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FAD-Linked Autofluorescence and Chemically-Evoked Zinc Changes at Hippocampal Mossy Fiber-CA3 Synapses

Bastos, Fatima M.C. ; Matias, Carlos M. ; Lopes, Ines O. ; Vieira, João P. LU ; Santos, Rosa M. ; Rosario, Luis M. ; Quinta-Ferreira, Rosa M. and Quinta-Ferreira, Maria Emília (2021)
Abstract
Glutamatergic vesicles in hippocampal mossy fiber presynaptic boutons release zinc, which plays a modulatory role in synaptic activity and LTP. In this work, a fluorescence microscopy technique and the fluorescent probe for cytosolic zinc, Newport Green (NG), were applied, in a combined study of autofluorescence and zinc changes at the hippocampal mossy fiber-CA3 synaptic system. In particular, the dynamics of flavoprotein (FAD) autofluorescence signals, was compared to that of postsynaptic zinc signals, elicited both by high K+ (20 mM) and by tetraethylammonium (TEA, 25 mM). The real zinc signals were obtained subtracting autofluorescence values, from corresponding total NG-fluorescence data. Both autofluorescence and zinc-related... (More)
Glutamatergic vesicles in hippocampal mossy fiber presynaptic boutons release zinc, which plays a modulatory role in synaptic activity and LTP. In this work, a fluorescence microscopy technique and the fluorescent probe for cytosolic zinc, Newport Green (NG), were applied, in a combined study of autofluorescence and zinc changes at the hippocampal mossy fiber-CA3 synaptic system. In particular, the dynamics of flavoprotein (FAD) autofluorescence signals, was compared to that of postsynaptic zinc signals, elicited both by high K+ (20 mM) and by tetraethylammonium (TEA, 25 mM). The real zinc signals were obtained subtracting autofluorescence values, from corresponding total NG-fluorescence data. Both autofluorescence and zinc-related fluorescence were raised by high K+. In contrast, the same signals were reduced during TEA exposure. It is suggested that the initial outburst of TEA-evoked zinc release might activate ATP-sensitive K+ (KATP) channels, as part of a safeguard mechanism against excessive glutamatergic action. This would cause sustained inhibition of zinc signals and a more reduced mitochondrial state. In favor of the “KATP channel hypothesis”, the KATP channel blocker tolbutamide (250 μM) nearly suppressed the TEA-evoked fluorescence changes. It is concluded that recording autofluorescence from brain slices is essential for the accurate assessment of zinc signals and actions. (Less)
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author
; ; ; ; ; ; and
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
host publication
Hippocampus - New Advances [Working Title]
editor
Zhang, Prof. Xinhua
publisher
IntechOpen
DOI
10.5772/intechopen.100898
language
English
LU publication?
no
id
f573775e-5c82-4c28-b737-01f3d0ab8997
date added to LUP
2021-11-09 10:22:48
date last changed
2021-11-15 13:08:29
@inbook{f573775e-5c82-4c28-b737-01f3d0ab8997,
  abstract     = {{Glutamatergic vesicles in hippocampal mossy fiber presynaptic boutons release zinc, which plays a modulatory role in synaptic activity and LTP. In this work, a fluorescence microscopy technique and the fluorescent probe for cytosolic zinc, Newport Green (NG), were applied, in a combined study of autofluorescence and zinc changes at the hippocampal mossy fiber-CA3 synaptic system. In particular, the dynamics of flavoprotein (FAD) autofluorescence signals, was compared to that of postsynaptic zinc signals, elicited both by high K+ (20 mM) and by tetraethylammonium (TEA, 25 mM). The real zinc signals were obtained subtracting autofluorescence values, from corresponding total NG-fluorescence data. Both autofluorescence and zinc-related fluorescence were raised by high K+. In contrast, the same signals were reduced during TEA exposure. It is suggested that the initial outburst of TEA-evoked zinc release might activate ATP-sensitive K+ (KATP) channels, as part of a safeguard mechanism against excessive glutamatergic action. This would cause sustained inhibition of zinc signals and a more reduced mitochondrial state. In favor of the “KATP channel hypothesis”, the KATP channel blocker tolbutamide (250 μM) nearly suppressed the TEA-evoked fluorescence changes. It is concluded that recording autofluorescence from brain slices is essential for the accurate assessment of zinc signals and actions.}},
  author       = {{Bastos, Fatima M.C. and Matias, Carlos M. and Lopes, Ines O. and Vieira, João P. and Santos, Rosa M. and Rosario, Luis M. and Quinta-Ferreira, Rosa M. and Quinta-Ferreira, Maria Emília}},
  booktitle    = {{Hippocampus - New Advances [Working Title]}},
  editor       = {{Zhang, Prof. Xinhua}},
  language     = {{eng}},
  month        = {{11}},
  publisher    = {{IntechOpen}},
  title        = {{FAD-Linked Autofluorescence and Chemically-Evoked Zinc Changes at Hippocampal Mossy Fiber-CA3 Synapses}},
  url          = {{http://dx.doi.org/10.5772/intechopen.100898}},
  doi          = {{10.5772/intechopen.100898}},
  year         = {{2021}},
}