Paeoniflorin (PF), one of the active chemical compounds identified from the root of Paeonia lactiflora Pall, has been well-established to exhibit various neuroprotective actions in the central nervous system (CNS) after long-term daily administration. In the present study, by using the
bee venom (BV) model of nociception and
hypersensitivity, antinociceptive effects of PF were evaluated by intraperitoneal administration in conscious rats. When compared with saline control, systemic pre- and post-treatment with PF resulted in an apparent antinociception against both persistent spontaneous nociception and primary heat
hypersensitivity, while for the primary mechanical
hypersensitivity only pre-treatment was effective. Moreover, pre- and early post-treatment with PF (5 min after BV injection) could successfully suppress the occurrence and maintenance of the mirror-image heat
hypersensitivity, whereas late post-treatment (3 h after BV) did not exert any significant impact. In the Rota-Rod treadmill test, PF administration did not affect the motor coordinating performance of rats. Furthermore, systemic PF application produced no significant influence upon BV-induced paw
edema and swelling. Finally, the PF-produced antinociception was likely to be mediated by endogenous
opioid receptors because of its
naloxone-reversibility. Taken together, these results provide a new line of evidence showing that PF, besides its well-established neuroprotective actions in the CNS, is also able to produce
analgesia against various 'phenotypes' of nociception and
hypersensitivity via
opioid receptor mediation.