Objective: To observe the influence of electroacupuncture (EA) on indocyanine green (ICG) metabolism in the liver and the action mechanism of acupuncture for hepatic regulation.
Methods: Forty Kunming mice were randomly divided into an EA group and a control group, 20 cases in each one. Combined with classical hepatic metabolism test of ICG, after tail vein injection of ICG, twenty mice were treated with EA at "Zusanli" (ST 36) for 20 min. The ICG fluorescence intensity and distribution in the liver were observed with animal in vivo fluorescence imaging apparatus during 20 min of EA and 60 min of needle withdrawal. Twenty mice, taken as control group, were treated with ICG injection and no EA. The differences of fluorescence intensity and distribution in both groups were compared.
Results: (1) There was blocking and gathered fluorescent sign in both groups when ICG was injected immediately. With the extension of observation time, the fluorescence brightness and area were increased until 30 min of injection. This was in accordance with known metabolism activities of ICG in the liver. (2) At 10 min and 20 min of EA and after needle withdrawal, compared with the control group, the fluorescence intensity in the liver of the EA group was weaker and the distribution area was smaller. (3) According to quantitative statistics of fluorescence intensity, at each time point of treatment, the value in the control group was higher than that in the EA group, which appeared regularly all along. As for the total mean difference of ICG fluorescence intensity at all time points, there was statistical difference between the two groups (P < 0.05).
Conclusion: EA could reduce fluorescence intensity and lasting time of ICG, indicating that EA accelerates metabolic process of ICG in the liver. Also it is feasible to apply animal in vivo fluorescence imaging technology to the principle research of acupuncture effect.