Pathway specificity of l-isoproterenol indicates β-adrenergic modulation of the Schaffer collateral pathway in field CA1 in the rat hippocampal slice

Behavioral relevance of norepinephrine is associated with neuronal processing underlying arousal, affect, attention, learning and memory, and is associated with β-adrenergic modifications of neuronal activation in the hippocampal formation. This study utilized l-isoproterenol to initiate pathway-specific activation of afferents to hippocampal CA1 pyramidal cells. The consistent effects of l-isoproterenol on the initiation of action potentials to field CA1 pyramidal neurons to single-pulse stimulation was repeatedly associated with the activation of the Schaffer collateral pathway. In contrast, l-isoproterenol plus single-pulse stimulation never elicited action potential initiation of the perforant pathway to CA1. We interpret these results as indicating that β-adrenergic modification underlies the augmentation of information processing via the Schaffer collateral pathway in the trisynaptic circuit vs the direct perforant pathway.