Pharmacological differentiation of the effects of co-activation of β-adrenergic and metabotropic glutamate receptors in rat hippocampus

Activation of metabotropic glutamate receptors (mGluRs) can potentiate the cAMP response elicited by activation of β-adrenergic receptors (βARs) in the hippocampus. We have shown that co-activation of mGluRs and βARs induces both an acute depression of excitatory synaptic transmission and a long-lasting excitation of CA1 pyramidal cells. However, these studies were performed using a non-selective mGluR agonist. We have now used subtype selective mGluR agonists, and report that while the acute depression of transmission exhibits a pharmacology consistent with mediation by this mGluR subtype, the lasting excitation of CA1 pyramidal cells may be mediated by an interaction between βARs and mGluRs that are coupled to phosphoinositide hydrolysis.