The Variation Of Opioid Peptides Gene Expression In Inflammatory-Pain Rats In Different Time After Electro-acupuncture

To observe the changes of after-time analgesic effect following time and study the mechanism of it on mRNA level, one hundred and twenty-six adult SD rats were randomly divided into three groups: electro-acupuncture (EA)group, model group and naive group, and each group was divided into six small groups again:1, 3,6,12,24,48hour group after acupuncture.The adjuvant arthritic(AA) rats were selected as the model of inflammatory-pain(chronic pain) , and rats in acupuncture group were needled one time. We observed the pain threshold and pain grade after 1, 3, 6,12, 24, 48hours after one-time acupuncture and detected the changes of POMC and PENK mRNA expression in hypothalamus and inflamed location in different time by in situ hybridization .Results showed pain grade of EA group was lower than that of model group in 1, 3, 6,12hour after EA. Pain threshold of EA group was higher than that of model group in 1, 3, 6, 12hours after EA, but had no difference compared with naive group all the time; Expression of POMC and PENK mRNA in hypothalamus and inflamed location of EA group was higher than model group in 1, 3, 6,12hour after the one-time EA and higher than the naive group all the time.Taken together, it is indicated that EA had effective therapeutic and analgesia on inflammatory-pain , after-time analgesic effect may last 12 hours and POMC and PENK mRNA expression in hypothalamus and inflamed location involved in the central and peripheral molecular mechanisms in reformation of after-time analgesic effect separately. The results also provided some theoretical foundations for the effect accumulation of acupuncture analgesia, and have certain reference value to select correctinterval time of EA for chronic pain in clinic.