Assessment of weight bearing changes and pharmacological antinociception in mice with LPS-induced monoarthritis using the Catwalk gait analysis system

Abstract

Aims We evaluated the possibility of using the video-based Catwalk gait analysis method to measure weight bearing changes and for testing pharmacological antinociception in freely moving mice with lipopolysaccharide (LPS)-induced monoarthritis. Main methods LPS or its solvent (PBS) was injected intra-articularly into the right hind (RH) limb ankle joint through the Achilles tendon of C57BL/6 mice. The Catwalk system was used to assess behavioral changes in freely moving mice. The effects of indomethacin on changes in LPS-inoculated mice were examined. Key findings Mice inoculated with LPS into the RH limb showed reduced paw pressure (measured as light intensity) and print area on the RH limb, whereas they exerted more pressure with the left hind (LH) and front limbs, showing a transfer of weight bearing from RH to LH and front limbs, which was significant at 2 days post-LPS inoculation. There were no differences between the front limbs. No changes were observed in the PBS injected controls. There were no changes in interlimb coordination (regularity index) in both PBS- and LPS-injected mice. Treatment with indomethacin (10 and 100 mg/kg) restored the weight bearing (measured as the ratio of the pressure exerted by the paws) and the print area ratios of LPS-inoculated mice similar to that observed in control mice. Significance This study shows that the Catwalk gait analysis system can be used to objectively quantify LPS-induced monoarthritis weight bearing changes in all four limbs and evaluate pharmacological antinociception in freely moving mice.