Ca2+ signaling in astrocytes from Ip3r2−/− mice in brain slices and during startle responses in vivo

Intracellular Ca2+ signaling is considered to be important for multiple astrocyte functions in neural circuits. However, mice devoid of inositol triphosphate type 2 receptors (IP3R2) reportedly lack all astrocyte Ca2+ signaling, but display no neuronal or neurovascular deficits, implying that astroc...

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Published in:Nature neuroscience 2015-04, Vol.18 (5), p.708-717
Main Authors: Srinivasan, Rahul, Huang, Ben S, Venugopal, Sharmila, Johnston, April D, Chai, Hua, Zeng, Hongkui, Golshani, Peyman, Khakh, Baljit S
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Language:eng
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Summary:Intracellular Ca2+ signaling is considered to be important for multiple astrocyte functions in neural circuits. However, mice devoid of inositol triphosphate type 2 receptors (IP3R2) reportedly lack all astrocyte Ca2+ signaling, but display no neuronal or neurovascular deficits, implying that astrocyte Ca2+ fluctuations are not involved in these functions. An assumption has been that the loss of somatic Ca2+ fluctuations also reflects a similar loss in astrocyte processes. We tested this assumption and found diverse types of Ca2+ fluctuations in astrocytes, with most occurring in processes rather than in somata. These fluctuations were preserved in Ip3r2-/- (also known as Itpr2-/- ) mice in brain slices and in vivo, occurred in end feet, and were increased by G protein-coupled receptor activation and by startle-induced neuromodulatory responses. Our data reveal previously unknown Ca2+ fluctuations in astrocytes and highlight limitations of studies that used Ip3r2-/- mice to evaluate astrocyte contributions to neural circuit function and mouse behavior.
ISSN:1097-6256
1546-1726