Effect of chrysin on nociception in formalin test and serum levels of noradrenalin and corticosterone in rats.

Objective: The levels of corticosterone and noradrenalin as the two nociception modulators modify after stress condition. The propose of current study was to investigate the effect of chrysin on formalin-induced nociceptive behaviors and serum levels of corticosterone and noradrenalin in rats.

Materials And Methods: Pain was induced by applying 20 μL of 5% formalin in distilled water in the subplantar of the right hind paw. Chrysin (50, 100 and 150 mg/kg, intraperitoneally (i.p.) was administered 60 min before formalin injection. Morphine (10 mg/kg, i.p.) was administered 30 min before formalin injection. The control group received the same volume of saline by i.p. injection 30 min before formalin injection.

Results: Chrysin treatment can significantly decrease formalin-induced pain in rat in a dose-dependent manner. Chrysin (150 mg/kg) significantly inhibit the first phase (P < 0.01), whereas, the all concentration of chrysin were affected on the later phase of formalin-induced pain (P < 0.05). Chrysin could significantly attenuate the content of corticosterone and noradrenalin in the serum versus to the control rats (P < 0.01).

Conclusion: The current study confirms that the chrysin decreased the nociceptive behaviors in the formalin test and indicate a correlation with decrease in serum corticosterone and noradrenalin levels.