SPERMINE DEPRESSES NMDA, K AMPA AND GABA(A)-MEDIATED SYNAPTIC TRANSMISSION IN THE RAT HIPPOCAMPAL SLICE PREPARATION/

The effects of spermine, an endogenous polyamine, were examined in are a CA1 of the rat hippocampal slice preparation. Spermine, at low milli molar concentrations, rapidly and potently depressed NMDA and K/AMPA-m ediated population EPSPs, and GABA-mediated monosynaptic population IP SPs. These effects contrast with its well-known potentiation of NMDA c urrents at lower concentrations. Our results raise the possibility tha t the large intracellular stores of spermine that are released after v arious neural insults could act as an endogenous neuroprotective mecha nism by:limiting excessive calcium entry.