用，并探讨 DHA 调节小胶质细胞极化的机制。我们在大鼠短暂性大脑中动脉闭塞再灌注模型后，每天腹腔内给予 DHA 5mg/kg，连续 3 天。采用 TTC 染色、HE 染色、Nissler 染色和 TUNEL 染色检测 DHA 对脑缺血再灌注损伤的保护作用。采用实时定量 PCR、免疫荧光、western blot 和酶联免疫吸附试验检测 M1 和 M2 小胶质细胞相关标志物及 PPARγ 介导的 ERK/AKT 信号通路蛋白的表达。结果发现，DHA 通过降低 M1 表型标志物（iNOS、CD16）的表达和增加 M2 表型标志物（Arg-1、CD206）的表达，显著改善脑损伤。DHA 还增加过氧化物酶体增殖物激活受体γ（PPARγ）mRNA 和蛋白的表达，增加通路蛋白 AKT 的表达，降低 ERK1/2 的表达。此外，DHA 促进抗炎因子 IL-10 的表达，降低促炎因子 TNF-α和 IL-1β的表达。然而，PPARγ 拮抗剂 GW9662 则大大阻断了这些有益作用。这些结果表明，DHA 可能通过激活 PPARγ 抑制 ERK 并激活 AKT 信号通路来调节小胶质细胞极化，从而减轻神经炎症，促进神经恢复，减轻脑缺血再灌注损伤。
