HFD对不同性别SD大鼠肠道菌群及室旁核小胶质细胞激活的影响

Difference in effect of HFD on intestinal microflora, fat metabolism, and brain microglia activation between female and male SD rats

摘要:

【目的】通过建立雌、雄性SD (Sprague-Dawley)大鼠模型，研究高脂饮食(high fat diet，HFD)对不同性别大鼠肠道菌群及室旁核(hypothalamic paraventricular nucleus，PVN)区小胶质细胞激活的影响。【方法】选取24只3周龄的SD大鼠，雌雄各半，随机分成雄性对照组(CM)、雌性对照组(CF)，雄性高脂组(HM)、雌性高脂组(HF)，共4组，每组6只。喂养至10周龄，收集大鼠新鲜粪便并提取细菌总基因组DNA，通过PCR扩增16S rDNA的V3+V4区域，进行高通量测序；采用气相色谱法分析大鼠盲肠内容物中短链脂肪酸(short chain fatty acids，SCFAs)含量；以real-time PCR技术分析PVN区小胶质细胞激活标记物CD11b和炎性细胞因子TNF-α、IL-6的mRNA相对表达水平。【结果】雌、雄高脂组分别与对照组相比，HM组大鼠肠道菌群总数及菌群多样性明显减少(P<0.05)，HF组大鼠肠道菌群丰度明显减少(P<0.05)。与CM组相比，HM组大鼠盲肠中乙酸含量显著下降(P<0.05)，且PVN区CD11b的mRNA相对表达水平显著升高(P<0.05)。【结论】高脂饮食可改变雌、雄大鼠的肠道菌群，导致其肠道菌群失调。然而，高脂饮食对肠道菌群与脑小胶质细胞的影响在不同性别间存在一定差异。研究表明，高脂饮食所致雄性大鼠肠道菌群的变化可能与脑小胶质细胞激活相关。

Abstract:

[Objective] To investigate the effect of high-fat diet (HFD) on intestinal microflora and expression levels of inflammatory cytokines in hypothalamic paraventricular nucleus (PVN) of female and male Sprague-Dawley (SD) rats. [Methods] A total of 24 3-week-old SD rats (12 males) were randomized into 4 groups (6 per group). They were given either control diet (male control group, CM; female control group, CF) or the 60% fat diet (high-fat male group, HM; high-fat female group, HF) until 10 weeks old when the fresh feces were collected and total genomic DNA was extracted. For high-throughput sequencing analysis, we amplified the V3+V4 regions of bacterial 16S rDNA by PCR (polymerase chain reaction). The content of short-chain fatty acids (SCFAs) in the caecal contents of rats was analyzed by gas chromatography. Real-time PCR was performed to analyze the mRNA expression of microglial marker CD11b and inflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 in the PVN. [Results]Reduction in quantity and diversity of intestinal microflora in the HM group (P<0.05) and decrease in abundance of the flora in HF group (P<0.05) were observed compared with those in the respective control groups. The acetic acid content in cecum was lower (P< 0.05), and mRNA expression of CD11b in PVN was higher (P<0.05) in HM group than in CM group. [Conclusion] HFD can alter the intestinal microflora of female and male rats, leading to the flora imbalance. However, the effect of HFD on intestinal microflora and brain microglia is different between female and male rats. The HFD-induced variation of intestinal microflora in male rats may be associated with brain microglia activation.