CO2 signaling mediates neurovascular coupling in the cerebral cortex

Neurovascular coupling is a fundamental brain mechanism that regulates local cerebral blood flow (CBF) in response to changes in neuronal activity. Functional imaging techniques are commonly used to record these changes in CBF as a proxy of neuronal activity to study the human brain. However, the mechanisms of neurovascular coupling remain incompletely understood. Here we show in experimental animal models (laboratory rats and mice) that the neuronal activity-dependent increases in local CBF in the somatosensory cortex are prevented by saturation of the CO2-sensitive vasodilatory brain mechanism with surplus of exogenous CO2 or disruption of brain CO2/HCO3- transport by genetic knockdown of electrogenic sodium-bicarbonate cotransporter 1 (NBCe1) expression in astrocytes. A systematic review of the literature data shows that CO2 and increased neuronal activity recruit the same vasodilatory signaling pathways. These results and analysis suggest that CO2 mediates signaling between neurons and the cerebral vasculature to regulate brain blood flow in accord with changes in the neuronal activity. The mechanism of neurovascular coupling ensures that the brain energy supply is sufficient to meet demand. Here the authors show that in this mechanism CO2 plays an important role in neuronal activity-dependent regulation of local brain blood flow.

Automated summary

The study indicates that CO2 plays a crucial role in regulating neurovascular coupling by mediating signaling between neurons and cerebral blood vessels to adjust local brain blood flow based on neuronal activity. The neurovascular coupling mechanism ensures an adequate energy supply for the brain to meet demands.