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Negative modulation of presynaptic activity by zinc released from schaffer collaterals
Author(s) -
Takeda Atsushi,
Fuke Sayuri,
Tsutsumi Wataru,
Oku Naoto
Publication year - 2007
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.21449
Subject(s) - schaffer collateral , chemistry , calcium , synaptic cleft , biophysics , neuroscience , synaptic vesicle , glutamate receptor , extracellular , long term potentiation , biochemistry , biology , membrane , vesicle , receptor , organic chemistry
The role of zinc in excitation of Schaffer collateral‐CA1 pyramidal cell synapses is poorly understood. Schaffer collaterals stained with ZnAF‐2 or ZnAF‐2DA, a membrane‐impermeable or a membrane‐permeable zinc indicator, respectively, were treated by tetanic stimulation (200 Hz, 1 sec). Extracellular and intracellular ZnAF‐2 signals were increased in the stratum radiatum of the CA1, in which Schaffer collateral synapses exist. Both the increases were completely blocked in the presence of 1 mM CaEDAT, a membrane‐impermeable zinc chelator, suggesting that 1 mM CaEDTA is effective for chelating zinc released from Schaffer collaterals. The role of Schaffer collateral zinc in presynaptic activity was examined by using FM4‐64, a fluorescent indicator for vesicular exocytosis. The decrease in FM4‐64 signal during tetanic stimulation (10 Hz, 180 sec) was enhanced in Schaffer collaterals in the presence of 1 mM CaEDTA but suppressed in the presence of 5 μM ZnC1 2 , suggesting that zinc released from Schaffer collaterals suppresses presynaptic activity during tetanic stimulation. When Schaffer collateral synapses stained with calcium orange AM, a membrane‐permeable calcium indicator, were regionally stimulated with 1 mM glutamate, calcium orange signal was increased in the CA1 pyramidal cell layer. This increase was enhanced in the presence of CaEDTA and attenuated in the presence of zinc. These results suggest that zinc attenuates excitation of Schaffer collateral synapses elicited with glutamate via suppression of presynaptic activity. © 2007 Wiley‐Liss, Inc.