INTRANIGRAL INJECTIONS OF SCH-23390 INHIBIT SKF-82958-INDUCED ROTATIONAL BEHAVIOR

The selective Dl receptor antagonist, SCH 23390, was injected into the pars reticulata region of the lesioned substantia nigra at various co ncentrations (3.0, 1.5, 1.0, 0.6 or 0.3 mM) just before a s.c. injecti on of either the selective D1 agonist, SKF 82958; the selective D2 ago nist, quinpirole; or the mixed D1-D2 receptor agonist, apomorphine. SC H 23390 pretreatment (1) had no significant effect on quinpirole rotat ional behavior, (2) attenuated apomorphine rotational behavior and (3) dose-dependently inhibited SKF 82958 rotational behavior with the hig hest SCH 23390 doses completely blocking SKF 82958 rotational behavior in some animals. These data provide further evidence that dopamine re lease in the midbrain may act as a neuromodulator of motor behavior, a nd that Dl receptors play a functional role in this process.