MiP2005: Session 2

Abstract without presentation                                 Mitochondrial Physiology Network 10.9: 30-31 (2005) - download pdf

 

Effects on gene regulation by reactive oxygen species during intermittent hypoxic training.

Liying Huang, W Lin, X Weng

Exercise Biochemistry Section Guangzhou, Institute of Physical Education, Guangzhou, China 510075. - hliying@sina.com

    Genetic mechanism relevant to reactive oxygen species (ROS) during intermittent hypoxic training were studied, so that the theory on exercise and hypoxic acclimatization is provided.

    One hundred and twenty male Sprague-Dawley rats were randomly divided into three groups: normoxia group, acute hypoxia group and intermittent hypoxic group. Normoxia group included normoxia control and normoxia training sub-groups; acute hypoxia group included acute hypoxia control, acute hypoxia exercise and acute hypoxia training sub-groups; intermittent hypoxic group included intermittent hypoxic control and intermittent hypoxic training sub-groups. Therefore there are totally 12 sub-groups, each one with 10 rats. During the 4 weeks experimental period, we employed the 14.5 % and 12.6 % concentrations of oxygen (equal to altitude 3000 m and 4000 m respectively) in the hypoxic chamber. The rats of acute hypoxia training were introduced to treadmill running on an incline of 0 at 25 m/min for 1 h every day for 4 weeks. The rats of intermittent hypoxic were exposed to hypoxia for 12 h every day for 4 weeks. In addition, intermittent hypoxic training rats were kept running out of chamber with 1 h training bouts at the speed of 25 m/min every day. Mitochondria ROS were assessed by methods of DCFH-DA. The mRNA level of HIF-1a, VEGF, NF-kB (p65), c-fos, c-jun, MnSOD, CuZnSOD, GSH-Px in heart tissue and EPO in kidney tissue were investigated by RT-PCR.

    The results show that ROS generation is required for the induction of HIF-1 mRNA. During hypoxia, these findings reveal that mitochondria-derived ROS are both required and sufficient to initiate HIF-1a stabilization during hypoxia. And hypoxia activated transcription of EPO, VEGF-MnSOD, NF-kB, c-fos, c-Jun. We therefore conclude that ROS participate in the signalling pathways involved in the activation of multiple transcription factors. It is also indicated that there is a close relation between hypoxic acclimatization and gene expression of HIF-1, EPO, VEGF, MnSOD, NF-kB, c-fos, c-Jun and hypoxic acclimatization.

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