Reduced Notch signaling in BBB vascular endothelial cells mediates high fat diet-induced alterations in brain glucose uptake and insulin signaling

Short term transition to high-fat diet (HFD) feeding causes rapid changes in the molecular architecture of the blood-brain-barrier (BBB), BBB permeability and brain glucose uptake. However, the precise mechanisms responsible for these changes remain elusive. Here we detected a rapid downregulation of Notch signaling after short-term HFD feeding. Conversely, Notch activation restores HFD-fed mouse serum induced reduction of Glut1 expression and glycolysis in cultured brain microvascular endothelial cells (BMECs). Selective, inducible expression of Notch-intracellular domain (IC) in BMECs prevents HFD-induced reduction of Glut1 expression and hypothalamic glucose uptake. Caveolin (Cav)-1 expression in BMECs is increased upon short term HFD feeding. However, NotchICBMECs mice display reduced caveola formation and BBB permeability. This ultimately translates into reduced hypothalamic insulin transport, action and systemic insulin sensitivity. Collectively, we highlight a critical role of Notch-signaling in the pleiotropic effects of short-term dietary transitions on BBB functionality.