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Spiral intercellular calcium waves in hippocampal slice cultures
M E Harris-White1, S A Zanotti, S A Frautschy
1Department of Medicine, UCLA/Veterans Affairs Medical Center, Sepulveda, CA 91343, USA.
Journal of Neurophysiology
|April 18, 1998
Summary
Astrocytes in the hippocampus exhibit complex intercellular calcium (Ca2+) waves, behaving like an excitable medium. Neuronal activity modulates these glial cell network signals.
Area of Science:
- Neuroscience
- Cell Biology
- Glial Cell Biology
Background:
- Intercellular calcium (Ca2+) signaling plays a crucial role in neuronal communication and network activity.
- Astrocytes, once considered passive support cells, are increasingly recognized for their active role in modulating synaptic transmission and brain function.
Purpose of the Study:
- To investigate the characteristics and cellular basis of spontaneous intercellular calcium waves in hippocampal slice cultures.
- To determine the role of astrocytes in propagating these calcium signals and their modulation by neuronal activity.
Main Methods:
- Organotypic hippocampal slice cultures from neonatal mice were used.
- Calcium imaging techniques were employed to visualize intercellular Ca2+ waves.
- Pharmacological agents (thapsigargin, NMDA, tetrodotoxin) and manipulation of extracellular calcium were used to probe the mechanisms.
Main Results:
- Spontaneous, localized intercellular Ca2+ waves involving 5-15 cells and extensive waves involving hundreds of cells were observed in CA1 and CA2 regions.
- These Ca2+ waves propagated primarily in astrocytes at rates of 5-10 µm/s and were independent of extracellular Ca2+ but sensitive to thapsigargin.
- Wave frequency and amplitude increased with NMDA application and decreased with Ca2+ removal or tetrodotoxin, indicating modulation by neuronal activity.
Conclusions:
- Hippocampal astrocytes exhibit complex intercellular Ca2+ signaling patterns characteristic of an excitable medium.
- Glial cell networks in the hippocampus may function as a dynamic signaling system modulated by neuronal activity, influencing overall brain function.