RESUMO
OBJECTIVE: To observe the effect of electroacupuncture (EA) of "Tianshu"(ST25) and "Dachangshu"(BL25) on the intestinal transit functionï¼ expression level of glial cell-derived neurotrophic factor (GDNF) and methylation level of GDNF gene promoter region in colon tissue of rats with slow transit constipation (STC)ï¼ so as to explore its mechanisms underlying improvement of STC. METHODS: Male Sprague-Dawley (SD) rats were randomized into controlï¼ salineï¼ model and EA groups (n=16 in each group). The STC model was replicated by gavage of compound diphenoxylate suspension (10 mL· kg-1· d-1) for 28 days. Rats of the saline group received the same dose of normal saline via gavage. EA (2 Hz/15 Hzï¼ 0.1-1 mA) was applied to bila-teral ST25 and BL25 for 15 minï¼ once daily for 14 days. The intestinal transmission function (the intestinal propulsion rate) was assessed by recording the first black grain stool discharge time and the number and weight of the discharged stool grains in 30 min after gavage of the activated carbon suspension (1 mL/100 gï¼ 150 g/L). The score of fecal trait and the weight of stool within 24 h were recorded. The ultrastructural changes of Cajal interstitial cells in the colon tissue were observed by transmission electron microscope. The expression levels of GDNF protein and mRNA in the colon tissue were detected by using Western blot and real-time fluorescent quantitative PCRï¼ separatelyï¼ and changes of methylation level in the promoter region of GDNF gene detected by using Bisulfite sequencing method. RESULTS: Compared with the control groupï¼ the time of the 1st black stool grain discharging was obviously prolongedï¼ and the number and weight of the discharged black stool grains were significantly decreased in the mo-del group (P<0.05)ï¼ suggesting a success of STC. The weight and trait score of stool in 24 hï¼ intestinal propulsive rateï¼ and the expression levels of GDNF protein and mRNA were significantly lower in the model group than in the control group (P<0.01ï¼ P<0.05). After EAï¼ the weight and trait score of stool within 24 hï¼ intestinal propulsive rateï¼and the expression levels of GDNF protein and mRNA were significantly increased in the EA group in contrast to the model group (P<0.01ï¼P<0.05). The total CpGs methylation level of GDNF gene in colon tissue was considerably higher in the model group than in the control group (P<0.05)ï¼ and markedly lower in the EA group than in the model group (P<0.05). No significant differences were found between the control and saline groups in all the above-mentioned indexes (P>0.05). CONCLUSION: EA of back-shu and front-mu acupoints can effectively improve symptoms of constipation and intestinal transport function in STC ratsï¼ which may be related to its function in up-regulating the expression of GDNF and down-regulating the methylation level in the promoter region of GDNF gene in colon tissue.
