Alpha 7 and beta 2*nicotinic receptors control monoamine-mediated locomotor response

Earlier studies reported exacerbated locomotor response to stress and tranylcypromine in beta 2 nicotinic acetylcholine receptor (nAChR) knockout (KO) mice. This study aimed to further assess the role of beta 2 and coexpressed nAChR subunits in the brain (alpha 4, alpha 6 and alpha 7) to control monoamine-mediated locomotor response, that is, response to novelty, saline, nicotine with tranylcypromine pretreatment, cocaine, d-amphetamine and morphine treatments. Results show that beta 2 KO mice were hyperreactive to novelty, cocaine and morphine. In contrast, alpha 7 KO mice were hyporeactive to tranylcypromine and cocaine. These results suggest that endogenous nAChR stimulation may exert a tonic control on monoamine-mediated locomotor responses. beta 2 and alpha 7-containing nAChR may contribute, respectively, to the inhibitory and permissive pathways of this tonic control