高脂饮食和丁酸钠干预对大鼠十二指肠线粒体能量代谢和肠钙吸收的影响

Effects of High-Fat Diet and Sodium Butyrate Intervention on Intestinal Mitochondrial Energy Metabolism and Intestinal Calcium Absorption in Rats

目的:探讨丁酸钠(sodium butyrate,NaB)对肥胖易感(obesity prone,OP)和肥胖抵抗(obesity resistant,OR)大鼠十二指肠线粒体能量代谢和肠钙吸收的影响。方法:将70只SD雄性大鼠随机分为5组:正常饮食组(CON)、肥胖易感组(OP)、肥胖易感NaB干预组(OP+4%NaB)、肥胖抵抗组(OR)及肥胖抵抗NaB干预组(OR+4%NaB)。每周监测大鼠体质量增加量和采食量,20周实验结束,采样分析其十二指肠氧化还原状态相关指标、线粒体抗氧化酶活力、能量代谢以及钙吸收和血钙稳态相关指标;采用实时荧光定量聚合酶链式反应对十二指肠抗氧化通路、钙离子转运相关基因表达进行分析;用Western blot对重要抗氧化蛋白表达水平进行分析。结果:与OP组相比,OP+4%NaB组大鼠体质量增加量显著降低(P<0.05),十二指肠总抗氧化能力(total antioxidant capacity,T-AOC)极显著增加(P<0.01),丙二醛(malondialdehyde,MDA)含量显著降低(P<0.05);十二指肠抗氧化相关基因Nrf2和NQO-1 mRNA表达极显著上调(P<0.01),GSK-3βmRNA表达显著下调(P<0.05);Nrf2蛋白表达显著上调(P<0.05);线粒体能量代谢指标乙酰CoA含量、NADH/NAD+极显著降低(P<0.01),ATP水平极显著升高(P<0.01);线粒体内部抗氧化酶相关指标活性氧(reactive oxygenspecies,ROS)含量极显著降低(P<0.01),锰-超氧化物歧化酶活力极显著升高(P<0.01),谷胱甘肽过氧化物酶(glutathion peroxidase,GSH-Px)活力显著升高(P<0.05);钙平衡实验相关指标尿钙排出量显著降低(P<0.05),钙贮留水平显著升高(P<0.05)。与OR组相比,OR+4%NaB组大鼠十二指肠中T-AOC和GSH-Px活力极显著升高(P<0.01),MDA含量显著降低(P<0.05);抗氧化相关基因Nrf2 mRNA表达显著上调(P<0.05);线粒体能量代谢指标ATP水平显著升高(P<0.05),其他指标无显著性变化(P>0.05)。与OR组相比,OR+4%NaB组大鼠钙平衡实验和血液钙稳态及钙离子转运相关指标也无显著性差异(P>0.05)。结论:Na B干预可提高OP和OR组大鼠十二指肠抗氧化能力,减少ROS产生,维护线粒体氧化还原稳态,增加OP大鼠肠钙贮留水平和钙离子转运能力,且干预效果在不同肥胖表型大鼠中存在差异,对OP表型效果最好。

Objective: To investigate the effects of sodium butyrate(NaB) on duodenum mitochondrial energy metabolism and calcium ion transport in obesity prone(OP) and obesity resistant(OR) rats. Methods: Seventy male Sprague-Dawley rats were randomly divided into: normal diet(CON), OP, OP supplemented with 4% NaB(OP + 4% NaB), OR and OR supplemented with 4% NaB(OR + 4% NaB) groups. Body mass gain and food intake were measured weekly. At the end of the 20-week feeding period, all rats were sacrificed. Then, duodenum tissue and plasma were collected quickly for determining antioxidant enzyme activities, mitochondrial energy metabolism, calcium absorption and blood calcium homeostasis-related indicators. Also, the expression of genes related to Ca2+ transport and antioxidant function in duodenum tissue were detected by quantitative real-time polymenose chain reaction(qPCR). The expression levels of important antioxidant proteins were analyzed by Western blot. Results: Compared with the OP group, the OP + 4% NaB group showed significantly decreased body mass gain(P < 0.05);and significantly increased total antioxidant capacity(T-AOC) in the duodenum(P < 0.01), decreased malondialdehyde(MDA) content(P < 0.05), up-regulated mRNA expression of the antioxidant related genes Nrf2 and NQO-1(P < 0.01), down-regulated mRNA expression of GSK-3β(P < 0.05), and up-regulated expression of Nrf2 protein(P < 0.05). In addition, in the OP + 4% NaB group, the mitochondrial energy metabolism indicators acetyl CoA content and NADH/NAD+ ratio were significantly decreased(P < 0.01), and ATP level was significantly increased(P < 0.01);the level of mitochondrial reactive oxygen species(ROS) was significantly decreased(P < 0.01);the activities of Mn-superoxide dismutase(P < 0.01) and glutathion peroxidase(GSH-Px)(P < 0.05) were significantly increased;urinary calcium excretion was significantly decreased(P < 0.05);and calcium storage level was significantly increased(P < 0.05). Compared with the OR group, the OR + 4% NaB group exhibited significantly increased T-AOC and GSH-Px activity in the duodenum(P < 0.01), decreased MDA content(P < 0.05), up-regulated mRNA expression of Nrf2(P < 0.05), and increased ATP level(P < 0.05), while there was no significant difference in the other mitochondrial energy metabolism-related indexes(P > 0.05). Also, compared with the OR group, the OR + 4% NaB group showed no significant difference in the indicators related to calcium balance, blood calcium homeostasis and calcium ion transport(P > 0.05). Conclusion: NaB intervention can improve the antioxidant capacity of the duodenum in OP and OR rats, reduce ROS production and maintain mitochondrial redox homeostasis. NaB can increase the intestinal calcium storage level and calcium ion transport capacity of OP rats, and the effect was greater for OP phenotype.