Mechanism Of Thermo TRP Participating In The Occurrence Of Bone Cancer Pain Of The Bone Metastases Rats

OBJECTVE:To observe the change of the cold stimulation threshold and the change of the expression of both TRPA1 and TRPM8 expressions in the dorsal root ganglion tissue of the bone metastases by the breast cancer.To investigate whether the mechanism of temperature pain-sensitive links with the occurrence of bone cancer pain and the thermoTRP channel superfamily represented by TRPA1 and TRPM8 are involved in the cold pain.METHODS:Forty-five Sprague Dawley male rats,weight ranging from 440g to 470g were randomly allocated into the model group,model-antagonist,normal group and Sham operation group.Paw withdrawal latency(PWL)of five rats from each group were determined one week before modeling,2,4,6 and 8 weeks after modeling respectively.Bone tissues from diseased knee were collected after putting to death 8 weeks after modeling so to observe pathological morphology at diseased bone tissues to evaluate the success of modeling.The levels of TRPA1 and TRPM8 gene and protein expression in rat dorsal root ganglion were detected by Hematoxylin-Eosin staining,Western Blot and Real-time PCRRESULTS:Bone cancer rats showed obvious cold hyperalgesia from two weeks after modeling to the latest follow-up,8 weeks after modeling.The abnormally low level of PWL can be increased by selective TRPA1 and TRPM8 ion channel blocker.The sham operation group was similar to the cold stimulation pain threshold of the blank group and maintained at a high level.Hematoxylin-Eosin staining:in the bone cancer pain model group,the tumor cells are filled with bone marrow cavity,trabecular bone is widely destroyed,modeling success;Western Blot:The expression of TRPAI and TRPM8 protein in dorsal root ganglion of rats with bone cancer pain was significantly higher than that in blank control group,sham operation group and model-channel blocker intervention group(P<0.05).Real-time PCR:mRNA expression of TRPA1 and TRP M8 in bone tissue of rats with bone cancer pain were significantly higher than those in blank control group,sham operation group and model-channel blocker intervention group(P<0.05).CONCLUSION:The mechanism of the occurrence of the bone cancer pain in the bone metastasis rats by the breast cancer consists the temperature pain.The thermo TRP channel protein superfamily members,represented by TRPA1 and TRPM8,were involved in the cold pain construction in the bone cancer pain of the rats with bone metastases by the breast cancer.