Activity Dependent Changes to Astrocyte Resting Calcium

Abstract

The majority of research regarding astrocyte calcium responses has focused on large transients produced in response to stimulation, while little is known about the regulation and role of resting calcium levels. Recent findings suggest that resting astrocyte calcium provides tonic regulation of nearby arterioles, emphasizing the importance of investigating this factor. Here we examine the effects of specific patterns of synaptic activity, specifically theta burst stimulation, on resting astrocyte calcium levels. We observed a significant, long-lasting decrease in resting calcium concentrations in these cells following stimulation, an effect that was inhibited by ionotropic and metabotropic glutamate receptor antagonists. This decrease in resting calcium levels was not observed in neurons, and may be involved in eliciting the vasoconstriction of nearby vessels observed following stimulation. These results demonstrate a novel calcium response in astrocytes that may be relevant to the physiological roles of these glial cells in the neurovascular unit.