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 μM isoproterenol (a β-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 β-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 β-adrenergic-activated mechanism.