Evidence for chelatable zinc in the extracellular space of the hippocampus, but little evidence for synaptic release of Zn

Alan R Kay

doi:10.1523/JNEUROSCI.23-17-06847.2003

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Evidence for chelatable zinc in the extracellular space of the hippocampus, but little evidence for synaptic release of Zn

Journal article

Open access

Peer reviewed

Evidence for chelatable zinc in the extracellular space of the hippocampus, but little evidence for synaptic release of Zn

Alan R Kay

The Journal of neuroscience, Vol.23(17), pp.6847-6855

07/30/2003

DOI: 10.1523/JNEUROSCI.23-17-06847.2003

PMCID: PMC6740710

PMID: 12890779

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Abstract

Zinc colocalizes with glutamate in the synaptic vesicles of certain glutamatergic vesicles in the mammalian brain. Here, I introduce a method for detecting Zn in the extracellular space of brain slices and another method for detecting the passage of Zn out of the slice. In both cases, the fluorimetric Zn probe FluoZin-3 is used in conjunction with a slow Zn chelator, Ca-EDTA, to reduce background fluorescence. In addition, a new Zn chelator, ethylenediiminodi-2-pentanedioic acid, with little affinity for Ca or Mg is introduced. These tools are then used to show that little Zn (approximately 2 nm) is released during the course of synaptic transmission into the extracellular space. However, when hippocampal slices are subjected to a high potassium stimulus (50 mM) combined with an increase in osmolarity, Zn is externalized in the Timm's-stained areas (approximately 6 nm). This stimulus also leads to even greater Zn elevations in area CA1 that is only weakly stained by the Timm's method. Nevertheless, even under these conditions, little if any Zn makes its way out of the slices. I present evidence for a layer of Zn in the extracellular space that maps onto the Timm's stained region of the hippocampus. This Zn veneer appears to be loosely associated with molecules in the extracellular space and may be the raison d'être for vesicular Zn.

Electric Stimulation

Synaptic Transmission - physiology

Rats, Wistar

Zinc - metabolism

Coloring Agents

Histocytochemistry - methods

Hippocampus - drug effects

Zinc - chemistry

Extracellular Space - metabolism

Osmolar Concentration

Synapses - metabolism

Sensitivity and Specificity

Binding, Competitive

Mice, Inbred C57BL

Chelating Agents - chemistry

Rats

Potassium - pharmacology

Stimulation, Chemical

Mice, Knockout

Hippocampus - metabolism

Patch-Clamp Techniques

Animals

Mice

Chelating Agents - metabolism

In Vitro Techniques

Fluorescent Dyes

Polycyclic Compounds

Details

Title: Subtitle: Evidence for chelatable zinc in the extracellular space of the hippocampus, but little evidence for synaptic release of Zn
Creators: Alan R Kay - Biological Sciences, University of Iowa, Iowa City, Iowa 52242, USA. alan-kay@uiowa.edu
Resource Type: Journal article
Publication Details: The Journal of neuroscience, Vol.23(17), pp.6847-6855
DOI: 10.1523/JNEUROSCI.23-17-06847.2003
PMID: 12890779
PMCID: PMC6740710
NLM abbreviation: J Neurosci
ISSN: 0270-6474
eISSN: 1529-2401
Publisher: United States
Grant note: NS35243 / NINDS NIH HHS
Comment: This work was supported by National Institute of Neurological Disorders and Stroke Grant NS35243.
Language: English
Date published: 07/30/2003
Academic Unit: Iowa Neuroscience Institute; Biology
Record Identifier: 9983991935102771

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