Motor depressant effects mediated by dopamine D-2 and adenosine A(2A) receptors in the nucleus accumbens and the caudate-putamen

We compared hypolocomotion and catalepsy mediated by striatal dopamine D-2 and adenosine A(2A) receptors using microinfusions of the adenosine A(2A) receptor agonist 2-p-(2-carboxyethyl) phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS21680) and the dopamine D-2 receptor antagonist raclopride into the nucleus accumbens and the caudate-putamen. The effective doses (ED(25/50)) of CGS21680 and raclopride which produced equivalent reductions of spontaneous locomotion after microinfusion into the nucleus accumbens were found to induce similar degrees of catalepsy after microinfusion into the caudate-putamen. This comparable, little separation of the effective doses of a dopamine D-2 receptor antagonist and an adenosine A(2A) receptor agonist to produce locomotor inhibition and catalepsy support the idea that adenosine A(2A) receptor agonists as potential antipsychotic agents may have a similiar therapeutic profile as dopamine D-2 receptor antagonists. (C) Elsevier Science B.V.