Effects of oral pergolide mesylate on nociceptive spinal cord reflexes in rats

The effects of orally administered pergolide mesylate on the flexor reflex were evaluated in chronic spinal rats. The mixed D1/D2 agonist pergolide (0.1 to 3.0 mg/kg) produced a dose-related decrease in the magnitude of the flexor reflex elicited by a tetanic stimulus. The effects of pergolide were blocked by haloperidol, demonstrating that the effects of pergolide were mediated through dopamine receptors. In contrast, the selective D2 agonist bromocriptine (3.0 to 30 mg/kg) had no effect on the flexor reflex. The present results are consistent with the interpretation that pergolide produces an antinociceptive action at the spinal cord level by stimulating both D1 and D2 dopamine receptors.