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Cholinergic agonists increase intracellular Ca2+ in cultured human microglia
L Zhang1, J G McLarnon, V Goghari
1Department of Medicine, Faculty of Medicine, The University of British Columbia, Vancouver, Canada.
Neuroscience Letters
|December 5, 1998
Summary
Human microglia, immune cells in the brain, possess functional muscarinic receptors. Cholinergic agonists like carbachol activate these receptors, causing calcium signals that may play a role in central nervous system (CNS) pathology.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are the primary immune cells of the central nervous system (CNS).
- Microglial activation can be influenced by neurotransmitters.
- Cholinergic signaling is crucial in various physiological and pathological processes within the CNS.
Purpose of the Study:
- To investigate the effects of cholinergic agonists on intracellular calcium levels ([Ca2+]i) in human microglia.
- To determine if human microglia express functional muscarinic receptors.
- To elucidate the role of calcium signaling in microglial responses to cholinergic stimulation.
Main Methods:
- Primary human microglia cultures were utilized.
- Fura-2 imaging was employed to measure intracellular calcium ([Ca2+]i) dynamics.
- Carbachol (CCh), a muscarinic agonist, was used to stimulate microglia.
- Atropine was used to assess receptor sensitivity.
Main Results:
- Carbachol (CCh) induced a transient increase in intracellular calcium ([Ca2+]i) in human microglia.
- The CCh-induced calcium response was sensitive to atropine, indicating muscarinic receptor involvement.
- Calcium release originated from intracellular stores.
- Repeated CCh applications led to desensitization of the calcium signaling response.
Conclusions:
- Human microglia express functional muscarinic receptors.
- Cholinergic agonists activate a calcium signaling pathway in microglia.
- This calcium signaling may act as a second messenger, influencing downstream cascades in CNS pathology.