β1-Adrenoceptor or α1-adrenoceptor activation initiates early odor preference learning in rat pups: Support for the mitral cell/cAMP model of odor preference learning

We proposed that mitral cell beta1-adrenoceptor activation mediates rat pup odor preference learning. Here we evaluate beta1-, beta2-, alpha1-, and alpha2-adrenoceptor agonists in such learning. The beta1-adrenoceptor agonist, dobutamine, and the alpha1-adrenoceptor agonist, phenylephrine, induced learning, and both exhibited an inverted U-curve dose-response relationship to odor preference learning. Phenylephrine-induced learning occurred in the presence of propranolol to prevent indirect activation of beta-adrenoceptors. Alpha1-adrenoceptor mediation may represent a novel mechanism inducing learning or may increase cAMP in mitral cells via indirect activation of GABA(B) receptors. Neither the beta2-adrenoceptor agonist, salbutamol, nor the alpha2-adrenoceptor agonist, clonidine, induced learning.