EFFECTS OF DOPAMINE RECEPTOR AGONISTS AND ANTAGONISTS ON BACLOFEN-INDUCED ANTINOCICEPTION IN FORM ALIN TEST

In this study, the influence of dopamine receptor agonists and antagonists on antinociception induced by bac10fen has been examined in the formalin test. The GABA-B agonist bac10fen induced antinociception in both phases of the formalin test in mice. The dopamine receptor agonists SKF 38393 and quinpirole also induced antinociception in both phases of the test. SKF 38393 but not quinpirole potentiated the response to bac10fen in the first phase of the test. The dopamine receptor antagonists SCH 23390 and sulpiride increased the response to baclofen in the first phase. Both drugs induced antinociception in the first phase of the fonnalin test. However, low doses of sulpiride increased the pain response in the second phase. The peripheral dopamine receptor antagonist domperidone did not alter the effect of the test by itself. Dopamine receptor mechanisms appear to interact with baclofen-induced antinociception.