The Intrinsic Mechanism Of The Individual Difference Of Electroacupuncture Analgesia Based On Opioid Peptide Degrading Enzyme

Objective Through the detection of tail flick latency(TFL)changes before and after electroacupuncture,to screen out response group and non-response group rats,to confirm the variation of electroacupuncture analgesia in rats;by detection of the content and protein expression of endogenous opioid peptide degrading enzyme and the content of enkephalin in rat hypothalamus(Hypo),to investigate the mechanism of variation of electroacupuncture analgesia in response group and non-response group rats;by detection of the content and protein expression of endogenous opioid peptide degrading enzyme and the content of enkephalin in rat periaqueductal gray(PAG),to have a further study on the mechanism of variation of electroacupuncture analgesia in response group and non-response group rats.Methods Partl 40 male Sprague-Dawley rats were used in this study,the Han 1h-202h acupoint nerve stimulators were used,and the parameters were as follows:the bilateral"Zusanli"(ST 30)and "Kunlun"(BL 60)points,dilatational wave frequency is 2/100Hz,and the intensity is 0.5-1.5mA(each 10min increase 0.5mA),30min for each treatment.According to the rats tail flick latency(TFL)before and after electroacupuncture,the changes in analgesia were evaluated.The response group were the group which TFL value changes was more than 30%,while the non-response group was less than 20%.Part2 After one week adaptive feeding,the response and non-response rats were sacrificed immediately after the treatment of electroacupuncture for only once,and the hypothalamus was removed to detect the protein expression of neutral endopeptidase(NEP)?aminopeptidase(AEP)by western blotting and the content of NEP?APN?met-enkephalin and leu-enkephalin by enzyme-linked immunosorbent assay.Part3 60 male Sprague-Dawley rats were screened as response and non-response group.After one week of adaptive feeding,the rats were sacrificed immediately after the treatment of electroacupuncture for only once,and the PAG was removed to detect the protein expression of neutral endopeptidase(NEP)?aminopeptidase(AEP)by western blotting and the content of NEP?APN?met-enkephalin and leu-enkephalin by enzyme-linked immunosorbent assay.Results Part1 As the pain threshold results showed,there were 12 rats whose TFL value changed more than 30%,which were classified into response group,while 18 rats whose TFL value changed less than 20%,which were classified into non-response group.10 rats were excluded.The response rats' TFL value after electroacupuncture was significantly longer than that before electroacupuncture(7.07±0.23 vs 9.31±0.29,p<0.01),while the non-response rats'TFL value had no difference before and after electroacupuncture(7.85±0.17 vs 7.36±0.31,p>0.05).Part2 After electroacupuncture treatment,opioid peptide degradation enzyme NEP and APN protein expression in Hypo of response group was obviously lower than that in nonresponse group(p<0.01);the content of met-enkephalin and leu-enkephalin in Hypo had no difference between response and non-response group(p>0.05).Part3 As the pain threshold results showed,there were 15 rats whose TFL value changed more than 30%,which were classified into response group,while 20 rats whose TFL value changed less than 20%,which were classified into non-response group.5 rats were excluded.The response rats' TFL value after electroacupuncture was significantly longer than that before electroacupuncture(7.34±0.17vs11.4±0.7,p<0.01),while the non-response rats'TFL value had no difference before and after electroacupuncture(7.72±0.18vs7.34±0.33,p>0.05).After electroacupuncture treatment,opioid peptide degradation enzyme NEP and APN protein expression in PAG of response group was obviously lower than that in nonresponse group(p<0.01);the content of met-enkephalin and leu-enkephalin in PAG had no difference between response and non-response group(p>0.05).Conclusions Electroacupuncture has analgesic effect,but its effect is different.The protein expression and content of opioid peptide degradation enzyme NEP and APN in PAG and Hypo were higher in non-response group than response group,which had significantly difference;while the content of met-enkephalin and leu-enkephalin in PAG and Hypo had no difference.The opioid peptide degradation enzyme may be one of the factors that affect the effectiveness of electroacupuncture analgesia;while the content of encephalin in the brain may not be the main factor,which possibly related to opioid receptor.