OBJECTIVETo observe the effects of electroacupuncture (EA) on the circadian rhythm and suprachiasmatic nucleus (SCN) epigenetic modification in mice with hepatocellular carcinoma (HCC), and to explore the epigenetics mechanism of EA on circadian rhythm in patients with HCC.

METHODSAccording to six zeitbeger time (ZT) of ZT0 (7:00), ZT4 (11:00), ZT8 (15:00), ZT12 (19:00), ZT16 (23:00) and ZT20 (3:00), a total of 108 eligible male C57BL/6J mice were divided into a blank group, a model group and an EA group at each ZT, 6 mice each group. Injection of H22 cancer cell suspension was used to establish the HCC model. After 11 days, EA (2 Hz/15 Hz, 0.2 mA) for 10 days was applied at "Ganshu" (BL 18) and "Zhiyang" (GV 9) in the EA group at each ZT, once a day, 15 min a time; the rats in the blank group and model group were treated with immobilization at the same time and under the same conditions. ClockLab (ACT-500) software was used to record the activity rhythm of mice. After 10 days intervention, MATLAB (R2007b) was used to export the circadian rhythm of mice, and the amplitude and peak phase of the mice were analyzed. The high-throughput epigenetics PCRarray array was applied to detect epigenetics-related gene expression in SCN.

RESULTS(1) After modeling, compared with the blank group, the amplitude of activity was decreased and peak phase was delayed in the model group and EA group at each ZT (all <0.05), but the difference of rhythm parameters between the model group and EA group was not significant (all > 0.05). (2) After intervention, compared with the model group, the amplitude of activity in the EA group at ZT 8 was increased and peak phase was advanced (both <0.05); the difference of the activity amplitude and peak phase between the EA group and model group at ZT0, ZT4, ZT12, ZT16 and ZT20 was not significant (all >0.05); compared with the ZT0, ZT4, ZT12, ZT16 and ZT20, the amplitude of activity in the EA group at ZT 8 was increased and peak phase was advanced (all <0.05). (3) The results of epigenetic PCRarray array showed that after intervention at ZT 8, compared with the blank group, the expression of 48 epigenetic-related genes in SCN of HCC mice was up-regulated; compared with the model group, the relative expression of 49 epigenetic-related genes in the SCN was down-regulated in the EA group; there were 23 epigenetic-related genes differentially expressed among the three groups.

CONCLUSIONEA has benign regulation on circadian rhythm of HCC mice, and achieves the best efficacy at ZT 8. EA at ZT 8 could down-regulate the overexpression of epigenetic-related genes.