In this study, we have expanded the characterization of the antinociceptive effect of BDS 391 demonstrating that, in rats: (a) the compound inhibits (1.2-12 ng/paw) overt pain, in the formalin test, and mechanical hyperalgesia (0.6-6.0 ng/paw) detected in a model of neuropathic pain; (b) intraplantar administration of ondansetron, a selective 5-HT3 receptor antagonist, blocks the effect of BDS 391, whereas ketanserin, a 5-HT2 receptor antagonist, partially reversed this effect, indicating the involvement of peripheral 5-HT2 and 5-HT3 receptors in BDS 391 antinociception; and (c) in binding assay studies, BDS 391 was not able to displace the selective 5-HT receptor antagonists, suggesting that this compound does not directly bind to these receptors.
Four days after 2',3'-dideoxycytidine administration, rats had developed thermal allodynia as well as mechanical hyperalgesia and allodynia, which dose-dependently decreased after epidural injection of MDL 11,939, a 5-HT2A receptor antagonist.