Study On The Local Analgesia Mechanism Of μ-opioid Receptors And Clinical Utility In Periphery

To provide a new method for pain management, we have taken knee joint synovium tissues of patients with chronic arthritis, exploring the change of mu-opioid receptors and G protein-cAMP signal transduction pathway in synoviocytes and possible mechanism. Mu-opioid receptors and mRNA expression were measured with immunhistochemistry, flow cytometer and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). Quantities of G protein and cAMP were measured by radioreceptor binding assay and radioimmunoassay respectively. The results showed that the expression of mu-opioid receptors and mRNA in arthritis group were higher than those in control group (P<0.05), so were the Quantities of G protein and cAMP (P<0.05). These might demonstrate that peripheral opioid analgesia is probably related to the increase of μ-opioid receptors in local chronic inflammatory tissue . G protein and cAMP might also participate in the process. In clinic, we detected that low-dose intra-articular morphine and tramadol could effectively relieve pain after arthroscopic knee surgery , and their analgesic efficacy could be enhanced when we combined morphine plus methylprednisolone. The results of this study could provide a new theory for practice of peripheral opioid local analgesia.