The Analgesia Effects Of Electro-acupuncture Or OFQ Combined With Buprenorphine On Chronic Inflammatory Pain Rats And Its Mechanisms

Objective : Buprenorphine,an agonist-antiagonist of opioid receptor, is widely used in chronic pain therapy .Electro-Acupuncture(EA),a method produced by combination of traditional medicine and morden technology, has some effects on pain relieving. However,there is no systemic study about the effects of EA combined with buprenorphine in chronic inflammatory pain therapy.In current study, the change of hyperalgesia score (HS), substance P(SP), and calcitonin gene-related peptide (CGRP) were investigated in spinal dorsal horn in CFA rats, trying to explore the relationship between hyperanalgesia state and neurological plasticity in spinal dorsal horn . The effects of EA and /or buprenorphine treatment and their neurological mechanism were also studied, in order to get some useful information for clinical chronic pain therapy.Method : 30 SD rats were devided into 5 groups: A control group;B. CFA group;C. EA group(Using EA management at the points of zusanli and yanglingquan with the frequency of 2Hz/100Hz, intensity≤2mA for 30min each time in the 4^th day and the 8^th day after CFA injection);D. buprenorphine group(1.5 μg buprenorphine was injected intrathecally from the 4^th day to the 10^thgroup(1.5 V- g buprenorphine was injected intrathecally from the 4th day to the 10th after CFA injection; E. EA+buprenorphine group (combination treatment using both EA and buprenorphine) . 50 u 1 Complete Freund's adjuvant (CFA) was injected into tibio-tarsal joint of rats in each group except for group A, to establish chronic pain model . Intrathecal catheterization was performed for intrathecal injection. The change of hyperalgesia score was observed by difference of paw withdral lantency between two hind limbs in hot plate experiment.Immunohistochemistry and computer image analysis system were used to observe the change of SP and CGRP in the spinal dorsal horn.Results : ?Four days after CFA injection,all rats showed thermal hyperalgesiamanifestation.Hyperalgesia scores were significantly elevated on the 10th day after CFA injection compared with that on the 4th day after CFA injection in buprenorphine group and EA group ; In group EA+buprenorphine ,hyperalgesia scores were elevated the on 9th day after CFA injection. Compared with CFA group, hyperalgesia scores were significantly elevated in group EA, group buprenorphine and group EA+buprenorphine ; there was significant difference between group EA+buprenorphine and group buprenorphine .? Compared with control group, expression of SP and CGRP in spinal dorsal horn were significantly increased in rats of CFA group. While, EA, buprenorphine, and EA+ buprenorphine treatment decreased the elevated expression significantly. There was significant difference between group EA+buprenorphine and group buprenorphine or between group EA+buprenorphine and group EA. ?Positive corelationship between SP and CGRP was found.Conclusion I? Monoarthritic rat model induced by injection of CFA into tibio-tarsal joint of rat is an useful method in the study of chronic inflammatory pain .? Inflammatory hyperalgesia state is related to additional expresion of SP...