| Objective:To reveals the analgesic effect and the characteristics of purine dynamic changes in acupoint area by acupuncture at different time points.Method:.After synchronizing rats’ activity rhythm to the ambient light/dark (LD) cycle, we used heat tail flick test to determine the pain threshold of them. Those rat’s reaction were maintain between 3s-10s are suitable for the experiment.The selected 108 rats were randomly divided into two groups which were modeling group (n=72) and control group (n=36). Inflammatory pain was induced by injecting CFA (total volume 0.1 ml) in the plantar surface of the rats’ right hind paw. Modeling group was distributed into model group (n=36) and acupuncture treatment group (n=36). Each group was classified into 6 subgroups (ZT0、ZT4、ZT8、ZT12、ZT16、ZT20). Then, in accordance with those different times, acupuncture was manipulated at "Zusanli" point for 30 minutes once a day in acupuncture treatment group.Heat tail flick test had also been used to determine the pain threshold of each group at different time points, in order to find the discrepancy between them. Microdialysis method had also been utilized to extract collected the tissue fluid of the "Zusanli" area at ZTO、ZT4、ZT8、 ZT12、ZT161 ZT20 time points. The ATP concentration had been tested and analyzed by HPLC.Results:.1, There’s no significant differences among the weight and basic pain threshold of each rats (P>0.05). In control group, the basic pain threshold peaked at ZTO and reached the bottom at ZT12 which entails time had a notable effect on pain threshold (P<0.05)2, After modeling, both the circadian rhythm of pain and the phase of the pain threshold had changed, which showed up peaked at ZT8 and reached bottom at ZT16, however, time had no obvious effect upon the pain threshold in model group (P=0.076, P>0.05).3, At the same time point, the pain threshold in acupuncture treatment group got a rising trend compared with that of model group. Time had an evident influence on pain threshold(P=0.047, P<0.05) which indicated the pain threshold at different time points are different.The interaction played an notable part in pain threshold.When compared the pain threshold between model group and acupuncture treatment group, they were significantly different (P=0.000, P<0.05).4, The ATP concentration at ZT12 in control group and that in model group were quite different(P=0.017, P<0.05); as well as at ZT16 between model group and acupuncture treatment group (P=0.022, P<0.05).5, In control group, the ATP concentration were different at various time points. Comparing ZT4 with ZT8 and ZT12 respectively, both of them were significantly different(P<0.05). In model group, the ATP concentration was also different at various time points. Here, compared the four time points in pairs, ZTO and ZT4, ZT4 and ZT 12, they got an observably different results, P=0.026, P< 0.05 and P=0.010, P<0.05 separately.6, Compared the ATP concentration of acupuncture treatment group with that of model group at ZT16, it was obviously higher in the former group than that in the latter one(P=0.022, P<0.05). Other value of ATP concentration in acupuncture treatment group were higher than those of model group, however, there was no significant difference (P>0.05)7, The ATP concentrations were significantly different in comparison among control group, model group and acupuncture treatment group, respectively. (P=0.000, P<0.05). Pain threshold was mainly influenced by the concentration of ATP, found a positive correlation(P=0.025, P<0.05); There’s also a positive correlation between processing methods(whether the rats were in healthy conditions or not and whether acupuncture was adopted (P=0.019, P< 0.05).Conclusion:1, Pain threshold in control group has a circadian rhythm, its crest value appeared at ZTO, valley value appeared at ZT12.2, Time has a conspicuous effect on pain threshold. In acupuncture treatment group, the rats’pain threshold rose up after acupuncture, its crest value appeared at ZT8, valley value appeared at ZT16.3, ATP in acupoint may involve in the peripheral response of time characteristics of acupuncture analgesia. |
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