title: Interactions between adenosine and dopamine receptor antagonists with different selectivity profiles: Effects on locomotor activity.
abstract: Forebrain dopamine (DA) is a critical component of the brain circuitry regulating behavioral activation. Adenosine A(2A) antagonists reverse many of the behavioral effects of DA antagonists, and A(2A) receptors are co-localized with D(2) receptors on striatal medium spiny neurons. The present work was undertaken to determine if the ability of an A(2A) antagonist, a non-selective adenosine antagonist, or an A(1) antagonist to reverse the locomotor effects of DA blockade in rats differed depending upon whether D(1) or D(2) family receptors were being antagonized. The adenosine antagonists MSX-3, caffeine, DPCPX and CPT were studied for their ability to reverse the locomotor suppression induced by the D(1) antagonist SCH 39166 (ecopipam) and the D(2) antagonist eticlopride. The D(1) and D(2) antagonists suppressed locomotion in all experiments. The adenosine A(2A) receptor antagonist MSX-3 (0.5-2.0 mg/kg IP) significantly reversed the suppression of locomotion induced by eticlopride. The non-selective adenosine antagonist caffeine (5.0-20.0 mg/kg IP) also reversed the effect of eticlopride, though the effect was not as robust as that seen with MSX-3. The adenosine A(1) antagonists DPCPX (0.375-1.5 mg/kg) and CPT (3.0-12.0 mg/kg IP) were unable to reverse the locomotor impairment elicited by eticlopride. Furthermore, the attenuation of locomotion induced by the D(1) antagonist could only be reversed by the highest dose of MSX-3, but not by caffeine, DPCPX or CPT. DA and adenosine receptor antagonists interact in the regulation of locomotor activation, but the nature of this interaction appears to depend upon the receptor selectivity profiles of the specific drugs being tested.
authors.affiliation: Dept. of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA.
authors.forename: Lyndsey E
authors.initials: LE
authors.lastname: Collins
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Galtieri
authors.forename: Patricia
authors.initials: P
authors.lastname: Collins
authors.forename: Shawnet K
authors.initials: SK
authors.lastname: Jones
authors.forename: Russell G
authors.initials: RG
authors.lastname: Port
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Paul
authors.forename: Jörg
authors.initials: J
authors.lastname: Hockemeyer
authors.forename: Christa E
authors.initials: CE
authors.lastname: Müller
authors.forename: John D
authors.initials: JD
authors.lastname: Salamone
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D016548:Prosencephalon / Q000187:drug effects*; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000187:drug effects* / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000145:classification / Q000378:metabolism
chemical_list: D018492:Dopamine Antagonists; D058915:Purinergic P1 Receptor Antagonists; D011954:Receptors, Dopamine; D018047:Receptors, Purinergic P1