The Effects Of Electro-acupuncture In Different Interval Times On Opioid Peptides Gene Expression In Inflammatory-pain Rats

Recently, many scholars have made a lot of studies on after effect and duration of electro-acupuncture(EA) analgesia on inflammation and their mechanisms. To observe accumulated EA analgesic effect on adjuvant-induced arthritis rats in different interval times, further sought to the best interval time of EA analgesia. We divided animals into three groups: control group, model group and EA group and used adjuvant-induced arthritis rats (with complete Freund's adjuvant) as the model of inflammatory pain. Began the treatment of EA at the first day after the model of inflammatory pain was made. Selected Xuanzhong and Kunlun points, chose 3h, 6h, 12h, 24h as the treatment interval times, 6 days was a course of treatment. After that, observed pain grade and determined pain threshold of adjuvant-induced arthritis rats and adopted in site hybridization histochemistry to detect opiomelanocortin(POMC) and proenkephalin(PENK) mRNA in hypothalamus and inflamed location in adjuvant-induced arthritis rats. The results suggested that the pain grade of control group was lower than that of EA group and model group obviously in each interval times (P<0.05), but EA group was lower than model group (P<0.05). Meanwhile, the pain threshold of control group was higher than that of EA group and model group obviously (P<0.01, P<0.05), but EA group was higher than model group(P<0.01). And the expression of POMC and PENK mRNA in hypothalamus and inflamed location of EA group were higher than the other groups (P<0.01), but model group was higher than control group (P<0.01). Moreover, contrasted with 3h, 6h and 12h in EA group the effects of 24h was the best on the index above mentioned (P<0.01). But there was no difference among 3h, 6h and 12h (P>0.05). The results indicated that EA had effective analgesia for inflammatory pain, contrasted with other groups, repetition treatment by every 24 hours can increase analgesia level obviously. The results also provided some experiment basements for selecting reasonable cure method and treatment interval time of EA analgesia in clinic and foundations for studying time-effect relationship of acupuncture analgesia.