Astrocytes are active participants in brain function

Astrocytes are electrically unexcitable cells that traditionally are regarded as the brain's support cells. A chief function of astrocytes is to maintain an optimal environment for synaptic transmission by tightly regulating interstitial ion and neurotransmitter concentrations. Other functions include production of neurotrophins and cytokines, and astrocytic endfeet are an essential part of the blood–brain barrier. In development, radial glial cells direct and support the migration of immature neurons. Several lines of work within the last few years have shown that astrocytes also participate more directly in neurotransmission. Astrocytes communicate with one another by calcium signaling and these calcium signals are transmitted to neurons. As such, astrocytes contribute to synaptic transmission. Recent reports have gone on to demonstrate that astrocytes are potent modulators of inhibitory transmission in the hippocampus and function as a necessary intermediary in long-term potentiation of GABAergic synapses (GABA is γ-aminobutyric acid).

Astrocytes have traditionally received little attention in the stroke field

Stroke research has paid little attention to astrocytes. During the last decade, the excitotoxin hypothesis has dominated the field. Since astrocytes are not sensitive to glutamate and survive exposure to 10 mM glutamate, it is not surprising that astrocytes have been regarded as minor players in the process of ischemic infarction. Also, astrocytes are highly resistant to ischemic conditions, whereas the viability of neurons is compromised within minutes.