The aim of the present study was to investigate the effects of
myricitrin, a
flavonoid with anti-inflammatory and antinociceptive action, upon persistent neuropathic and inflammatory
pain. The
neuropathic pain was caused by a partial
ligation (2/3) of the sciatic nerve and the inflammatory
pain was induced by an intraplantar (i.pl.) injection of 20 microL of complete
Freund's adjuvant (CFA) in adult Swiss mice (25-35 g). Seven days after sciatic nerve constriction and 24 h after CFA i.pl. injection, mouse pain threshold was evaluated through
tactile allodynia, using Von Frey Hair (VFH) filaments. Further analyses performed in CFA-injected mice were paw
edema measurement, leukocytes infiltration, morphological changes and
myeloperoxidase (MPO)
enzyme activity. The intraperitoneal (i.p.) treatment with
myricitrin (30 mg/kg) significantly decreased the paw withdrawal response in persistent neuropathic and inflammatory
pain and decreased mouse paw
edema. CFA injection increased 4-fold MPO activity and 27-fold the number of neutrophils in the mouse paw after 24 h.
Myricitrin strongly reduced MPO activity, returning to basal levels; however, it did not reduce neutrophils migration. In addition,
myricitrin treatment decreased morphological alterations to the epidermis and dermis papilar of mouse paw. Together these results indicate that
myricitrin produces pronounced anti-allodynic and anti-edematogenic effects in two models of
chronic pain in mice. Considering that few drugs are currently available for the treatment of
chronic pain, the present results indicate that
myricitrin might be potentially interesting in the development of new clinically relevant drugs for the management of this disorder.