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[Possible role of the AMPA/KA receptors in cultured Müller cells]
1Department of Ophthalmology, Kitasato University School of Medicine, Kanagawa-ken, Japan.
Abstract:
AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate)/KA (kainate) receptors have been demonstrated in cultured Müller cells in a study on cytosolic free calcium ions ([Ca2+]i). The action of these receptors may be expressed under pathological rather than physiological conditions. 1. Critical concentration in response to AMPA was determined in retinal neurons and Müller cells. At 0.05mM AMPA, in all neurons and in only a limited number of Müller cells (20%) cytosolic calcium transients occurred. 2. The level of lactate dehydrogenase (LDH) and the change in [Ca2+]i following AMPA administration were measured before and after exposure to 0.5mM KA. Neither morphological change nor leakage of LDH could be detected after 24 hours. When AMPA was administered, the responsive cell number was higher for KA-exposed cells than for control cells. Müller cells may be concluded to resist neurotoxic agents and may possibly be involved in the survival mechanism of retinal neurons.
Insights
Müller cells show resistance to neurotoxic agents, potentially aiding retinal neuron survival. AMPA/kainate receptor activation influences calcium signaling in these cells, particularly under pathological conditions.
Area of Science:
- Neuroscience
- Cell Biology
- Ophthalmology
Context:
- Müller cells, crucial for retinal function, express AMPA/kainate receptors.
- Receptor activity is more pronounced under pathological conditions than physiological ones.
- Cytosolic free calcium ions ([Ca2+]i) are key indicators of cellular response.
Purpose:
- To investigate the role and response of AMPA/kainate receptors in cultured Müller cells.
- To determine the critical concentration of AMPA for inducing calcium transients.
- To assess Müller cell resistance to neurotoxic agents and their potential role in retinal neuron survival.
Summary:
- AMPA/kainate receptors were studied in cultured Müller cells focusing on cytosolic calcium ([Ca2+]i) changes.
- A critical concentration of 0.05mM AMPA induced calcium transients in neurons and 20% of Müller cells.
- KA exposure increased AMPA responsiveness in Müller cells without causing cell damage or LDH leakage, suggesting neuroprotective potential.
Impact:
- Müller cells exhibit resistance to neurotoxic insults.
- These cells may play a role in the survival mechanisms of retinal neurons.
- Findings provide insights into glial cell responses in the retina.