Morphological profile determines the frequency of spontaneous calcium events in astrocytic processes

Majority of spontaneous Ca2+ events start in thin astrocytic processes
Higher surface ‐to‐volume ratio of the process is responsible for larger intracellular Ca2+ fluctuations
Larger intracellular Ca2+ fluctuations trigger Ca2+‐dependent Ca2+ release AbstractAstrocytes express a complex repertoire of intracellular Ca2+ transients (events) that represent a major form of signaling within individual cells and in astrocytic syncytium. These events have different spatiotemporal profiles, which are modulated by neuronal activity. Spontaneous Ca2+ events appear more frequently in distal astrocytic processes and independently from each other. However, little is known about the mechanisms underlying such subcellular distribution of the Ca2+ events. Here, we identify the initiation points of the Ca2+ events within the territory of single astrocytes expressing genetically encoded Ca2+ indicator GCaMP2 in culture or in hippocampal slices. We found that most of the Ca2+ events start in an optimal range of thin distal processes. Our mathematical model demonstrated that a high surface ‐to‐volume of the thin processes leads to increased amplitude of baseline Ca2+ fluctuations caused by a stochastic opening of Ca2+ channels in the plasma membrane. Suprathreshold fluctuations trigger Ca2+‐induced Ca2+ release from the Ca2+ stores by activating inositol 1,4,5 ‐trisphosphate (IP3) receptors. In agreement with the model prediction, the spontaneous Ca2+ events frequency depended on t...

Source: Glia - November 22, 2018 Category: Neurology Authors: Yu ‐Wei Wu, Susan Gordleeva, Xiaofang Tang, Pei‐Yu Shih, Yulia Dembitskaya, Alexey Semyanov Tags: RESEARCH ARTICLE Source Type: research