Microglia modulate the cerebrovascular reactivity through ectonucleotidase CD39
Microglia and the border-associated macrophages contribute to the modulation of cerebral blood flow, but the mechanisms have remained uncertain. Here, we show that microglia regulate the cerebral blood flow baseline and the responses to whisker stimulation or intra-cisternal magna  injection of adenosine triphosphate, but not intra-cisternal magna injection of adenosine in mice model. Notably, microglia repopulation corrects these cerebral blood flow anomalies. The microglial-dependent regulation of cerebral blood flow requires the adenosine triphosphate-sensing P2RY12 receptor and ectonucleotidase CD39 that initiates the dephosphorylation of extracellular adenosine triphosphate into adenosine in both male and female mice. Pharmacological inhibition or CX3CR1-CreER-mediated deletion of CD39 mimics the cerebral blood flow anomalies in microglia-deficient mice and reduces the upsurges of extracellular adenosine following whisker stimulation. Together, these results suggest that the microglial CD39-initiated breakdown of extracellular adenosine triphosphate co-transmitter is an important step in neurovascular coupling and the regulation of cerebrovascular reactivity. Overall design: Three groups are included. Five mice were included in each group. The first group is control group, in which mice were treated with control food. The second group is PLX3397 food treated mice group. In this group microglia were depleted by CSF1r inhibitor. The third group is repopulation group. In this group, mice were first treated with PLX3397 to deplete microglia and then put back to control food for microglia to repopulate.