Increased beta adrenoceptor activation overcomes conditioned olfactory learning deficits induced by serotonin depletion.

It was hypothesized that 5-HT2 receptors in the olfactory bulb prime the bulbar response to a beta adrenoceptor mediated unconditioned stimulus (UCS) during odor preference learning in 1-week-old rat pups. The ability of 4 mg/kg of isoproterenol + stroking and 6 mg/kg of isoproterenol + no stroking to induce normal odor preference learning in pups depleted of bulbar 5-HT in the present study supports the hypothesis. The inverted-U curve relation between UCS strength and learning also appears to occur within the bulb.