Autoradiographic analysis of dopamine receptor-stimulated [S-35]GTP gamma S binding in rat striatum

Autoradiographic analysis of [S-35]GTP gammaS binding was used to investiga te functional activation of dopamine receptors in rat striatum. Dopamine-st imulated [S-35]GTP gammaS binding was observed with a maximal increase of 3 8% over basal activity. A similar stimulatory response was obtained with th e D-2, agonist quinpirole, but not SKF-238393, a D-1, agonist. The effect o f dopamine was blocked by the D-2 antagonist raclopride, but was unaffected by SCH-23990, a D-1, antagonist. There appeared to be a differential distr ibution of dopamine-stimulated [S-35]GTP gammaS binding, with the lowest ac tivity obtained in the medial portion of the caudal striatum. These results demonstrate, using an autoradiographic approach, (i) that dopamine stimula ted [S-35]GTP gammaS binding in the rat striatum occurs through activation of D-2, receptors, and (ii) that the effects of dopamine activation vary in different areas of the rat striatum. (C) 2000 Elsevier Science B.V. All ri ghts reserved.