A novel approach for vital visualization and studying of neurons containing Ca2+‐permeable AMPA receptors

• Published in: Journal of neurochemistry 2023-03, Vol.164 (5), p.583-597
• Main Authors: Gaidin, Sergei G., Maiorov, Sergei A., Laryushkin, Denis P., Zinchenko, Valery P., Kosenkov, Artem M.
• Format: Article
• Language: English
• Subjects: 1‐Naphthyl acetyl spermine; Ca2+‐permeable AMPA receptors; Calcium; Calcium channels; Calcium channels (voltage-gated); Calcium influx; Calcium ions; Calcium permeability; Cell culture; GABAergic neurons; Glutamic acid receptors; hippocampal cell culture; N-Methyl-D-aspartic acid receptors; Nervous system; Neurons; paroxysmal depolarization shift; Permeability; Receptors; Synapses; Synaptic plasticity; Synaptogenesis; vesicular GABA transporter; Visualization; α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid; α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors; γ-Aminobutyric acid
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/jnc.15729

Calcium‐permeable AMPA receptors (CP‐AMPARs) play a pivotal role in brain functioning in health and disease. They are involved in synaptic plasticity, synaptogenesis, and neuronal circuits development. However, the functions of neurons expressing CP‐AMPARs and their role in the modulation of network activity remain elusive since reliable and accurate visualization methods are absent. Here we developed an approach allowing the vital identification of neurons containing CP‐AMPARs. The proposed method relies on evaluating Ca2+ influx in neurons during activation of AMPARs in the presence of NMDAR and KAR antagonists, and blockers of voltage‐gated Ca2+ channels. Using this method, we studied the properties of CP‐AMPARs‐containing neurons. We showed that the overwhelming majority of neurons containing CP‐AMPARs are GABAergic, and they are distinguished by higher amplitudes of the calcium responses to applications of the agonists. Furthermore, about 30% of CP‐AMPARs‐containing neurons demonstrate the presence of GluK1‐containing KARs. Although CP‐AMPARs‐containing neurons are characterized by more significant Ca2+ influx during the activation of AMPARs than other neurons, AMPAR‐mediated Na+ influx is similar in these two groups. We revealed that neurons containing CP‐AMPARs demonstrate weak GABA(A)R‐mediated inhibition because of the low percentage of GABAergic synapses on the soma of these cells. However, our data show that weak GABA(A)R‐mediated inhibition is inherent to all GABAergic neurons in the culture and cannot be considered a unique feature of CP‐AMPARs‐containing neurons. We believe that the suggested approach will help to understand the role of CP‐AMPARs in the mammalian nervous system in more detail. We proposed the method of a vital visualization of neurons containing calcium‐permeable AMPA receptors. Application of the selective AMPARs agonists in the presence of NMDAR, KAR antagonists and blockers of voltage‐gated calcium channels allow identifying neurons with CP‐AMPARs by a [Ca2+]i elevation in the soma. We believe that the proposed method will help the researchers to better understand the physiological role of CP‐AMPARs in brain functioning.