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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 and oligomycin on synaptic vesicle numbers. (A) Number of lucid small synaptic vesicles after superfusion with control (green), RNS60 (red), or RNS60 after presynaptic injection of oligomycin (blue) in the presence of RNS60. (B) Number of clatherin-coated vesicles under the same three conditions as in panel (A). (C) Number of large, irregular vesicles under the same three conditions as in panel (A). ***p < 0.0001, **p < 0.001, *p < 0.05, Kruskal-Wakkus test.
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Figure 7: Effect of RNS60 and oligomycin on synaptic vesicle numbers. (A) Number of lucid small synaptic vesicles after superfusion with control (green), RNS60 (red), or RNS60 after presynaptic injection of oligomycin (blue) in the presence of RNS60. (B) Number of clatherin-coated vesicles under the same three conditions as in panel (A). (C) Number of large, irregular vesicles under the same three conditions as in panel (A). ***p < 0.0001, **p < 0.001, *p < 0.05, Kruskal-Wakkus test.

Mentions: There was a statistically significant decrease in SSV number in RNS60 ASW superfused terminals compared with control terminals (Figure 7A, red and green). By contrast, the number of CCVs was higher in RNS60 than control (Figure 7B, red and green) synapses but this difference did not reach significance. In addition, a large increase in the number of large vesicles (Figure 7C, red and green) suggests an increased vesicular turnover, as would be expected from an increased ATP level at the presynaptic terminal. These results are in accordance with our research on the relation between mitochondria and vesicular formation and availability (Ivannikov et al., 2013).


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 and oligomycin on synaptic vesicle numbers. (A) Number of lucid small synaptic vesicles after superfusion with control (green), RNS60 (red), or RNS60 after presynaptic injection of oligomycin (blue) in the presence of RNS60. (B) Number of clatherin-coated vesicles under the same three conditions as in panel (A). (C) Number of large, irregular vesicles under the same three conditions as in panel (A). ***p < 0.0001, **p < 0.001, *p < 0.05, Kruskal-Wakkus test.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Effect of RNS60 and oligomycin on synaptic vesicle numbers. (A) Number of lucid small synaptic vesicles after superfusion with control (green), RNS60 (red), or RNS60 after presynaptic injection of oligomycin (blue) in the presence of RNS60. (B) Number of clatherin-coated vesicles under the same three conditions as in panel (A). (C) Number of large, irregular vesicles under the same three conditions as in panel (A). ***p < 0.0001, **p < 0.001, *p < 0.05, Kruskal-Wakkus test.
Mentions: There was a statistically significant decrease in SSV number in RNS60 ASW superfused terminals compared with control terminals (Figure 7A, red and green). By contrast, the number of CCVs was higher in RNS60 than control (Figure 7B, red and green) synapses but this difference did not reach significance. In addition, a large increase in the number of large vesicles (Figure 7C, red and green) suggests an increased vesicular turnover, as would be expected from an increased ATP level at the presynaptic terminal. These results are in accordance with our research on the relation between mitochondria and vesicular formation and availability (Ivannikov et al., 2013).

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