Munenori Nagao

Mechanisms of Action of the Gasotransmitter Hydrogen Sulfide in Modulating Contractile Activity of Longitudinal Muscle of Rat Ileum

AimThis study aims to determine mechanisms of action of the gasotransmitter hydrogen sulfide (H2S) on contractile activity in longitudinal muscle of rat ileum.MethodsIleal longitudinal muscle strips were prepared to measure isometric contractions. Effects of sodium hydrosulfide (NaHS), a donor of H2S, were evaluated on spontaneous contractile activity and after enhanced contractile activity with bethanechol. l-cysteine was evaluated as a potential endogenous donor of H2S. We evaluated involvement of extrinsic nerves, enteric nervous system, visceral afferent nerves, nitric oxide, and KATP+ channel and KCa+ channel activity on the action of H2S using non-adrenergic/non-cholinergic conditions, tetrodotoxin, capsaicin, l-NG-nitro arginine (l-NNA), glibenclamide, and apamin, respectively, as well as electrical field stimulation.ResultNaHS dose-dependently and reversibly inhibited spontaneous and bethanechol-stimulated contractile activity (p < 0.05). l-cysteine had no inhibitory effect. Non-adrenergic/non-cholinergic conditions, tetrodotoxin, capsaicin, l-NNA, glibenclamide, or apamin had no major effect on total contractile activity by NaHS, although both tetrodotoxin and apamin decreased the frequency of bethanechol-enhanced contractile activity (p < 0.05). We could not demonstrate H2S release by electrical field stimulation but did show that inhibition of cystathionine β synthase, an endogenous source of H2S, augmented the inhibitory effect of low-frequency electrical field stimulation.ConclusionH2S inhibits contractile activity of ileal longitudinal muscle dose-dependently but not through pathways mediated by the extrinsic or enteric nervous system, visceral afferent nerves, nitric oxide, KATP+ channels, or KCa+ channels.

Surgical Treatment of Chronic Intestinal Pseudo-Obstruction: Report of Three Cases

Abstract.We report the cases of three patients with chronic intestinal pseudo-obstruction (CIP) whose quality of life (QOL) was improved by palliative surgery in combination with home parenteral nutrition (HPN). Loop enterostomy and shortening of the gastrointestinal tract was performed with good results in all three patients to relieve abdominal distension that was progressive despite treatment with prokinetic drugs. Oral intake was also improved after surgical treatment in one patient who underwent massive resection of the jejunoileum. HPN maintained a satisfactory nutritional state in all patients. These three case reports serve to demonstrate that surgical intervention to improve QOL should be considered for patients with CIP if medication is not effective and symptoms are progressive.

Biliopancreatic limb plays an important role in metabolic improvement after duodenal–jejunal bypass in a rat model of diabetes

BACKGROUND AND AIMS Roux-en-Y gastric bypass improves glucose metabolism in clinical practice, and duodenal-jejunal bypass (DJB), an experimental bypass procedure, also improves metabolism in animals. However, the mechanism remains controversial; especially, the role of the biliopancreatic limb (BP-limb) remains unclear. Our aim was to examine the importance of the function of the BP-limb after DJB using a novel operative model. METHODS Otsuka Long-Evans Tokushima Fatty rats with diabetes were divided into the following groups: DJB with a short alimentary limb (A-limb) and long BP-limb (B-DJB group), DJB with jejunectomy (J-DJB group) in which the entire length of the jejunum used for the BP-limb of the B-DJB group was excised; and a sham operation group. Glucose tolerance, plasma bile acid levels, and the gut microbiota were assessed postoperatively. RESULTS Glucose tolerance was improved and weight gain was suppressed after surgery in the B-DJB group. In contrast, these effects were cancelled in the J-DJB group. The plasma levels of bile acids in the B-DJB group were greater than those in other groups. The analysis of gut microbiota showed distinct differences between the B-DJB and other groups; especially, the relative abundance of genus Bifidobacterium was much higher in the B-DJB group. CONCLUSION The BP-limb played an important role in the control of weight gain, glucose tolerance, and increased plasma bile acid levels after DJB in this rat model of type 2 diabetes mellitus. Plasma bile acids and gut microbiota may be involved in these processes.

Octreotide in control of multiple liver metastases from gastrinoma

The somatostatin analogue octreotide was effective in controlling systemic effects related to multiple liver metastases from a gastrinoma. A 61-year-old man underwent distal gastrectomy for gastrinoma in the duodenum, because a curative resection was not feasible due to metastases found in paraaortic lymph nodes during operation. Multiple liver metastases, associated with an increase in serum gastrin concentration, were found by magnetic resonance imaging 16 months after the operation. Although chemotherapy with dimethyltrizenoimidazole carboxamide was not effective, subcutaneous administration of octreotide was effective in controlling the growth of the liver metastases and in stabilizing serum gastrin. The patient now receives subcutaneous injections of octreotide, at 200 µg a day, twice a week, as an outpatient.

Intracolonic capsaicin stimulates colonic motility and defecation in conscious dogs.

BACKGROUND The aim of this study was to investigate the effects of intracolonic capsaicin on colonic motility and defecation. METHODS The effects of capsaicin (1, 2, 5, and 10 mg) administrated into the proximal colon on ileocolonic motility and defecation were studied in neurally intact dogs with or without various antagonists (atropine, hexamethonium, ondansetron, propranolol, and FK224), dogs with extrinsic denervation of an ileocolonic segment, and dogs with enterically isolated ileocolonic loops equipped with strain gauge force transducers. RESULTS Capsaicin at 5 and 10 mg evoked giant migrating contractions in a dose-independent manner, and it induced defecations with more than 90% probability in neurally intact dogs. These effects of capsaicin were abolished by atropine and hexamethonium. Ondansetron inhibited the capsaicin-induced increase in colonic motility but did not affect the induction of defecation. The other antagonists had no effect. In dogs with extrinsic denervation, capsaicin did not evoke giant migrating contractions in the colon but still induced defecation in 30-40% of experiments. In dogs with ileocolonic loops, capsaicin did not stimulate colonic motility nor induce defecation. CONCLUSION These results indicate that intracolonic capsaicin causes giant migrating contractions and defecation. Intact extrinsic innervation, continuity of the colon, and intraluminal contents were considered necessary for this effect.

Factors Affecting the Bowel Function after Proctocolectomy and Ileal J Pouch–Anal Anastomosis for Ulcerative Colitis

The aim was to study determinants of postoperative bowel function after restorative proctocolectomy for ulcerative colitis. Medical records of patients who underwent proctocolectomy with ileal J pouch-anal anastomosis (IPAA) in two- or three-stage operations and whose status of defecation was known via a questionnaire were retrospectively reviewed. Bowel function, including stool frequency, stool consistency, and degree of nighttime soiling, was correlated with age at the time of surgery, time after ileostomy closure, mean resting anal pressure, longitudinal length of ileal J pouch, and duration of fecal diversion by using univariate and multivariate analyses. Stool frequency decreased significantly with time after ileostomy closure in both univariate and multivariate analyses. Stool frequency tended to be less in patients having a long J pouch, but the correlation was not significant (P=0.071) in univariate analysis. Nighttime soiling ameliorated with time after ileostomy closure in multivariate, but not univariate, analysis. Deterioration of nighttime soiling was seen in patients whose duration for fecal diversion was long, both in univariate (P=0.068) and multivariate (P=0.052) analyses. Stool consistency was related to none of the five factors investigated. These results indicate that as the time after surgery increases, stool frequency decreases and nighttime soiling ameliorates. Delaying ileostomy closure because of anticipated postoperative incontinence does not significantly alter postoperative continence.

SERPINI1 regulates epithelial-mesenchymal transition in an orthotopic implantation model of colorectal cancer

An increasingly accepted concept is that the progression of colorectal cancer is accompanied by epithelial–mesenchymal transition (EMT). In our study, in order to characterize the properties of EMT in 16 colorectal cancer cell lines, the cells were first orthotopically implanted into nude mice, and the tumors in vivo, as well as cells cultured in vitro, were immunostained for EMT markers. The immunostaining revealed that seven of the cells had an epithelial phenotype with a high expression of E‐cadherin, whereas other cells showed opposite patterns, such as a high expression of vimentin (CX‐1, COLO205, CloneA, HCT116, and SW48). Among the cells expressing vimentin, some expressed vimentin in the orthotopic tumors but not in the cultured cells (SW480, SW620, and COLO320). We evaluated these findings in combination with microarray analyses, and selected five genes: CHST11, SERPINI1, AGR2, FBP1, and FOXA1. Next, we downregulated the expression of SERPINI1 with siRNA in the cells, the results of which showed reverse‐EMT changes at the protein level and in the cellular morphology. Along with immunohistochemical analyses, we confirmed the effect of the intracellular and secreted SERPINI1 protein of SW620 cells, which supported the importance of SERPINI1 in EMT. The development of therapeutic strategies targeting EMT is ongoing, including methods targeting the transforming growth factor‐β signaling pathway as well as the Wnt pathway. SERPINI1 is an important regulator of EMT. Our findings help to elucidate the signaling pathways of EMT, hopefully clarifying therapeutic pathways as well.

Effect of ileo-jejunal transposition on ileal longitudinal smooth muscle contractility in vitro in rats.

The aim of the present paper was to study the effects of ileo-jejunal transposition (IJT) on ileal contractile activity in vitro in rats. Male Sprague-Dawley rats were divided into three groups: control, IJT, and sham. In rats with IJT, the distal ileum was interposed isoperistaltically into the proximal jejunum. The jejunoileum was transected and anastomosed at three sites in the sham group. Rats were sacrificed 17–20 weeks postoperatively and the ileal segment was removed. Isometric contractile activity of the isolated ileal longitudinal muscle was measured in tissue chambers. Spontaneous contractile activity was decreased in the IJT group (0.16 ± 0.03 g/min per mg tissue) as compared with the control group (0.25 ± 0.02 g/min per mg tissue, p < 0.05). The motor response to cholinergic agonist bethanechol in the IJT group was greater than in the control group above 10-6 M dosage. The dose-response curves to adrenergic agonist norepinephrine did not differ between groups. A nitric oxide synthase inhibitor reversed electrical field stimulation-induced inhibition of spontaneous activity in all groups. These results indicate that the response to bethanechol in the IJT group was enhanced in rat ileal longitudinal smooth muscle and this may be an adaptive response to compensate for decreased spontaneous contractile activity.

Increased Bile Acid Signals After Duodenal-Jejunal Bypass Improve Non-alcoholic Steatohepatitis (NASH) in a Rodent Model of Diet-Induced NASH

BackgroundThe increasing incidence of non-alcoholic steatohepatitis (NASH) has resulted in it becoming a common cause of liver-related mortality; however, no efficient treatment has been established. It has been reported that bariatric surgery improves metabolic comorbidities, such as diabetes mellitus and NASH. Although the mechanism is unclear, it is thought that the changes in bile acid (BA) signaling via its nuclear receptor, farnesoid X receptor (FXR), produce various metabolic effects. We sought to investigate the effects and mechanisms of bariatric surgery on NASH improvement.MethodsMale Sprague-Dawley rats were fed by a high-fat and high-fructose diet, which results in obesity, insulin resistance, and NASH. Rats underwent duodenal-jejunal bypass (DJB), which is a main component of bariatric procedures. The liver pathological findings and the expression level of mRNA of FXR were investigated. The plasma BA level was measured in peripheral and portal vein blood.ResultsDJB suppressed weight gain, improved insulin resistance, and ameliorated NASH mainly in a point of inflammation. The plasma BA level along with the expression of FXR and its target transcriptional factor, small heterodimer partner (SHP), in the liver were elevated.ConclusionsDJB has a direct effect on NASH improvement, and there is a possibility that an anti-inflammatory effect is functioning as a part of the mechanism. The increase of plasma bile acid level followed by the stimulation of FXR signaling may contribute to this phenomenon.

Fecal stream is essential for adaptive induction of glucose-coupled sodium transport in the remnant ileum after total proctocolectomy

Our previous studies demonstrated that sodium glucose cotransporter 1 (SGLT-1) was induced in the remnant ileum of total colectomized rats via the action of factors other than hyperaldosteronism. The aim of the present study was to clarify whether fecal stream is required for the enhancement of SGLT-1-mediated sodium transport. Twenty-seven pairs of ileal tissues were obtained from the proximal and distal side, respectively, of loop ileostomy after total proctocolectomy. Mucosae were mounted in an Ussing chamber to evaluate glucose-coupled sodium transport. Levels of SGLT-1 mRNA in proximal and distal mucosae were compared by Northern blotting. Villous height and crypt depth were measured to test for correlations between mucosal structure and SGLT-1-mediated sodium transport or mRNA expression levels. Both glucose-coupled sodium transport and expression of SGLT-1 mRNA were significantly lower in distal mucosae relative to proximal mucosae. In distal mucosae, villous height, but not crypt depth, was significantly lower than in proximal mucosae, demonstrating a positive correlation between villous height and SGLT-1 function and expression. Comparative studies of proximal and distal mucosae demonstrated that in addition to hormonal changes, fecal stream is required for full induction of the sodium transport system (which includes SGLT-1-mediated transport) in the remnant ileum following total proctocolectomy.