The blood-brain barrier(BBB)maintains a stable microenvironment for neural function.Its disruption causes leakage of blood-borne factors and cells into the brain,leading to the damage of neural tissues.The mechanisms underlying the BBB formation remain largely elusive.In the present study,we find that microRNA-132(miR-132),a neuron-enriched microRNA,is required for the integrity of zebrafish brain vasculature during development.Knockdown of miR-132 in zebrafish with miR-132 morpholino results in severe intracranial hemorrhage,and a lot of blood cells are accumulated in the brain ventricles and even brain parenchyma.Interestingly,the defects can be mimicked by specific knockdown of miR-132 in neurons with miR-132 sponge,indicating that neuronal miR-132 is necessary for brain vessel integrity.Using cell cultures,we further find that miR-132 can be transferred from neurons into endothelial cells via exosomes.Mechanistically,miR-132 targets eukaryotic elongation factor 2 kinase(eEF2K)to regulate the expression of VE-cadherin,which is important for blood vessel integrity.Thus,our findings demonstrate that neuronal miR-132 can regulate the development of brain vessel integrity via a cell-cell communication process.