5-HZ STIMULATION OF CA3 PYRAMIDAL CELL AXONS INDUCES A BETA-ADRENERGIC MODULATED POTENTIATION AT SYNAPSES ON CA1, BUT NOT CA3, PYRAMIDAL CELLS

In mouse hippocampal slices, long-term potentiation (LTP) at Schaffer collateral fiber synapses onto CA1 pyramidal cells could be induced by brief trains of 5-Hz synaptic stimulation (30 s) or by longer trains of 5-Hz stimulation (3 min) delivered during beta-adrenergic receptor activation. In contrast, 5-Hz stimulation, either alone or in the pres ence of the beta-adrenergic receptor agonist isoproterenol, failed to induce LTP at associational-commissural (assoc-com) fiber synapses ont o CA3 pyramidal cells. Our results suggest that although CA3 pyramidal cells give rise to both the Schaffer collateral fiber synapses in CA1 and the assoc-com fiber synapses in CA3, the induction of LTP at thes e synapses may be regulated by different activity- and modulatory neur otransmitter-dependent processes. (C) 1998 Elsevier Science B.V.