瘦素和BDNF在DSS诱导的小鼠结肠炎中的作用及其机制研究

Study on Role and Mechanism of Leptin and BDNF in DSS Induced Colitis in Mice

背景:瘦素、脑源性神经营养因子(BDNF)表达异常是溃疡性结肠炎(UC)发生的重要环节,但两者在UC中的作用机制尚不明确。目的:探讨瘦素、BDNF对DSS诱导的小鼠结肠炎的影响及其机制。方法:选取36只雄性8~10周龄健康瘦素缺陷型ob小鼠和瘦素正常表达的野生型(WT)小鼠,随机分为WT实验组、ob实验组、WT对照组、ob对照组。实验组小鼠给予3%DSS溶液自由饮用7 d诱导结肠炎模型,对照组给予蒸馏水。造模结束后评估小鼠疾病活动指数(DAI)评分、结肠长度、行为学状态和内脏敏感性,以实时荧光定量PCR法检测结肠和海马中瘦素、BDNF mRNA表达,蛋白质印迹法检测结肠BDNF蛋白表达。结果:与相应对照组相比,WT实验组和ob实验组小鼠DAI评分和内脏敏感性明显增高(P<0.05),结肠BDNF mRNA和蛋白表达显著增加(P<0.05)。与WT对照组相比,WT实验组小鼠出现焦虑、抑郁样行为,海马中瘦素、BDNF mRNA表达显著降低(P<0.05)。相关性分析结果显示WT实验组小鼠焦虑与结肠长度呈正相关(P<0.05),与DAI评分呈负相关(P<0.05);抑郁、结肠BDNF mRNA表达与结肠长度呈负相关(P<0.05),与DAI评分呈正相关(P<0.05);海马中瘦素与焦虑呈正相关(P<0.05),与抑郁呈负相关(P<0.05);结肠BDNF mRNA表达与内脏敏感性呈负相关(P<0.05)。结论:结肠BDNF的分泌与瘦素表达有关,瘦素和BDNF能通过介导焦虑、抑郁情绪和内脏敏感性参与DSS诱导的小鼠结肠炎。

Abnormal expression of leptin and brain⁃derived neurotrophic factor(BDNF)is an important link in the occurrence of ulcerative colitis(UC),but the mechanism of leptin and BDNF in UC is still unclear.Aims:To explore the effect and mechanism of leptin and BDNF in DSS induced colitis in mice.Methods:Thirty⁃six male 8⁃10 weeks healthy leptin⁃deficient ob mice and leptin⁃normal expressing wild type(WT)mice were selected and randomly divided into WT experimental group,ob experimental group,WT control group and ob control group.The mice in experimental groups were given 3%DSS solution for 7 days to induce colitis model,and the mice in control group were given distilled water.After modeling,disease activity index(DAI)score,colon length,behavior and visceral sensitivity were observed.The mRNA expressions of leptin and BDNF in colon and hippocampus were detected by real⁃time fluorescent quantitative PCR,and the protein expression of BDNF in colon was detected by Western blotting.Results:Compared with corresponding control groups,DAI score,visceral sensitivity in WT experimental group and ob experimental group were significantly increased(P<0.05),mRNA and protein expressions of BDNF in colon were significantly increased(P<0.05).Compared with WT control group,anxiety and depression⁃like behavior were found in WT experimental group,mRNA expressions of leptin,BDNF in hippocampus were significantly decreased(P<0.05).Correlation analysis showed that anxiety was positively correlated with length of colon in WT experimental group(P<0.05),and negatively correlated with DAI score(P<0.05);depression,expression of BDNF mRNA in colon were negatively correlated with length of colon(P<0.05),and positively correlated with DAI score(P<0.05);leptin in hippocampus was positively correlated with anxiety(P<0.05),while was negatively correlated with depression(P<0.05);expression of BDNF mRNA in colon was negatively correlated visceral sensitivity(P<0.05).Conclusions:Colonic BDNF secretion is associated with leptin expression,and both may be involved in the DSS⁃induced colitis in mice by mediating anxiety,depression and visceral sensitivity.