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GABA induces Ca2+ transients in astrocytes
M Nilsson1, P S Eriksson, L Rönnbäck
1Institute of Neurobiology, University of Göteborg, Sweden.
Neuroscience
|June 1, 1993
Summary
This study shows that GABA receptors on type 1 astrocytes can trigger calcium signals. These signals are influenced by GABA uptake blockers, suggesting intracellular calcium mobilization.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Astrocytes play crucial roles in brain function.
- GABAergic signaling is vital for neuronal communication.
- The role of GABA receptors in astrocyte calcium signaling is not fully understood.
Purpose of the Study:
- To investigate the presence and function of GABAA and GABAB receptors in rat cortical astrocytes.
- To determine the mechanisms underlying GABA-induced calcium transients in astrocytes.
Main Methods:
- Primary cultures of rat cortical astrocytes were used.
- Cytosolic calcium levels ([Ca2+]i) were measured using Fura-2/AM.
- Astrocytes were stimulated with GABA, muscimol (GABAA agonist), and baclofen (GABAB agonist).
- Antagonists (bicuculline, phaclofen) and GABA uptake blockers were employed.
Main Results:
- Both GABAA and GABAB receptor stimulation evoked calcium transients in type 1 astrocytes.
- Responses varied (single-phase, biphasic) and showed latency.
- Response frequency increased in mixed astroglial/neuronal cultures.
- GABA-evoked responses were partially dependent on extracellular calcium and internal stores.
- GABA uptake blockers reduced GABA-evoked calcium rises.
- Nifedipine did not affect GABA-evoked calcium transients.
Conclusions:
- Type 1 astrocytes express functional GABAA and GABAB receptors.
- GABA receptor activation elevates astrocyte intracellular calcium via direct/indirect pathways involving calcium channels and internal stores.
- GABA may also act on intracellular sites to mobilize calcium.