Systemic injection of peptidoglycan (PGN) special polymers, which are the primary structural components of most bacterial cell walls, leads to acute inflammation and pain behavior. This study was conducted to confirm that an intraplantar injection of PGN evoked hindpaw inflammation and hyperalgesia, and to evaluate the effects of bee venom (BV) pretreatment of an acupoint on PGN induced inflammation and hyperalgesia.

Inflammation and hyperalgesia were induced by injecting PGN into the plantar surface of one hindpaw of the rats. Inflammation and hyperalgesia were then evaluated by measuring the thickness of the hindpaw using a caliper and the paw withdrawal time (PWT) in response to noxious thermal stimulus (48℃ hot water). In addition, spinal cord c-fos expression was quantitatively analyzed. The BV pretreatment was injected at the acupoint located 5 mm lower and 5 mm lateral to the anterior tubercle of the tibia in the hind limb.

The PGN groups showed increased in paw thickness and spinal c-fos expression two hours after PGN injection, as well as decreased PWT in response to noxious thermal stimulus for each tested time. BV pretreatment of the acupoint was found to inhibit hindpaw thickness and led to a significant increase in PWT, but did not significantly inhibit spinal cord c-fos expression induced by PGN injection.

These results indicated that BV pretreatment has both an anti-inflammatory and antinociceptive effect in PGN induced inflammatory pain, which suggests that peptidoglycan may be useful as an inflammatory agent for inflammatory pain models.