Action Mode of Gut Motility, Fluid and Electrolyte Transport in Chronic Constipation

Effects of garlic-derived fructan and oligofructose mixtures on intestinal health and constipation relief in mice

BACKGROUND

Garlic polysaccharides (GPs) constitute over 75% of the dry weight of garlic. They are characterized by fructan with a 2,1-β-d-Fruf backbone and 2,6-β-d-Fruf branches. Studies have suggested a role for GPs in regulating gut microbiota but whether they possess a comprehensive function in maintaining intestinal well-being and can serve as effective prebiotics remains unknown. To explore this, varied doses of GPs (1.25-5.0 g kg-1 body weight) and inulin (as a positive control) were administered to Kunming mice via gavage, and their effects on the intestinal epithelial, chemical, and biological barriers were assessed. A constipation model was also established using loperamide to investigate the potential effects of GPs on the relief of constipation.

RESULTS

Administration of GPs significantly upregulated expression of tight-junction proteins and mucins in Kunming mouse small-intestine tissue. Garlic polysaccharides elevated cecal butyric acid content, reduced the abundance of Desulfobacterota, and decreased the ratio of Firmicutes to Bacteroidetes (the F/B ratio). Garlic polysaccharides also promoted the growth of Bacteroides acidifaciens and Clostridium saccharogumia. Tax4Fun functional predictions suggested the potential of GPs to prevent human diseases, reducing the risk of insulin resistance, infectious diseases, and drug resistance. Garlic polysaccharides also exhibited a beneficial effect in alleviating loperamide-induced constipation symptoms by enhancing small intestinal transit, softening stool consistency, accelerating bowel movements, and promoting the release of excitatory neurotransmitters.

CONCLUSIONS

These findings highlight the important role of GPs in maintaining gut fitness by enhancing intestinal barrier function and peristalsis. Garlic polysaccharides are promising prebiotics, potentially contributing to overall intestinal well-being and health. © 2024 Society of Chemical Industry.

Total Flavonoids of Aurantii Fructus Immaturus Regulate miR-5100 to Improve Constipation by Targeting Fzd2 to Alleviate Calcium Balance and Autophagy in Interstitial Cells of Cajal

Aurantii Fructus Immaturus total flavonoids (AFIF) is the main effective fraction extracted from AFI, which has a good effect on promoting gastrointestinal motility. This study aimed to investigate AFIF which regulates miR-5100 to improve constipation symptoms in mice by targeting Frizzled-2 (Fzd2) to alleviate interstitial cells of Cajal (ICCs) calcium ion balance and autophagy apoptosis. The constipated mouse model was induced by an antibiotic suspension, and then treated with AFIF. RNA-seq sequencing, luciferase assay, immunofluorescence staining, transmission electron microscopy, ELISA, flow cytometry, quantitative polymerase chain reaction (PCR), and Western blot were applied in this study. The results showed that AFIF improved constipation symptoms in antibiotic-induced constipated mice, and decreased the autophagy-related protein Beclin1 levels and the LC3-II/I ratio in ICCs. miR-5100 and its target gene Fzd2 were screened as key miRNAs and regulator associated with autophagy. Downregulation of miR-5100 caused increased expression of Fzd2, decreased proliferation activity of ICCs, increased apoptotic cells, and enhanced calcium ion release and autophagy signals. After AFIF treatment, miR-5100 expression was upregulated and Fzd2 was downregulated, while autophagy-related protein levels and calcium ion concentration decreased. Furthermore, AFIF increased the levels of SP, 5-HT, and VIP, and increased the expression of PGP9.5, Sy, and Cx43, which alleviated constipation by improving the integrity of the enteric nervous system network. In conclusion, AFIF could attenuate constipation symptoms by upregulating the expression of miR-5100 and targeting inhibition of Fzd2, alleviating calcium overload and autophagic death of ICCs, regulating the content of neurotransmitters, and enhancing the integrity of the enteric nervous system network.

A Novel Herbal Composition Alleviates Functional Constipation, Reduces Gastrointestinal Transit Time, and Improves Bowel Function in Adults: A Double-Blind, Randomized Clinical Study

BACKGROUND AND OBJECTIVE

A recent proof-of-concept pilot clinical study has demonstrated that consumption of CL18100F4, a proprietary herbal blend of Withania somnifera root and Abelmoschus esculentus fruit extracts, significantly relieved the participants from functional constipation and improved their quality of life. The objective of the present randomized, double-blind, placebo-controlled study was to reevaluate the efficacy and tolerability of CL18100F4 in a larger number of subjects.

METHODS

Male and female subjects (n = 135; age: 25-60 years), selected through Rome-IV criteria for functional constipation, were randomized into placebo and 300 or 500 mg of CL18100F4 groups and supplemented daily over 60 consecutive days. The primary efficacy outcome measure was Patient Assessment of Constipation-Symptoms (PAC-SYM), evaluated at baseline and on days 7, 30, and 60 of supplementation. The secondary efficacy parameters included Patient Assessment of Constipation-Quality of Life (PAC-QOL), Gastrointestinal Symptom Rating Scale (GSRS) scores, Gastrointestinal Transit Time (GIT), and Complete Spontaneous Bowel Movement (CSBM). Serum levels of Interleukin (IL)-6, IL-10, cortisol, gastrin, serotonin, Diamine oxidase (DAO), and Zonulin were measured.

RESULTS

CL18100F4 supplementation significantly (p < 0.001) reduced the PAC-SYM, PAC-QOL, GSRS scores, and GIT and improved CSBM scores. CL18100F4 significantly improved (p < 0.001) sleep quality and decreased depression and anxiety symptoms in the participants. Notably, relief in constipation symptoms and improved gastrointestinal (GI) function were reported starting from day 7. Furthermore, CL18100F4 supplementation significantly (p < 0.001) increased the serum levels of IL-10, DAO, serotonin, gastrin, reduced IL-6, cortisol, and Zonulin. No major adverse events were observed. Participants' vital signs, hematology, clinical biochemistry, and urinalysis parameters were within the normal ranges.

CONCLUSION

The present investigation demonstrates that CL18100F4 is tolerable and efficacious in relieving functional constipation, alleviating GI dysfunction, and improving associated non-GI factors in male and female adults.

Brown Seaweed Byproduct Extracts Improve Intestinal Motility and Auto-Inflammation in Mice with Loperamide-Induced Constipation

Sargassum fusiforme and Sargassum fulvellum are types of brown algae used for their nutritional value and medicinal properties, including anti-inflammatory, antioxidant, and anticancer effects. Despite their importance in various industries, many seaweed byproducts containing dietary fiber and polysaccharides are discarded in landfills. These byproducts can be recycled and repurposed for different applications. In this study, we investigated the impact of S. fusiforme food processing byproducts (MbP-SFF) and S. fulvellum food processing byproducts (MbP-SFV) on improving intestinal motility and reducing inflammation in mice with constipation induced by loperamide. To evaluate this, mice were orally administered 500 mg/kg/day of the byproducts once daily for 8 days. Constipation was induced by 5 mg/kg/day of loperamide for two days after oral administration for 6 days. Each sample contained approximately 70% carbohydrates. MbP-SFF had 52.0% mannuronic acid and 18.8% guluronic acid, while MbP-SFV had 36.9% mannuronic acid and 32.9% guluronic acid. These byproducts enhanced fecal excretion and intestinal motility by modulating inflammatory responses. Furthermore, they restored the balance of the gut microbiota disrupted by loperamide, increasing beneficial Bifidobacterium and reducing harmful Staphylococcus aureus. Overall, MbP-SFF and MbP-SFV improved intestinal motility and inflammation by influencing the gut microbiota and inflammatory responses in a loperamide-induced mouse model. These byproducts show potential as ingredients in functional foods aimed at enhancing gut health, potentially reducing waste disposal costs and addressing environmental concerns associated with their utilization.

Review article: do stimulant laxatives damage the gut? A critical analysis of current knowledge

Stimulant laxatives are well established as first- or second-line treatments for constipation and although they have a reliable therapeutic effect, alleged safety concerns still exist, particularly with long-term use. The potential harmful effects on the gastrointestinal system (including carcinogenicity) of the long-term use of diphenylmethane [bisacodyl, sodium picosulfate (SPS)] and senna stimulant laxatives were assessed in a comprehensive review of the publications identified in literature searches performed in PubMed and Embase up to and including June 2023. We identified and reviewed 43 publications of interest. While stimulant laxatives at supratherapeutic doses have been shown to cause structural alterations to surface absorptive cells in animals and humans, these effects are reversible and not considered clinically relevant. No formal long-term studies have demonstrated morphological changes in enteric neural elements or intestinal smooth muscle with bisacodyl or SPS in humans. Furthermore, there is no convincing evidence that stimulant laxatives are associated with the development of colon cancer, and in fact, chronic constipation itself has been reported to potentially increase the risk of colon cancer, therefore, the use of stimulant laxatives might reduce this risk. Many studies suggesting a possible harmful effect from laxatives were limited by their failure to consider confounding factors such as concomitant neurological disease, metabolic disorders, and age. These findings highlight the lack of evidence for the harmful effects of laxatives on the colon, and thus, the benefits of treatment with stimulant laxatives, even in the long-term, should be reconsidered for the management of patients with constipation.

Considering traditional Chinese medicine as adjunct therapy in the management of chronic constipation by regulating intestinal flora

Chronic constipation is one of the most common gastrointestinal disorders worldwide. Due to changes in diet, lifestyle, and the aging population, the incidence of chronic constipation has increased year by year. It has had an impact on daily life and poses a considerable economic burden. Nowadays, many patients with chronic constipation try to seek help from complementary and alternative therapies, and traditional Chinese medicine (TCM) is often their choice. The intestinal flora play an important role in the pathogenesis of constipation by affecting the body's metabolism, secretion, and immunity. Regulating the intestinal flora and optimizing its composition might become an important prevention and treatment for chronic constipation. TCM has unique advantages in regulating the imbalance of intestinal flora, and its curative effect is precise. Therefore, we reviewed the relationship between intestinal flora and chronic constipation as well as advances in research on TCM as adjunct therapy in the management of chronic constipation by regulating intestinal flora. Some single Chinese herbs and their active ingredients (e.g., Rheum palmatum, Radix Astragalus, and Cistanche deserticola), some traditional herbal formulations (e.g., Jichuan decoction, Zengye decoction, and Zhizhu decoction) and some Chinese patent medicines (e.g., Maren pills and Shouhui Tongbian capsules) that are commonly used to treat chronic constipation by regulating intestinal flora are highlighted and summarized. Moreover, some external forms of TCM, and especially acupuncture, have also been found to improve intestinal movement and alleviate constipation symptoms by regulating intestinal flora. We hope this review can contribute to an understanding of TCM as an adjunct therapy for chronic constipation and that it can provide useful information for the development of more effective constipation therapies.

Activation of ASIC3/ERK pathway by paeoniflorin improves intestinal fluid metabolism and visceral sensitivity in slow transit constipated rats

Slow transit constipation (STC) is one of the most common gastrointestinal disorders in children and adults worldwide. Paeoniflorin (PF), a monoterpene glycoside compound extracted from the dried root of Paeonia lactiflora, has been found to alleviate STC, but the mechanisms of its effect remain unclear. The present study aimed to investigate the effects and mechanisms of PF on intestinal fluid metabolism and visceral sensitization in rats with compound diphenoxylate-induced STC. Based on the evaluation of the laxative effect, the abdominal withdrawal reflex test, enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, western blot, and immunohistochemistry were used to detect the visceral sensitivity, fluid metabolism-related proteins, and acid-sensitive ion channel 3/extracellular signal-regulated kinase (ASIC3/ERK) pathway-related molecules. PF treatment not only attenuated compound diphenoxylate-induced constipation symptoms and colonic pathological damage in rats but also ameliorated colonic fluid metabolic disorders and visceral sensitization abnormalities, as manifested by increased colonic goblet cell counts and mucin2 protein expression, decreased aquaporin3 protein expression, improved abdominal withdrawal reflex scores, reduced visceral pain threshold, upregulated serum 5-hydroxytryptamine, and downregulated vasoactive intestinal peptide levels. Furthermore, PF activated the colonic ASIC3/ERK pathway in STC rats, and ASIC3 inhibition partially counteracted PF's modulatory effects on intestinal fluid and visceral sensation. In conclusion, PF alleviated impaired intestinal fluid metabolism and abnormal visceral sensitization in STC rats and thus relieved their symptoms through activation of the ASIC3/ERK pathway.

Pharmacologic Treatment of Chronic Constipation

Chronic constipation is a common disease that can impair the quality of life, with a prevalence of 14% globally and 16.5% in South Korea. Straining, hard stools, the sensation of incomplete evacuation, the sensation of anorectal blockage, and manual maneuvers to facilitate defecation are the related symptoms of chronic constipation. On the other hand, medications commonly referred to as laxatives are the essentials of treatment for constipation compared to non-pharmacological treatment, such as lifestyle modifications, biofeedback, or surgery. Unfortunately, there is still an unmet need to determine if pharmacological treatment for constipation is being administered appropriately. Therefore, there are many disadvantages as to whether the indications and side effects of laxatives are adequately considered and prescribed as the primary treatment modality for constipation in a real clinical situation in Korea. Laxatives are generally recommended as the next step for patients in whom organic causes have been excluded and have not responded to initial non-pharmacologic therapies such as dietary fiber intake and exercise. Laxatives can be classified as bulk-forming laxatives, osmotic laxatives, stimulant laxatives, and other novel laxatives. On the other hand, there are distinct mechanisms underlying constipation, and appropriate administration is the most decisive. Therefore, the present investigators prepared this review to discuss appropriate pharmacological strategies for chronic constipation in Korea. Moreover, this paper also includes suggestions for appropriate pharmacological treatment options for special patient populations.

Feasibility and repeatability of ultrasound-guided surface electroenterography to measure colonic slow wave motility in healthy adults

Surface electroenterography is a potential non-invasive alternative to current diagnostics of colonic motility disorders. However, electrode positioning in electroenterography is often based on general anatomy and may lack generalizability. Furthermore, the repeatability of electroenterography measurements is unknown. This study aimed to evaluate ultrasound-guided electrode positioning for electroenterography measurements and to determine the repeatability of those measurements. In ten healthy adults, two electroenterography procedures were performed, consisting of fasting, ultrasound-guided electrode localization and two 20-minute electroenterography recordings separated by a meal. The dominant frequency, the mean power density (magnitude of colonic motility) and the power percent difference (relative pre- to postprandial increase in magnitude) were determined. Repeatability was determined by Lin's concordance correlation coefficient. The results demonstrated that the dominant frequency did not differ between pre- and postprandial recordings and was 3 cpm, characteristic of colonic motility. The mean power density increased between the pre- and postprandial measurements, with an average difference of over 200%. The repeatability of both the dominant frequency and power density was poor to moderate, whereas the correlation coefficient of the power percent difference was poor. Concluding, ultrasound-guided surface electroenterography seems able to measure the gastrocolic reflex, but the dissatisfactory repeatability necessitates optimization of the measurement protocol.

Coadministration of Lactulose with Probiotics Ameliorates Loperamide-Induced Constipation in Mice

We evaluated the efficacy of mixtures of lactulose with probiotic strains to ameliorate constipation and to identify suitable probiotic strains. Constipation was induced in Institute of Cancer Research mice (6-week-old, male) by the administering loperamide (5 mg/kg, twice a day) orally for 5 days, whereas the control group was not treated. To evaluate the laxative effects of the lactulose-probiotic and lactulose-magnesium hydroxide mixtures, fecal parameters, the gastrointestinal (GI) transit ratio, and fecal short-chain fatty acid (SCFA) content were analyzed. The administration of lactulose and Bacillus licheniformis or Saccharomyces boulardii significantly improved stool number and water content, which were reduced by loperamide. The GI transit ratio was significantly increased compared with that of the control group. The combined administration of lactulose and probiotics (B. licheniformis or S. boulardii) increased total SCFA content, including that of acetate, more effectively compared with lactulose alone. Similarly, coadministration of lactulose and magnesium hydroxide improved the loperamide-induced changes in fecal parameters and GI transit as well as increased total SCFA content. Overall, the combination of lactulose and probiotics relieves the symptoms of constipation by increasing SCFA content and is more effective compared with lactulose alone.

Advancing peristalsis deciphering in mouse small intestine by multi-parameter tracking

Assessing gastrointestinal motility lacks simultaneous evaluation of intraluminal pressure (ILP), circular muscle (CM) and longitudinal muscle (LM) contraction, and lumen emptying. In this study, a sophisticated machine was developed that synchronized real-time recordings to quantify the intricate interplay between CM and LM contractions, and their timings for volume changes using high-resolution cameras with machine learning capability, the ILP using pressure transducers and droplet discharge (DD) using droplet counters. Results revealed four distinct phases, BPhase, NPhase, DPhase, and APhase, distinguished by pressure wave amplitudes. Fluid filling impacted LM strength and contraction frequency initially, followed by CM contraction affecting ILP, volume, and the extent of anterograde, retrograde, and segmental contractions during these phases that result in short or long duration DD. This comprehensive analysis sheds light on peristalsis mechanisms, understand their sequence and how one parameter influenced the other, offering insights for managing peristalsis by regulating smooth muscle contractions.

Peripherally-active mu-opioid receptor antagonists for constipation in critically ill patients receiving opioids: A case-series and a systematic review and meta-analysis of the literature

BACKGROUND

Constipation is frequent in critically ill patients, and potentially related to adverse outcomes. Peripherally-active mu-opioid receptor antagonists (PAMORAs) are approved for opioid-induced constipation, but information on their efficacy and safety in critically ill patients is limited. We present a single-center, retrospective, case-series of the use of naldemedine for opioid-associated constipation, and we systematically reviewed the use of PAMORAs in critically ill patients.

METHODS

Case-series included consecutive mechanically-ventilated patients; constipation was defined as absence of bowel movements for >3 days. Naldemedine was administered after failure of the local laxation protocol. Systematic review: PubMed was searched for studies of PAMORAs to treat opioid-induced constipation in adult critically ill patients.

PRIMARY OUTCOMES

time to laxation, and number of patients laxating at the shortest follow-up.

SECONDARY OUTCOMES

gastric residual volumes and adverse events.

KEY RESULTS

A total of 13 patients were included in the case-series; the most common diagnosis was COVID-19 ARDS. Patients had their first bowel movement 1 [0;2] day after naldemedine. Daily gastric residual volume was 725 [405;1805] before vs. 250 [45;1090] mL after naldemedine, p = 0.0078. Systematic review identified nine studies (two RCTs, one prospective case-series, three retrospective case-series and three case-reports). Outcomes were similar between groups, with a trend toward a lower gastric residual volume in PAMORAs group.

CONCLUSIONS & INFERENCES

In a highly-selected case-series of patients with refractory, opioid-associated constipation, naldemedine was safe and associated to reduced gastric residuals and promoting laxation. In the systematic review and meta-analysis, the use of PAMORAs (mainly methylnaltrexone) was safe and associated with a reduced intolerance to enteral feeding but no difference in the time to laxation.

Lactic acid bacteria in relieving constipation: mechanism, clinical application, challenge, and opportunity

Constipation is a prevalent gastrointestinal symptom that can considerably affect a patients' quality of life. Although several drugs have been used to treat constipation, they are associated with high costs, side effects, and low universality. Therefore, alternative intervention strategies are urgently needed. Traditional lactic acid bacteria (LAB), such as Bifidobacterium and Lactobacillus, play a vital role in regulating intestinal microecology and have demonstrated favorable effects in constipation; however, a comprehensive review of their constipation relief mechanisms is limited. This review summarizes the pathogenesis of constipation and the relationship between intestinal motility and gut microbiota, elucidates the possible mechanism by which LAB alleviates of constipation through a systematic summary of animal and clinical research, and highlights the challenges and applications of LAB in the treatment of constipation. Our review can improve our understanding of constipation, and advance targeted microecological therapeutic agents, such as LAB.

Constipation in Patients With Chronic Kidney Disease

Constipation is a frequent symptom in patients with chronic kidney disease (CKD). This review outlines the mechanisms and management of constipation in patients with CKD from a physician's perspective. Common causes of constipation in patients with CKD include concomitant medications, low dietary fiber intake, water-restricted diet, lack of physical activity, altered gut microbiota, and reduced gastrointestinal motility. Constipation has a negative impact on overall health, and, in particular, the presence of constipation has been associated with worsening kidney function and increased risk of developing advanced stages of CKD. Although lifestyle and dietary modifications may not always be practical for patients with CKD, they are recommended because they are beneficial as they lower mortality in patients with CKD. The use of laxatives containing magnesium salts, bulking agents, and osmotic laxatives may have insufficient efficacy and may be associated with adverse effects. In contrast, lactulose and lubiprostone have been shown to exhibit reno-protective effects. Linaclotide and plecanatide have very limited systemic absorption and appear safe in patients with CKD. Tenapanor reduces paracellular intestinal phosphate absorption in addition to blocking sodium uptake by enterocytes, and provides additional benefit in patients patients with CKD who have hyperphosphatemia and constipation. Prucalopride leads to improvements in bowel function and constipation-related symptoms in cases in which response to conventional laxatives are inadequate. However, the dose of prucalopride should be reduced to 1 mg once daily for patients with CKD. In conclusion, there are important advances on the impact and treatment of constipation in patients with CKD.

Microbiota regulation in constipation and colorectal cancer

The relevance of constipation to the development and progression of colorectal cancer (CRC) is currently a controversial issue. Studies have shown that changes in the composition of the gut microbiota, a condition known as ecological imbalance, are correlated with an increasing number of common human diseases, including CRC and constipation. CRC is the second leading cause of cancer-related deaths worldwide, and constipation has been receiving widespread attention as a risk factor for CRC. Early colonoscopy screening of constipated patients, with regular follow-ups and timely intervention, can help detect early intestinal lesions and reduce the risks of developing colorectal polyps and CRC. As an important regulator of the intestinal microenvironment, the gut microbiota plays a critical role in the onset and progression of CRC. An increasing amount of evidence supports the thought that gut microbial composition and function are key determinants of CRC development and progression, with alterations inducing changes in the expression of host genes, metabolic regulation, and local and systemic immunological responses. Furthermore, constipation greatly affects the composition of the gut microbiota, which in turn influences the susceptibility to intestinal diseases such as CRC. However, the crosstalk between the gut microbiota, constipation, and CRC is still unclear.

Fu Brick Tea Alleviates Constipation via Regulating the Aquaporins-Mediated Water Transport System in Association with Gut Microbiota

This study aimed to investigate the amendatory effects of Fu brick tea aqueous extract (FTE) on constipation and its underlying molecular mechanism. The administration of FTE by oral gavage (100 and 400 mg/kg·bw) for 5 weeks significantly increased fecal water content, improved difficult defecation, and enhanced intestinal propulsion in loperamide (LOP)-induced constipated mice. FTE also reduced colonic inflammatory factors, maintained the intestinal tight junction structure, and inhibited colonic Aquaporins (AQPs) expression, thus normalizing the intestinal barrier and colonic water transport system of constipated mice. 16S rRNA gene sequence analysis results indicated that two doses of FTE increased the Firmicutes/Bacteroidota (F/B) ratio at the phylum level and increased the relative abundance of Lactobacillus from 5.6 ± 1.3 to 21.5 ± 3.4% and 28.5 ± 4.3% at the genus level, subsequently resulting in a significant elevation of colonic contents short-chain fatty acids levels. The metabolomic analysis demonstrated that FTE improved levels of 25 metabolites associated with constipation. These findings suggest that Fu brick tea has the potential to alleviate constipation by regulating gut microbiota and its metabolites, thereby improving the intestinal barrier and AQPs-mediated water transport system in mice.

Luteolin ameliorates loperamide-induced functional constipation in mice

Functional constipation (FC) is one of the most common gastrointestinal disorders characterized by hard stools and infrequent bowel movements, which is associated with dysfunction of the enteric nervous system and intestinal motility. Luteolin, a naturally occurring flavone, was reported to possess potential pharmacological activities on intestinal inflammation and nerve injury. This study aimed to explore the role of luteolin and its functional mechanism in loperamide-induced FC mice. Our results showed that luteolin treatment reversed the reduction in defecation frequency, fecal water content, and intestinal transit ratio, and the elevation in transit time of FC models. Consistently, luteolin increased the thickness of the muscular layer and lessened colonic histopathological injury induced by loperamide. Furthermore, we revealed that luteolin treatment increased the expression of neuronal protein HuC/D and the levels of intestinal motility-related biomarkers, including substance P (SP), vasoactive intestinal polypeptide (VIP), and acetylcholine (ACh), as well as interstitial cells of Cajal (ICC) biomarker KIT proto-oncogene, receptor tyrosine kinase (C-Kit), and anoctamin-1 (ANO1), implying that luteolin mediated enhancement of colonic function and contributed to the anti-intestinal dysmotility against loperamide-induced FC. Additionally, luteolin decreased the upregulation of aquaporin (AQP)-3, AQP-4, and AQP-8 in the colon of FC mice. In summary, our data showed that luteolin might be an attractive option for developing FC-relieving medications.

Probiotics, prebiotics, and synbiotics in chronic constipation: Outstanding aspects to be considered for the current evidence

This integrative aimed to evaluate the effects and the potential mechanism of action of prebiotics, probiotics, and synbiotics on constipation-associated gastrointestinal symptoms and to identify issues that still need to be answered. A literature search was performed in the PubMed database. Animal models (n = 23) and clinical trials (n = 39) were included. In animal studies, prebiotic, probiotic, and synbiotic supplementation showed a decreased colonic transit time (CTT) and an increase in the number and water content of feces. In humans, inulin is shown to be the most promising prebiotic, while B. lactis and L. casei Shirota probiotics were shown to increase defecation frequency, the latter strain being more effective in improving stool consistency and constipation symptoms. Overall, synbiotics seem to reduce CTT, increase defecation frequency, and improve stool consistency with a controversial effect on the improvement of constipation symptoms. Moreover, some aspects of probiotic use in constipation-related outcomes remain unanswered, such as the best dose, duration, time of consumption (before, during, or after meals), and matrices, as well as their effect and mechanisms on the regulation of inflammation in patients with constipation, on polymorphisms associated with constipation, and on the management of constipation via 5-HT. Thus, more high-quality randomized control trials (RCTs) evaluating these lacking aspects are necessary to provide safe conclusions about their effectiveness in managing intestinal constipation.

Cannabis sativa L. alleviates loperamide-induced constipation by modulating the composition of gut microbiota in mice

MaZiRenWan (MZRW) is the most frequently used Traditional Chinese Medicine formula to treat chronic constipation, Cannabis sativa L. is regarded as a monarch drug in MZRW. However, the targets of Cannabis sativa L. that enhance colonic motility and improve constipation symptoms remain unknown. This study was designed to investigate the laxative effect and underlying mechanism of the water extract of Cannabis sativa L. (WECSL) using a loperamide-induced constipation mouse model. We found that WECSL treatment significantly improved intestinal motility and water-electrolyte metabolism, decreased inflammatory responses, prevented gut barrier damage, and relieved anxiety and depression in constipated mice. WECSL also structurally remodeled the composition of the gut microbiota and altered the abundance of bacteria related to inflammation, specifically Butyricicoccus and Parasutterella. Moreover, WECSL failed to relieve constipation symptoms following intestinal flora depletion, indicating that WECSL alleviates constipation symptoms depending on the gut microbiota. Our research provides a basis for WECSL to be further investigated in the treatment of constipation from the perspective of modern medicine.

Gut microbiota: a new avenue to reveal pathological mechanisms of constipation

Constipation is very pervasive all over the world. It is a common multifactorial gastrointestinal disease, and its etiology and pathomechanism are not completely clear. Now, increasing evidence shows that intestinal flora is closely related to constipation. Intestinal flora is the largest microbiota in the human body and has powerful metabolic functions. Intestinal flora can produce a variety of metabolites, such as bile acids, short-chain fatty acids, tryptophan metabolites, and methane, which have important effects on intestinal motility and secretion. The host can also monitor the intestinal flora and regulate gut dysbacteriosis in constipation. To explore the relationship between intestinal flora and host, the combination of multiomics technology has become the powerful and effective method. Furthermore, the homeostasis restoration of intestinal flora also provides a new strategy for the treatment of constipation. This review aims to explore the interaction between intestinal flora and host in constipation, which contributes to disclose the pathogenesis of constipation and the development of novel drugs for the treatment of constipation from the perspective of intestinal flora. KEY POINTS: • This review highlights the regulation of gut microbiota on the intestinal motility and secretion of host. • The current review gives an insight into the role of the host on the recognition and regulation of intestinal ecology under constipation. • The article also introduces some novel methods of current gut microbiota research and gut microbiota-based constipation therapies.

Prevention of Loperamide-Induced Constipation in Mice and Alteration of 5-Hydroxytryotamine Signaling by Ligilactobacillus salivarius Li01

Although Ligilactobacillus salivarius Li01 (Li01) has shown much promise in preventing multiple gastrointestinal diseases, the potential of the probiotic in alleviating constipation and the related mechanisms remain unclear. In this study, the effects of Li01 were evaluated in a loperamide-induced constipation mouse model. The results demonstrated that Li01 intervention can relieve constipation symptoms by improving water content, quantity, and morphology of feces and act as an intestinal barrier structure protector. Furthermore, Li01 can modulate gut motility (gastrointestinal transit rate), the fluid transit-associated expression of aquaporins, and the serum parameters vasoactive intestinal peptide, substance P, and somatostatin. Constipation significantly increased the levels of 5-hydroxytryotamine (5-HT) in serum (p < 0.01) and decreased the levels in the intestine (p < 0.001). Due to its function of elevating the expression of tryptophan hydroxylase 1, this was reversed after Li01 treatment. Li01 also promoted the expression of 5-HT receptor 3 and 4, indicating that the 5-HT signaling pathway may play a critical role in the mechanism by which Li01 alleviate constipation symptoms. Additionally, Li01 significantly altered the gut microbiota composition by enhancing the ratio of Firmicutes/Bacteroidetes and increasing the abundance of Rikenellaceae_RC9 genera. Based on the above results, Li01 may have the potential to effectively alleviate constipation by regulating the 5-HT pathway and alteration of the gut microbiota.

Efficacy and MicroRNA-Gut Microbiota Regulatory Mechanisms of Acupuncture for Severe Chronic Constipation: Study Protocol for a Randomized Controlled Trial

Background

Severe chronic constipation (SCC) is a common functional gastrointestinal (GI) disorder associated with disruptions in GI motility. Abnormalities between gut microbiota and microRNAs (miRNAs) are implicated in the pathogenesis of GI motility in SCC. Acupuncture has been shown to improve constipation-related symptoms and rebalance the gut microbiota. This protocol proposed a plan to explore the hypothesis that the efficacy of acupuncture is associated with the crosstalk between gut microbes and miRNAs in patients with SCC.

Methods

This trial is designed as a randomized, sham-controlled trial involving 80 patients and 40 healthy volunteers. A total of 80 patients with SCC (≤2 mean spontaneous, complete bowel movements per week [CSBMs]) will be randomly allocated to receive either 16-session acupuncture at true acupoints or non-penetrating sham acupuncture at non-acupoints for 4 weeks. The primary outcome will be the proportion of patients with ≥3 mean weekly CSBMs over weeks 1–4 and 5–8. Secondary efficacy endpoints include bowel movements, stool consistency, degree of straining, and the quality of life. Healthy volunteers will not receive any clinical intervention. Fasting plasma and fecal samples will be analyzed by 16S rRNA third-generation sequencing and miRNA high-throughput sequencing technologies. Finally, a tripartite network analysis will be used to investigate the interactions among clinical efficacy, miRNAs, and intestinal microbiota.

Discussion

From the perspective of microRNA-gut microbiota regulatory mechanisms, our results will partially illuminate the crucial role of fecal miRNAs and intestinal microbiota to understand how acupuncture exerts its anti-constipation role.

Trial registration

This trial is registered with ChiCTR2100048831, registered 18 July 2021; ethical approval has been obtained from the Sichuan Regional Ethics Review of Committee on Traditional Chinese Medicine, approval ID: 2021KL-023.

Preclinical experimental models for assessing laxative activities of substances/products under investigation: a scoping review of the literature

Constipation is a common gastrointestinal problem worldwide. Its impact on health can range from an unpleasant problem to being seriously troublesome. When lifestyle modification fails to deal with constipation, laxatives are the mainstay of therapy. There are several types of laxatives currently available; however, there still remains a need for better laxatives because certain currently available laxatives are not appropriate for or accessible to some patients. Preclinical experiments to study the laxative potential of substances/products of interest are vital to improving that situation. The selection of appropriate experimental models for assessing the laxative activities of substances/products under investigation is crucial to achieving valid and meaningful results. This article provides a scoping review of the literature, outlining, and summarizing models currently being used in preclinical experiments assessing the laxative activities of substances/products under investigation. The review includes both screening models, e.g., the isolated organ bath system, in vivo fecal assessment and intestinal transit assay, and confirmation models, e.g., in vivo constipation models. Chemical substances/drugs used to induce constipation in in vivo constipation models, e.g., loperamide, diphenoxylate, montmorillonite, and clonidine, as well as standard laxative agents used as a positive control in experimental models, e.g., bisacodyl, carbachol, lactulose, sodium picosulfate, castor oil, phenolphthalein, and yohimbine, are described in detail. The purpose of this article is to assist researchers in the design and implementation of preclinical experimental models for assessing laxative activities of substances/products under investigation to achieve valid and meaningful preclinical results prior to experimentation in humans.