title: Arrays of microLEDs and astrocytes: biological amplifiers to optogenetically modulate neuronal networks reducing light requirement.
abstract: In the modern view of synaptic transmission, astrocytes are no longer confined to the role of merely supportive cells. Although they do not generate action potentials, they nonetheless exhibit electrical activity and can influence surrounding neurons through gliotransmitter release. In this work, we explored whether optogenetic activation of glial cells could act as an amplification mechanism to optical neural stimulation via gliotransmission to the neural network. We studied the modulation of gliotransmission by selective photo-activation of channelrhodopsin-2 (ChR2) and by means of a matrix of individually addressable super-bright microLEDs (μLEDs) with an excitation peak at 470 nm. We combined Ca2+ imaging techniques and concurrent patch-clamp electrophysiology to obtain subsequent glia/neural activity. First, we tested the μLEDs efficacy in stimulating ChR2-transfected astrocyte. ChR2-induced astrocytic current did not desensitize overtime, and was linearly increased and prolonged by increasing μLED irradiance in terms of intensity and surface illumination. Subsequently, ChR2 astrocytic stimulation by broad-field LED illumination with the same spectral profile, increased both glial cells and neuronal calcium transient frequency and sEPSCs suggesting that few ChR2-transfected astrocytes were able to excite surrounding not-ChR2-transfected astrocytes and neurons. Finally, by using the μLEDs array to selectively light stimulate ChR2 positive astrocytes we were able to increase the synaptic activity of single neurons surrounding it. In conclusion, ChR2-transfected astrocytes and μLEDs system were shown to be an amplifier of synaptic activity in mixed corticalneuronal and glial cells culture.
authors.affiliation: School of Electric and Electronic Engineering - Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom.
authors.forename: Rolando
authors.initials: R
authors.lastname: Berlinguer-Palmini
authors.affiliation: Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Narducci
authors.affiliation: School of Electric and Electronic Engineering - Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom.
authors.forename: Kamyar
authors.initials: K
authors.lastname: Merhan
authors.affiliation: Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy.
authors.forename: Arianna
authors.initials: A
authors.lastname: Dilaghi
authors.affiliation: Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy.
authors.forename: Flavio
authors.initials: F
authors.lastname: Moroni
authors.affiliation: Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Masi
authors.affiliation: Department of Health Science, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy.
authors.forename: Tania
authors.initials: T
authors.lastname: Scartabelli
authors.affiliation: Department of Health Science, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Landucci
authors.affiliation: Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Sili
authors.affiliation: Department of Health Science, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Schettini
authors.affiliation: Institute of Biomedical Engineering, Imperial College, London, United Kingdom.
authors.forename: Brian
authors.initials: B
authors.lastname: McGovern
authors.affiliation: Tyndall National Institute of Technology, Cork, Ireland.
authors.forename: Pleun
authors.initials: P
authors.lastname: Maskaant
authors.affiliation: School of Electric and Electronic Engineering - Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom.
authors.forename: Patrick
authors.initials: P
authors.lastname: Degenaar
authors.affiliation: Department of Neuroscience, Psychology, Drug Research and Child Health Section of Pharmacology and Toxicology, University of Florence, Florence, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Mannaioni
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000528:radiation effects; D000075402:Channelrhodopsins; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology; D008027:Light; D008297:Male; D009415:Nerve Net / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D009474:Neurons / Q000378:metabolism* / Q000528:radiation effects*; D055095:Optics and Photonics / Q000295:instrumentation*; D062308:Optogenetics / Q000295:instrumentation*; D051381:Rats; D013997:Time Factors; D014162:Transfection
chemical_list: D000075402:Channelrhodopsins; D018698:Glutamic Acid; D002118:Calcium