Influence of chemical stimulation of central dopaminergic system on the open field behaviour of rats.

Influence of some substances known to selectively modify the brain levels of dopamine, was studied on the Open Field behaviour in rats. Of the agents studied, I-dopa, benztropine and amantadine showed some similarity with amphetamine in exhibiting a high degree of complex stereotyped behaviour in rats. The complex stereotyped behaviour due to amphetamine and the similarity shown by these antiparkinsonian agents has been explained on the basis of brain dopamine levels. On the other hand apomorphine depressed the Open Field behaviour and produced a typical stereotyped biting in rats. Since 6-hydroxydopamine significantly prevented this biting behaviour, it has been suggested that the action of apomorphine is dependent on the presence of (i) functional state of catecholamine neurons and (ii) a separate receptor, responsible for the behavioural actions of apomorphine.