The role of Ca2+ in the generation of spontaneous astrocytic Ca2+ oscillations

Parri, H. R. and Crunelli, Vincenzo ORCID: https://orcid.org/0000-0001-7154-9752 2003. The role of Ca2+ in the generation of spontaneous astrocytic Ca2+ oscillations. Neuroscience 120 (4) , pp. 979-992. 10.1016/S0306-4522(03)00379-8

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Abstract

Astrocytes in the rat thalamus display spontaneous [Ca2+]i oscillations that are due to intracellular release, but are not dependent on neuronal activity. In this study we have investigated the mechanisms involved in these spontaneous [Ca2+]i oscillations using slices loaded with Fluo-4 AM (5 μM) and confocal microscopy. Bafilomycin A1 incubation had no effect on the number of spontaneous [Ca2+]ioscillations indicating that they were not dependent on vesicular neurotransmitter release. Oscillations were also unaffected by ryanodine. Phospholipase C (PLC) inhibition decreased the number of astrocytes responding to metabotropic glutamate receptor (mGluR) activation but did not reduce the number of spontaneously active astrocytes, indicating that [Ca2+]iincreases are not due to membrane-coupled PLC activation. Spontaneous [Ca2+]iincreases were abolished by an IP3 receptor antagonist, whilst the protein kinase C (PKC) inhibitor chelerythrine chloride prolonged their duration, indicating a role for PKC and inositol 1,4,5,-triphosphate receptor activation. BayK8644 increased the number of astrocytes exhibiting [Ca2+]i oscillations, and prolonged the responses to mGluR activation, indicating a possible effect on store-operated Ca2+ entry. Increasing [Ca2+]oincreased the number of spontaneously active astrocytes and the number of transients exhibited by each astrocyte. Inhibition of the endoplasmic reticulum Ca2+ ATPase by cyclopiazonic acid also induced [Ca2+]itransients in astrocytes indicating a role for cytoplasmic Ca2+in the induction of spontaneous oscillations. Incubation with 20 μM Fluo-4 reduced the number of astrocytes exhibiting spontaneous increases. This study indicates that Ca2+ has a role in triggering Ca2+release from an inositol 1,4,5,-triphosphate sensitive store in astrocytes during the generation of spontaneous [Ca2+]i oscillations.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences Neuroscience and Mental Health Research Institute (NMHRI)
ISSN:	0306-4522
Last Modified:	25 Oct 2022 10:05
URI:	https://orca.cardiff.ac.uk/id/eprint/61090

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