Objective: To evaluate the effect of modulating gut microbiota for improving brain injury in rats with post-stroke depression.
Methods: Adult SD rats were randomized into normal control, middle cerebral artery occlusion (MCAO), post-stroke depression (PSD), PSD with fecal transplantation, PSD with antibiotics (rifaximin), PSD with probiotics (lactobacilli), and PSD with fluoxetine treatment groups (n=9). Neurological function scores of the rats were determined, and the changes in sugar water preference and immobility time in forced swimming test were observed; plasma levels of trimethylamine N-oxide (TMAO) and hydrogen sulfide (H2S) were detected with ELISA, Occludin, and the expressions of occludin, caudin-5 and IgG proteins Ⅰ the brain tissues were determined using Western blotting.
Results: Compared with those in the control group, the rats in MCAO and PSD groups had significantly increased neurological function scores, TMAO level, the ratio of TMAO/H2S, and immobility time in forced swimming test with a lowered level of H2S (P < 0.05). These changes were more obvious in PSD rats, which also exhibited a reduced sugar water preference with increased IgG protein and decreased occluding and caudin-5 expressions in the brain tissue (P < 0.05). TMAO/H2S ratio in PSD rats was positively correlated with neurological function score (R2=0.3235, P=0.0269) and immobility time in swimming (R2=0.6290, P=0.0004) and negatively with sugar water preference (R2=-0.4534, P=0.0059). Treatment with fecal transplantation, antibiotics, probiotics and fluoxetine all significantly reduced neurological function scores, immobility time in forced swimming, TMAO/H2S ratio, and IgG protein expression and increased sugar water preference and brain occludin and caudin-5 expressions of the PSD rats (P < 0.05).
Conclusion: In PSD rats, TMAO/H2S ratio is correlated with neurological function score, immobility time in forced swimming and sugar water preference, and modulating intestinal flora can improve neurological function and depressive symptoms and improve the integrity of the blood-brain barrier.
目的: 研究肠道菌对卒中后抑郁大鼠脑损伤的作用。
方法: SD大鼠随机分为对照组、MCAO组（大脑中动脉栓塞模型）、PSD组（卒中后抑郁大鼠）、粪便移植组（卒中后抑郁大鼠，正常大鼠粪便菌液处理）、抗生素组（卒中后抑郁大鼠，利福昔明处理）、益生菌组（卒中后抑郁大鼠，乳酸杆菌处理）、氟西汀组（卒中后抑郁大鼠，氟西汀处理），每组9只（相关性分析中，每组15只）。对大鼠神经功能评分，检测糖水偏好度和强迫游泳静止不动时间，ELISA法检测大鼠血浆中菌群代谢产物氧化三甲胺（TMAO）、硫化氢（H2S）含量，Western blot方法检测大鼠脑组织中Occludin、caudin-5、IgG蛋白表达。
结果: 与对照组比较，MCAO组、PSD组大鼠神经功能评分升高，强迫游泳静止不动时间增加，TMAO水平升高，H2S水平降低，TMAO/H2S比值升高（P＜0.05）；与对照组比较，PSD组大鼠糖水偏好度降低（P＜0.05）；与MCAO组比较，PSD组大鼠神经功能评分升高，强迫游泳静止不动时间增加，糖水偏好度降低，TMAO水升高，H2S水平降低，TMAO/H2S比值升高（P＜0.05）。卒中后抑郁大鼠TMAO/H2S比值与神经功能评分、强迫游泳静止不动时间正相关（R2=0.3235，P=0.0269；R2=0.6290，P=0.0004），与糖水偏好度负相关（R2=0.4534，P=0.0059）。与对照组相比，PSD组大鼠IgG蛋白相对表达量升高，Occludin、caudin-5蛋白相对表达量降低（P＜0.05）；与PSD组比较，粪便移植组、抗生素组、益生菌组、氟西汀组大鼠神经功能评分和强迫游泳静止不动时间均降低，糖水偏好度升高，TMAO/H2S比值降低，IgG蛋白相对表达量降低，Occludin、caudin-5蛋白相对表达量升高（P＜0.05）。
结论: 卒中后抑郁大鼠TMAO/H2S比值与神经功能评分、强迫游泳静止不动时间、糖水偏好度相关，调节肠道菌群可改善卒中后抑郁大鼠神经功能和抑郁症状，改善大鼠血脑屏障。
Keywords: TMAO/H2S; blood-brain barrier; intestinal flora; post-stroke depression.