We investigated whether the magnitude of exercise-induced hyperthermia influences intestinal permeability and tight junction gene expression. Twenty-nine male Wistar rats were divided into four groups: rest at 24 °C and exercise at 13 °C, 24 °C or 31 °C. The exercise consisted of a 90-min treadmill run at 15 m/min, and different ambient temperatures were used to produce distinct levels of exercise-induced hyperthermia. Before the experimental trials, the rats were treated by gavage with diethylenetriaminepentaacetic acid labeled with technetium-99 metastable as a radioactive probe. The rats' core body temperature (TCORE) was measured by telemetry. Immediately after the trials, the rats were euthanized, and the intestinal permeability was assessed by measuring the radioactivity of blood samples. The mRNA levels of occludin and zonula occludens-1 (ZO-1) genes were determined in duodenum samples. Exercise at 24 °C increased TCORE to values close to 39 °C, without changing permeability compared with the resting trial at the same environment. Meanwhile, rats' TCORE exceeded 40 °C during exercise at 31 °C, leading to greater permeability relative to those observed after exercise in the other ambient temperatures (e.g., 0.0037%/g at 31 °C vs. 0.0005%/g at 13 °C; data expressed as medians; p < 0.05). Likewise, the rats exercised at 31 °C exhibited higher mRNA levels of ZO-1 and occludin genes than the rats exercised at 24 °C or 13 °C. The changes in permeability and gene expression were positively and significantly associated with the magnitude of hyperthermia. We conclude that marked hyperthermia caused by exercise in the warmer environment increases intestinal permeability and mRNA levels of tight junction genes.

中文翻译：

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体育锻炼引起的高热程度与大鼠肠道通透性和紧密连接基因表达的变化有关

我们调查了运动引起的体温过高的程度是否会影响肠道通透性和紧密连接基因的表达。29 只雄性 Wistar 大鼠分为四组：24°C 休息和 13°C、24°C 或 31°C 运动。该练习包括以 15 m/min 的速度在跑步机上跑步 90 分钟，并且使用不同的环境温度来产生不同程度的运动诱发的体温过高。实验前，用锝99亚稳态标记的二亚乙基三胺五乙酸作为放射性探针对大鼠进行管饲。通过遥测法测量大鼠的核心体温（TCORE）。试验结束后立即对大鼠实施安乐死，并通过测量血液样本的放射性来评估肠道通透性。在十二指肠样本中测定了 occludin 和 zonula occludens-1 (ZO-1) 基因的 mRNA 水平。与相同环境下的静息试验相比，在 24 °C 下运动将 TCORE 增加到接近 39 °C 的值，而不会改变渗透率。同时，大鼠在 31°C 运动期间的 TCORE 超过 40°C，导致相对于在其他环境温度运动后观察到的渗透性更高（例如，31°C 时为 0.0037%/g，而 13°C 时为 0.0005%/g °C；数据表示为中位数；p < 0.05）。同样，在 31°C 运动的大鼠表现出比在 24°C 或 13°C 运动的大鼠更高的 ZO-1 和 occludin 基因的 mRNA 水平。渗透性和基因表达的变化与体温过高的程度呈显着正相关。