Antinociceptive effect of lipopolysaccharide from Pantoea agglomerans on streptozotocin-induced diabetic mice

The antinociceptive effect of lipopolysaccharide from Pantoea agglomerans (LPSp) in streptozotocin-induced diabetic mice was examined. Although subcutaneous (s.c.) administration of LPSp produced a dose-dependent inhibition of the tail-flick response in both non-diabetic and diabetic mice, the antinociceptive response was greater in diabetic mice than in non-diabetic mice. The antinociceptive effects of LPSp in both diabetic and non-diabetic mice were significantly antagonized by s.c. administration of naltrindole, a selective δ-opioid receptor antagonist or nor-binaltorphimine, a selective κ-opioid receptor antagonist, but not by β-funaltrexamine, a selective μ-opioid receptor antagonist. These results suggest that LPSp produces a marked antinociceptive effect in diabetic mice through the activation of δ- and κ-opioid receptors.