title: Enhanced synaptic transmission at the squid giant synapse by artificial seawater based on physically modified saline.
abstract: Superfusion of the squid giant synapse with artificial seawater (ASW) based on isotonic saline containing oxygen nanobubbles (RNS60 ASW) generates an enhancement of synaptic transmission. This was determined by examining the postsynaptic response to single and repetitive presynaptic spike activation, spontaneous transmitter release, and presynaptic voltage clamp studies. In the presence of RNS60 ASW single presynaptic stimulation elicited larger postsynaptic potentials (PSP) and more robust recovery from high frequency stimulation than in control ASW. Analysis of postsynaptic noise revealed an increase in spontaneous transmitter release with modified noise kinetics in RNS60 ASW. Presynaptic voltage clamp demonstrated an increased EPSP, without an increase in presynaptic ICa(++) amplitude during RNS60 ASW superfusion. Synaptic release enhancement reached stable maxima within 5-10 min of RNS60 ASW superfusion and was maintained for the entire recording time, up to 1 h. Electronmicroscopic morphometry indicated a decrease in synaptic vesicle density and the number at active zones with an increase in the number of clathrin-coated vesicles (CCV) and large endosome-like vesicles near junctional sites. Block of mitochondrial ATP synthesis by presynaptic injection of oligomycin reduced spontaneous release and prevented the synaptic noise increase seen in RNS60 ASW. After ATP block the number of vesicles at the active zone and CCV was reduced, with an increase in large vesicles. The possibility that RNS60 ASW acts by increasing mitochondrial ATP synthesis was tested by direct determination of ATP levels in both presynaptic and postsynaptic structures. This was implemented using luciferin/luciferase photon emission, which demonstrated a marked increase in ATP synthesis following RNS60 administration. It is concluded that RNS60 positively modulates synaptic transmission by up-regulating ATP synthesis, thus leading to synaptic transmission enhancement.
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.
authors.forename: Soonwook
authors.initials: S
authors.lastname: Choi
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.
authors.forename: Eunah
authors.initials: E
authors.lastname: Yu
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Rabello
authors.affiliation: Department of Cell and Molecular Biology, Riberão Preto School of Medicine, University of São Paulo Ribeirão Preto, Brazil.
authors.forename: Suelen
authors.initials: S
authors.lastname: Merlo
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA.
authors.forename: Ajmal
authors.initials: A
authors.lastname: Zemmar
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.
authors.forename: Kerry D
authors.initials: KD
authors.lastname: Walton
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Departments of Neurology and Physiology/Pharmacology, The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center Brooklyn, NY, USA.
authors.forename: Herman
authors.initials: H
authors.lastname: Moreno
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Cell and Molecular Biology, Riberão Preto School of Medicine, University of São Paulo Ribeirão Preto, Brazil.
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Moreira
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.
authors.forename: Mutsuyuki
authors.initials: M
authors.lastname: Sugimori
authors.affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.
authors.forename: Rodolfo R
authors.initials: RR
authors.lastname: Llinás
keywords: calcium current; neurotransmitter release; physically modified water; squid giant synapse; synaptic transmission optimization