Induction of long-lasting potentiation by sequenced applications of isoproterenol.

Norepinephrine is associated with long-lasting modifications of neuronal activation in hippocampal slices. Long-lasting potentiation is produced by a single application of 1.0 microM isoproterenol (a beta-adrenergic antagonist) to the dentate gyrus. The results of the present work indicate that a much lower 75 nM concentration of isoproterenol produces long-lasting potentiation in the dentate gyrus if it is perfused in two applications separated by a 30 min wash. The potentiation so produced is prevented by beta-adrenergic receptor antagonists, but not prevented by the NMDA receptor antagonist aphosphonopentanoic acid. The implication of these results is that long-lasting potentiation in the dentate gyrus can be produced by more than one beta-adrenergic-activated mechanism.