Activity-dependent regulation of vascular cholesterol metabolism acts as a negative feedback mechanism for neurovascular coupling
Brain function is dependent on a continuous supply of bloodborne oxygen and nutrients. Because neurons require a greater supply of oxygen and nutrients when active, there is increased local blood flow following neuronal activity. The underlying mechanisms of this hyperemia are termed neurovascular coupling (NVC). Many complex processes contribute to NVC, and there is still much unknown about how vascular physiology adapts to changes in neuronal activity and blood flow. Here we show that neuronal activity increases brain endothelial expression of genes related to cholesterol synthesis and uptake in vivo, and that shear stress is sufficient for upregulation of these genes in vitro. We previously found that treatment with PLX5622 induces upregulation of the same cassette of cholesterol-related genes in brain endothelial cells. In the present study, we find that increasing brain endothelial cholesterol synthesis and/or uptake, either with PLX5622 or targeted AAV-mediated expression of LDLR, inhibits brain arteriole dilation in response to capillary K+ stimulation, and this deficit is rescued by cholesterol depletion. Together, these data suggest that neuronal activity regulates brain endothelial cholesterol, which in turn blocks endothelial retrograde signaling and vasodilation, thus acting as a negative feedback mechanism for NVC.