Diverse Calcium Signaling in Astrocytes: Insights from a Computational Model

Astrocytes are complex cells that influence a variety of brain functions and behaviors. They are active cells that show a sharp increase in intracellular Ca2+ concentration in response to neurotransmitters (events called Ca2+ signals). The main source of intracellular Ca2+ is the stores in endoplasmic reticulum (ER), released by the activation of IP3 receptor channels on the ER membrane. As neurons, astrocytes from different brain regions show distinct Ca2+ signals. In addition, astrocytes can also show different patterns of Ca2+ responses. It is not yet clear how the diversity of astrocyte response emerge from the same mechanisms. Here we present a two variable astrocyte compartmental model for the Ca2+ and IP3 dynamics. We show that Ca2+ signals with different characteristics can emerge from changing the parameters associated with the Ca2+ and IP3 dynamics and the transmembrane current. We also show that global Ca2+ signals are required for the model to trigger different patterns of Ca2+ responses. The model present here can be used to simulate astrocytes from different brain regions and with distinct types of response.