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Enhanced synaptic transmission at the squid giant synapse by artificial seawater based on physically modified saline.

Choi S, Yu E, Rabello G, Merlo S, Zemmar A, Walton KD, Moreno H, Moreira JE, Sugimori M, Llinás RR - Front Synaptic Neurosci (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.

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.

No MeSH data available.


Related in: MedlinePlus

Effect of RNS60 on ATP synthesis. (A) The levels of luciferin/luciferase light emission in control ASW (Cont) and 3 and 6 min following RNS60 superfusion. (B) Presynaptic and postsynaptic action potentials in control ASW. (C) Action potentials recorded 3 min after superfusion with RNS60. (D) Action potentials recorded 6 min after superfusion with RNS60. (E) Drawing of presynaptic (green) and postsynaptic (red) element is superimposed on photograph of postsynaptic light emission. Presynaptic light emission is shown above the drawing. (F) Postsynaptic light emission 2 and 5 min after superfusion with RNS60. Note increase in postsynaptic resting potential in (C,D), indicating an improvement of postsynaptic axon viability that is consistent with the increased level of ATP measured at the postsynaptic terminal following RNS60 ASW superfusion.
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Figure 5: Effect of RNS60 on ATP synthesis. (A) The levels of luciferin/luciferase light emission in control ASW (Cont) and 3 and 6 min following RNS60 superfusion. (B) Presynaptic and postsynaptic action potentials in control ASW. (C) Action potentials recorded 3 min after superfusion with RNS60. (D) Action potentials recorded 6 min after superfusion with RNS60. (E) Drawing of presynaptic (green) and postsynaptic (red) element is superimposed on photograph of postsynaptic light emission. Presynaptic light emission is shown above the drawing. (F) Postsynaptic light emission 2 and 5 min after superfusion with RNS60. Note increase in postsynaptic resting potential in (C,D), indicating an improvement of postsynaptic axon viability that is consistent with the increased level of ATP measured at the postsynaptic terminal following RNS60 ASW superfusion.

Mentions: There was a clear increase in ATP levels from control levels, as indicated by the increased light emission recorded 3 and 6 min after the superfusate was changed from control to RNS60 ASW (Figure 5A). During this same period there was a small decrease in the resting potential of the presynaptic terminal, but no change in the action potential amplitude (Figures 5B–D). There was an increase in the resting potential in the postsynaptic axon from control levels at 3 min (Figures 5B,C). The resting potential continued to improve between 3 and 6 min after starting RNS60 superfusion. Unlike the presynaptic element, there was increase in the amplitude of the postsynaptic action potential (Figures 5B–D). An increase in postsynaptic ATP in the presence of RNS60 ASW is shown in Figures 5E,F. The results indicate that the increase in synaptic transmission following RNS60 superperfusion is accompanied by an increase in ATP levels in both the presynaptic and postsynaptic terminals.


Enhanced synaptic transmission at the squid giant synapse by artificial seawater based on physically modified saline.

Choi S, Yu E, Rabello G, Merlo S, Zemmar A, Walton KD, Moreno H, Moreira JE, Sugimori M, Llinás RR - Front Synaptic Neurosci (2014)

Effect of RNS60 on ATP synthesis. (A) The levels of luciferin/luciferase light emission in control ASW (Cont) and 3 and 6 min following RNS60 superfusion. (B) Presynaptic and postsynaptic action potentials in control ASW. (C) Action potentials recorded 3 min after superfusion with RNS60. (D) Action potentials recorded 6 min after superfusion with RNS60. (E) Drawing of presynaptic (green) and postsynaptic (red) element is superimposed on photograph of postsynaptic light emission. Presynaptic light emission is shown above the drawing. (F) Postsynaptic light emission 2 and 5 min after superfusion with RNS60. Note increase in postsynaptic resting potential in (C,D), indicating an improvement of postsynaptic axon viability that is consistent with the increased level of ATP measured at the postsynaptic terminal following RNS60 ASW superfusion.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921564&req=5

Figure 5: Effect of RNS60 on ATP synthesis. (A) The levels of luciferin/luciferase light emission in control ASW (Cont) and 3 and 6 min following RNS60 superfusion. (B) Presynaptic and postsynaptic action potentials in control ASW. (C) Action potentials recorded 3 min after superfusion with RNS60. (D) Action potentials recorded 6 min after superfusion with RNS60. (E) Drawing of presynaptic (green) and postsynaptic (red) element is superimposed on photograph of postsynaptic light emission. Presynaptic light emission is shown above the drawing. (F) Postsynaptic light emission 2 and 5 min after superfusion with RNS60. Note increase in postsynaptic resting potential in (C,D), indicating an improvement of postsynaptic axon viability that is consistent with the increased level of ATP measured at the postsynaptic terminal following RNS60 ASW superfusion.
Mentions: There was a clear increase in ATP levels from control levels, as indicated by the increased light emission recorded 3 and 6 min after the superfusate was changed from control to RNS60 ASW (Figure 5A). During this same period there was a small decrease in the resting potential of the presynaptic terminal, but no change in the action potential amplitude (Figures 5B–D). There was an increase in the resting potential in the postsynaptic axon from control levels at 3 min (Figures 5B,C). The resting potential continued to improve between 3 and 6 min after starting RNS60 superfusion. Unlike the presynaptic element, there was increase in the amplitude of the postsynaptic action potential (Figures 5B–D). An increase in postsynaptic ATP in the presence of RNS60 ASW is shown in Figures 5E,F. The results indicate that the increase in synaptic transmission following RNS60 superperfusion is accompanied by an increase in ATP levels in both the presynaptic and postsynaptic terminals.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Marine Biological Laboratory Woods Hole, MA, USA ; Department of Neuroscience and Physiology, New York University School of Medicine New York, NY, USA.

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.

No MeSH data available.


Related in: MedlinePlus