Amphetamine- and apomorphine-induced alteration of the behavior of rats submitted to a competitive situation in a straight runway

The influence of various doses of apomorphine and amphetamine on the behavior of rats submitted to a competitive situation for food in a straight runway was studied. Both drugs significantly increased the number of victories. Experiments performed to verify whether pretreatment with pimozide or chlorpromazine would antagonize this effect were not conclusive since the neuroleptics disrupted the competitive behavior of several animals and failed to block the increase of victories induced by apomorphine and amphetamine in the remaining rats. Larger doses of the neuroleptics could not be used because these stopped the animals competing. The possibility that apomorphine and amphetamine increased the number of victories by acting, respectively, through a direct effect on central dopamine receptors and by releasing dopamine from the storage sites, and the eventual role played by catecholamines on the competitive behavior studied are discussed.