Calcium dynamics in astrocyte processes during neurovascular coupling

Nat Neurosci. 2015 Feb;18(2):210-8. doi: 10.1038/nn.3906. Epub 2014 Dec 22.

Abstract

Enhanced neuronal activity in the brain triggers a local increase in blood flow, termed functional hyperemia, via several mechanisms, including calcium (Ca(2+)) signaling in astrocytes. However, recent in vivo studies have questioned the role of astrocytes in functional hyperemia because of the slow and sparse dynamics of their somatic Ca(2+) signals and the absence of glutamate metabotropic receptor 5 in adults. Here, we reexamined their role in neurovascular coupling by selectively expressing a genetically encoded Ca(2+) sensor in astrocytes of the olfactory bulb. We show that in anesthetized mice, the physiological activation of olfactory sensory neuron (OSN) terminals reliably triggers Ca(2+) increases in astrocyte processes but not in somata. These Ca(2+) increases systematically precede the onset of functional hyperemia by 1-2 s, reestablishing astrocytes as potential regulators of neurovascular coupling.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / cytology
  • Astrocytes / metabolism*
  • Calcium Signaling / physiology*
  • Cerebrovascular Circulation / physiology*
  • Mice
  • Mice, Transgenic
  • Olfactory Bulb / cytology
  • Olfactory Bulb / metabolism*
  • Olfactory Receptor Neurons / metabolism
  • Olfactory Receptor Neurons / physiology*
  • Receptor, Metabotropic Glutamate 5 / metabolism
  • Synapses / metabolism*

Substances

  • Grm5 protein, mouse
  • Receptor, Metabotropic Glutamate 5