Intravenously administered cell-permeant calcium buffer decreases evoked synaptic potentials in rat dentate gyrus in vivo.
We examined the effects of the neuroprotective cell-permeant Ca2+ buffer, 2-aminophenol-N,N,O-triacetic acid acetoxymethyl ester (APTRA-AM, 20-40 mg/kg), on synaptically evoked potentials in the dentate gyrus of awake rats. Intravenous APTRA-AM (20 mg/kg) decreased the evoked potentials with peak effects approximately 6 h after infusion, and recovery to control levels by 24 h. Peak decrease in the population spike (PS) amplitude was by 72+/-17% of control, and the excitatory postsynaptic potential (EPSP) slope was decreased by 31+/-12%. APTRA-AM (40 mg/kg), decreased the PS amplitude and EPSP slope by 58+/-7% and 31+/-6% of pre-drug levels, respectively. These effects were qualitatively similar to the presynaptically mediated decreases in synaptic potentials previously demonstrated in vitro with APTRA-AM. These results indicate that the cell-permeant Ca2+ buffer, APTRA-AM, attenuates hippocampal excitability in vivo, most likely by decreasing synaptic neurotransmission.
Spigelman
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I
Section of Oral Biology, UCLA School of Dentistry, Los Angeles CA 90095-1668, USA. igor@ucla.edu
Obenaus
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A
Mazarati
A
A
Wasterlain
C G
CG
D000818:Animals; D002021:Buffers; D002118:Calcium / Q000502:physiology*; D018891:Dentate Gyrus / Q000187:drug effects*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects; D007275:Injections, Intravenous; D008297:Male; D009410:Nerve Degeneration / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000187:drug effects*
D002021:Buffers; D002118:Calcium