Rat Model Of Functional Dyspepsia Research Articles

Effects of Saikosaponin D on Apoptosis, Autophagy, and Morphological Structure of Intestinal Cells of Cajal with Functional Dyspepsia.

Functional dyspepsia (FD) is one of the most common gastrointestinal diseases, with a global prevalence of 10%-30%. However, the specific pathogenesis of FD has not yet been determined. As such, the aim of this study was to investigate the effects of saikosaponin D (SSD) administration on the apoptosis, autophagy, and morphological structure of the intestinal cells of Cajal (ICCs) in FD. Methods：A rat model of FD was constructed by stimulating the rat tail with a sponge clamp at one-third of the distal tail length. An autophagy model was constructed for ICCs using glutamate. The apoptosis rate in each group of cells was determined using flow cytometry. The expressions of ghrelin and substance P (SP) were detected using ELISA. The body weight and food intake of male and female rats in the SSD group were consistently higher than those in the model group. The SSD group showed substantial improvement compared with the model group, with no inflammatory cell infiltration and normal gastric mucosal structures. After intervention with SSD, the ultrastructure of the ICCs considerably improved and was clear. Compared with the model group, the expressions of LC3 I/II, ghrelin, and SP proteins in the SSD group were significantly upregulated, and the apoptosis rate was significantly reduced. The administration of SSD improved ICC morphology and structure, inhibited excessive autophagy, and improved FD, a gastrointestinal motility disorder, by regulating ghrelin and SP levels.

Electroacupuncture improves low-grade duodenal inflammation in FD rats by reshaping intestinal flora through the NF-κB p65/NLRP3 pyroptosis pathway

Electroacupuncture (EA) is an effective alternative for the treatment of functional dyspepsia (FD). It reduces low-grade duodenal inflammation and improves the symptoms of FD by downregulating the expression of NF-κB p65 and NLRP3, but its mechanism needs to be elucidated. To examine the regulatory effect of electroacupuncture (EA) on intestinal flora and NF-κB p65/NLRP3 pyroptosis pathway in FD rats. The FD rat model was established via multi-factor stress intervention for two weeks. The rats were randomly divided into the NC group, model group, NF-kB inhibitor group (NF-κB inhibitor BAY 11–7082 was administered), EA group, and EA + NF-kB inhibitor group. After 14 days of treatment, the rats were sacrificed, and the protein and mRNA levels of NF-κB p65, IκB, and NLRP3 in the duodenum were evaluated by Western blotting assays and real-time fluorescent quantitative PCR. The Illumina MiSeq sequencing platform was used to analyze the V4 region of the 16S rRNA gene of intestinal flora and predict functional genes. The concentration of short-chain fatty acids (SCFAs) in feces was assessed by metabolomics. EA can decrease low-grade duodenal inflammation and promote gastrointestinal motility in FD rats. This effect is mediated by inhibition of the NF-κB p65/NLRP3 pyroptosis pathway, an increase in the alpha and beta diversity of gut microbiota in the duodenum, an increase in the abundance of beneficial bacteria at the phylum and genus levels, and an increase in the content of SCFAs. The protective effect of EA against FD might involve multiple hierarchy and pathways. EA may remodel intestinal flora by inhibiting the NF-κB p65/NLRP3 pyroptosis pathway, thereby improving low-grade duodenal inflammation in FD rats.

Chaihu Shugan Powder inhibits interstitial cells of cajal mitophagy through USP30 in the treatment of functional dyspepsia

Ethnopharmacological relevanceChaihu Shugan Powder (CHSGP) has significant clinical efficacy in the treatment of functional dyspepsia (FD), but the specific mechanism requires further study. Aim of studyThe aim of this study was to investigate the therapeutic effect of CHSGP on FD rats and the underlying mechanism of the effect on interstitial cells of cajal (ICC) mitophagy. Materials and methodsThe tail-clamping stimulation method was utilized to establish an FD rat model in vivo. Gastric emptying rate and small intestinal propulsion rate test, H&E staining, and Immunohistochemistry were conducted to evaluate the therapeutic effects of CHSGP on FD rats. In vitro, the regulatory effect of CHSGP on CCCP-mediated ICC mitophagy was further investigated by CCK8, Transmission electron microscope, immunofluorescence co-staining, Quantitative polymerase chain reaction and Western blot to reveal the potential mechanisms of CHSGP inhibited ICC mitophagy. ResultsAnimal experiments provided evidence that CHSGP promoted gastric motility, increased ICC numbers, reduced Parkin expression, and elevated USP30 expression in FD rats. In vitro, further mechanism research demonstrated that CHSGP decreased LC3Ⅱ/LC3Ⅰ、PINK1、Parkin、PHB2 protein expression and increased USP30 protein expression. Furthermore, CHSGP increased Mfn2 protein expression by suppressing activation of the PINK1/Parkin pathway when USP30 is knocked down, consequently reducing CCCP-induced ICC mitophagy. ConclusionsThese results suggest that CHSGP may treat FD against CCCP-induced ICC mitophagy by the up-regulation of via PINK1/Parkin pathway.

Rhizoma Atractylodis Macrocephalae-Assessing the influence of herbal processing methods and improved effects on functional dyspepsia.

Background: The unique pharmaceutical methods for the processing of botanical drugs according to the theory of traditional Chinese medicine (TCM) affect clinical syndrome differentiation and treatment. The objective of this study was to comprehensively elucidate the principles and mechanisms of an herbal processing method by investigating the alterations in the metabolites of Rhizoma Atractylodis Macrocephalae (AMR) processed by Aurantii Fructus Immaturus (AFI) decoction and to determine how these changes enhance the efficacy of aqueous extracts in treating functional dyspepsia (FD). Methods: A qualitative analysis of AMR before and after processing was conducted using UPLC-Q-TOF-MS/MS, and HPLC was employed for quantitative analysis. A predictive analysis was then conducted using a network analysis strategy to establish a botanical drug-metabolite-target-disease (BMTD) network and a protein-protein interaction (PPI) network, and the predictions were validated using an FD rat model. Results: A total of 127 metabolites were identified in the processed AMR (PAMR), and substantial changes were observed in 8 metabolites of PAMR after processing, as revealed by the quantitative analysis. The enhanced aqueous extracts of processed AMR (PAMR) demonstrate improved efficacy in treating FD, which indicates that this processing method enhances the anti-inflammatory properties and promotes gastric motility by modulating DRD2, SCF, and c-kit. However, this enhancement comes at the cost of attenuating the regulation of motilin (MTL), gastrin (GAS), acetylcholine (Ach), and acetylcholinesterase (AchE). Conclusion: Through this series of investigations, we aimed to unravel the factors influencing the efficacy of this herbal formulation in improving FD in clinical settings.

Deciphering the function of Xiangsha-Liujunzi-Tang in enhancing duodenal mucosal barrier by inhibiting MC/Tryptase/PAR-2 signaling pathway in functional dyspepsia rats

Ethnopharmacological relevanceXiangsha-Liujunzi-Tang (XSLJZT) is a classical formula for treating the diseases of digestive system, which can effectively and significantly improve the symptoms of functional dyspepsia (FD) patients. The main function of XSLJZT is to benefit Qi and spleen, and harmonize stomach. Aim of the studyThe purpose of this study was to investigate the intervention effect of XSLJZT on duodenal mucosal injury in FD rats and the response mechanism of MC/Tryptase/PAR-2 signal pathway. Materials and methodsUltra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was employed to qualitatively and quantitatively identify the chemical component of XSLJZT. A comprehensive modeling method (iodoacetamide infusion + irregular diet + swimming exhaustion) was used to construct the FD rat model. XSLJZT decoction was given to intervene FD rats for 2 weeks. The indicators of digestive function including body mass, 3-h food intake, visceral sensitivity, gastric emptying rate and intestinal propulsion rate were routinely measured for FD rats. The pathological changes of duodenum and microstructure of intestinal epithelial cells were observed by HE staining and transmission electron microscopy respectively. The inflammatory factors (VCAM-1, IL-6, TNF-α, and ICAM-1) and histamine content were evaluated by enzyme-linked immunosorbent assay (ELISA). The expression levels of Tryptase, PAR-2, ZO-1, β-catenin, p–NF–κBp65 and p-ERK1/2 in duodenal tissues were measured by Western blot (WB) and immunofluorescence colony-staining (IFC). ResultsXSLJZT administration significantly improved the survival of FD rats, increased body mass and 3-h food intake, improved visceral sensitivity, and restored gastric emptying rate and intestinal propulsion rate. HE staining showed that XSLJZT recovered the structure of duodenal mucosal and reduced inflammatory infiltration. ELISA revealed that XSLJZT reduced the content of inflammatory factors (VCAM-1, IL-6, TNF-α, and ICAM-1) and histamine. In addition, WB and IFC uncovered that the protein levels of ZO-1 and β-catenin were up-regulated and MC/Tryptase/PAR-2 signaling pathway was inhibited by XSLJZT. ConclusionXSLJZT significantly improved the integrity of duodenal mucosa and decreased the inflammation in FD rats through the inhibition of MC/Tryptase/PAR-2 signaling pathway response.

Pitongshu Alleviates the Adverse Symptoms in Rats with Functional Dyspepsia Through Regulating Visceral Hypersensitivity Caused by 5-HT Overexpression.

The aim of the study was to explore the efficacy as well as the mechanism of action of Pitongshu (PTS) on rats with functional dyspepsia (FD) induced by iodoacetamide gavage and tail clamping. The bioactive components of PTS were obtained from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), whereas the potential targets of PTS were obtained from the Similarity Ensemble Approach (SEA), TCMSP, and Swiss Target Prediction Database. The disease targets were obtained from the DisGeNET database, whereas Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed using the R Software. The method of iodoacetamide gavage combined with tail clamping was used to establish the FD rat model in this study. Body weight, food intake, gastrointestinal motility, gastric acidity and secretion, and the mechanical pain threshold of rats were measured. The open-field test was also performed. The stomach and duodenum were histologically observed. The levels of serotonin (5-HT), Calcitonin Gene-Related Peptide (CGRP), Motilin (MTL), and Gastrin (GAS) in gastric tissues were detected by ELISA. A total of 139 bioactive components and 17 potential targets of PTS were identified through a network pharmacology approach. The results of GO and KEGG enrichment analyses indicated that PTS could reduce the 5-HT secretion of gastric tissues through the serotonergic synaptic pathway and alleviate the symptoms of FD, indicating that PTS plays a therapeutic role. The results of animal experiments showed that PTS could increase body weight and food intake, improve autonomous activity, and decrease gastric acidity and secretion in FD rats. Furthermore, gastric sensitivity increased in FD rats, and PTS treatment could significantly decrease it. The results of ELISA showed that the overexpression of 5-HT and CGRP was decreased after PTS treatment in FD rats. Lastly, PTS could significantly improve gastrointestinal motility, as well as the levels of GAS and MTL in FD rats. PTS may reduce 5-HT secretion by regulating the serotonergic synaptic pathway, thereby reducing visceral sensitivity and alleviating the symptoms of FD.

Fructus Aurantii Extracts Ameliorate Intestinal Inflammation and Regulate the Intestinal Barrier through Fc Epsilon RI Signaling Pathway

Fructus Aurantii (FA) is the dry and immature fruit of Citrus aurantium L. and its rutaceous cultivars. FA has been widely used to treat digestive system diseases since ancient China, and it promotes gastrointestinal (GI) motility in functional dyspepsia (FD), but its potential therapeutic mechanisms remain unclear. We examined the effects of FA ethanol extracts in an iodoacetamide (IA)-induced FD rat model. Firstly, key FA therapy targets for FD were gathered using systematic pharmacology. Combined with systemic pharmacological analyses, plasma metabolomics based on UPLC-QTOF-MS were conducted. Then, MetaboAnalyst was used to jointly analyze systemic pharmacology targets and metabolomic metabolites to select key metabolic pathways. Finally, the key path is verified by experiments. FA exerted distinct therapeutic effects in anti-inflammation and promoting gastrointestinal motility in our IA-induced FD rat model. When compared with the model group, FA down-regulated the inflammatory factors interleukin 1β and tumor necrosis factor-α. At the same time, FA up-regulated tight junction proteins in the intestinal epithelial barrier. Through the integrated analysis of metabolomics and systemic pharmacology, we conducted experimental verification on Fc epsilon RI signaling pathway. When compared with the model group, FA down-regulatedphospho-mitogen activated protein kinase, phospho-extracellular signal regulated kinase1/2, myosin light chain kinase, and phospho-myosin regulatory light chain protein levels. Thus, FA ameliorated FD by regulating the Fc epsilon RI signaling pathway. Our integrated strategy identified underlying FA mechanisms toward FD treatment and provided a foundation for FA development as a clinical agent for FD.

Auricular Vagus Nerve Stimulation Improves Visceral Hypersensitivity and Gastric Motility and Depression-like Behaviors via Vago-Vagal Pathway in a Rat Model of Functional Dyspepsia.

We evaluated the effects of aVNS on visceral hypersensitivity, gastric motility and open field test (OFT) activity in iodoacetamide (IA)-treated rats. The autonomic function was assessed; blood samples and tissues were collected and analyzed by an enzyme-linked immunosorbent assay and western blot. Vagotomy was performed to investigate the role of vagal efferent nerve. aVNS reduced the electromyography response to gastric distension, improved gastric emptying and increased the horizontal and vertical motion scores of the OFT in IA-treated rats. The sympathovagal ratio was increased in IA-treated rats but normalized with aVNS. The serum cytokines TNF-α, IL-6, IL-1β and NF-κBp65 were increased in IA-treated rats and decreased with aVNS. The hypothalamus-pituitary-adrenal axis was hyperactive in IA-treated rats but inhibited by aVNS. The expression of duodenal desmoglein 2 and occludin were all decreased in IA-treated rats and increased with aVNS but not sham-aVNS. Vagotomy abolished the ameliorating effects of aVNS on gastric emptying, horizontal motions, serum TNF-α and duodenal NF-κBp65. aVNS improves gastric motility and gastric hypersensitivity probably by anti-inflammatory mechanisms via the vago-vagal pathways. A better understanding on the mechanisms of action involved with aVNS would lead to the optimization of the taVNS methodology and promote taVNS as a non-pharmacological alternative therapy for FD.

Zhizhu Kuanzhong, a traditional Chinese medicine, alleviates gastric hypersensitivity and motor dysfunction on a rat model of functional dyspepsia.

Ethnopharmacological relevance: Zhizhu Kuanzhong (ZZKZ) is a traditional Chinese medicine modified from classic formula Zhizhu decoction in "Synopsis of Golden Chamber" (Han Dynasty in the 3rd century) and the Zhizhu pill in "Differentiation on Endogenous" in Jin Dynasty (1,115-1,234). ZZKZ contains four botanical drugs, including Citrus × Aurantium L [Rutaceae; Aurantii Fructus Immaturus], Atractylodes Macrocephala Koidz. [Compositae; Rhizoma Atractylodis Macrocephalae], Bupleurum Chinense DC [Apiaceae; Radix Bupleuri Chinensis], and Crataegus Pinnatifida Bunge [Rosaceae; Fructus Crataegi Pinnatifidae], which have been widely used in clinical therapy for functional dyspepsia (FD). Aim of the study: This study aimed to evaluate the pharmacological effects and mechanisms of action of ZZKZ on gastric hypersensitivity and motor dysfunction in a rat model of FD. Materials and methods: FD was induced in Sprague-Dawley rats by neonatal gastric irritation with 0.1% iodoacetamide. The FD rats were treated with ZZKZ (0.5g/kg, 1.0g/kg, or 1.5g/kg respectively) by gavage for 7days, while domperidone (3mg/kg) acted as treatment control. Body weight gain, food intake, gastric emptying, and intestinal propulsion were also measured. Ex vivo gastric smooth muscle activity recordings and greater splanchnic afferent (GSN) firing recordings were employed to evaluate gastric motility and sensation. Particularly, the role of 5-HT in the action of ZZKZ in improving gastric dysmotility and hypersensitivity was explored. Results: ZZKZ promoted weight gain, food intake, gastric emptying, and intestinal propulsion in FD rats. ZZKZ promoted spontaneous and ACh-induced contractions of gastric smooth muscle strips in FD rats, alleviated spontaneous activity, and chemical (acid perfusion) and mechanical (intragastric distension) stimulated GSN firing in FD rats. ZZKZ ameliorated gastric smooth muscle contraction and GSN firing induced by 5-HT in FD rats. ZZKZ stimulated the release of serum 5-HT, with reduced 5-HT3 receptor and increased 5-HT4 receptor mRNA expression in the guts of FD rats. Conclusion: This study demonstrated that ZZKZ improves FD-related gastric hypersensitivity and motor dysfunction and should be an effective compound for relieving FD symptoms. The gastric 5-HT system with lower 5-HT3 activity and increased 5-HT4 distribution is involved in the mechanisms of ZZKZ underlying the treatment of FD.

Investigation of the improving effect of raw and charred hawthorn on functional dyspepsia based on interstitial cells of Cajal

BackgroundRaw hawthorn (RH) is a traditional Chinese medicine commonly used to treat indigestion. Charred hawthorn (CH) is obtained from RH by charring. It is reported that the effect of CH treatment on dyspepsia is stronger than RH. However, this has not been fully proven. The purpose of this study was to compare the effects of RH and CH on functional dyspepsia (FD) model rats. And contribute to the development of dietary therapy for dyspepsia.MethodsSPF-grade male SD rats were divided into 5 groups: the control group, the model group, the Mos group, the RH group, and the CH group. The FD rat model was established by using the methods of water restriction, fasting, tilting cage restraint, day and night upside down, swimming, and tail damping. The body weight of rats in each group was recorded. And the gastric emptying rate, intestinal propulsive rate, and the levels of motilin (MTL), gastrin (GAS), and 5-HT in serum were compared in each group. The expression of C-kit in the stomach and small intestine of each group was compared by immunofluorescence and PCR.ResultsRH and CH could increase weight, improve the gastric emptying rate and intestinal propulsive rate, and promote the secretion of motilin (MTL), gastrin (GAS), and 5-HT in the serum of FD rats. RH and CH can upregulate the expression of the characteristic protein c-kit of ICC in the stomach and small intestine of FD model rats, and the effect of CH is stronger than RH.ConclusionRH and CH may increase the number of interstitial cells of Cajal (ICC) in the gastrointestinal tract by upregulating c-kit expression, thus improving gastrointestinal motility in FD model rats. And compared with RH, CH has certain advantages.

PO009 / #997 MULTI-TARGETING REGULATION OF AURICULAR VAGUS NERVE STIMULATION ON VISCERAL HYPERSENSITIVITY AND GASTRIC MOTILITY IN A RODENT MODEL OF FUNCTIONAL DYSPEPSIA: E-POSTER VIEWING

Functional dyspepsia (FD) is one of the common recurrent clinical diseases. It was perceived to benefit most from pharmacotherapy although most treatments have modest effects, and adverse event profile has recently been recognized. Evidence has shown the auricular vagus nerve stimulation (aVNS) is effective for functional dyspepsia (FD) recently. This study aimed to observe the mechanism of auricular vagus nerve stimulation (aVNS) on brain-gut peptides and facilitatory mediators of the inflammation in a rat model of FD.

Multi-omics analysis reveals the metabolic regulators of duodenal low-grade inflammation in a functional dyspepsia model.

Several gastrointestinal phenotypes and impairment of duodenal mucosal barrier have been reported in clinical studies in patients with functional dyspepsia (FD). Due to the preferential colonization of the mucosa, intestinal microbes and their metabolites are commonly involved in host metabolism and immune responses. However, there are no studies on the intertwined correlation among multi-level data. For more comprehensive illustrating, a multi-omics analysis focusing on the duodenum was performed in the FD rat model. We found that differential microbiomes in the duodenum were significantly correlated with the biosynthesis of lipopolysaccharide and peptidoglycan. The innate immune response-related genes, which were upregulated in the duodenum, were associated with the TLR2/TLR4-NFκB signaling pathway. More importantly, arachidonyl ethanolamide (anandamide, AEA) and endocannabinoid analogues showed linear relationships with the FD phenotypes. Taken together, multi-level data from microbiome, transcriptome and metabolome reveal that AEA may regulate duodenal low-grade inflammation in FD. These results suggest an important cue of gut microbiome–endocannabinoid system axis in the pathogenesis of FD.

Multi-targeting regulation of auricular vagus nerve stimulation on gastric hypersensitivity and gastric dysmotility in a rodent model of functional dyspepsia

Background: Evidences have shown the auricular vagus nerve stimulation (aVNS) is effective for functional dyspepsia (FD) recently. This study aimed to observe the mechanism of aVNS on facilitatory mediators of the inflammation in a rat model of functional dyspepsia. Methods: Thirty-six 5 d-old male Sprague Dawley rats were randomly divided into control groups (n = 12), model group (n = 12), aVNS group (n = 6) and sham-aVNS group (n = 6). Except for the control rats, all other rats were treated with iodoacetamide gavage. After the model was developed successfully, rats in aVNS group and sham-aVNS group received aVNS and sham-aVNS respectively, 30 min/1 time per day for 14 consecutive days. The control group and model group received no intervention. Gastric sensitivity after 1-week of intervention and gastric emptying after 2-week of intervention were adopted to assess the effect of aVNS. Brain-gut peptides, facilitatory mediators of the inflammation in serum were tested by ELISA, and α7 nicotinic acetylcholine receptor (α7-nAchR) in antrum tissue were tested by Immunohistochemistry to explore the mechanism of aVNS. Results: Compared with the control group, the gastric sensitivity was increased, gastric emptying decreased, and there was no structural damage in the gastric antrum in the model group. aVNS reduced visceral hypersensitivity and improved gastric emptying but not sham-aVNS. cholecystokinin, glucagon-like peptide-1, peptide, tumor necrosis factorα and interleukin 6 were all increased, while ghrelin and α7-nAchR decreased in model rats (P < 0.01 for all, compared with the control group). aVNS can normalize them. Conclusion: The aVNS can decrease the gastric sensitivity and increase gastric emptying, the mechanism was related to its regulation of brain-gut peptides and facilitatory mediators of the inflammation. The ameliorating effect was related to cholinergic mechanism.

The role of amygdala neuropsin/serpinb6 pathway in the regulation of gastric hypersensitivity and anxiety by electroacupuncture.

To investigate whether the neuropsin pathway in the amygdala and stomach may participate in the development of anxiety-related gastric hypersensitivity, and whether electroacupuncture (EA) at the Zusanli acupoint could improve this condition by regulating such pathway in the rat model of functional dyspepsia (FD). A total of 48 SD rats were randomly divided into the control group, FD model group and FD + EA group (stimulation at Zusanli acupoint for 30 min daily for 7 consecutive days). Abdominal withdrawal reflex (AWR) score and open field test were used to evaluate visceral hypersensitivity and anxiety-like disorder, respectively. Electrical activity in the amygdala nucleus in each group was recorded by extracellular electrophysiology. Neuropsin and serpinb6 protein expressions in the amygdala and stomach were detected by Western blot. AWR score in the FD group increased but did not differ after EA therapy than that in the contro group. Both the center square entries and center entries ratio in the FD group were lower than those in the control and FD + EA groups. The total number and frequency of amygdala nucleus discharges induced by gastric distension in the FD group were significantly higher than those in the control and FD + EA groups. Expression of neuropsin increased and that of serpinb6 decreased in the gastric mucosa and amygdale in the FD group, while no change was observed in gastric mucosa after EA therapy. EA stimulation at the Zusanli acupoint may improve visceral hypersensitivity and anxiety in FD rats through the neuropsin/serpinb6 pathway.

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

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

Effects of transcutaneous auricular vagus nerve stimulation on autonomic nervous function in rats with functional dyspepsia

To observe the effect of transcutaneous auricular vagus nerve stimulation (taVNS) on the autonomic nerve function in a rat model of functional dyspepsia (FD), so as to explore the mechanism of taVNS underlying regulation of FD. SD rats were randomly divided into normal control group(n=8) and FD model group(n=26).The FD model was replicated with iodoacetamide gavage. The FD model rats were randomly divided into model, taVNS, sham-taVNS and Zusanli(ST36) groups, with 6 rats in each group. Rats in the taVNS group received electrical stimulation of auricular concha,while the sham-taVNS group received no electrical stimulation and rats in the ST36 group received stimulation at ST36 for 30 min once daily for 14 consecutive days. Cervical trapezius electromyography score and abdominal withdrawal reflex (AWR) score were used to evaluate gastric sensitivity. Histopathological changes of the gastric antrum tissue were observed under microscope after H.E. staining. Autonomic nerve function in rats was recorded and assessed by heart rate variability(HRV). The content of acetylcholine (Ach) and the expression of Ach receptor M3R in gastric antrum was detect by ELISA and Western blot, separately. Compared with the normal control group, the cervical trapezius electromyography and AWR scores of the model group increased (P<0.01, P<0.001), and there was no erosion in the gastric antral mucosa and muscle layer. The high-frequency power (HF) in HRV decreased (P<0.05), the ratio of low-frequency power/high-frequency power (LF/HF) increased (P<0.001), and the Ach content and its receptor M3R expression in gastric antrum tissue decreased (P<0.05). Following interventions, the cervical trapezius electromyography and AWR scores decreased (P<0.01,P<0.001, P<0.05), HF in HRV increased and LF/HF decreased(P<0.01，P<0.05,P<0.001), and the content of Ach in gastric antrum tissue and the expression of its receptor M3R increased (P<0.01, P<0.05) in both taVNS and ST36 groups relevant to the model group. taVNS can increase the activity of the vagus nerve and regulate the balance of the autonomic nerve function, which may be one of the mechanisms of taVNS in reducing the gastric sensitivity of rats with FD. In regulating the vagus nerve function, taVNS and acupuncture at ST36 acupoint have the similar effects.

Effects of transcutaneous auricular vagus nerve stimulation on intestinal ligandins in a rat model of functional dyspepsia

ObjectiveTranscutaneous auricular vagus nerve stimulation (taVNS) can relieve the symptoms of functional dyspepsia (FD) and improve the quality of life of patients, however, the mechanism underlying this effect remains unclear. Therefore, this study aimed to investigate the effects of taVNS on the expression of intestinal mucosal ligandins. MethodsThis study was conducted on 24 specific Spathogen-free Sprague–Dawley rats (12 males and 12 females). The rat model of FD was established by tail-clip stimulation. After FD was established successfully, all rats were randomized to either the normal group (n = 6), model group (n = 6), taVNS group (n = 6), or sham-taVNS group (n = 6). After two weeks of the respective intervention, the score of their general conditions, 3 h food intake, gastric emptying rate, and the histology of gastric antrum tissues were observed to evaluate modeling success, and then the effect of taVNS was evaluated. Western blotting was used to assess the expression of the tight junction ligandins —ZO-1 and occludin—and the adhesion ligandin—β-catenin—in the duodenum. The effect of taVNs on the expression of intestinal mucosal barrier ligandins—ZO-1, occludin, and β-catenin—in FD rats was preliminarily investigated. ResultsWhen the model-induced period was finished, the manifestations of FD in the model group rats were mental exhaustion, reduced activities, decreased score of the general conditions, and decreased 3 h food intake, compared to the normal group rats. In addition, minimal eosinophil infiltration, without any mucosal erosion or ulcer, was observed in the gastric antrum mucosa. At the end of the study, the mental state of the FD rats improved, and their activities and gastric emptying rate increased in the taVNS group rats. Compared to the normal rats, the duodenal mucosa had less expression of the tight junction ligandins ZO-1 and occludin, but β-catenin expression remained unchangedin the model rats. The expression of the tight junction ligandins ZO-1 and occludin were increased in the duodenal mucosa of model rats after the taVNS intervention. ConclusionTaVNS can improve the gastric motility and mental state of rats with FD. It may play a therapeutic role by improving the expression of the tight junction ligandin ZO-1 and occludin in the duodenal mucosa, while also repairing the duodenal mucosal barrier.

Vagal gut-brain signaling mediates amygdaloid plasticity, affect, and pain in a functional dyspepsia model.

Functional dyspepsia (FD) is associated with chronic gastrointestinal distress and with anxiety and depression. Here, we hypothesized that aberrant gastric signals, transmitted by the vagus nerve, may alter key brain regions modulating affective and pain behavior. Using a previously validated rat model of FD characterized by gastric hypersensitivity, depression-like behavior, and anxiety-like behavior, we found that vagal activity — in response to gastric distention — was increased in FD rats. The FD phenotype was associated with gastric mast cell hyperplasia and increased expression of corticotrophin-releasing factor (Crh) and decreased brain-derived neurotrophic factor genes in the central amygdala. Subdiaphragmatic vagotomy reversed these changes and restored affective behavior to that of controls. Vagotomy partially attenuated pain responses to gastric distention, which may be mediated by central reflexes in the periaqueductal gray, as determined by local injection of lidocaine. Ketotifen, a mast cell stabilizer, reduced vagal hypersensitivity, normalized affective behavior, and attenuated gastric hyperalgesia. In conclusion, vagal activity, partially driven by gastric mast cells, induces long-lasting changes in Crh signaling in the amygdala that may be responsible for enhanced pain and enhanced anxiety- and depression-like behaviors. Together, these results support a “bottom-up” pathway involving the gut-brain axis in the pathogenesis of both gastric pain and psychiatric comorbidity in FD.

D-galacturonic acid ameliorates the intestinal mucosal permeability and inflammation of functional dyspepsia in rats.

Functional dyspepsia (FD) is a gastrointestinal disease caused by imbalanced gastrointestinal function. Traditional treatments are deemed to be limited, and new therapeutic drugs are required. New study suggested that duodenal low-grade inflammation and increased intestinal permeability play an important role in the pathogenesis of FD. Previous studies have shown that polysaccharides containing D-galacturonic acid (GA) could modulate intestinal immune activity in vitro and in animal models. However, the ability of GA monomer to improve intestinal mucosal permeability and inflammation in FD has not been clearly elucidated. A FD rat model was established using iodoacetamide (IA). FD Rats were administrated different doses of GA. Subsequently, the body weight and behavioral sensitivity of the rats were measured and evaluated; the permeability of the intestinal barrier was measured by determining D-lactose, lactulose/mannitol ratio (LMR), and permeability-related genes [desmocollin-2 (DSC2), TJP1, and OCLN] in FD rats. Also, inflammatory cells [cluster of differentiation (CD)3+ cells and mast cells] were assessed by immunohistochemistry, and the levels of immune-related factors, such as the Toll-like receptor-nuclear factor kappa B (TLR/NF-κB) pathway, were monitored by reverse transcription quantitative polymerase chain reaction (RT-qPCR) or western blot assays. Our results suggested that GA could markedly increase the body weight and attenuate the behavioral sensitivity of FD rats. Moreover, GA also has an obvious ameliorating effect on the intestinal mucosal permeability and inflammatory response of FD rats. Furthermore, we found that GA could markedly downregulate TLR2, TLR4, and NF-κB in FD rats. These findings indicate that GA could significantly attenuate the intestinal mucosal permeability and inflammation FD rats. The effect of GA was partially mediated by the TLR/NF-κB signaling pathway.

Electroacupuncture Ameliorates Gastric Hypersensitivity via Adrenergic Pathway in a Rat Model of Functional Dyspepsia

Electroacupuncture (EA) is effective in treating visceral pain associated with functional dyspepsia (FD). The aim of this study was to explore the effect of chronic EA (CEA) on gastric hypersensitivity and the involvement of sympathetic nervous system in a rodent model of FD. Gastric hypersensitivity in adulthood was induced by iodoacetamide (IA) in neonatal rats. The IA-treated rats were randomized to receive no treatment (control), sham-CEA, CEA, or adrenergic antagonists, for one week. Gastric sensitivity to graded gastric distensions was then assessed by electromyogram (EMG) analysis. Autonomic functions were assessed from the spectral analysis of heart rate variability (HRV) to derive the low-frequency (LF, sympathetic activity) and high-frequency (HF, mainly vagal activity) components expressed as percentage of total spectral power. Blood was collected for the measurement of corticosterone (CORT) and norepinephrine (NE). 1) CEA, but not sham-CEA, reduced the EMG response to graded gastric distension in IA-treated control rats at 40 mmHg (128 ± 6% vs. 171 ± 15%, p = 0.009), 60 mmHg (204 ± 14% vs. 271 ± 24%, p = 0.010) and 80 mmHg (269 ± 19% vs. 364 ± 33%, p = 0.025), respectively. 2) CEA, but not sham CEA, increased HF component (0.61 ± 0.02 vs. 0.46 ± 0.04 in IA-treated rats, p = 0.003) and decreased LF component (0.39 ± 0.02 vs. 0.54 ± 0.04, p = 0.003). 3) Adrenergic antagonists reduced the EMG response to graded gastric distension. 4) CEA significantly reduced plasma CORT and NE in IA-treated rats. EA ameliorates gastric hypersensitivity in IA-treated rats and the effect may be related to the improved sympathovagal balance and the decrease of stress hormones.