LASTING EFFECTS OF DOPAMINE-RECEPTOR AGONISTS UPON STRIATAL DOPAMINE RELEASE IN FREE-MOVING RATS - AN IN-VIVO VOLTAMMETRIC STUDY

It is now well known that dopamine (DA) receptors agonists can reduce striatal DA release. These compounds are generally thought to produce short-term effects. However, in a recent in vivo study we have reporte d that the D-1/D-2 receptor agonist apomorphine might induce decrement s in striatal DA release that lasted several hours. In order to establ ish whether the effect of apomorphine was idiosyncratic or extended to other DA receptor agonists, we have investigated the effects of the s elective D-1 receptor agonist SKF 38393 and of the selective D-2 recep tor agonist LY 171555 upon striatal DA release using differential puls e voltammetry and multi-fibre carbon electrodes selective for DA. Resu lts support that these DA receptor agonists can reduce DA release for several hours. The effects of SKF 38393 and of LY 171555 would be DA r eceptor-mediated since they can be blocked by the selective D-1 recept or antagonist SCH 23390 and the selective D-2 receptor antagonist sulp iride respectively. These findings are discussed at the light of curre nt literature including methodological and biological data.