Background:
Reactive oxygen species (ROS) play a central role in cigarette smoking-induced atherogenesis. The present study aims to assess the smoking-induced acute oxidative stress within vasculatures, and evaluates whether the resveratrol, a natural polyphenol antioxidant, can counteract this ROS production, using a customized, high resolution intravital optical imaging in real-time.
Methods and Results:
20-week-old male C57BL/6 mice were divided into four groups according to the preceding administration of resveratrol (R) (25mg/kg via gavage, for 7 days) and exposure to cigarette smoke (CS). To in vivo assess acute oxidative stress in blood vessels, dihydroethidium, which forms a red fluorescence (ethidium, excitation/emission: 520nm/610nm) upon reaction with ROS, was injected intraperitoneally. During CS exposure, temporal changes of fluorescence signals from the mouse cremaster muscle including vasculatures were assessed by intravital optical imaging for 15 minutes. Fluorescence signals were much more pronounced in CS exposed mice than controls (p<0.001). Resveratrol p.o. significantly reduced the CS-induced ROS signals compared to the non-treated group (fluorescence signal to noise ratio, SNR, 2.51±0.09 vs. 12.52±2.116, p=0.0002) (Figure A). Without CS exposure, fluorescence signals in targeted vasculatures were very low showing no difference between groups (SNR, 1.65±0.19 vs. 1.53±0.07, p=0.80) (Figure A). Lipid peroxidation was increased in CS group and significantly attenuated in resveratrol-treated mice (Figure B). Fluorescence microscopy and immunostainings corroborated the in vivo findings.
Conclusions:
The intravital optical imaging was able to in vivo estimate the dynamic changes of ROS production by CS exposure. Our data demonstrated that even a brief exposure to CS increased oxidative stress in vasculatures promptly, and the resveratrol exerts protective effects against the CS-induced acute oxidative stress.
Real-Time, In Vivo Determination of Dynamic Changes in Lung and Heart Tissue Oxygenation Using EPR Oximetry
