Irritable Bowel Syndrome Rats Research Articles

FMT and TCM to treat diarrhoeal irritable bowel syndrome with induced spleen deficiency syndrome- microbiomic and metabolomic insights

BackgroundDiarrheal irritable bowel syndrome (IBS-D) is a functional bowel disease with diarrhea, and can be associated with common spleen deficiency syndrome of the prevelent traditional Chinese medicine (TCM) syndrome. Fecal microbiota transplantation (FMT) could help treating IBS-D, but may provide variable effects. Our study evaluated the efficacy of TCM- shenling Baizhu decoction and FMT in treating IBS-D with spleen deficiency syndrome, with significant implications on gut microbiome and serum metabolites.MethodsThe new borne rats were procured from SPF facility and separated as healthy (1 group) and IBS-D model ( 3 groups) rats were prepared articially using mother’s separation and senna leaf treatment. 2 groups of IBS-D models were further treated with TCM- shenling Baizhu decoction and FMT. The efficacy was evaluated by defecation frequency, bristol stool score, and intestinal tight junction proteins (occludin-1 and claudin-1) expression. Microbiomic analysis was conducted using 16 S rRNA sequencing and bioinformatics tools. Metabolomics were detected in sera of rats by LC-MS and annotated by using KEGG database.ResultsSignificant increment in occludin-1 and claudin-1 protein expression alleviated the diarrheal severity in IBS-D rats (P < 0.05) after treatment with FMT and TCM. FMT and TCM altered the gut microbiota and regulated the tryptophan metabolism, steroid hormone biosynthesis and glycerophospholipid metabolism of IBS-D rats with spleen deficiency syndrome.The microbial abundance were changed in each case e.g., Monoglobus, Dubosiella, and Akkermansia and othe metabolic profiles.ConclusionFMT and TCM treatment improved the intestinal barrier function by regulating gut microbiota and improved metabolic pathways in IBS-D with spleen deficiency syndrome.

Improvement effect and mechanism of XuanFuDaiZhe tang on rats with diarrheal irritable bowel syndrome induced by colorectal dilation

Ethnopharmacological relevanceXuanFuDaiZhe Tang (XFDZT) is used in traditional Chinese medicine (TCM) to treat diarrhoea-predominant irritable bowel syndrome (IBS-D). Our laboratory has demonstrated that XFDZT remarkably improves various gastrointestinal motility disorders in animal models. However, previous studies have only focused on one or several protein targets without systematically investigating dynamic changes and protein interrelations. Aim of the studyTo explore the mechanisms underlying the therapeutic action of XFDZT in IBS-D using a network pharmacology approach and in vivo experiments. Materials and methodsThe active compounds of XFDZT were selected from TCM Systems Pharmacology and TCM Integrated databases, and potential targets were identified using the Swiss Target Prediction databases. Targets related to IBS-D were mined from the DisGeNet, Drug Bank, and Therapeutic Target databases. The intersecting protein–protein interactions (PPIs) of the drug–disease crossover genes were analysed, and a central PPI network was constructed using the STRING database and Cytoscape 3.7.2. Following Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, a gene pathway network was constructed to identify key target genes and pathways. Using haematoxylin and eosin staining and western blotting, we validated how XFDZT controls water expression in the body to treat IBS-D infection. ResultsFirst, the results showed that XFDZT contained 1037 active ingredients and 1458 corresponding targets. After intersecting the 252 IBS targets, 108 targets were identified. The main targets of XFDZT were albumin, aquaporins such as AQP1 and AQP3, calmodulin, and the cellular enzyme CYP2C9. GO and KEGG enrichment predicted that the action pathways were the neuroactive ligand–receptor interaction, calcium signalling pathway, serotonergic synapse signalling pathway, cGMP–PKG signalling pathway, cAMP signalling pathway, and MLCK–MLC signalling pathway. Second, an IBS-D rat model was constructed using colorectal dilation (CRD). CRD can significantly induce IBS-D symptoms such as diarrhoea, abdominal pain, and anxiety and depression-like behaviour in rats. XFDZT (10, 20, and 40 g/kg) administered for 14, 21, and 28 days significantly reversed these changes in IBS-D rats in a time- and dose-dependent manner, suggesting that XFDZT significantly improved IBS-D. Finally, the mechanism by which XFDZT improves IBS-D was explored from the perspective of AQPs, tight junction proteins, and motility-related proteins in colon tissue. Compared with the control group, the protein expression of AQP1, AQP3, and AQP8 in the colon tissue of IBS-D rats was significantly downregulated, whereas the protein expression of AQP7 was significantly upregulated. The expression of tight junction-related proteins claudin-1, occludin, and ZO-1 in colon tissue was significantly downregulated, whereas the expression of motility-related proteins p-MLC, MLC, MLCK, and CaM in colon tissue was significantly upregulated, suggesting that IBS-D rats had AQP disorders, epithelial intercellular connections, and motility in colon tissue. The above changes were significantly reversed by XFDZT administration (5, 10, and 20 g/kg) for 14 days. ConclusionXFDZT significantly improved diarrhoea, abdominal pain, anxiety, and depression in IBS-D rats, and its mechanism of action may be related to the regulation of AQPs, tight junction proteins, and the MLCK–MLC pathway. This study provided a pharmacological experimental basis for the development of XFDZT as a novel drug for the treatment of IBS-D.

The neurotensin receptor 1 agonist PD149163 alleviates visceral hypersensitivity and colonic hyperpermeability in rat irritable bowel syndrome model.

An impaired intestinal barrier with the activation of corticotropin-releasing factor (CRF), Toll-like receptor 4 (TLR4), and proinflammatory cytokine signaling, resulting in visceral hypersensitivity, is a crucial aspect of irritable bowel syndrome (IBS). The gut exhibits abundant expression of neurotensin; however, its role in the pathophysiology of IBS remains uncertain. This study aimed to clarify the effects of PD149163, a specific agonist for neurotensin receptor 1 (NTR1), on visceral sensation and gut barrier in rat IBS models. The visceral pain threshold in response to colonic balloon distention was electrophysiologically determined by monitoring abdominal muscle contractions, while colonic permeability was measured by quantifying absorbed Evans blue in colonic tissue invivo in adult male Sprague-Dawley rats. We employed the rat IBS models, i.e.,lipopolysaccharide (LPS)- and CRF-induced visceral hypersensitivity and colonic hyperpermeability, and explored the effects of PD149163. Intraperitoneal PD149163 (160, 240, 320 μg kg-1) prevented LPS (1 mg kg-1, subcutaneously)-induced visceral hypersensitivity and colonic hyperpermeability dose-dependently. It also prevented the gastrointestinal changes induced by CRF (50 μg kg-1, intraperitoneally). Peripheral atropine, bicuculline (a GABAA receptor antagonist), sulpiride (a dopamine D2 receptor antagonist), astressin2-B (a CRF receptor subtype 2 [CRF2] antagonist), and intracisternal SB-334867 (an orexin 1 receptor antagonist) reversed these effects of PD149163 in the LPS model. PD149163 demonstrated an improvement in visceral hypersensitivity and colonic hyperpermeability in rat IBS models through the dopamine D2, GABAA, orexin, CRF2, and cholinergic pathways. Activation of NTR1 may modulate these gastrointestinal changes, helping to alleviate IBS symptoms.

Electroacupuncture at different frequencies improves visceral pain in IBS rats through different pathways.

The aim of this study was to investigate the frequency dependence of electroacupuncture (EA) in alleviating chronic visceral pain in patients with irritable bowel syndrome (IBS) and the differences in the gut microbiota and metabolites as potential mechanisms to explain frequency dependence. A visceral hyperalgesia model was established by colorectal instillation of 2,4,6-trinitrobenzene sulfonic acid in rats, and EA treatment at 2/10 Hz, 2/50 Hz and 2/100 Hz was applied at ST25. Visceral sensation was quantified by the abdominal withdrawal reflex score and the area under the curve of the rectus abdominis electromyogram in response to colorectal distension. Ultrastructural morphological damage of colonic tissue of the rats was examined by transmission electron microscopy. 16S rRNA gene sequencing and 1H-nuclear magnetic resonance spectroscopy were applied to study the differences in the gut microbiota and to perform metabonomic profiling of the colonic tissue. EA at ST25 at different frequencies attenuated chronic visceral pain, ultrastructural morphological damage to colonic tissue and disruption of the gut microbiota in IBS rats. The frequency of 2/100 Hz has more regulatory pathways than 2/10 Hz and 2/50 Hz. In addition, IBS rats exhibited colonic metabolic disorders, and pantothenate was significantly upregulated after EA treatment at different frequencies. Very low-density lipoprotein and 2-hydroxybutyrate were significantly increased in the 2/10 Hz group, while low density lipoprotein, very low-density lipoprotein, 2-hydroxybutyrate, methylmalonate and alpha-hydroxyisobutyric acid were significantly increased in the 2/100 Hz group. EA at ST25 at different frequencies attenuated chronic visceral pain through different gut microbiota and metabolic pathways.

WenTongGanPi decoction alleviates diarrhea-predominant irritable bowel syndrome by improving intestinal barrier

Ethnopharmacological relevanceWenTongGanPi Decoction (WTGPD) is a representative medical practice of the Fuyang School of Traditional Chinese Medicine (TCM), which originated from the classical Lu's Guizhi method. WTGPD places emphasis on the balance and functionality of yang qi, and is effective in treating TCM symptoms related to liver qi stagnation and spleen yang deficiency. In TCM, diarrhea-predominant irritable bowel syndrome (IBS-D) is often diagnosed as liver depression and spleen deficiency, and the use of WTGPD has shown significant therapeutic effect. However, the underlying mechanism of WTGPD treating IBS-D remains unclear. Aim of the studyTo explore the effect and mechanism of WTGPD in the treatment of IBS-D. Materials and methodsAn IBS-D model with liver depression and spleen deficiency was constructed by chronic immobilization stress stimulation and sennae folium aqueous gavage. The impact of WTGPD on IBS-D rats was evaluated through measurements of body weight, fecal water content, and abdominal withdrawal reflex (AWR). Intestinal permeability was assessed using hematoxylin-eosin (HE), alcian blue-periodic acid schiff (AB-PAS), immunofluorescence (IF) staining, and quantitative real-time PCR (qRT-PCR). The components of WTGPD were analyzed using UPLC-Q-TOF-MS. The underlying mechanisms were investigated through network pharmacology, transcriptomics sequencing, western blot (WB), molecular docking, and 16S rRNA sequencing. ResultsWTGPD treatment effectively alleviated diarrhea and abnormal pain in IBS-D rats (P < 0.05). It enhanced the intestinal barrier function by improving colonic structure and increasing the expression of tight junction proteins (P < 0.05). A total of 155 components were identified in WTGPD. Both network pharmacology and transcriptomics sequencing analysis highlighted MAPK as the key signaling pathway in WTGPD's anti-IBS-D effect. The WB results showed a significant decrease in p-p38, p-ERK and p-JNK expression after WTGPD treatment (P < 0.0001). Guanosine, adenosine and hesperetin in WTGPD may be involved in regulating the phosphorylation of p38, ERK and JNK. Additionally, WTGPD significantly enhanced microbial diversity and increased the production of colonic valeric acid in IBS-D rats (P < 0.01). ConclusionIn conclusion, our findings suggest that WTGPD can effectively alleviate IBS-D and improve intestinal barrier likely via inhibiting MAPK signal pathway and improving micobial dysbiosis.

Mechanisms of Peitu Yimu acupuncture in repairing intestinal mucosal barrier by regulating CRF/CRFR1 pathway in diarrhea-predominant irritable bowel syndrome rats.

To investigate the effect of Peitu Yimu(strengthening spleen and soothing liver) acupuncture on intestinal mucosal barrier function and corticotropin-releasing factor (CRF)/CRF receptor 1 (CRFR1) pathway in rats with diarrhea-predominant irritable bowel syndrome (IBS-D), so as to explore its underlying mechanism in alleviating IBS-D. Forty female SD rats were randomly divided into blank, model, electroacupuncture (EA), and agonist groups, with 10 rats in each group. Except for the blank group, rats in the other groups were given folium sennae infusion by gavage combined with chronic unpredictable mild stress to establish IBS-D model. Rats in the EA group received acupuncture at "Tianshu"(ST25) and EA at "Zusanli"(ST36) and "Taichong"(LR3) (2 Hz/15 Hz) on one side for 20 min, with the side chosen alternately every other day, for 14 days after modeling. Rats in the agonist group received acupuncture 30 min after intravenous injection of CRFR1 agonist urocortin, with the same manipulation method and time as the EA group. Before and after intervention, visceral pain threshold and stool Bristol scores were measured. Elevated plus maze test and open field test were used to detect anxiety and depression like behavior of rats. ELISA was used to detect the contents of CRF and CRFR1 in rats serum. Immunohistochemistry was used to detect the positive expressions of CRF, CRFR1, zonula occludens protein 1(ZO-1), occlusal protein(Occludin), and closure protein 1 (Claudin-1) in colon tissue. Compared with the blank group, the visceral pain threshold, open arm time percentage (OT%), total distance of movement in the open field test, and positive expression of ZO-1, Occludin, and Claudin-1 in colon were decreased (P<0.01, P<0.05), while Bristol stool scores, serum CRF and CRFR1 contents, and positive expressions of CRF and CRFR1 in colon were increased (P<0.01) in the model group. After intervention and compared with the model group, the visceral pain threshold, OT%, total distance of movement in the open field test, and positive expressions of ZO-1, Occludin, and Claudin-1 in colon were increased (P<0.05, P<0.01), while Bristol stool scores, serum CRF and CRFR1 contents, and positive expressions of CRF and CRFR1 in colon were decreased (P<0.01) in the EA group；the Bristol stool scores, serum CRF content, and CRF positive expression in colon were significantly decreased in the agonist group (P<0.01). Peitu Yimu acupuncture can significantly improve visceral hypersensitivity and anxiety-depression state in IBS-D rats. Its mechanism may be related to the inhibition of CRF/CRFR1 pathway and restoration of intestinal tight junction protein expressions.

Da-Jian-Zhong decoction alleviates diarrhea-predominant irritable bowel syndrome via modulation of gut microbiota and Th17/Treg balance

Ethnopharmacological relevanceDa-Jian-Zhong decoction (DJZD) is a herbal formula clinically used for abdominal pain and diarrhea induced by spleen-Yang deficiency syndrome. Recently, treatment of diarrhea-predominant irritable bowel syndrome (IBS-D) with DJZD has received increasing attention, but the underlying mechanism of action remains elusive. Aim of the studyWe aimed to evaluate the therapeutic effect of DJZD on IBS-D rats and to elucidate the underlying mechanisms. Materials and methodsAn IBS-D rats model was constructed using a two-factor superposition method of neonatal maternal separation and Senna folium aqueous extract lavage. Moreover, the effect of DJZD was evaluated based on the body weight, rectal temperature, abdominal withdrawal reflex (AWR), and Bristol stool scale score (BSS). The factors that regulate the DJZD effects on IBS-D were estimated using whole microbial genome, transcriptome sequencing (RNA-Seq), flow cytometry, and quantitative reverse transcription polymerase chain reaction (RT-qPCR) analyses. ResultsWe found that DJZD alleviated the symptoms of IBS-D rats, with the low-dose (2.4 g/kg) as the better ones, as shown by the higher body weight and lower AWR score and BSS. At the phylum level, the relative abundance of Bacteroidetes was obviously increased, and at the genus level, Lactobacillus and Parabacteroides were increased, while that of Firmicutes_bacterium_424 and Ruminococcus gnavus was decreased in DJZD group. Furthermore, the significantly enriched GO terms after treatment with DJZD mainly included the immune response, positive regulation of activated T cell proliferation, and positive regulation of interleukin-17 (IL-17) production. Importantly, flow cytometry analysis further revealed that the T helper cell type 17/regulatory T cell (Th17/Treg) balance contributed to the DJZD-induced alleviation of IBS-D symptoms, as DJZD downregulated Th17/Treg ratio and Th17 cell-related cytokines IL-17 and IL-6 levels in the colon. ConclusionsThese results demonstrated that DJZD has a good therapeutic effect on IBS-D rats, probably by maintaining the homeostasis of gut microbiota and regulating Th17/Treg balance and its related inflammatory factors.

Chang-Kang-Fang alleviates diarrhea predominant irritable bowel syndrome (IBS-D) through inhibiting TLR4/NF-κB/NLRP3 pathway

Ethnopharmacological relevanceChang-Kang-Fang (CKF), originated from traditional Chinese medicine (TCM) formulas, has been utilized to treat diarrhea predominant irritable bowel syndrome (IBS-D) based on clinical experience. However, the underlying mechanism of CKF for treating IBS-D remains unclear and need further clarification. Aim of the studyThe objective of this present investigation was to validate the efficacy of CKF on IBS-D model rats and to uncover its potential mechanism for the treatment of IBS-D. Materials and methodsWe first established the IBS-D rat model through neonatal maternal separation (NMS) in combination with restraint stress (RS) and the administration of senna decoction via gavage. To confirm the therapeutic effect of CKF on treating IBS-D, abdominal withdrawal reflex (AWR) scores, the quantity of fecal pellets, and the fecal water content (FWC) were measured to evaluate the influence of CKF on visceral hypersensitivity and the severity of diarrhea symptom after the intragastric administration of CKF for 14 days. Subsequently, enzyme linked immunosorbent assay (ELISA) was applied to assess the effect of CKF on neuropeptides substance P (SP) and 5-hydroxytryptamine (5-HT), as well as inflammatory cytokines in serum and in intestinal tissues. Further, colonic pathological changes, the amount of colonic mast cells, and the expression level of occludin in rat colon tissues, were investigated by hematoxylin-eosin (HE) staining, toluidine blue staining, and immunohistochemistry, respectively. To explore the underlying mechanisms, alterations in colonic RNA transcriptomics for the normal, model, and CKF treatment groups were assessed using RNA sequencing (RNA-Seq). Subsequently, quantitative real-time polymerase chain reaction (qRT-PCR), Western blot (WB), and immunofluorescence (IF) assays were applied to validate the effect of CKF on predicted pathways in vivo and in vitro. In addition, to elucidate the potential active compounds in CKF, 11 representative components found in CKF were selected, and their anti-inflammation potentials were evaluated using LPS-treated RAW264.7 cell models. ResultsCKF treatment significantly reduced the number of fecal pellets, attenuated visceral hypersensitivity, and decreased 5-HT and SP concentrations in serum and colon tissues, along with a reduction in colonic mast cell counts, correlating with improved symptoms in IBS-D rats. Meanwhile, CKF treatment reduced the colonic inflammatory cell infiltration, lowered the levels of IL-6, TNF-α, and IL-1β in serum and colon tissues, and increased the occludin protein expression in colon tissues to improve inflammatory response and colonic barrier function. RNA-Seq, in conjugation with our previous network pharmacology analysis, indicated that CKF might mitigate the symptoms of IBS-D rats by inhibiting the Toll like receptor 4/Nuclear factor kappa-B/NLR family pyrin domain-containing protein 3 (TLR4/NF-κB/NLRP3) pathway, which was confirmed by WB, IF, and qRT-PCR experiments in vivo and in vitro. Furthermore, coptisine, berberine, hyperoside, epicatechin, and gallic acid present in CKF emerged as potential active components for treating IBS-D, as they demonstrated in vitro anti-inflammatory effects. ConclusionOur findings demonstrate that CKF effectively improves the symptoms of IBS-D rats, potentially through the inhibition of the TLR4/NF-κB/NLRP3 pathway. Moreover, this study unveils the potential bioactive components in CKF that could be applied in the treatment of IBS-D.

Tranilast alleviates visceral hypersensitivity and colonic hyperpermeability by suppressing NLRP3 inflammasome activation in irritable bowel syndrome rat models

Visceral hypersensitivity resulting from compromised gut barrier with activated immune system is a key feature of irritable bowel syndrome (IBS). Corticotropin-releasing factor (CRF) and Toll-like receptor 4 (TLR4) activate proinflammatory cytokine signaling to induce these changes, which is one of the mechanisms of IBS. As activation of the NLRP3 inflammasome by lipopolysaccharide (LPS) or TLR4 leads to release interleukin (IL)-1β, the NLRP3 inflammasome may be involved in the pathophysiology of IBS. Tranilast, an anti-allergic drug has been demonstrated to inhibit the NLRP3 inflammasome, and we evaluated the impact of tranilast on visceral hypersensitivity and colonic hyperpermeability induced by LPS or CRF (IBS rat model). Visceral pain threshold caused by colonic balloon distention was measured by monitoring abdominal muscle contractions electrophysiologically. Colonic permeability was determined by quantifying the absorbed Evans blue within the colonic tissue. Colonic protein levels of NLRP3 and IL-1β were assessed by immunoblot or ELISA. Intragastric administration of tranilast (20–200 mg/kg) for 3 days inhibited LPS (1 mg/kg)-induced visceral hypersensitivity and colonic hyperpermeability in a dose-dependent manner. Simultaneously, tranilast also abolished these alterations induced by CRF (50 µg/kg). LPS increased colonic protein levels of NLRP3 and IL-1β, and tranilast inhibited these changes. β-hydroxy butyrate, an NLRP3 inhibitor, also abolished visceral hypersensitivity and colonic hyperpermeability caused by LPS. In contrast, IL-1β induced similar GI alterations to LPS, which were not modified by tranilast. In conclusion, tranilast improved visceral pain and colonic barrier by suppression of the NLRP3 inflammasome in IBS rat models. Tranilast may be useful for IBS treating.

Efficacy of Shu-yi-ning-chang decoction on IBS-D: Modulating Nr4a3 pathway to reduce visceral hypersensitivity.

To evaluate the therapeutic effect of SYNC in diarrhea irritable bowel syndrome (IBS-D) and explore its underlying mechanism through transcriptomic sequencing (RNA-Seq). A rat model of IBS-D was constructed to elucidate the effects of SYNC. Abdominal withdrawal reflex (AWR), fecal water content (FWC), and recording body weight were calculated to assess visceral sensitivity in rats. Histopathological changes in the colon and alterations in mast cell (MC) count were determined. Immunohistochemistry was employed to assess mast cell tryptase (MCT) expression in rat colons. Serum levels of corticotropin-releasing Hormone (CRH), interleukin-6 (IL-6), calcitonin gene-related peptide (CGRP), and 5-hydroxytryptamine (5-HT) were quantified using ELISA. RNA-Seq of colon tissue was performed, followed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Western blot analysis was conducted to quantify the expression levels of key proteins in the Nr4a3 pathway in the colon and hypothalamus tissues of rats. SYNC alleviated visceral hypersensitivity and mood disorders in rats with IBS-D. Moreover, it was positively correlated with its dosage and the observed effects, such as the enhancement of the colon's mucosal lining condition and reduction in the number and activation of MCs within the model group. SYNC reduced the expression levels of factors related to the brain-gut axis and inflammatory markers in the bloodstream. RNA-Seq analysis indicated that SYNC down-regulated the expression of Nr4a3 and PI3K. These SYNC-targeted genes primarily played roles in immune regulation and inflammatory responses, correlating with the modulation of Nr4a3 and the PI3K/AKT pathway. Western blot analysis further confirmed SYNC's influence on inflammation-related MC activation by downregulating key proteins in the Nr4a3/PI3K pathway. SYNC inhibited mast cell activation and attenuated visceral hypersensitivity in the colon tissues of IBS-D rats. These effects were mediated by the Nr4a3/PI3K signaling pathway.

A multi-omics study reveals the therapeutic effect of Linderae Radix water extract on irritable bowel syndrome (IBS-D)

Linderae Radix (Lindera aggregata (Sims) Kosterm) is a traditional Chinese medicine known for its capability to regulate qi and relieve pain, particularly in the context of gastrointestinal disorders. While our previous research has demonstrated the efficacy of the Linderae Radix water extract (LRWE) in the treatment of diarrhea-predominant irritable bowel syndrome (IBS-D), the precise mechanisms remain elusive. This study aims to provide a comprehensive understanding of the therapeutic effects of LRWE on IBS-D through multi-omics techniques. 16S rRNA gene sequencing combined with LC-MS metabolomics was employed to investigate the effect of LRWE on the gut microbiota and metabolites of IBS-D rats. Spearman correlation analysis was performed on the gut microbiota and metabolites. LRWE administration significantly ameliorated IBS-D rats' symptoms, including diarrhea, visceral hypersensitivity, and low-grade intestinal inflammation. Gut microbiota analysis revealed that LRWE influenced the diversity of the gut microbiota in IBS-D rats by significantly reducing the relative abundance of Patescibacteria and Candidatus Saccharimonas, while increasing the relative abundance of Jeotgalicoccus. Serum metabolomic analysis identified 16 differential metabolites, associated with LRWE's positive effects on IBS-D symptoms, focusing on glyoxylate and dicarboxylic acid metabolism, and cysteine and methionine metabolism. Spearman analysis demonstrated a strong correlation between cecal microbiota composition and serum metabolite levels. This study elucidates that LRWE plays a crucial role in the comprehensive therapeutic approach to IBS-D by restoring the relative abundance of gut microbiota and addressing the disturbed metabolism of endogenous biomarkers. The identified bacteria and metabolites present potential therapeutic targets for IBS-D.

Effects of mild moxibustion on visceral hypersensitivity via SCF/c-kit signaling pathway in diarrhea-predominant irritable bowel syndrome rats with syndrome of liver-qi stagnation and spleen deficiency

To observe the effect of mild moxibustion on stem cell factor (SCF)/tyrosine kinase receptor (c-kit) signaling pathway and visceral hypersensitivity of diarrhea predominant irritable bowel syndrome (IBS-D) model rats with liver-qi stagnation and spleen deficiency syndrome, so as to explore its mechanisms underlying improvement of IBS-D. A total of 24 male Wistar rats were randomly divided into normal, IBS-D model, medication and mild moxibustion groups, with 6 rats in each group. The IBS-D model was established by glacial acetic acid (4%) enema plus restraint stress stimulation once daily for 14 days. Rats of the medication group were treated by gavage of pivamium bromide (15 mg/kg) once a day for 14 days. Mild moxibustion was applied to bilateral "Tianshu"(ST25), "Shangjuxu"(ST37) and "Taichong"(LR3) for 20 min, once daily for 14 consecutive days. After the intervention, the rats' general state of each group were observed. The rate of loose stools (LSR), and the minimum volume threshold for abdominal withdrawal reflex(AWR) were observed, and the open field test was used to assess the state of rats' motor activities (including rearing times, grooming times and total number of square-crossings in 5 min). Morphological changes of the colon tissue were observed by hematoxylin-eosin (H.E.) staining, The count of mast cells (MC) in the colon tissues was determined by toluidine blue staining. Contents of serum 5-hydroxytryptamine (5-HT) and substance P (SP) were determined by enzyme-linked immunosorbent assay (ELISA). The relative expression levels of SCF and c-kit mRNAs and proteins in the colon tissues were detected by real-time quantitative PCR and Western blot, respectively. Compared with the normal group, the body weight, minimum volume threshold of AWR, total numbers of square-crossing, rearing times and grooming times were significantly decreased (P<0.05), and the LSR, number of MC, contents of 5-HT and SP, and the expression levels of SCF and c-kit mRNAs and proteins were considerably increased in the model group (P<0.01). In comparison with the model group after interventions, the body weight, minimum volume threshold of AWR, total numbers of square-crossing, rearing times and grooming times were apparently increased in both medication and moxibustion groups (P<0.05, P<0.01), and the LSR, number of MC, 5-HT and SP contents in both medication and moxibustion groups, and the expression levels of SCF and c-kit mRNA and protein in the moxibustion group (not in the medication group) were obviously decreased (P<0.05, P<0.01). H.E. staining showed that in the model group, a small amount of inflammatory cells in the mucosal layer of colon tissue could be seen. in the medication group, a small number of lymphocytes in colon tissue were observed, while in the mild moxibustion group, a small amount of neutrophils in colon tissue were observed. Mild moxibustion can reduce visceral hypersensitivity and improve abdominal pain, diarrhea and locomotion state in IBS-D rats with liver-qi stagnation and spleen deficiency syndrome, which may be associated with its functions in reducing the number of MC and the levels of 5-HT and SP and down-regulating the activities of SCF/c-kit signaling pathway.

Electroacupuncture protects the intestinal mucosal barrier in diarrhea-predominant Irritable Bowel Syndrome rats by regulating the MCs/Tryptase/PAR-2/MLCK pathway.

The pathogenesis of diarrhea-predominant irritable bowel syndrome (IBS-D) is related to damage to the intestinal mucosal barrier function. Based on the Mast cell (MC)/Tryptase/Protease-activated receptor-2 (PAR-2)/Myosin light chain kinase (MLCK) pathway, this study explored the effect of electroacupuncture (EA) on IBS-D rats and its possible mechanism of protecting the intestinal mucosal barrier. The IBS-D rat model was established by mother-offspring separation, acetic acid enema, and chronic restraint stress. The efficacy of EA on IBS-D rats was evaluated by observing the rate of loose stool (LSP) and the minimum volume threshold of abdominal withdrawal reflex (AWR) in rats. Mast cells and the ultrastructure of intestinal mucosa were observed by H&E staining, toluidine blue staining, and transmission electron microscopy. The expression levels of Tryptase, PAR-2, MLCK, zonula occludens-1 (ZO-1), and Occludin in rats were detected by ELISA, qRT-PCR, and western blot. After 7 days of intervention, compared to the IBS-D group, the loose stool rates of rats in IBS-D + EA group and IBS-D + ketotifen group were decreased (P < 0.01), the minimum volume thresholds of AWR were improved (P < 0.01), the inflammation of colon tissue decreased, the number of MCs were decreased (P < 0.01), the expression of Tryptase, PAR-2, and MLCK were lowered (P < 0.01, P < 0.05), and the expression of ZO-1 and Occludin were enhanced (P < 0.01, P < 0.05). Compared to the EA group, there was no significant difference in each index between the ketotifen groups (P > 0.05). EA has a good therapeutic effect on IBS-D rats. Regulating the MCs/Tryptase/PAR-2/MLCK pathway may be a mechanism to protect the intestinal mucosal barrier.

Protective effect of Pediococcus pentosaceus Li05 on diarrhea-predominant irritable bowel syndrome in rats.

Pediococcus pentosaceus Li05 (Li05) has demonstrated potential benefits in various intestinal and liver diseases, but its potential and mechanisms in relieving diarrhea have not been understood. The objective of this research was to examine the effects and mechanisms of Li05 in rats with diarrhea-predominant irritable bowel syndrome (IBS-D) induced by wrap restrain stress (WRS) and 4% acetic acid. The results demonstrated that Li05 effectively alleviated weight loss, visceral sensitivity and diarrhea in rats with IBS-D. It also improved intestinal and systemic inflammation by reducing the levels of chemokines and proinflammatory cytokines (GRO/KC, RANTES, IL-1β, IL-7, and IL-18). The 5-hydroxytryptamine (5-HT) signaling pathway is involved in regulating excessive intestinal motility and secretion in IBS-D. Li05 effectively reduced the expression levels of the 5-HT3B receptor (5-HT3BR) (p < 0.01) in the intestine. Additionally, Li05 intervention had a regulatory effect on the gut composition, with a decrease in the abundance of [Ruminococcus] gauvreauii group, Dubosiella, Erysipelatoclostridium and Blautia, and an increase in the abundance of Alloprevotella, Anaerotruncus and Mucispirillum. Furthermore, Li05 induced significant changes in fatty acid and amino acid metabolism in the gut of rats with IBS-D. These findings indicate that Li05 exhibits an effective improvement in IBS-D symptoms by reducing inflammation and modulating gut microbiota and metabolism. Based on the above results, Li05 holds promise as a potential probiotic for managing IBS-D.

Effect of acupuncture on the expression of neuropeptides and related inflammatory factors in rats with diarrhea-predominant irritable bowel syndrome.

To observe the effect of acupuncture on the expressions of neuropeptides and related inflammatory factors in rats with diarrhea-predominant irritable bowel syndrome(IBS-D), so as to explore the mechanism of acupuncture in the treatment of IBS-D. Male Wistar rats were randomly divided into blank group, model group, medication group, and acupuncture group, with 6 rats in each group. Except for the blank group, the other groups were subjected to 14-day "acetic acid enema + restraint stress" to establish the IBS-D rat model. After successful modeling, the medication group received gavage of pinaverium bromide(15 mg/kg) once a day, and the acupuncture group received acupuncture at "Baihui"(GV20) and bilateral "Tianshu"(ST25), "Shangjuxu"(ST37), "Zusanli"(ST36), and "Taichong"(LR3) for 20 min every day, both groups were treated continuously for 14 days. The general state of the rats in each group was observed, and the body weight of the rats was measured. The open-field experiment was conducted to measure the horizontal and vertical movements, and the number of fecal pellets of rats. The histopathological morphology of hypothalamus and colon of rats was observed by HE staining. Toluidine blue staining was used to observe and count the mast cells(MCs) in the colon tissue of rats. ELISA was used to detect the serum contents of tumor necrosis factor-α(TNF-α) and interleukin(IL)-10. Real-time fluorescence quantitative PCR was performed to detect the mRNA expressions of calcitonin gene-related peptide(CGRP) in the hypothalamus and colon tissue. Western blot was used to detect the expressions of corticotropin-releasing factor(CRF) in the hypothalamus and colon tissue. HE staining showed that there was inflammatory cell infiltration in the lamina propria of colon in the model group, and it was reduced in the other groups. Compared with the blank group, the model group showed significantly decreased body weight, decreased walking distance and upright times in open field experiment, decreased serum IL-10 contents(P<0.05, P<0.01), increased fecal pellet number (P<0.01), increased MC number in the colon tissue, serum TNF-α contents, and CGRP mRNA expressions and CRF expressions in the hypothalamus and colon tissue(P<0.01). Compared with the model group, both medication and acupuncture groups showed significantly increased body weight, walking distance and upright times in the open-field experiment, and serum IL-10 contents(P<0.01, P<0.05), significantly decreased fecal pellet number (P<0.05), significantly decreased MC number in the colon tissue, serum TNF-α contents, and CGRP mRNA expressions in the hypothalamus and colon tissue(P<0.01)；at the same time, the acupuncture group showed significantly decreased CRF expressions in the hypothalamus and colon tissue(P<0.01, P<0.05). There was no significant difference in the above indicators between the medication group and the acupuncture group. Acupuncture can improve the general and emotional state, inflammatory response, and neuropeptide expression in rats with IBS-D, and alleviate the symptoms of IBS-D, which may be related to the regulation of neuropeptides and inflammatory factors levels.

The Effect and Mechanism of Sancao Lichang Decoction on Diarrhea- Predominant Irritable Bowel Syndrome by Regulating Tlr4/Myd88/Nf-Κb Pathway.

To evaluate the effect of Sancao Lichang decoction as traditional Chinese medicine on diarrhea-predominant irritable bowel syndrome (IBS-D) and TLR4/MyD88/NF-κB pathway. Traditional Chinese medicine has made significant progress in preventing and treating irritable bowel syndrome, and its efficacy has been validated by clinical practice. Sancao Lichang decoction is an empirical prescription developed by professor Tang Decai that has been used for many years to treat chronic diarrhoea with good curative effec. Still, its mechanism of action on IBS-D is unknown. The study sample of Fifty SD rats was randomly divided into a blank group, model group, low-dose group, medium-dose group, and high-dose group (n = 10). The IBS-D rat models were established by restraining stress method and acetic acid enema. After different treatments, defecation frequency, fecal water content (FWC), serum IL-6 and TNF-α contents, and protein level of TLR4/MyD88/NF-κB in colon tissues were detected separately. The indexes of rats in each group were significantly different. The increase in body weight in the medium-dose and high-dose groups was significantly higher than that in the model group (p < 0.05). Compared with the model group, the medium and high dose groups had lower diarrhea frequency, FWC, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) (p < 0.05). The expression levels of TLR4, MyD88, and NF-κB protein in the colon of the three groups treated with Sancao-Lichan decoction were significantly lower than those in the model group (p < 0.01). After different treatments, the colonic mucosa of rats in each group was stained with HE, which proved that the structural damage of colonic mucosa was improved after treatment with Sancao Lichang decoction, and the improvement effect was dose-dependent. Sancao Lichang decoction may reduce IBS-D by inhibiting TLR4/MyD88/NF-κB pathway, inhibiting the inflammatory response, and improving intestinal mucosal barrier function.

Lactobacillus plantarum AR495 improves stress-induced irritable bowel syndrome in rats by targeting gut microbiota and Mast cell-PAR2-TRPV1 signaling pathway

Probiotics have great potential in regulating intestinal pain. In this study, the effects of Lactobacillus plantarum AR495 on the visceral sensitivity and gut microbiota of irritable bowel syndrome (IBS) rats were studied. The results showed that tryptase released after mast cell activation and degranulation plays a key role in visceral pain, and L. plantarum AR495 reduced the stimulation of colonic mast cells and the expression of protease-activated receptor 2 (PAR2) and TRPV1 in dorsal root ganglia. Research further showed that supplementation with L. plantarum AR495 increased the level of short-chain fatty acids (SCFAs) and enhanced the barrier function of the colon. In addition, the microbiota analysis of the colon indicated that L. plantarum AR495 promoted the proliferation of Bifidobacterium and inhibited the proliferation of Lachnospiraceae, which alleviated the imbalance of the intestinal microbiota caused by IBS to a certain extent. In total, L. plantarum AR495 might reduce visceral sensitivity through the Mast cell-PAR2-TRPV1 signaling pathway by maintaining the homeostasis of the intestinal barrier.

NGF/PI3K/TRPV1 pathway mediates the regulation of visceral pain by acupuncture at "Shangjuxu" (ST37) in irritable bowel syndrome rats with chronic visceral hyperalgesia.

To investigate the effect of manual acupuncture at "Shangjuxu"(ST37) on nerve growth factor(NGF)/phosphatidylinositol 3-kinase(PI3K)/transient receptor potential vanilloid 1(TRPV1) signaling pathway in rats with chronic visceral hyperalgesia of irritable bowel syndrome (IBS), so as to explore its underlying mechanism in treating IBS chronic visceral hyperalgesia. IBS chronic visceral hyperalgesia model was established by colorectal dilation stimulation for 2 weeks for SD pups at 8 d after birth, which were fed until 8-week age after the stimulation. Then the verified successfully modeled adult rats were randomly divided into model, Shangjuxu, and non-acupoint groups, with 6 rats in each group, and 6 unmodeled rats were selected as normal group. On the next day of model evaluation, rats in the Shangjuxu group received acupuncture at right ST37 while rats in the non-acupoint group received acupuncture at the non-meridian and non-acupoint point in the right hypochondrium, both for 15 min, with manual twisting of mild reinforcing and reducing performed for 30 s at an interval of 5 min, once a day, for a total of 7 d. Abdominal withdrawal reflex(AWR) score was used to evaluate the degree of chronic visceral pain in rats. Western blot and real-time fluorescence quantitative PCR were used to detect the colonic protein and mRNA expressions of NGF, tropomyosin receptor kinase A (TrkA), PI3K and TRPV1. The positive expressions of PI3K and TRPV1 proteins in the colon of rats were detected by immunohistochemistry method. Compared with the normal group, AWR scores corresponding to 4 pressure levels of 20, 40, 60 and 80 mm Hg, mRNA and protein expressions of NGF, TrkA, PI3K and TRPV1 in colon tissue, and positive expressions of PI3K and TRPV1 in colon tissue were significantly increased(P<0.05) in the model group. After intervention, compared with the model group, rats in the Shangjuxu group had reduced AWR scores corresponding to 4 pressure levels of 20, 40, 60 and 80 mm Hg, lower colonic mRNA and protein expressions of NGF, TrkA, PI3K and TRPV1, and decreased positive expressions of PI3K and TRPV1 in colon tissue(P<0.05), while there were no significant differences in the above indexes of the non-acupoint group. Manual acupuncture at ST37 can alleviate IBS chronic visceral hyperalgesia in rat and its analgesic effect may be related to regulating NGF/PI3K/TRPV1 signaling pathway.

Linderae Radix water extract treats diarrhea-predominant irritable bowel syndrome in rats: a serum metabolomics study

This study aims to investigate the mechanism of Linderae Radix water extract(LRWE) in the prevention and treatment of diarrhea-predominant irritable bowel syndrome(IBS-D) based on serum metabolomics. Eighteen 2-week-old male SD rats were randomized into control, IBS-D model, and LRWE groups. The rats in other groups except the control group received gavage of senna concentrate combined with restraint stress for the modeling of IBS-D. The rats in the LRWE group were administrated with LRWE(5.4 g·kg~(-1)) by gavage, and those in the control and IBS-D model groups with an equal volume of distilled water for a total of 14 days. The visceral sensitivity was evaluated by the abdominal withdrawal reflex(AWR) score, and the degree of diarrhea was assessed by the fecal water content(FWC). The morphological changes of the colon and the morphology and number of goblet cells were observed by hematoxylin-eosin(HE) and periodic acid-schiff(PAS) staining, respectively. Ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) was used for the screening of the potential biomarkers in the rat serum and their related metabolic pathways. The results showed that LRWE reduced the AWR score, decreased FWC, and alleviated visceral sensitivity and diarrhea symptoms in IBS-D rats. HE and PAS staining showed that LRWE mitigated low-grade intestinal inflammation and increased the number of mature secretory goblet cells in the colonic epithelium of IBS-D rats. A total of 25 potential biomarkers of LRWE in treating IBS-D were screened out in this study, which were mainly involved in riboflavin, tryptophan, glycine, serine and threonine metabolism, glyoxylate and dicarboxylate metabolism, and cysteine and methionine metabolism. The regulatory effects were the most significant on the riboflavin and tryptophan metabolism pathways. LRWE may alleviate the visceral hypersensitivity by promoting energy metabolism and amino acid metabolism, enhancing intestinal barrier function, and improving intestinal immune function in IBS-D rats.

Vagus Nerve Stimulation Relives Irritable Bowel Syndrome and the Associated Depression via α7nAChR-mediated Anti-inflammatory Pathway.

The present study is designed to investigate the role of vagus nerve in the treatments of irritable bowel syndrome (IBS) and the associated central nervous system disorders. An IBS animal model was established by giving acetic acid and chronic-acute stress (AA-CAS) treatment in adult male Wistar rats. Subdiaphragmatic vagotomy (SDV) and vagus nerve stimulation (VNS) were performed to intervene the excitability of vagus nerve. Permeability of blood brain barrier (BBB) was measured and agonist and antagonist of α7 nicotinic acetylcholine receptor (α7nAChR) were used to explore the relevant mechanisms. AA-CAS treatment resulted in abnormal fecal output, increased visceral sensitivity, depressive-like behaviors, and overexpression of inflammatory mediators, all of which were reversed by VNS treatment. The effects of VNS could also be observed when α7nAChR agonist was applied. Whereas α7nAChR antagonist (methyllycaconitine, MLA) reversed VNS's effects. Interestingly, VNS also reduced the increased permeability of blood brain barrier (BBB) following AA-CAS treatment in IBS rats. SDV treatment only show temporary efficacy on AA-CAS-induced symptoms and had no effect on the permeability of BBB. The intestinal abnormalities and depressive symptoms in IBS rats can be improved by VNS treatment. This positive effect of VNS was achieved through α7nAChR-mediated inflammatory pathway and may also be associated with the decreased of BBB permeability.