Neurons and glial cells of the central nervous system (CNS) communicate and work together to function and execute an array of complex tasks. In addition to them a third cell type which also works to keep the brain alive are the cerebral endothelial cells that create the vascular system which supply and deliver oxygen and nutrients. The cerebral endothelium is also specialized with a blood-brain barrier (BBB) that is important for protecting the CNS from harmful substances and for regulating

more »

... ss only to certain ions and nutrients for optimal maintenance and support of CNS activities. A complex of tight junction proteins which include occludin, Claudin-1/3, Claudin-5, and ZO1-3 are thought to keep the endothelium impermeable, while a system of transporters, such as GLUT1 and P-gp are involved in regulating the molecular trafficking across the BBB. The endothelium is also characterized by a low pinocytotic activity compared to vessels in peripheral organs. A lot is known on the formation and composition of the BBB, but less is understood on the maintenance. This is probably due to the heterogeneity of the cerebral endothelium, which makes it difficult to study. However, the cerebrovascular function is supported by a combination of interactions with glia, pericytes, and nerve cells, known together as the neurovascular unit (NVU). A number of in vitro studies show that co-8