Wall climbing, odors from the home nest and catecholaminergic activity in rat pups.

The present investigation examined the relationship among wall climbing, home nest odors, circadian rhythmicity and catecholaminergic activity. In the first experiment, a catecholaminergic agonist, amphetamine, was observed to induce wall climbing in 10- but not 15-day old rat pups. It was observed in the second experiment that an alpha-adrenergic antagonist, phentolamine, attenuated wall climbing elicited by foot shock in 10-day old rat pups without affecting general locomotor activity. However, haloperidol, a dopaminergic antagonist, was observed to decrease both shock-elicited wall climbing and general locomotor activity in rat pups at this age. These results support the hypothesis that wall climbing may be partially mediated by catecholaminergic activity. Home nest odors decreased both amphetamine-induced wall climbing for animals tested during the dark cycle in Experiment 1 and shock-induced wall climbing for subjects tested both during the light and dark phases in Experiment 2. This attenuation by home nest odors of both drug- and shock-elicited wall climbing suggests the further hypothesis that home nest odors may influence the level of catecholaminergic activity.