RESUMO
OBJECTIVE: To observe the effect of electroacupuncture (EA) on the rhythm of running-wheel activity of hepatocellular carcinoma (HCC) mice and the expression of Per 1 and Per 2 (circadian rhythm genes) in the hypothalamic suprachiasmatic nucleus (SCN), so as to investigate its mechanism underlying regulating circadian rhythm. METHODS: A total of 108 male C 57 BL / 6 J mice were randomly divided into control, HCC model and EA groups which were further assigned to six zeitbeger (environmental light-dark cycle) time (ZT) point (ZT 0, ZT 4, ZT 8, ZT 12, ZT 16 and ZT 20) subgroups. The HCC model was established by injection of H 22 cancer cell (abdominal 3rd generation, 10 µL) suspension into the larger live lobe. Mice of the control group received saline injection of the liver lobe. EA (2 Hz/15 Hz, 0.2 mA) was applied to bilateral "Ganshu" (BL 18) and "Zhiyang" (GV 9) for 15 min, once daily for 10 days. Mice of the control and model groups received the same binding-fixing to those of the EA group. Circadian running-wheel activity of 12 hâ¶12 h light darkness (LD) cycle (activity onset and acrophase of actogram, amplitude or peak of periodogram) was recorded by using ClockLab (ACT-500) software and analyzed by MATLAB (R 2007 b) before and after EA treatment. The pathological changes of liver cells were observed under light microscope after sectioning and Hï¼E. staining. The expression levels of Per 1 mRNA and Per 2 mRNA in the liver tissues were determined by fluorogenic quantitative real time-PCR. RESULTS: (1) Following modeling, the amplitude of periodogram of running-wheel activity was significantly lowered at ZT 0, ZT 4, ZT 8, ZT 12, ZT 16, and ZT 20 relevant to the control group (P<0.05). After EA intervention, the amplitude of periodogram at ZT 8 (15ï¼00) was considerably increased relevant to the model group (P<0.05), and the acrophase at ZT 8 was remarkably advanced (P<0.05). No significant changes were found in the onset time and periods of periodogram at the 6 time-points after modeling and EA intervention (P>0.05). (2) The expression levels of Per 1 mRNA and Per 2 mRNA in the SCN were significantly up-regulated at the 6 time-points in the model group relevant to the control group (P<0.05), and obviously down-regulated at ZT 8 after EA intervention relevant to the model group (P<0.05)ï¼. CONCLUSION: EA can benignly regulate the rhythm of running-wheel activity of HCC mice, which may be closely related to its effect in down-regulating the expression of circadian rhythm genes Per 1 and Per 2 in the SCN.
