Interplay between nitric oxide and VIP in CCK-8-induced phasic contractile activity in the rabbit sphincter of Oddi

Sphincter of Oddi Function and Risk Factors for Dysfunction

The sphincter of Oddi (SO) is a smooth muscle valve regulating the flow of biliary and pancreatic secretions into the duodenum, initially described in 1887 by the Italian anatomist, Ruggero Oddi. SO dysfunction (SOD) is a broad term referring to numerous biliary, pancreatic, and hepatic disorders resulting from spasms, strictures, and relaxation of this valve at inappropriate times. This review brings attention to various factors that may increase the risk of SOD, including but not limited to: cholecystectomy, opiates, and alcohol. Lack of proper recognition and treatment of SOD may be associated with clinical events, including pancreatitis and biliary symptoms with hepatic enzyme elevation. Pharmacologic and non-pharmacologic approaches are discussed to help recognize, prevent, and treat SOD. Future studies are needed to assess the treatment benefit of agents such as calcium-channel blockers, glyceryl trinitrate, or tricyclic antidepressants in patients with SOD.

Effects of sphincter of Oddi motility on the formation of cholesterol gallstones

AIM: To investigate the mechanisms and effects of sphincter of Oddi (SO) motility on cholesterol gallbladder stone formation in guinea pigs.

METHODS: Thirty-four adult male Hartley guinea pigs were divided randomly into two groups, the control group (n = 10) and the cholesterol gallstone group (n = 24), which was sequentially divided into four subgroups with six guinea pigs each according to time of sacrifice. The guinea pigs in the cholesterol gallstone group were fed a cholesterol lithogenic diet and sacrificed after 3, 6, 9, and 12 wk. SO manometry and recording of myoelectric activity were obtained by a multifunctional physiograph at each stage. Cholecystokinin-A receptor (CCKAR) expression levels in SO smooth muscle were detected by quantitative real-time PCR (qRT-PCR) and serum vasoactive intestinal peptide (VIP), gastrin, and cholecystokinin octapeptide (CCK-8) were detected by enzyme-linked immunosorbent assay at each stage in the process of cholesterol gallstone formation.

RESULTS: The gallstone formation rate was 0%, 0%, 16.7%, and 83.3% in the 3, 6, 9, and 12 wk groups, respectively. The frequency of myoelectric activity in the 9 wk group, the amplitude of myoelectric activity in the 9 and 12 wk groups, and the amplitude and the frequency of SO in the 9 wk group were all significantly decreased compared to the control group. The SO basal pressure and common bile duct pressure increased markedly in the 12 wk group, and the CCKAR expression levels increased in the 6 and 12 wk groups compared to the control group. Serum VIP was elevated significantly in the 9 and 12 wk groups and gastrin decreased significantly in the 3 and 9 wk groups. There was no difference in serum CCK-8 between the groups.

CONCLUSION: A cholesterol gallstone-causing diet can induce SO dysfunction. The increasing tension of the SO along with its decreasing activity may play an important role in cholesterol gallstone formation. Expression changes of CCKAR in SO smooth muscle and serum VIP and CCK-8 may be important causes of SO dysfunction.

Biliary tract pressure before and after endoscopic papillary balloon dilation treatment for common bile duct stones

AIM: To determine the biliary tract pressure before and after endoscopic papillary balloon dilation (EPBD) treatment for common bile duct stones.

METHODS: Clinical data for 96 patients with common bile duct stones who successfully underwent EPBD and biliary manometry from September 2011 to January 2014 were retrospectively analyzed.

RESULTS: Biliary tract pressure was significantly higher in patients with common bile duct stones than in healthy controls, which could be relieved by EPBD. Biliary tract pressure in patients who underwent cholecystectomy was higher than in patients with gallbladder stones. After operation, there were 2 cases of hyperamylasemia, 2 cases of acute pancreatitis and 2 cases of mild cholangitis, all of which resolved after non-operative treatment. The incidence of complications was 6.3% (6/96). No serious complications occurred.

CONCLUSION: EPBD treatment can effectively solve biliary obstruction and reduce biliary pressure.

Effects of cholecystectomy on the changes of motility of Beagle dogs' sphincter of Oddi

PURPOSE

To observe the effect of cholecystectomy on the changes of motion pattern of Beagle dogs' sphincter of Oddi (SO), and investigate the modulatory role of nitric oxide (NO) and cholecystokinin (CCK) in the regulation of SO.

METHODS

Pressure of common bile duct, SO motility, response to bolus injections of cholecystokinin (CCK, 20 ng/kg and 100 ng/kg), basal pressure (BP) and phasic contraction amplitude (PCA) were measured respectively by manometry in six Beagle dogs before and after cholecystectomy.

RESULTS

After cholecystectomy, the pressure and diameter of common bile ducts (CBD) was significantly increased (p<0.01); BP and phasic contraction frequency (PCF) were also increased, however, no significant differences were found between the two groups; the SO motilities was not significantly changed. The relaxation responded to physiological dose of CCK (20ng/kg) was decreased, while bolus-dose of CCK (100ng/kg) induced rapid contractions and decreased PCA after cholecystectomy. The regulation pattern of SO pressure modulated by NO and its inhibitor had changed after cholecystectomy.

CONCLUSION

After cholecystectomy in Beagle dogs, no obviously change of motion pattern of SO was observed through self-compensation, but these compensations may lead to some changes of regulation pattern of CCK and NO on SO.

Block by nitrate tolerance of meal-induced insulin sensitization in conscious rabbits

PURPOSE

Hemodynamic nitrate tolerance has been shown to result in an insulin-resistant state. We studied whether nitrate tolerance induced by a 7-day continuous exposure to transdermal nitroglycerin influenced the meal-induced insulin sensitization phenomenon in rabbits.

METHODS

Changes in insulin sensitivity in response to feeding in conscious rabbits were determined by rapid insulin sensitivity test, in both nitrate-tolerant and nitrate-intolerant animals. In a separate series of experiments with anesthetized rabbits with or without nitrate tolerance, the hyperinsulinemic euglycemic glucose clamping methods was used to study the effect of intraportal infusion of cholecystokinin (CCK) on whole-body insulin sensitivity.

RESULTS

Rabbits with normal feeding exhibited a 46 ± 6% increase in insulin sensitivity as compared with their matching fasting controls. A 7-day period of treatment with patches releasing 0.07 mg of nitroglycerin per hour yielded nitrate tolerance and a state of insulin resistance and no increase in insulin sensitivity in response to food. Intraportal infusion of CCK8 (0.3-3.0 μg/kg over 20 minutes) resulted in a dose-dependent increase in insulin sensitivity in normal but not in nitrate-tolerant, fasted anesthetized animals.

CONCLUSIONS

Nitrate tolerance blocks both the meal-induced insulin sensitization phenomenon and the insulin-sensitizing effect of intraportal CCK.

Reduced myoelectric activity in the sphincter of Oddi in a new model of chronic cholangitis in rabbits: an in vivo and in vitro study

BACKGROUND

Chronic cholangitis caused by hepatolithiasis is a common disease in Southeast Asia. Few studies have addressed the effects of chronic cholangitis on cyclic activity of the sphincter of Oddi (SO). In this study, we investigated the changes of myoelectric activity in rabbits with chronic cholangitis in vivo and in vitro.

METHODS

Chronic cholangitis was induced in rabbits by initially introducing three pieces of 2-0 silk suture and sequentially injecting E. coli into the choledochus through the tube in ductus cysticus. In in vivo experiments, myoelectric activity of SO was recorded by a circular electrode through the jejunum stump in conscious animals. In in vitro experiments, the SO was completely isolated and the myoelectric activity was recorded by a circular electrode in a 10-mL organ bath filled with Krebs solution, with or without addition of cholecystokinin-8 (CCK-8), KCl, ionomycin or induction of capacitative calcium entry (CCE).

KEY RESULTS

In comparison with control and non-infected rabbits, the rabbits with chronic cholangitis showed higher levels of alkaline phosphatase and gamma-glutamyltransferase and significant pathological changes including increased inflammatory infiltration and collagen deposition in mucosae or muscular layer. Cyclic myoelectric activity of SO at phases 2 and 3 of migrating motor complex and the excitatory response to CCK-8 were dramatically decreased in animals with chronic cholangitis. Myoelectric activity of SO was also significantly decreased in vitro with or without agonists or with induction of CCE.

CONCLUSIONS & INFERENCES

Myoelectric activity of SO and its response to agonists are decreased in rabbits with chronic cholangitis both in vivo and in vitro.

Effect of four medications associated with gastrointestinal motility on Oddi sphincter in the rabbit

AIM

Modulatory drugs of gastrointestinal (GI) motility are a possibility for use to relieve the main clinical presentation of sphincter of Oddi (SO) dysfunctions which are not easily distinguished from those occurring in high prevalence functional GI disorders. The aim of this study was to investigate the effects of GI motility modulators including pinaverium, domperidone, trimebutine, and tegaserod on the contractile activity of SO stimulated by carbachol in the rabbit.

METHODS

The contraction responses precontracted by carbachol (0.1 microM) of in vitro rabbit SO rings were evaluated before and after the addition of a series concentration (10(-13) to 10(-3)M) of pinaverium, domperidone, trimebutine, and tegaserod.

RESULTS

Pinaverium induced a concentration-dependent relaxation of isolated SO rings (10(-13) vs. 10(-7) vs. 10(-3)M = 16.6 +/- 4.8 vs. 47.1 +/- 5.5 vs. 81.2 +/- 6.2%, p < 0.001 by ANOVA) precontracted with carbachol (0.1 microM). Tegaserod did not significantly effect (10(-13) vs. 10(-7) vs. 10(-3)M = 2.3 +/- 2.2 vs. 6.7+/- 2.1 vs. 10.1 +/- 2.3%, p > 0.05 by ANOVA) SO motility, but domperidone seemed to stimulate SO contractions (10(-12) vs. 10(-7) vs. 10(-3)M = -2.2 +/- 1.5 vs. -13.9 +/- 2.0 vs. -21.0 +/- 2.7%, p < 0.05 by ANOVA). At low doses (10(-13) to 10(-7)M), trimebutine stimulated SO contraction (-8.7 +/- 1.4 vs. -9.3 +/- 2.0%); however, high doses (10(-6) to 10(-3)M) of trimebutine inhibited SO motility (-5.9 +/- 1.7 vs. 14.5 +/- 2.0%, p < 0.05 by ANOVA).

CONCLUSION

Pinaverium totally inhibits contractions induced by carbachol and tegaserod has no effect on carbachol-induced contractions. Domperidone stimulates contractions induced by carbachol. Trimebutine could either stimulate or inhibit SO contractions depending on its dosage.

Neurohormonal regulation of the sphincter of Oddi

The control of sphincter of Oddi (SO) motor activity is complex and involves interactions between the SO smooth muscle with nerves, bioactive agents, and presumably interstitial cells of Cajal. Disturbances in SO motility are known to be related to painful clinical conditions, such as SO dysfunction and acute pancreatitis. Understanding normal SO motility and comparing this to disturbed SO motility patterns may identify mechanisms that could be targeted for future pharmacologic intervention. The effect on SO motility of recently identified neurotransmitters/neuropeptides, such as purines and orexins, is currently being determined. Furthermore, because the control of SO motility is complex, investigations with known bioactive agents, such as cholecystokinin and nitric oxide, are continuing. This review summarizes research investigating SO motility and function performed in 2005 and 2006.