Effects of Sargassum plagiophyllum extract pretreatment on tissue histology of constipated mice

Purpose: To evaluate the toxicity of the dried seaweed, Sargassum plagiophyllum, extract (SPE) pretreatment in constipated mice.Methods: The dried seaweed powder was mixed with distilled water and extracted by autoclave at 121°C. Antioxidant activity of the extract was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Human normal colon cells were pretreated with SPE at 0 - 100 μg/mL for 24 h before challenging them with 100 μM hydrogen peroxide (H2O2). Intracellular reactive oxygen species (ROS) were quantified using 2',7'- dichlorodihydrofluorescein diacetate (H2DCFDA). Male ICR mice were pretreated for 14 consecutive days with SPE at 100, 500 and 1,000 mg/kg or lactulose at 500 mg/kg. Body weight and food intake were recorded daily. Constipation was induced with loperamide on days 12, 13 and 14 and fecal pellets evacuated over a 4-hr period. The ileum, liver, kidney, and spleen were collected for histopathological examination.Results: The IC50 for the radical scavenging capacity of SPE was 343.90 ± 4.21 μg/mL compared to 14.14 ± 0.71 μg/mL for ascorbic acid. Pretreatment with SPE was significantly reduced ROS production in human normal colon cells. Oral administration of all doses of SPE and lactulose for 14 consecutive days had no effect on food intake or body weight when compared to the normal control group. Defecation was significantly more frequent in mice pretreated with SPE at 100 mg/kg than in the constipation control group. Histopathological examination of the ileum, liver, kidney and spleen of pretreated constipated mice revealed no toxic effect from either SPE or lactulose. On the other hand, the loss of mucus-producing cells in the ileum of constipated mice was significantly lower in mice pretreated with SPE.Conclusions: These findings support the safety of SPE supplementation and may broaden itsapplication in clinical fields as an alternative drug or supplement for constipation management

Fluoxetine affects intestinal motility via 5-HT3 and muscarinic receptors in ex vivo mouse model

Fluoxetine, a selective serotonin reuptake inhibitor anti-depressant, causes undesirable side effects, including diarrhea and constipation. This research investigated the direct effects of fluoxetine at 0.001, 0.01, 0.1, 1, 10, and 100 μM on duodenal and proximal colonic tissue contractions. The investigation aimed to determine related mechanisms using an isolated mouse intestine model. Our study showed that fluoxetine at 0.001 μM increased the amplitude of contraction in colonic tissue but decreased the amplitude in duodenal tissue. The direct application of higher concentrations of fluoxetine (1, 10, and 100 μM) reduced the amplitude of contractions in proximal colonic tissue. Moreover, we found that the stimulatory effect of 0.001 μM fluoxetine on the tone of contractions could be prevented by pre-incubating the tissue in ondansetron and atropine. Our findings suggest that the inhibition of the effect of fluoxetine was mainly mediated via 5-HT3 receptors and muscarinic signaling. These findings might explain the conflicting gastrointestinal symptoms caused by fluoxetine

Impact of the F508del mutation on ovine CFTR, a Cl- channel with enhanced conductance and ATP-dependent gating

Cross-species comparative studies are a powerful approach to understand the epithelial Cl- channel cystic fibrosis transmembrane conductance regulator (CFTR), which is defective in the genetic disease cystic fibrosis (CF). Here, we investigate the single-channel behaviour of ovine CFTR and the impact of the most common CF mutation, F508del-CFTR, using excised inside-out membrane patches from transiently transfected CHO cells. Like human CFTR, ovine CFTR formed a weakly inwardly rectifying Cl- channel regulated by PKA-dependent phosphorylation, inhibited by the open-channel blocker glibenclamide. However, for three reasons, ovine CFTR was noticeably more active than human CFTR. First, single-channel conductance was increased. Second, open probability was augmented because the frequency and duration of channel openings were increased. Third, with enhanced affinity and efficacy, ATP more strongly stimulated ovine CFTR channel gating. Consistent with these data, the CFTR modulator phloxine B failed to potentiate ovine CFTR Cl- currents. Like its impact on human CFTR, the F508del mutation caused a temperature-sensitive folding defect, which disrupted ovine CFTR protein processing and reduced membrane stability. However, the F508del mutation had reduced impact on ovine CFTR channel gating in contrast to its marked effects on human CFTR. We conclude that ovine CFTR forms a regulated Cl- channel with enhanced conductance and ATP-dependent channel gating. This phylogenetic analysis of CFTR structure and function demonstrates that subtle changes in structure have pronounced effects on channel function and the consequences of the CF mutation F508del. This article is protected by copyright. All rights reserved

Effects of plant oligosaccharides derived from dragon fruit on gut microbiota in proximal and distal colon of mice

Prebiotic oligosaccharides are used as supplements to improve colon health. Oligosaccharides derived from dragon fruit (DFO) are a mixture of fructo-oligosaccharides (FOS), and have prebiotic properties that increase beneficial bacteria in vitro. This study aimed to investigate changes in gut microbiota in the colon of mice fed a diet supplemented with DFO. Treatment groups were fed 100, 500, and 1000 mg/kg of DFO, 1000 mg/kg FOS and distilled water. The results showed that DFO did not change the body weight of mice, but altered microbiota in the proximal and distal colon. Populations of Blautia, Parabacteroides, and Bacteroides were among the highest proportions of bacteria represented after all treatments. Lactobacillus was also found in the proximal and distal colon. Moreover, qPCR results showed that Bifidobacteria increased in the distal colon of mice treated with 100 and 1000 mg/kg DFO for 14 days, while Lactobacilli increased in the proximal colon of mice treated with 500 mg/kg DFO for 7 days. In contrast, Enterococci decreased in the proximal colon of mice that were given 100, 500, and 1000 mg/kg of DFO and 1000 mg/kg of FOS for 14 days. These results suggested that DFO is capable of increasing populations of beneficial bacteria while decreasing populations of some other bacteria

A novel model of adenine-induced chronic kidney disease-associated gastrointestinal dysfunction in mice: The gut-kidney axis

Although constipation is a common complication of chronic kidney disease (CKD), there is no animal model that can be used to study the association between renal impairment and gastrointestinal function without interfering with the gastrointestinal tract of the model. Therefore, we determined whether adenine could induce CKD in association with gastrointestinal dysfunction. Six-week-old ICR mice were intraperitoneally injected with saline, 25, 50, or 75 mg adenine/kg body weight for 21 days. Blood urea nitrogen (BUN), plasma creatinine, and renal histopathology were evaluated. Defecation status was evaluated from defecation frequency and fecal water content. Colonic smooth muscle contraction was measured by the organ bath technique, and transepithelial electrical resistance (TEER) was measured using an Ussing chamber. In the 50 mg/kg treatment group, BUN and creatinine were significantly increased compared with control, and inflammatory cell infiltration, glomerular necrosis, tubular dilatation, and interstitial fibrosis were observed in renal tissues. Mice in this group also showed a significant decrease in defecation frequency, fecal water content, colonic motility index, and TEER. Overall, 50 mg/kg of adenine was the best dose to induce CKD with associated constipation and intestinal barrier impairment. Therefore, this adenine administration model can be recommended for CKD-associated gastrointestinal dysfunction research

Sargassum plagiophyllum Extract Enhances Colonic Functions and Modulates Gut Microbiota in Constipated Mice

Constipation is a symptom that is widely found in the world’s population. Various dietary supplementations are used to relieve and prevent constipation. Seaweed is widely used for its health benefits. In this study, we aimed to investigate the effects of Sargassum plagiophyllum extract (SPE) on functions of the gastrointestinal tract and gut microbiota. The results show that SPE pretreatment increased the frequency of gut contraction, leading to reduce gut transit time. SPE pretreatment also significantly increased the secretion of Cl− and reduced Na+ absorption, increasing fecal water content in constipated mice (p < 0.05). In addition, the Bifidobacteria population in cecal contents was significantly higher in constipated mice pretreated with 500 mg/kg SPE for 14 days than in untreated constipated mice (p < 0.05). Our findings suggest that SPE can prevent constipation in loperamide-induced mice. This study may be useful for the development of human food supplements from S. plagiophyllum, which prevent constipation