Tetrodotoxin reveals action of spermine at presynaptic N-methyl-D-aspartate receptors.
By testing the effect of spermine on N-methyl-D-aspartate (NMDA)-evoked [3H]noradrenaline release in rat hippocampal slices, we revealed a presynaptic spermine-sensitive NMDA receptor most probably localized on noradrenergic terminals. Spermine (1 mM), per se totally inactive, was able to reverse the tetrodotoxin-induced blockade of the NMDA effect, restoring tritium efflux to approximately 50% of the NMDA-evoked release measured in the absence of tetrodotoxin. This effect was partially antagonized by D(-)-2-amino-7-phosphonoheptanoic acid. Our results may help to elucidate the role that spermine exerts on excitatory amino acids receptors.
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CNS&CV Research Group, Farmitalia Carlo Erba-Erbamont Group, Milano, Italy.
Facheris
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Fariello
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RG
D000818:Animals; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects*; D013096:Spermine / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology*
D016194:Receptors, N-Methyl-D-Aspartate; D013096:Spermine; D013779:Tetrodotoxin; D009638:Norepinephrine