高纤维素饲料对小鼠小胶质细胞成熟活化的影响
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摘要
目的比较高纤维素饮食与低纤维素饮食在离乳小鼠肠道代谢后产生的短链脂肪酸水平,探讨不同纤维素饮食对小鼠脑内小胶质细胞成熟活化的影响。方法新生SPF级C57BL/6小鼠分别采用低纤维素饲料(低纤维素饲料组)和高纤维素饲料(高纤维素饲料组)喂养,采用色谱法检测不同饲料喂养小鼠盲肠内容物中3种主要短链脂肪酸(乙酸、丙酸、丁酸)的水平,组织免疫荧光法比较小鼠脑内小胶质细胞的发育与分布情况,荧光定量PCR检测LPS刺激后小鼠脑内与小胶质细胞活化相关基因的表达情况。结果高纤维素饲料组小鼠盲肠内乙酸水平明显高于低纤维素饲料组(P<0.05),而两组盲肠内丙酸和丁酸水平及脑内小胶质细胞的数量和分布差异无统计学意义(P>0.05)。LPS颅内刺激后高纤维素饲料组小鼠脑内与小胶质细胞活化相关的炎症因子IL-1β、IL-6、TNF-α、IL-12、CCL2、CCL5、CCL7mRNA表达水平均明显高于低纤维素饲料组,差异有统计学意义(P<0.05)。结论饲料中的纤维素含量可影响离乳小鼠脑内小胶质细胞的成熟活化,可能与纤维素被肠道菌群代谢后产生的乙酸水平不同有关。
Objective To compare the levels of short-chain fatty acids produced by high-fiber diet and low-fiber diet in the intestinal metabolism of mice for exploring the effects of different fiber diets on the activation and function of microglia in mouse brain. Methods Mice fed with low-fiber and high-fiber diets were detected for the levels of three major short-chain fatty acids(acetic acid, propionic acid, butyrate) in the cecum. The distributions of microglia in the brain of different diet mice were compared by immunofluorescence. Real-time fluorescence quantitative PCR was used to detect expressions of genes associated with microglia activation in mouse brain between the above two groups of mice. Results The acetate level in the cecum of mice in high fiber diet group was higher than that of mice in low fiber diet group. There were no significant differences between the two groups in the levels of propionic acid and butyrate and the number and distribution of microglia. However, the levels of microglial activationassociated inflammatory cytokines such as IL-1β, IL-6, TNF-α, IL-12, CCL2, CCL5 and CCL7 mRNA were higher in high fiber diet group than in low fiber diet group after the intracranial stimulation by LPS. Conclusion The quantity of fiber in the diet after weaning can affect the maturation and activation of microglia in the brain, which may because of different levels of acetic acid after metabolism of different dietary structures by the intestinal flora.
Objective To compare the levels of short-chain fatty acids produced by high-fiber diet and low-fiber diet in the intestinal metabolism of mice for exploring the effects of different fiber diets on the activation and function of microglia in mouse brain. Methods Mice fed with low-fiber and high-fiber diets were detected for the levels of three major short-chain fatty acids(acetic acid, propionic acid, butyrate) in the cecum. The distributions of microglia in the brain of different diet mice were compared by immunofluorescence. Real-time fluorescence quantitative PCR was used to detect expressions of genes associated with microglia activation in mouse brain between the above two groups of mice. Results The acetate level in the cecum of mice in high fiber diet group was higher than that of mice in low fiber diet group. There were no significant differences between the two groups in the levels of propionic acid and butyrate and the number and distribution of microglia. However, the levels of microglial activationassociated inflammatory cytokines such as IL-1β, IL-6, TNF-α, IL-12, CCL2, CCL5 and CCL7 mRNA were higher in high fiber diet group than in low fiber diet group after the intracranial stimulation by LPS. Conclusion The quantity of fiber in the diet after weaning can affect the maturation and activation of microglia in the brain, which may because of different levels of acetic acid after metabolism of different dietary structures by the intestinal flora.
引文
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[2] Prinz M, Priller J. Microglia and brain macrophages in the molecular age:from origin to neuropsychiatric disease[J]. Nat Rev Neurosci, 2014, 15(5):300-312.
[3] Daniel E, Anna LH, Diego J, et al. Host microbiota constantly control maturation and function of microglia in the CNS[J]. Nat Neurosci, 2015, 18(7):965-979.
[4] So D, Whelan K, Rossi M, et al. Dietary fiber intervention on gut microbiota composition in healthy adults:a systematic review and meta-analysis[J]. Am J Clin Nutr, 2018, 107(6):965-983.
[5] Thackray LB, Handley SA, Gorman MJ. Oral antibiotic treatment of mice exacerbates the disease severity of multiple flavivirus infections[J]. Cell Reports, 2018, 22(13):3440-3453.e6.
[6] Xiaojiao Z, Yuuping Q, Wei Z, et al. A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids[J]. Metabolomics, 2013, 9(4):818-827.
[7] Filipe DV, Estelle G, Louise MH, et al. Gut microbiota regulates maturation of the adult enteric nervous system via enteric serotonin networks[J]. Proc Natl Acad Sci U S A, 2018,115(25):6458-6463.
[8] Kelly JR, Minuto C, Cryan JF, et al. Cross talk:The microbiota and neurodevelopmental disorders[J]. Front Neurosci, 2017, 11:490.
[9] Michell-Robinson MA, Touil H, Healy LM, et al. Roles of microglia in brain development, tissue maintenance and repair[J]. Brain, 2015, 138(5):1138-1159.
[10] Yaming W, Marina C, Kaitlin M, et al. TREM2 lipid sensing sustains microglia response in an Alzheimer's disease model[j].Cell, 2015, 160(6):1061-1071.
[11] Holscher HD, Dietary fiber and prebiotics and the gastrointestinal microbiota[J]. Gut Microbes, 2017, 8(2):172-184.
[12] Lin JJ, Kuang F. Signaling pathways in which microglia participate in neuropathic pain mechanisms[J]. Chin J Neuroanat, 2011, 27(5):575-578.[林家骥,邝芳.小胶质细胞理病参与神经病理性痛机制的几个信号通路[J].神经解剖学杂志,2011,27(5):575-578.]
[13] Duan L, Zhang XD, Miao WY, et al. PDGFRβcells rapidly relay inflammatory signal from the circulatory system to neurons via chemokine CCL2[J]. Neuron, 2018, 100(1):183-200.