Differential Proteomics Research On Spinal Dorsal Horn Tissue From Rats With Chronic Post-surgical Pain

ObjectiveTo establish a rat model of chronic post-surgical pain(CPSP) evoked by thoracotomy and extract total proteins from spinal dorsal horn tissue on the surgical side; and then identify the proteins in different expression by using proteomic techniques and detect an identified protein by western blotting.Methods1. Establish a rat model of chronic postoperative pain caused by thoracotomyThirty-six male SD rats, weighing250g～350g, were randomly divided into three groups(n=12):control group, sham group and model group. Rats were anesthetized and supported by mechanical ventilation after anesthetic induction. The right pleura between the right4th and5th ribs was opened. A retractor was placed between these two ribs and opened8mm for60min. Animals in sham group were received pleural incision only. After surgery, animals were tested for mechanical allodynia using electronic von frey and cold allodynia using acetone applied to the incision.2. Differential proteomics research on spinal dorsal horn tissueAt first, we established the rat model of chronic post-thoracotomy pain. After the model was established successfully, the rats were invided into CPSP group and non-CPSP group. Second, the total proteins from spinal dorsal horn tissues were extracted. At last, we identified the proteins in different expression by using proteomic techniques and detected an identified protein by western blotting.Results1. The rat model of CPSP evoked by thoracotomy:compared to the response of rats from sham group, the threshold to mechanical stimulation started to decrease at1st postoperative day(P<0.01)and increased gradually after3days; however, MWT of some of these rats declined significantly on7th postoperative day and continued to decrease until32nd postoperative day. Therefore, the incidence rate of chronic post-thoracotomy pain was41.7%in model group. In addition, the numbers of scratches following the application of acetone markedly increased in model group rats compared with those in the sham group (P<0.01). There were no significant differences in mechanical allodynia and cold hyper-sensitibity between the sham group and control group (P>0.05).2. Differential proteomics research:58differential proteins were identified by using proteomics techniques. And these proteins consisted of members of proteins with diverse functions, including proteins related to cytoskeleton, transportation, signal transduction, energy metabolism and so on.3. The result of western blotting was consistent with that of proteomic analysis and identification. The expression of glutaminase was significantly higher in CPSP group than in non-CPSP group.Conclusions1. The results of the present study suggest that the model of persistent postoperative pain evoked by thoracotomy is stable and repeatable, which may help to study the mechanisms and treatment of chronic postoperative pain.2. The identified proteins might be important candidate molecules, which might take part in the development of CPSP.