On the mechanism of amphetamine-induced behavioural changes in the mouse. III. Effects of apomorphine and Fla 63.

The effects on 18 items of dexamphetamine-induced behaviour of increasing the ratio of dopaminergic to noradrenergic activity have been investigated in mice. The dopamine-beta-oxidase inhibitor bis-(4-methyl-1-homopiperazinyl-thiocarbonyl)-disulfide (Fla 63) produced varying degrees of reduction in the intensity of all items except raised body position, which was enhanced. Apomorphine alone induced compulsive gnawing and increased locomotor activity but produced long-lasting suppression of these and certain other items induced by dexamphetamine. Vocalisation, touch and startle responses and stereotyped sniffing were, however, unaffected while compulsive grooming and elevated body position were enhanced. The results are discussed in the context of the relative contribution of noradrenergic and dopaminergic mechanisms to the behavioural effects of dexamphetamine.