Effects of a Single Opioid Dose on Gastrointestinal Motility in Rabbits (Oryctolagus cuniculus): Comparisons among Morphine, Butorphanol, and Tramadol

The aim of this study was to evaluate and compare the effects of single doses of butorphanol, morphine, and tramadol on gastrointestinal motility in rabbits (Oryctolagus cuniculus) using non-invasive imaging methods, such as radiographic barium follow through and ultrasonographic contraction counts. Time-lapse radiographic and ultrasound examinations were performed before and after a single intramuscular dose of 5 mg kg−1 butorphanol, 10 mg kg−1 morphine, or 10 mg kg−1 tramadol. Pyloric and duodenal contraction counts by ultrasonography and radiographic repletion scores for the stomach and caecum were analysed using a mixed linear model. No significant effect was noted on ultrasound examinations of pyloric and duodenal contractions after administration of an opioid treatment. Morphine had a significant effect on the stomach and the caecum repletion scores, whereas butorphanol had a significant effect only on the caecum repletion score. Tramadol had no significant effect on the stomach or caecum repletion scores. The present findings suggest that a single dose of 5 mg kg−1 butorphanol or 10 mg kg−1 morphine temporarily slows gastrointestinal transit in healthy rabbits, preventing physiological progression of the alimentary bolus without the induction of ileus. In contrast, a single dose of 10 mg kg−1 tramadol has no such effects.

Gastrointestinal motility and Intestinal structure following oral exposure to acrylamide in Wistar rats

Introduction: Acrylamide, a byproduct of the cooking process, has been reported to be a toxicant with likely carcinogenic properties. Its impairment of gastric function has been previously reported. In this study its effects on gastrointestinal motility and intestinal structure was investigated in male Wistar rats.Methods: Forty-five rats (120-180g) were divided into 3 equal groups (n=15) and treated p.o with either 0.2ml distilled-water, or acrylamide (7.5mg/kg and 15mg/kg respectively) for 28days. Thereafter, gastric emptying and intestinal motility was assessed. Intestinal structure (duodenum, jejunum and ileum), mucosal and intestinal cell counts were evaluated using histological techniques.Results: Gastric emptying and intestinal transit time increased (p<0.05) in the experimental (acrylamidetreated; 7.5mg/kg and 15mg/kg) groups compared to control. Mucosal cell counts (duodenum, jejunum and ileum) and ileum intestinal cell counts (p<0.05) were reduced in the experimental groups compared to control. Compared to control, duodenal samples of the experimental groups showed severe coagulative necrosis and sloughing off of the villi, luminal filling with necrotic debris, disruption and necrosis of the crypts of Lieberkühn, moderate polymorphonuclear cell infiltration and vascular congestion. These pathologies albeit with less severity were also observed in the jejunum and ileum of acrylamide treated groups.Conclusion: Increased oral exposure to acrylamide impairs gastric emptying, intestinal motility, mucus secretion and compromises digestive and absorptive functions of the small intestines, especially the duodenum. These observations may be ascribed to acrylamide-induced impaired neuronal signaling, autonomic neuropathy, oxidative stress, inflammation and cell necrosis. Keywords: Acrylamide, gastrointestinal tract, gastric emptying, intestinal motility, small intestines

The Advantages and Disadvantages of Prokinetics

Prokinetics are medications that enhance gastrointestinal contractility; they improve the symptoms of patients with delayed gastrointestinal motility. Prokinetics have conventionally been used to stimulate gastrointestinal propulsion and to treat symptoms correlated with motility problems, including gastroparesis and constipation. 5-Hydroxytryptamine receptor 4 (5-HT4) agonists, such as cisapride, very effectively increased human gastrointestinal tract motility. However, cisapride sometimes induced serious tachyarrhythmia; the drug was thus withdrawn from the market. Thereafter, many prokinetics have been developed to treat delayed gastrointestinal motility. However, some exhibit serious side-effects. Recently, a new, highly selective serotonin receptor agonist, prucalopride, has been introduced; there is as yet no evidence of serious cardiac side- effects. The drug has been approved by the Food and Drug Administration to treat chronic constipation. Thus, recently introduced, highly selective agents appear to show promise as treatments for gastrointestinal dysmotility; there seem to be no serious side-effects.

Electroacupuncture Regulates TRPV1 through PAR2/PKC Pathway to Alleviate Visceral Hypersensitivity in FD Rats

Visceral hypersensitivity (VH) is the predominant pathogenesis of functional dyspepsia (FD). Duodenal hypersensitivity along with nausea further reduces the comfort level in gastric balloon dilatation and inhibits gastric receptive relaxation. The potential mechanism behind electroacupuncture- (EA-) mediated alleviation of VH has not been elucidated. In an FD rat model with tail clamping stress, iodine acetamide (IA) induced VH. The rats were treated with EA with or without PAR2 antagonist FSLLRY-NH2, and the body weight, gastric sensitivity, compliance, and gastrointestinal motility were determined. Mast cells and activated degranulation were stained with toluidine blue (TB) staining and visualized under a transmission electron microscope (TEM). Immunofluorescence was used to detect the expression of PAR2, PKC, and TRPV1 in the duodenum and dorsal root ganglion (DRG) and that of CGRP, SP in DRG, and c-fos in the spinal cord. EA alone and EA + antagonist enhanced the gastrointestinal motility but diminished the expression of TRPV1, CGRP, SP, and c-fos-downstream of PAR2/PKC pathway and alleviated VH in FD rats. However, there was no obvious superposition effect between the antagonists and EA + antagonists. The effect of EA alone was better than that of antagonists and EA + antagonists 2 alone. EA-induced amelioration of VH in FD rats was mediated by TRPV1 regulation through PAR2/PKC pathway. This protective mechanism involved several pathways and included several targets.

Laxative Effects of Phlorotannins Derived from Ecklonia cava on Loperamide-Induced Constipation in SD Rats

This study investigated the laxative effects of phlorotannins (Pt) derived from Ecklonia cava (E. cave) on chronic constipation by evaluating alterations in stool parameters, gastrointestinal motility, histopathological structure, mucin secretion, gastrointestinal hormones, muscarinic cholinergic regulation, and fecal microbiota in SD rats with loperamide (Lop)-induced constipation subjected to Pt treatment. Stool-related parameters (including stool number, weight, and water contents), gastrointestinal motility, and length of intestine were significantly enhanced in the Lop+Pt-treated group as compared to the Lop+Vehicle-treated group. A similar recovery was detected in the histopathological and cytological structure of the mid-colon of Lop+Pt-treated rats, although the level of mucin secretion remained constant. Moreover, rats with Lop-induced constipation subjected to Pt treatment showed significant improvements in water channel expression, gastrointestinal hormone secretions, and expression of muscarinic acetylcholine receptors M2/M3 (mAChRs M2/M3) and their mediators of muscarinic cholinergic regulation. Furthermore, the Lop+Pt-treated group showed a significant recovery of Bifidobacteriaceae, Muribaculaceae, Clostridiaceae, and Eubacteriaceae families in fecal microbiota. Taken together, these results provide the first evidence that exposure of SD rats with Lop-induced constipation to Pt improves the constipation phenotype through the regulation of membrane water channel expression, GI hormones, the mAChR signaling pathway, and fecal microbiota.

Development of colonic transit time and ultrasound imaging tools as objective indicators for assessing abnormal defecation associated with food intake: a narrative review based on previous scientific knowledge

Background Functional gastrointestinal disorders (FGIDs) involve chronic or persistent gastrointestinal symptoms. Laboratory tests show no organic lesions, and the symptoms are due to dysfunction. The most typical FGID is irritable bowel syndrome (IBS). In IBS patients, defecation disorders are common and have adverse effects on daily life. The proper evaluation and analysis of colonic transit are important for the management of defecation disorders in IBS patients. In addition, dietary intake and lifestyle affect colonic transit. An accurate assessment of such factors can guide management, leading to improvements in colonic transit and the resolution of defecation disorders. Main topic The Rome IV diagnostic criteria for IBS are based on subjective symptoms, which must be communicated and explained by the patient, limiting their application. Colonic transit time and ultrasonography are objective tools that can be used to diagnose IBS. In particular, previous studies used colonic transit to accurately distinguish between constipation and normal stool passage and to assess delayed gastrointestinal motility. Diet and lifestyle modifications can improve colonic transit and ameliorate bowel dysfunction. Conclusion Colonic transit can be improved by modifying lifestyle factors. Defecation disorders in IBS patients may be resolved by focusing on such factors. In the future, methods of visualizing defecation disorders due to impaired gastrointestinal motility and objective indicators of the associated abdominal symptoms need to be investigated.