Spontaneous astrocytic Ca2+ activity abounds in electrically suppressed ischemic penumbra of aged mice

We report preserved spontaneous Ca2+ activity in neurons, and increased astrocytic Ca2+ activity in the penumbra of old mice. AbstractExperimental focal cortical ischemic lesions consist of an ischemic core and a potentially salvageable peri ‐ischemic region, the ischemic penumbra. The activity of neurons and astrocytes is assumed to be suppressed in the penumbra because the electrical function is interrupted, but this is incompletely elucidated. Most experimental stroke studies used young adult animals, whereas stroke is prevalent in the elderly population. Using two‐photon imaging in vivo, we here demonstrate extensive but electrically silent, spontaneous Ca2+ activity in neurons and astrocytes in the ischemic penumbra of 18 ‐ to 24‐month‐old mice 2–4 hr after middle cerebral artery occlusion. In comparison, stroke reduced spontaneous Ca2+ activity in neurons and astrocytes in adult mice (3 –4 months of age). In aged mice, stroke increased astrocytic spontaneous Ca2+ activity considerably while neuronal spontaneous Ca2+ activity was unchanged. Blockade of action potentials and of purinergic receptors strongly reduced spontaneous Ca2+ activity in both neurons and astrocytes in the penumbra of old stroke mice. This indicates that stroke had a direct influence on mechanisms in presynaptic terminals and on purinergic signaling. Thus, highly dynamic variations in spontaneous Ca2+ activity characterize the electrically compromised penumbra, with remarkable differenc...
Source: Glia - Category: Neurology Authors: Tags: RESEARCH ARTICLE Source Type: research