The contribution of astrocyte signalling to neurovascular coupling.

The tight spatial and temporal coupling between neuronal activity and blood flow ensures that active brain regions receive an adequate supply of oxygen and energetic metabolites. There clearly is still an enormous amount of experimental and theoretical work to be done to unravel the precise mechanism of neurovascular coupling, but over the last decade significant advances have been made. The most recent studies confirm the original finding that the activation of Ca(2+) elevations in astrocyte endfeet is an essential step but also reveal new levels of complexity in the astrocyte control of neurovascular coupling. The recent evidence for a link between Ca(2+) signalling in astrocytes and local metabolic states of the brain tissue has broad implications for the interpretation of data from functional brain imaging studies. Unraveling the full molecular mechanism of the astrocyte control of cerebral blood flow represents a formidable challenge in neurobiological research in the years to come that might also create opportunities for the development of new therapeutic strategies for cerebrovascular diseases such as ischemic stroke, hypertension and migraine as well as neurodegenerative diseases as Alzheimer's disease. Copyright 2009 Elsevier B.V. All rights reserved.