Mechanism of thermoTRP Participating in Cold Hyperalgesia of Rat with Experimental Knee Osteoarthritis

OBJECTIVE To observe both TRPA1 and TRPM8 expressions in synovial tissues of rats with cold hyperalgesia induced by experimental knee osteoarthritis(KOA). METHODS 45 Sprague Dawley male rats， weight ranging from 440g to 470g were randomly individed into the model group， modelantagonist and normal group. Paw withdrawal latency (PWL) of five rats from each group was determined one week before modeling， 2， 4， 6 and 8 weeks after modeling， respectively. 8 weeks after modeling， the rats were killed and synovial and cartilage tissues from diseased knee were collected， to observe pathological morphology at cartilage tissues and to determine the protein and gene expressions of TRPA1 and TRPM8 at synovial tissues. RESULTS KOA rats showed obvious cold hyperalgesia from two weeks after modeling to the latest followup， 8 weeks after modeling. The abnormally low level of PWL could be increased by TRPA1 and TRPM8 ion channel blocker. CONCLUSION Upregulating expressions of TRPA1 and TRPM8 participate in the occurrence mechanism of KOA cold hyperalgesia.