| 研究実績の概要 |
Physical exercise enhances fitness and overall health and wellness. Bouts of aerobic and anaerobic exercise induce an acute state of oxidative stress
caused by an increase in reactive oxygen species (ROS), but there is little agreement which processes generate ROS and where, if they are important and how they are controlled. We produced transgenic mice expressing redox-sensitive GFP in skeletal muscle, and set up imaging systems to record muscle redox state in live anesthetized animals.
Determining the conditions necessary for induction of oxidative stress during skeletal muscle activation in mice in vivo, preliminary experiments indicated that some amount of muscle fiber injury is necessary to induce oxidative stress during skeletal muscle activation. Simple electrical stimulation of muscle did not induce oxidation of the skeletal muscle glutathione pool. Injured muscle fibers became oxidized, but this oxidation did not spread to adjacent fibers in the absence of muscle activation.
We therefore built a system to combine precisely controlled muscle injury with electrical stimulation of muscled fibers to mimic exercise, and record muscle redox state during and after combinations of exercise and injury. The system was successfully tested in skin, producing about 200 micrometer diameter injuries.
Tissue-scale gradients of hydrogen peroxide have been reported to mediate rapid wound detection in zebrafish and to be required for tadpole tail regeneration. Our tests showed that oxidative stress occurs not immediately but within minutes after injury, in live mammalian skin.
|
| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
Preliminary results indicated the necessity for muscle fiber injury to induce oxidative stress during exercise. Our preliminary results were based serendipitously injured muscle fibers or mechanical injury produced with a lancing device. Use of the lancing device is accompanied by a delay between mechanical injury and recording redox state in the injured area caused by placing the muscle on a cover slip and locating the site of injury. The extent of injury is also not adjustable due to mechanical limitations and repeatability was rather poor. We therefore implemented a system to produce a microscopic thermal injury with a fiber-coupled infrared laser (1.5W,1470 nm). Precise damage could be produced through cover glass in a precise location, and the extent of injury can be adjusted by varying laser firing time and power.
|
| 今後の研究の推進方策 |
We will use the laser injury system to record oxidative stress in live muscle resulting from the interplay between injury and muscle activation. As planned, we will the continue dissecting the molecular pathways inducing oxidative stress, possible comparing muscle with skin, where we have obtained similar results.
We think that this oxidative stress signalling is mediated by normally intracellular danger-associated molecular patterns released from injured cells.
Our technology should allow us to record oxidative stress and injury-mediated signaling during exercise with unprecedented sensitivity and single cell resolution, and gain new insights into the mechanism(s) mediating oxidative stress signalling in vivo.
|
