Effect Of Retrograde Colonic Electrical Stimulation On Colonic Transit And Stressinduced Visceral Hypersensitivity In Rats With Irritable Bowel Syndrome

Chapter 1 Effect of colonic electrical stimulation on visceral hypersensitivity in rats with irritable bowel syndromeObjective To investigate whether stress-induced visceral hypersensitivity could be alleviated by colonic electrical stimulation(CES), looking for a valuable new approach in treating irritable bowel syndrome(IBS).Methods 48 male rats were divided into model group and control group, visceral hypersensitivity model was induced by a 6-d heterotypic intermittent stress protocol composed of 2 stressors, which included restraint stress for 40 min, forced swimming stress for 20 min, the extent of visceral hypersensitivity was quantified by electromyography(EMG) and abdominal with-drawal reflex(AWR) scores of colorectal distension(CRD) at different pressures. After the modeling, all rats were equipped with electrodes in descending colon. After recovering from surgery, CES with long pulses,CES with trains of short pulses, sham CES was performed. Finally, the extent of visceral hypersensitivity will quantified again in model group.Results 1.Rats displayed an increased sensitivity to colorectal distention(CRD), after a 6-d heterotypic intermittent stress compared to control group at different distention pressures(p<0.01). 2. CES with trains of short pulses and long pulses significantly attenuated the hypersensitive responses to colorectal distention compared with sham CES group(p<0.01).Conclusion CES with long pulses, CES with trains of short pulses all can significantly alleviates stress-induced visceral hypersensitivity.Chapter 2 Effect of retrograde colonic electrical stimulation on colonic transit in rats with irritable bowel syndromeObjective To evaluate the effects of retrograde colonic electrical stimulation(RCES)with trains of short pulses and RCES with long pulses on colonic transit in irritable bowel syndrome(IBS)rats.Methods 48 male rats were randomly divided into model group and control group, visceral hypersensitivity model was induced by a 6-d heterotypic intermittent stress protocol composed of 2 stressors, the extent of visceral hypersensitivity was quantified by EMG and AWR scores.After the modeling, all rats were equipped with electrodes in descending colon for retrograde electrical stimulation and a PE tube for perfusing phenol red saline solution in the ileocecus. After recovering from surgery, RCES with long pulses, RCES with trains of short pulses, sham RCES was performed in colonic serosa of rats for 40 min in 6 groups of 8 each, including 3 groups of visceral hypersensitivity rats and 3 groups of health rats. Colonic transit was assessed by calculating the output of phenol red from the anus every 10 min for 90 min.Results The effects of RCES on rats colon transmission: in IBS rats, the colonic emptying were 77.4±3.4%, 74.8±2.4% and 64.2±1.6% in the sham RCES group, long pulses group and trains of short pulses group at 90 min; in healthy rats, the colonic emptying was 65.2±3.5 %, 63.5±4.0 % and 54.0±2.5% in the sham RCES group, long pulses group and trains of short pulses group at 90 min.Conclusion RCES with trains of short pulses has an inhibitory effect of colonic transit, both in visceral hypersensitivity rats and healthy rats.