Antinociceptive effect of certain dihydroxy flavones in mice

This study was designed to evaluate the antinociceptive action of four dihydroxy flavone derivatives; 3,3'-dihydroxy flavone, 5,6-dihydroxy flavone, 3,7-dihydroxy flavone and 6,3'-dihydroxy flavone and to investigate the mechanisms involved.

The antinociceptive effect of dihydroxy flavones was investigated in mice employing acetic acid induced abdominal constrictions, formalin-induced nociception, and hot plate assay procedures. The effects following pretreatment with naloxone, yohimbine, ondansetron, haloperidol, bicuculline and glibenclamide were also studied by acetic acid assay to reveal the involvement of opioid, adrenergic, tryptaminergic, dopaminergic, GABAergic or potassium channels respectively in the antinociceptive action of these compounds.

Dihydroxy flavone derivatives significantly reduced the number of abdominal constrictions in acetic acid assay. The paw licking response time during both the early and late phases of formalin-induced nociception was reduced in a dose dependent manner by dihydroxy flavones treatment. A significant increase in reaction time was also evident in hot plate assay after dihydroxy flavones treatment. The antinociceptive effect of dihydroxy flavones in the acetic acid assay was significantly attenuated by pretreatment with either naloxone or bicuculline. However, pretreatment of animals with yohimbine, ondansetron, haloperidol, or glibenclamide did not alter the response.

All the four investigated dihydroxy flavones produced dose related antinociception through mechanisms that involve an interaction with opioid and GABAergic pathways.