Lysionotin exerts antinociceptive effects in various models of nociception induction.

Background: Lysionotin, a natural flavonoid extracted from Methods: The antinociceptive effects of various lysionotin doses (50, 100, 150, and 200 μg/kg) were assessed in mice using the acetic acid-induced writhing test, hot plate test, and formalin-induced paw licking assay. The effects were compared to those of mice treated with acetylsalicylic acid or morphine in the presence or absence of naloxone (an opioid receptor antagonist). Capsaicin- and glutamate-induced paw licking tests were also used to evaluate the involvement of the vanilloid and glutamatergic systems, respectively. Results: Lysionotin produced significant dose-dependent inhibition of nociceptive behavior in the acetic acid-induced writhing test, showing 60% inhibition at a dose of 200 μg/kg. Lysionotin also caused a significant increase in the latency period in response to the hot plate test (76.4% at 200 μg/kg), and significantly inhibited both the neurogenic and inflammatory phases in the formalin-induced paw licking test. Naloxone significantly reverses the effect of lysionotin in both hot plate test and formalin-induced paw licking test. Moreover, lysionotin significantly inhibited the neurogenic nociception induced by intraplantar injections of glutamate and capsaicin (57% and 67.2%, respectively at a dose of 200 μg/kg). Thus, lysionotin exhibited peripheral and central antinociception through the modulation of vanilloid receptors, opioid receptors, and the glutamatergic system. Conclusion: Lysionotin possesses antinociceptive activity on adult mice that is mediated through both central and peripheral pathways.