阿片系统在针刺镇痛外周机制中的作用

以往工作已证明内阿片系统参与关节炎大鼠针刺镇痛的中枢机制,本文拟进一步探讨其在外周镇痛中的作用。在右侧外踝注射弗氏佐剂形成急性关节炎的大鼠,电针双侧环跳穴10分钟,患侧痛阈提高明显优于健侧。全身注射纳络酮(250μg)可完全阻断针刺镇痛效应并出现更明显的痛觉过敏,局部注射20μg 纳络酮就可阻断针刺镇痛效应。全身注射吗啡可引起剂效相关的镇痛效应,且患侧镇痛效应明显优于健侧。以上结果说明内源性阿片系统也参与针刺镇痛的外周机制。针刺可能促使炎症区释放内阿片肽,作用在被炎症致敏的阿片受体,导致炎症区产生更强的针刺镇痛效应。

The Role of OLS in Peripheral Acupuncture Analgesia in Arthritic Rats

Our previous work has shown that opiate-like substance(OLS)is involved in the centralmechanism of acupuncture analgesia(AA)in the arthritic rats.In this paper,the role of OLS inperipheral mechanism of AA is further studied.Twenty four hours after a subcutaneous injectionof Freund's adjuvant into the right ankles,acute arthritis with typical symptoms developed in allthe rats.Following needling at Huantiao points for 10 minutes,the pain threshold(PT)wasraised by 42. 3%(P<0.05)in the inflammed ankles and by 5.6% in the non-inflammed ones.When systemically administered a dose of 250 and 100μg,naloxone(Nx)could completely andpartially(49.6%)block AA respectively.While locally injected a dose of 100μg even 20μg,Nxcould completely antagonize AA.After systemic administration of morphine(10,5.0,2.5,1.25mg/kg),PT rise was dose-related,and PT was raised by 86.5±22.7% in the affected anklesand by 32.9±14.9% in the normal ankles at 5 mg/kg in dose.It is evident that the opiate recep-tors in the imflammed area should by sensitized.These results demonstrate that activation of en-dogenous opiate system may also be involved in the peripheral AA.Acupuncture may enhance therelease of peripheral OLS which can act at the sensitized opiate receptors,leading to more potentanalgesic effect in the inflammed area.