Effects of the Putative Polyamine Antagonists Diethylenetriamine and 1,1 0-Diaminodecane on N-Methyl-D-Aspartic Acid-Stimulated [3H]Norepinephrine Release from Rat Hippocampal Slices1

N-Methyl-D-aspartic acid (NMDA, 500 MM) stimulated the net release of [3H]norepinephrine from rat hippocampal slices. The putative polyamine inverse agonist 1,1 0-diaminodecane (DA1 0) dose-dependently inhibited NMDA-stimulated release with a cal-culated lC value of 33 M. The putative polyamine competitive antagonist diethylenetriamine (DET) partially inhibited (maximum effect 40%) NMDA-stimulated release at 1 mM which was the highest concentration tested. DET (1 mM) but not DA1 0 also partially inhibited potassium-stimulated release of norepinephnne from hippocampal slices. Neither DET or DA1 0 significantly altered the nonstimulated basal efflux of neurotransmitter. The inhibition of NMDA-stimulated release produced by 1 00 zM DA1 0 or 1 mM DET was not attenuated by addition of the polyamines spermine or spermidine up to 1 mM. In addition, the lC value for DA1 0-induced inhibition of NMDA-stimulated neurotransmit