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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

Reduction of spontaneous synaptic release following oligomycin administration. Plot of noise amplitude as a function of frequency (note double log coordinates). Red, control ASW; green, 7 min after addition of oligomycin; blue, 22 min after oligomycin administration and 12 min after changing superfusate to RNS60 ASW. Black, extracellular recording.
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Figure 6: Reduction of spontaneous synaptic release following oligomycin administration. Plot of noise amplitude as a function of frequency (note double log coordinates). Red, control ASW; green, 7 min after addition of oligomycin; blue, 22 min after oligomycin administration and 12 min after changing superfusate to RNS60 ASW. Black, extracellular recording.

Mentions: Presynaptic intracellular oligomycin injection (0.25 mg/ml) during control ASW superfusion markedly reduced spontaneous release from control levels (compare Figure 6, red vs. green). This occurred rapidly in all experiments. A reduction of more than an order of magnitude occurred within the first 7 min after oligomycin injection into the presynaptic terminal. Changing the superfusion to RNS60 ASW 22 min after injection of oligomycin failed to increase spontaneous transmitter release (Figure 6, blue trace, recorded 12 min after the start of RNS60 ASW superfusion). Similar findings were noted in 5 experiments. Thus, RNS60 ASW failed to rescue synaptic transmission from the reduction caused by ATP depletion.


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)

Reduction of spontaneous synaptic release following oligomycin administration. Plot of noise amplitude as a function of frequency (note double log coordinates). Red, control ASW; green, 7 min after addition of oligomycin; blue, 22 min after oligomycin administration and 12 min after changing superfusate to RNS60 ASW. Black, extracellular recording.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Reduction of spontaneous synaptic release following oligomycin administration. Plot of noise amplitude as a function of frequency (note double log coordinates). Red, control ASW; green, 7 min after addition of oligomycin; blue, 22 min after oligomycin administration and 12 min after changing superfusate to RNS60 ASW. Black, extracellular recording.
Mentions: Presynaptic intracellular oligomycin injection (0.25 mg/ml) during control ASW superfusion markedly reduced spontaneous release from control levels (compare Figure 6, red vs. green). This occurred rapidly in all experiments. A reduction of more than an order of magnitude occurred within the first 7 min after oligomycin injection into the presynaptic terminal. Changing the superfusion to RNS60 ASW 22 min after injection of oligomycin failed to increase spontaneous transmitter release (Figure 6, blue trace, recorded 12 min after the start of RNS60 ASW superfusion). Similar findings were noted in 5 experiments. Thus, RNS60 ASW failed to rescue synaptic transmission from the reduction caused by ATP depletion.

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