L'étude in vivo de l'impact de la pression pulsée sur les capillaires cérébraux de souris
Many decades of research have given us a better understanding of the effects of atherosclerosis on different organs.  For example, works on the cardiovascular effects of atherosclerosis have improved the prevention, screening and treatment resulting in a better prognosis.  The effects of atherosclerosis on cerebral vessels are misunderstood even if the link between brain function and cerebral perfusion is well known. With the improvements in brain imaging, there are more possibilities to better define the physiopathology of brain perfusion and the impact of disease on cerebral microvasculature.  First, this work reviews the theory behind the development of two-photon laser microscopy (TPLM) and the measure of hemodynamics in small vessels such as cerebral capillaries in mice.  We also describe how we measured cerebral hemodynamics in anesthetized mice: red blood cell speed, red blood cell flux, blood hematocrit, and vessel diameter.  We compared results obtained between normal mice (WT ; n=6) and pathological mice (ATX ; n=6), all aged 3 months old.  ATX mice are well recognized to develop early atherosclerosis and served as a model for high pulse pressure.  We measured 209 cerebral capillaries (103 on WT mice and 106 on ATX mice).  ATX mice tend to show a trend toward a higher red blood cell speed (+40%), higher red blood cell flux (+12%) and higher capillary flux (+14%) in ATX mice.  Mean hematocrit (35±4% vs 33±2% ; p=0.71) and mean vessel diameter (4.88±0.22μm vs 4.86±0.20μm ; p=0.23)  were not statistically different between both groups. Red blood cell speed showed a weak correlation with vessel diameter (r=0.39) and red blood cell flux (r=0.59).  In conclusion, the TPLM should permit a better understanding of the effect of vascular disease in cerebral hemodynamics.  However, the effect of high pulse pressure on cerebral microvasculature needs to be better defined.
Microscopie laser 2-photons Cerebral hemodyamics Two-photon laser microscopy Cerebral pulse pressure Red blood cell velocity