Investigating The Effect And Mechanism Of Pain On Subcutaneous Walker256 Tumor Development In Wistar Rats

[Objective] To establish a new rat model combining pain with tumor,and also investigate the mechanism of pain to cancer development,and provide a scientific basis for clinical application of cancer pain treatment.[Methods] Wistar rats were randomly assigned into three groups(the trial,sham and control group).For the trial group,chronic constriction injury of the sciatic nerve(CCI)rat and subcutaneous xenograft rat was integrated.For the sham group,the operation was performed in the same manner like CCI model until the sciatic nerve was visible without touc hing it.For the control group,only subcutaneous injection of tumor cells was given to.7 days after operation,xenograft models were established by subcutaneous inoculation with Walker256 breast cancer cells to the rats.Based on these models,the rats' pain related behaviour and appetite as well as neoplasm associated volume and weight were measured and recorded.Flow cytometry was used to analysis the proportions of lymphocytic subgroups level such as CD4+,CD8+ T cells,nature killer cells and Treg cells as well as CD4+/CD8+ T cell rate from peripheral blood among three groups.[Results] CCI subcutaneously tumor-burdened rat model had been successfully established.When giving 10^8 cells per rat subcutaneously,the body weight of rats in trial group lost much comparing with other two groups'.After 11 days' observation,all the rats burdened with tumor experienced s ubcutaneous tumor resection.The weight of tumors in trial group much heavier than that from other two groups',and the volume of the tumors in the trial group presented much larger comparing with other two groups'.The flow cytometry demonstrated that the proportion of T cell in the trial group was lower than other groups;CD4+ T cell had no significant change with other groups;CD8+ T cell was higher than other groups;CD4+/CD8+ T cell rate was lower than other groups;NK cell had no difference comparing with other groups;Treg cell from the trial group was higher than sham group,wheareas compari ng with the control group without much difference.[Conclusion] Pain may be a potential element to cancer development.Neuropathic pain may be the impetus of cancer development.Immune system might play a significant role in the development of cancer induced by pain.