Electroacupuncture at ST25 inhibits jejunal motility:Role ofsympathetic pathways and TRPV1

AIM: To investigate whether electroacupuncture(EA) at ST25 affects jejunal motility in vivo and if so, whether a sympathetic pathway is involved.METHODS: Jejunal motility was assessed using a manometric balloon placed in the jejunum approximately about 3-5 cm away from the suspensory ligament of the duodenum in anesthetized animals. The effects of EA at ST25 were measured in male Sprague-Dawley rats, some of which were treated with propranolol or clenbuterol(EA intensities: 1, 3, 5, 7, and 9 m A), and in male transient receptor potential vanilloid-1(TRPV1)(capsaicin receptor) knockout mice(EA intensities: 1, 2, and 4 m A).RESULTS: Anesthetized rats exhibited three types of fasting jejunal motor patterns(types A, B, and C), and only type C rats responded to EA stimulation. In type C rats, EA at ST25 significantly suppressed the motor activity of the jejunum in an intensity-dependent manner. The inhibitory effect of EA was weakened by propranolol(β adrenoceptor antagonist) and disappeared with clenbuterol(β adrenoceptor agonist) induced inhibition of motility, suggesting that the effect of EA on motility is mediated via a sympathetic pathway. Compared with wild-type mice, EA at ST25 was less effective in TRPV1 knockout mice, suggesting that this multi-modal sensor channel participates in the mechanism. CONCLUSION: EA at ST25 was found to inhibit jejunal motility in an intensity-dependent manner, via a mechanism in which sympathetic nerves and TRPV1 receptors play an important role.

Development of a novel mouse constipation model

AIM: To establish a novel mouse constipation model. METHODS: Animals were randomly divided into three groups, and intragastrically administered 0-4?℃ saline(ice-cold group) or 15-20?℃ saline(saline control group) daily for 14 d, or were left untreated(blank control group). Stools were collected 3-24 h after treatment to record the wet and dry weights and the stool form. Intestinal propulsion experiments were carried out and defecation time was measured for six days continuously after suspending treatments. The expressions of PGP9.5 were detected by immunohistochemistry.RESULTS: Based on the percentage of stool weight changes compared with baseline(before irritation) in 9-14 d, stool weight changes were classified into three levels. Each level shows a different body state, which is state Ⅰ(no change: plus or minus 5%), state Ⅱ(slightly decreased: 5%-15%) and state Ⅲ(decreased: 15%-25%). In state Ⅲ, between day 9-14, the stool weights decreased by 15%-25% compared with the baseline, and changed at a rate > 10% compared with blank control values, and the stools became small and dry. Additionally, intestinal functions degenerated in these animals, and PGP9.5-positive expression markedly decreased in jejunum, ileum and proximal colon myenteric plexus.CONCLUSION: Irritation with ice-cold saline is a stable, repeatable method in building constipation model in mice for exploring the pathogenesis and treatment options of constipation, and the change of stool weight and size may serve as a useful tool to judge a constipation model success or not.