RESUMO
Objective: To observe the effects of electroacupuncture (EA) of different frequencies on transmission function, electromyography, nitric oxide synthase (NOS) content and interstitial cells of Cajal (ICC) expression of colon in rat models with slow transit constipation (STC). Methods: Of the 50 healthy male Wistar rats, 10 were randomly selected as a normal group and fed with ordinary diet, and the remaining 40 rats were fed with the diet added with the compound diphenoxylate at a dose of 8 mg/(kg·bw) each day for continuous 120 d. The 40 successfully established STC rat models were randomly divided into a model group, a low-frequency EA group (2 Hz), a high-frequency EA group (100 Hz), and a variable-frequency EA group (2 Hz/100 Hz), with 10 rats in each group. Rats in the normal and the model groups were not given any treatment; the low-frequency EA and the high-frequency EA groups were given EA at Tianshu (ST 25), Zusanli (ST 36) and Zhigou (TE 6) with continuous wave at the designated frequency, and the variable-frequency EA group received sparse-dense wave (2 Hz/100 Hz) EA at the same acupoints, once a day for a total of 15 d. After treatment, the colonic transmission function, electromyography, NOS content and ICC expression (calculated by the difference in the area of the C-kit positive cells) of the rats in each group were measured. Results: For the colonic transmission function, compared with the normal group, the first black stool excretion durations of rats in the other groups were significantly prolonged (all P<0.05); compared with the model group, the first black stool excretion durations of rats in the three EA groups were significantly shortened (all P<0.05), which was significantly shorter in the variable-frequency EA group than in the low-frequency EA and high-frequency EA groups (both P<0.05). For the colonic electromyography, compared with the normal group, the amplitude was significantly increased and the frequency was accelerated in rats of the other groups (all P<0.05); compared with the model group, the amplitude was significantly reduced and the frequency was slowed down in the three EA groups (both P<0.05); compared with the low-frequency EA and the high-frequency EA groups, the amplitude was reduced and the frequency was significantly reduced in rats of the variable-frequency EA group (both P<0.05). Compared with the normal group, the colonic NOS contents were significantly increased in the other groups (all P<0.05); compared with the model group, the NOS contents were significantly reduced in the three EA groups (all P<0.05); compared with the low-frequency EA and the high-frequency EA groups, the content was significantly reduced in the variable-frequency EA group (all P<0.05). For the area of rat colonic C-kit-positive cells, compared with the normal group, the areas were significantly reduced in rats of other groups (all P<0.05); compared with the model group, the areas were increased significantly in the three EA groups (all P<0.05); compared with the low-frequency EA group, the area was increased significantly in the variable-frequency EA group (P<0.05). Conclusion: EA, especially EA at the 2 Hz/100 Hz variable-frequency, has a positive treatment effect on the STC model rats. It may improve rats' colonic function by regulating the electromyography, NOS content and ICC expression of colon.
RESUMO
Objective:To observe the effects of electroacupuncture (EA) of different frequencies on the expression levels of substance P (SP) and vasoactive intestinal peptide (VIP) in the colon of rats with slow transit constipation (STC).Methods:One hundred healthy male Sprague-Dawley (SD) rats were randomly divided into a normal group,a model group,a low-frequency EA group,a high-frequency EA group and a variable-frequency EA group,with 20 rats in each group.The rats in the normal group were fed with normal diet.The rats in the other groups were fed with phenethylpiperidine in the diet at a dose of 8 mg/(kg·bw) per day,for 120 d,to establish the STC model.Rats in the normal group and the model group did not receive any treatment;rats in the low-frequency EA group were treated with 2 Hz continuous wave EA,rats in the high-frequency EA group were treated with 100 Hz continuous wave EA,and rats in the variable-frequency EA group were treated with 2 Hz/100 Hz sparse-dense EA.The current intensity of the EA was determined by the slight vibration of the rat limbs without painful screaming.The intervention was performed once a day,15 min/time for continuous 15 d.After treatment,the intestinal transit function and the expression levels of SP and VIP in the colon of the rats in each group were determined.Results:After treatment,the defecation duration of the first dark stool in the model group was significantly longer than that in the normal group (P＜0.05);the defecation durations of the first dark stool in the low-frequency EA group,high-frequency EA group and variable-frequency EA group were significantly shorter than the duration in the model group (all P＜0.05);compared with the low-frequency EA group,the first dark stool defecation duration of rats in the variable-frequency EA group was significantly shorter (P＜0.05);compared with the normal group,the SP and VIP expression levels in the colon of the model group were significantly decreased (both P＜0.01);the SP and VIP expression levels in the colon of the low-frequency EA group,the high-frequency EA group and the variable-frequency EA group were significantly higher than those in the model group (all P＜0.05);compared with the high-frequency EA group,the SP expression levels in the colon in the low-frequency EA group and the variable-frequency EA group were significantly increased (both P＜0.05);compared with the low-frequency EA group,the VIP expression levels in the colon in the high-frequency EA group and the variable-frequency EA group were significantly increased (both P＜0.05).Conclusion:EA improves the intestinal function of STC model rats by regulating the expression levels of SP and VIP in rat colon.The EA stimulation with 100 Hz continuous wave,2 Hz/100 Hz sparse-dense wave shows a better improvement in the colonic transit function in STC rats,followed by 2 Hz continuous wave.