M. Galarreta et al., NICOTINAMIDE ADENINE DINUCLEOTIDES MIMIC ADENOSINE INHIBITION ON SYNAPTIC TRANSMISSION BY DECREASING GLUTAMATE RELEASE IN RAT HIPPOCAMPAL SLICES, Neuroscience letters, 159(1-2), 1993, pp. 55-58
To assess the possible inhibitory action of nicotinamide adenine dinuc
leotides on the synaptic release of glutamate, electrophysiological an
d biochemical experiments were performed on rat hippocampal slices. Pe
rfusion of adenosine, 8-nicotinamide adenine dinucleotide (NAD) or bet
a-nicotinamide adenine dinucleotide phosphate (NADP), reversibly inhib
ited the field excitatory postsynaptic potentials (fEPSP). Dose-respon
se curves for their inhibitory action showed that these three substanc
es had a similar potency in the range of concentrations from 0.1 muM t
o 100 muM. NADP and adenosine (100 muM) halved the K+-induced release
of endogenous glutamate and aspartate, leaving gamma-amino-butyric aci
d (GABA) levels unchanged. 3-Isobutyl-1-methylxanthine (IBMX) 200 muM,
an antagonist of the P1-purinoreceptors, antagonized the depressant e
ffects of these coenzymes on both fEPSP and also on amino acid release
. Based on these results we propose that nicotinamide adenine dinucleo
tides, similar to adenosine, inhibit excitatory synaptic transmission
in the rat hippocampus by decreasing glutamate release from synaptic t
erminals.