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Intravenously administered cell-permeant calcium buffer decreases evoked synaptic potentials in rat dentate gyrus in
I Spigelman1, A Obenaus, A Mazarati
1Section of Oral Biology, UCLA School of Dentistry, Los Angeles CA 90095-1668, USA. igor@ucla.edu
Abstract:
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.