Liver adaptations may be critical for regular exercise and high aerobic capacity to protect against metabolic disease, but mechanisms remain unknown. Bile acids (BAs) synthesized in the liver are bioactive and can putatively modify energy metabolism. Regular exercise influences BA metabolism in rodents but effects in humans are unknown. This study tested if female subjects screened for high aerobic capacity (Hi-Fit, n=19) (VO_2peak≥45 mL/kg/min) have increased hepatic BA synthesis and different circulating BA composition compared to those matched for age and body mass with low aerobic capacity (Lo-Fit, n=19) (VO_2peak≤35 mL/kg/min). Diet patterns, activity level, stool, and blood were collected at baseline before receiving a 1-week standardized, eucaloric diet. After the 1-week standardized diet, stool and blood were again collected, and an Oral Glucose Tolerance Test (OGTT) was performed to assess insulin sensitivity and postprandial BA response. Contrary to our hypothesis, serum 7α-hydroxy-4-cholesten-3-one (C4), a surrogate of BA synthesis was not different between groups while Hi-Fit women had lower fecal BA concentrations compared to Lo-Fit. However, Lo-Fit women had a higher and more sustained rise in circulating conjugated BAs during the OGTT. Hi-Fit women showed a significant post-OGTT elevation of the secondary BA, lithocholic acid (LCA), a potent TGR5 agonist, in contrast to Lo-Fit where no response was observed. A one-week control diet eliminated most differences in circulating BA species between groups. Overall, the results emphasize the importance of using a standardized diet when evaluating BAs and indicate that regular exercise and aerobic capacity modulate BA metabolism under postprandial conditions.

中文翻译：

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有氧能力的差异影响年轻女性的胆汁酸代谢。

肝脏适应对于定期锻炼和高有氧能力以预防代谢疾病可能至关重要，但其机制仍不清楚。肝脏中合成的胆汁酸（BA）具有生物活性，可以改变能量代谢。定期运动会影响啮齿动物的 BA 代谢，但对人类的影响尚不清楚。本研究测试了筛选出高有氧能力的女性受试者 (Hi-Fit, n=19) (VO _2peak ≥45 mL/kg/min) 与年龄和体重匹配的女性受试者相比，是否具有增加的肝脏 BA 合成和不同的循环 BA 组成有氧能力低（Lo-Fit，n=19）（VO _2peak ≤35 mL/kg/min）。在接受为期 1 周的标准化无热量饮食之前，在基线时收集饮食模式、活动水平、粪便和血液。1周标准化饮食后，再次采集粪便和血液，并进行口服葡萄糖耐量试验（OGTT）以评估胰岛素敏感性和餐后BA反应。与我们的假设相反，血清 7α-羟基-4-胆甾烯-3-酮 (C4)（BA 合成的替代物）在各组之间没有差异，而 Hi-Fit 女性的粪便 BA 浓度低于 Lo-Fit。然而，Lo-Fit 女性在 OGTT 期间循环结合 BA 的上升幅度更高且更持续。Hi-Fit 女性在 OGTT 后表现出次要 BA、石胆酸 (LCA)（一种有效的 TGR5 激动剂）显着升高，而 Lo-Fit 则没有观察到任何反应。一周的对照饮食消除了各组之间循环 BA 物种的大部分差异。总体而言，结果强调了在评估 BA 时使用标准化饮食的重要性，并表明定期运动和有氧能力可调节餐后条件下的 BA 代谢。