SYSTEMIC AND INTRASTRIATAL THEOPHYLLINE HAVE OPPOSITE EFFECTS ON DOPAMINE AND DOPAMINE METABOLITES MEASURED BY INTRASTRIATAL MICRODIALYSIS IN THE RAT

Using a model of intrastriatal microdialysis, we studied the effect of theophylline, an A(1) and A(2A) adenosine receptor antagonist on stri atal dopamine (DA) and DA metabolites. Systemic administration of theo phylline (10 and 50 mg/kg) significantly reduced striatal extracellula r (EC) levels of DA and its metabolites, 3,4-dihydroxyphenylacetic aci d (DOPAC) and 4-hydroxy-3-methoxy-phenylacetic acid (HVA). Intrastriat al administration of theophylline (10(-2) M) significantly increased D A and its metabolites (DA, +120%; DOPAC, +28%: HVA +30%). Contradictor y effects of systemic and intrastriatal theophylline point to theophyl line interactions with different receptors possibly at different locat ions.