Mesolimbic deficits exacerbate amphetamine treatment: clinical implications for drug abusers

Amphetamine, a common drug used by abusers, is able to produce a schizophreniform psychosis in man. The experiment reported here examined amphetamine in relation to its role in the nucleus accumbens septi (NAS) and the globus pallidus. The effects produced by apomorphine, a direct dopamine (DA) agonist, were compared with those of amphetamine, a known indirect DA agonist. The data revealed that amphetamine in NAS-lesioned animals produced very active stereotypy which intensified with time. This effect was blocked by pallidal lesioning. Apomorphine in pallidectomised rats produced persistent stereotypy, but of diminished intensity. The results are discussed in terms of the mediating roles of the NAS and globus pallidus on behavioural sequelae. (AU)

Effects of interruption of pallidal function on striatal-mediated motor activity: relevance to concepts in neurology and psychiatry

This work was conducted to evaluate the effects of bilateral lesion of the globus pallidus on spontaneous motor behaviour and drug-induced stereotypy. The evidence suggests that the pallidus is necessary for the expression of normal motor behaviour. Bilateral lesioned rats manifested hypoactivity. This hypoactivity or response depression was counteracted by low and high doses of amphetamine. Apomorphime (1.0 mg/kg) induced a normalizing effect on spontaneous motor activity in lesioned rats. However this higher dose of apomorphine induced marked stereotypic activity in lesioned rats. The results of this work raise important implications for certain motor disorders and the psychoses. (AU)