Extrapyramidal and mesolimbic involvement with the stereotypic activity of D- and L-amphetamine

Abstract

The electrolytic brain lesion technique was use to investigate the role of the dopamine-containing areas and pathways of the extrapyramidial and mesolimbic systems in the mediation of the stereotyped behaviour patterns induced by D- and L-amphetamine in the rat. Interruption of the ascending dopaminergic neurones from the mesencephalon at the level of the lateral hypothalamus did not modify the dose-dependent stereotypy induced by D- or L-amphetamine, whilst a lesion placed in the rostral hypothalamus to interrupt the dopaminergic innervation to the mesolimbic brain areas was shown to abolish the wearker intensity component of stereotypy (sniffing and repetitive head movements). Of the areas innervated by this pathway, lesion of the tuberculum olfactorium, but not the nucleus interstitialis stria terminalis or nucleus accumbens septi, also abolished sniffing behaviour. Lesions placed in the neostriatal area of the extrapyramidal system were without significant effect whilst lesion of the paleostriatum abolished all components of stereotypy. Lesion of the central amygdaloid nucleus only abolised the more intense components of both D- and L-amphetamine stereotypy (bitting, gnawing and licking). The brain studies demonstrate a differential involvement of the dopamine-containing areas of the mesolimbic and extrapyramidal brain regions, and the associated dopaminergic neurones which ascend from the mesencephalon, with the stereotyped behaviour patterns induced by both D- and L-amphetamine.