Study On The Effect Of Analgesia In Bone Cancer Pain Induced By Lentivirus-mediated RNA Interference The Expression Of GDNF Gene

Background:Bone pain is common symptom in the cancer patients especially with bone metastases and the underlying mechanisms of cancer induced bone pain are not known clearly. Clinical therapy is far from meeting the need of patients. Therefore, the aim of this paper is to explore the endogenous analgesic mechanisms and develop new biotherapy. Objective:1) To establish rats bone cancer pain models with intra-tibial injections of rat femoral mammary carcinoma MRMT-1cells.2) To construct lentivirus contain recombinant vector of Homo sapiens glial cell-derived neurotrophic factor isoform (GDNF):psiHIV-GDNF-mU6.3) To study the therapeutic effect of psiHIV-GDNF-mU6recombinant.4) To study the underlying mechanisms of psiHIV-GDNF-mU6recombinant.Methods:1) To duplicate rats bone cancer pain models with intra-tibial injections of rat femoral mammary carcinoma MRMT-1cells, and then test and evaluate the model from pain behavior and morphology;2) To design and construct lentivirus contain recombinant vector of Homo sapiens glial cell-derived neurotrophic factor isoform (GDNF):psiHIV-GDNF-mU6;3) Successful models rats with stabile physiclal status were choosed for intrathecal tube indwelling. These rats were randomly divided into4groups according to different drugs which infused into subarachnoid space through the intrathecal tubes:Saline, Morphine,psiHIV-U6, psiHIV-GDNF-mU6. To observe the changes of thermal and mechanical pain threshold from preoperative to7days and14days after administration.4) To detect the levels of GDNF, GFAP, PERK, and substance P calcitonin gene-related Peptide and c-fos by immunofluorescent staining technique, RT-PCR and Western blot analysis. Results:1) The clone of bone cancer pain models of rats has been made successfully.2) The recombinant of psiHIV-GDNF-mU6has been constructed successfully.3) Mechanical pain threshold increased in Morphine group and psiHIV-GDNF-mU6group than other groups at14d after administration (P<0.05), while there is no difference at7d after administration. Thermal pain threshold increased in Morphine group and psiHIV-GDNF-mU6group than other groups at7d and14d after administration(P<0.05).4) Significant astrocytic activation occurred in Saline and psiHIV-U6group.5) RNA interference effectively decreased the express level of GDNF.6) The express level of SP、CGRP、c-fos and PERK and the change of pain behavior show the same tendency. Conclusions:1) rat bone cancer pain model with intra-tibial injections of rat femoral mammary carcinoma MRMT-1cells is available model, osteoclasia and the change of pain behavior have been both detected.2) Astrocytic had been activated significantly in Saline and psiHIV-U6group.3) The administration of recombinant of psiHIV-GDNF-mU6in subarachnoid space is effective to bone cancer pain model. ERK/MAPK passageway may work in the analgesia of the recombinant of psiHIV-GDNF-mU6.4) The effect of cascade amplification initiated by astrocytic released GDNF, SP, CGRP and ERK/MAPK pathway maybe the base of Hyperalgesia in bone cancer pain.