Voluntary exercise prior to traumatic brain injury alters miRNA expression in the injured mouse cerebral cortex

MicroRNAs (miRNAs) may be important mediators of the profound molecular and cellular changes that occur after traumatic brain injury (TBI). However, the changes and possible roles of miRNAs induced by voluntary exercise prior to TBI are still not known. In this report, the microarray method was used to demonstrate alterations in miRNA expression levels in the cerebral cortex of TBI mice that were pretrained on a running wheel (RW). Voluntary RW exercise prior to TBI: i) significantly decreased the mortality rate and improved the recovery of the righting reflex in TBI mice, and ii) differentially changed the levels of several miRNAs, upregulating some and downregulating others. Furthermore, we revealed global upregulation of miR-21, miR-92a, and miR-874 and downregulation of miR-138, let-7c, and miR-124 expression among the sham-non-runner, TBI-non-runner, and TBI-runner groups. Quantitative reverse transcription polymerase chain reaction data (RT-qPCR) indicated good consistency with the microarray results. Our microarray-based analysis of miRNA expression in mice cerebral cortex after TBI revealed that some miRNAs such as miR-21, miR-92a, miR-874, miR-138, let-7c, and miR-124 could be involved in the prevention and protection afforded by voluntary exercise in a TBI model.微小RNA（microRNAs，miRNAs）可能是创伤性脑损伤（TBI）后发生的显著分子与细胞变化的重要介导因子。然而，目前尚不清楚创伤性脑损伤前自主运动所诱导的miRNA表达变化及其潜在作用。本研究采用微阵列技术，对预先接受跑轮（RW）自主运动的TBI小鼠大脑皮层内的miRNA表达水平变化进行了分析。创伤性脑损伤前的自主跑轮运动可产生两方面效应：其一，可显著降低TBI小鼠的死亡率，改善其翻正反射的恢复进程；其二，可使多种miRNA的表达水平发生差异性改变，部分miRNA表达上调，其余则表达下调。此外，在假手术-未运动组、TBI-未运动组及TBI-运动组中，我们观察到miR-21、miR-92a与miR-874整体呈现上调表达，而miR-138、let-7c及miR-124则呈现下调表达。定量逆转录聚合酶链反应（quantitative reverse transcription polymerase chain reaction，RT-qPCR）检测结果与微阵列分析结果具有良好的一致性。本研究通过微阵列技术分析TBI小鼠大脑皮层的miRNA表达情况后发现，miR-21、miR-92a、miR-874、miR-138、let-7c及miR-124等多种miRNA可能参与了自主运动对TBI模型小鼠的预防与保护作用。