[Aging and brain circulation. Role of the extracellular matrix of brain microvessels].

Maintenance of normal brain activity is dependent among other factors on the maintenance of a functional blood-brain barrier (BBB), localised mainly at the capillary wall of cerebral microcirculation. The modifications of the BBB during aging play an important role in cognitive decline with aging as well as in dementias. A review of the experiments of our laboratory over the last decades is presented, on the interaction of endothelial cells with their basement membranes, both together representing a functional unit of BBB. The action of proteolytic enzymes on the basement membrane increases BBB permeability by increasing the transcellular transport activity of endothelial cells. Flavonoid drugs protect BBB from proteolytic activity by interacting with collagen fibers and protecting sensitive peptide bonds from attack by proteolytic enzymes. These drugs enhance also the resynthesis of degraded basement membranes.