Evaluation of a modified rat model for functional dyspepsia

Chaihu Shugan San promotes gastric motility in rats with functional dyspepsia by regulating Drp-1-mediated ICC mitophagy

CONTEXT

Chaihu Shugan San (CHSGS) was effective in the treatment of functional dyspepsia (FD).

OBJECTIVE

To investigate the mechanism of CHSGS in FD through dynamin-related protein 1 (Drp-1)-mediated interstitial cells of cajal (ICC) mitophagy.

MATERIALS AND METHODS

Forty Sprague-Dawley (SD) rats were randomly divided into control, model, mdivi-1, mdivi-1 + CHSGS and CHSGS groups. Tail-clamping stimulation was used to establish the FD model. Mdivi-1 + CHSGS and CHSGS groups were given CHSGS aqueous solution (4.8 g/kg) by gavage twice a day. Mdivi-1 (25 mg/kg) was injected intraperitoneally once every other week for 4 w. Mitochondrial damage was observed by corresponding kits and related protein expressions were assessed by Immunofluorescence and (or) Western Blot.

RESULTS

Compared with the mean value of the control group, superoxide dismutase (SOD) and citrate synthase (CS) in the model group were decreased by 11% and 35%; malondialdehyde (MDA) and reactive oxygen species (ROS) were increased by 1.2- and 2.8-times; ckit fluorescence and protein expressions were decreased by 85% and 51%, co-localization expression of LC3 and voltage dependent anion channel 1 (VDAC1), Drp-1 and translocase of the outer mitochondrial membrane 20 (Tom20) were increased by 10.1- and 5.4-times; protein expressions of Drp-1, Beclin-1, and LC3 were increased by 0.5-, 1.4-, and 2.5-times whereas p62 was decreased by 43%. After mdivi-1 and (or) CHSGS intervention, the above situation has been improved.

DISCUSSION AND CONCLUSION

CHSGS could improve mitochondrial damage and promote gastric motility in FD rats by regulating Drp-1-mediated ICC mitophagy.

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

Background

Raw 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.

Methods

SPF-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.

Results

RH 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.

Conclusion

RH 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.

Hesperidin promotes gastric motility in rats with functional dyspepsia by regulating Drp1-mediated ICC mitophagy

Hesperidin is one of the main active ingredients of Citrus aurantiumL. (Rutaceae) and tangerine peel, which have anti-inflammatory and antioxidant effects. In previous study, we found that gastric motility disorder in functional dyspepsia (FD) rats accompanied by excessive autophagy/mitochondrial swelling and even vacuolization in the interstitial cells of cajal (ICC), but the exact mechanism has not yet been investigated. Therefore, we used different doses of hesperidin (50 mg/kg, 100 mg/kg, and 200 mg/kg) to intervene in FD rats, and found that medium doses of hesperidin (100 mg/kg) significantly increased gastric motility in FD rats. Subsequently, FD rats were randomly divided into control group, model group, mdivi-1 group, mdivi-1+hesperidin group and hesperidin group, and mitochondrial division inhibitor (mdivi-1) was injected intraperitoneally to further investigate whether hesperidin could regulate dynamin-related protein 1 (Drp1)-mediated mitophagy in ICC to improve mitochondrial damage. The results showed that compared with the model group, the serum malondialdehyde (MDA) level decreased and the superoxide dismutase (SOD) level increased in the mdivi-1 and hesperidin groups (p < 0.001). Transmission electron microscopy (TEM) observed that the mitochondrial nuclear membrane was intact in gastric tissues with a clear internal cristae pattern, and autophagy lysosomes were rare. The co-localization expression of microtubule associated protein 1 light chain 3 (LC3) and voltage dependent anion channel 1 (VDAC1), Drp1 and translocase of the outer mitochondrial membrane 20 (Tom20) was significantly decreased (p < 0.001), the protein expression of mitochondrial Drp1, Beclin1 and LC3 were significantly decreased (p < 0.001), the protein expression of mitochondrial P62 and ckit in gastric tissue were significantly increased (p < 0.05, p < 0.001). The above situation was improved more significantly by the synergistic intervention of mdivi-1 and hesperidin. Therefore, hesperidin can improve mitochondrial damage and promote gastric motility in FD rats by regulating Drp1-mediated ICC mitophagy.

Effects of Electroacupuncture on Gastrointestinal Motility Function, Pain, and Inflammation via Transient Receptor Potential Vanilloid 1 in a Rat Model after Colonic Anastomoses

Background. Complications after colon surgery are a major obstacle to postoperative recovery. The purpose of this study was to investigate the effect of electroacupuncture (EA) at Zusanli (ST36) on gastrointestinal motility in rats after colonic anastomosis and the mechanism of transient receptor potential vanillin 1 (TRPV1) channel in regulating gastrointestinal motility, pain, and inflammation. Methods. The rats were randomly divided into six groups, including the control, model, EA, sham-EA, capsaicin, and capsaicin+EA groups, with preoperative capsaicin pretreatment and EA treatment at ST36 acupoint after surgery. Rats were treated using EA at ST36 or sham acupoints after surgery for 5 days. Capsaicin was intraperitoneally injected into rats 3 hours before surgery. Gastrointestinal motility was assessed by measuring the gastric residue, small intestinal propulsion in vivo, contractile tension, and frequency of isolated muscle strips in vitro. The mechanical withdrawal threshold (MWT) of abdominal incision skin and spontaneous nociceptive scores were observed and recorded in rats after colon anastomosis. The expressions of TRPV1, substance P (SP), neurokinin 1 (NK1) receptor, nuclear factor kappa-B (NF-κB), interleukin- (IL-) 6, L-1β, and tumor necrosis factor- (TNF-) α were determined. Results. Compared with the model group, electroacupuncture at ST36 point could significantly reduce the residual rate of stomach in rats after operation and increase the propulsive force of the small intestine and the contraction tension of the isolated smooth muscle. Electroacupuncture also increased postoperative day 3 MWT values and decreased postoperative spontaneous nociception scores. In addition, electroacupuncture treatment downregulated the expressions of IL-6, IL-1β, TNF-α, TRPV1, NF-κB, SP, and NK1 receptors in the colon tissue of rats after colonic anastomosis. Conclusions. Our study showed that electroacupuncture at ST36 acupoint could improve gastrointestinal motility in rats after colonic anastomosis and relieve intestinal inflammation and pain. The mechanism may be to inhibit the activation of NF-κB and SP/NK1 receptor signaling pathways by inhibiting TRPV1.

Effect of Kvass on Improving Functional Dyspepsia in Rats

Functional dyspepsia (FD) is a common digestive system disease, and probiotics in the treatment of FD have a good curative effect. Patients with gastrointestinal diseases often show a poor response to traditional drug treatments and suffer from adverse reactions. Kvass can be used as a functional drink without side effects to improve the symptoms of FD patients. The results showed that compared with those of the model group, the body weight and food intake of the treatment group were significantly increased (P < 0.05), and the gastric residual rate of the treatment group was significantly decreased (P < 0.05); the amount of pepsin in the treatment group was significantly higher than that in the model group (P < 0.05); a high dose of Kvass could increase the contents of ghrelin, motilin (MTL), and gastrin (GAS) in the plasma and decrease the contents of vasoactive intestinal peptide (VIP) in the plasma; the contents of ghrelin, MTL, and GAS in the gastric antrum were also increased in the high-dose group. Kvass beverage can significantly improve the gastrointestinal function of rats, which may be because it can improve the contents of ghrelin, MTL, GAS, and VIP in both the serum and gastric antrum by regulating the expression of short-chain fatty acids in the colon.

Effects of Ganoderic Acid A on Gastrointestinal Motility and Brain-Gut Peptide in Rats with Functional Dyspepsia

Objective

The therapeutic effect of drugs for functional dyspepsia (FD) is still limited. Ganoderic acid A (GAA) has anti-inflammatory and cellular protective activities. The aim of this study is to explore the therapeutic effect of GAA on FD.

Methods

The FD rat model was established via tail damping and forced exercise fatigue. The gastric emptying rate and intestinal propulsion rate of the rats in each group were then detected, and the pathological damage of gastric antrum and duodenum tissues was observed by hematoxylin-eosin (HE) staining. An enzyme-linked immunosorbent assay (ELISA) was conducted to determine the levels of motilin (MTL), vasoactive intestinal peptide (VIP), leptin, gastrin (GAS), calcitonin gene-related peptide (CGRP), and somatostatin (SS) in plasma, and Western blot was used to detect the protein expression levels of occludin, zonula occluden-1 (ZO-1), and junctional adhesion molecule-1 (JAM-1) in the duodenal tissue.

Results

Treatment with GAA significantly raised the gastric emptying rate and intestinal propulsion rate of FD rats and histologically alleviated the gastric and duodenal damage. Meanwhile, GAA positively regulated the secretion of brain-gut proteins, such as upregulation of MTL, GAS, and SS and downregulation of VIP, leptin, and CGRP. In addition, GAA treatment increased the protein expression levels of occludin, ZO-1, and JAM-1 in the duodenal tissue of the FD rats.

Conclusion

GAA may exhibit protective effects on FD by regulating the secretion of brain-gut peptide, protecting the intestinal barrier and improving gastrointestinal motility.

Changes in intestinal barrier protein expression and intestinal flora in a rat model of visceral hypersensitivity

BACKGROUND

Destruction of the intestinal mucosal barrier and visceral hypersensitivity are main pathogenesis of irritable bowel syndrome (IBS). The study aimed to establish a rat model of visceral hypersensitivity and explore mechanisms involved the changes of the intestinal barrier protein expression and intestinal flora.

METHODS

A rat model of visceral hypersensitivity was established and evaluated using abdominal withdrawal reflex (AWR) scores, colonic paracellular permeability, and gastrointestinal motility. The expression of tight junction proteins, aquaporin proteins (AQPs), phosphorylated ERK, and proteinase-activated receptor-2 (PAR-2) was determined. The intestinal microflora was evaluated by high-throughput sequencing of the 16S rRNA gene.

KEY RESULTS

In model rats, AWR score and fecal water content were significantly increased, gastrointestinal motilities were disorder and characterized by an inhibition of gastric motility and an enhancement of small intestinal and colonic movement. The expressions of colonic occludin, ZO-1, AQP3, and AQP8 were decreased but claudin-2 and claudin-4 were markedly increased. Imbalance of intestinal flora appeared and showed an obvious decrease of Lactobacillus and an increase of Clostridiales_bacterium. Additionally, the total serine protease activity in feces, the expressions of PAR2 and phosphorylated ERK in the colon tissues were increased significantly.

CONCLUSION AND INFERENCES

The model rats of visceral hypersensitivity possess the decreased expression of occludin, ZO-1, AQP3, AQP8, and the increased expression of claudin-2 and claudin-4, meanwhile develop an imbalance of intestinal flora which probably increase serine protease activity, thereby activating the PAR2/ERK signaling and causing the intestinal barrier disorder.

The Influence of Stomach Back-Shu and Front-Mu Points on Insular Functional Connectivity in Functional Dyspepsia Rat Models

Functional Dyspepsia (FD) is a common functional gastrointestinal disease, which can reduce the quality of life in patients. Prior research has indicated that insula is closely related to FD and that acupuncture can regulate the functional connectivity (FC) of FD. Therefore, we hypothesized that acupuncture on FD was effected through the insular pathway. To test our hypothesis, we performed electroacupuncture (EA) on FD rat models and then examined the FC between insula and other brain regions through resting-state functional magnetic resonance imaging (rs-fMRI). Seven-day-old male infant Sprague-Dawley (SD) rats were randomly divided into control group, FD model group, and FD acupuncture group, with twelve rats per group (n = 36). Upon establishing successful models, the FD acupuncture group was subjected to EA intervention using Stomach back-shu (BL-21) and front-mu (RN-12) points for ten consecutive days for durations of 20 minutes each day. After intervention, each group was subject to rs-fMRI. The digital image data obtained were analyzed using FC analysis methods. Subsequently, gastric ligation was performed to measure gastric emptying rates. Before EA intervention, the FD model group exhibited decreased functional connections between the insula and a number of brain regions. After EA intervention, FD acupuncture group exhibited increasing FC between insula and regions when compared to the FD model group, such as the primary somatosensory cortex (S1), hippocampal CA3 (CA3), polymorphic layer of dentate gyrus (PoDG), caudate putamen (CPu), and oral pontine reticular nuclei (PnO) (P < 0.05); decreasing FC was also exhibited between insula and regions such as the bilateral primary and secondary motor cortexes (M1/2), paraventricular hypothalamic nucleus (PVA), and limbic cortex (LC). These findings indicate that the effective treatment of FD using EA may be through regulating the abnormal FC between insula and several brain regions, in particular CA3, PoDG, and PVA.

The Effects of Low-Dose and High-Dose Decoctions of Fructus aurantii in a Rat Model of Functional Dyspepsia

BACKGROUND Fructus aurantii is a flavonoid derived from Citrus aurantium (bitter orange) that is used in traditional Chinese medicine (TCM) to treat gastric motility disorders. This study aimed to investigate the effects of low-dose and high-dose decoctions of Fructus aurantii in a rat model of functional dyspepsia (FD). MATERIAL AND METHODS Sprague-Dawley rats (n=90) were divided into nine study groups: the control group, the FD model group, the domperidone-treated (Domp) group, the low-dose raw Fructus aurantii (FA-L) group, the high-dose raw Fructus aurantii (FA-H) group, the low-dose Fructus aurantii with stir-fried wheat bran (Bran-L) group, the high-dose Fructus aurantii with stir-fried wheat bran (Bran-H) group, the low-dose Fructus aurantii with stir-fried wheat bran and honey (Honey-L) group, and the high-dose Fructus aurantii with stir-fried wheat bran and honey (Honey-H) group. The FD rat model was established by semi-starvation, followed by tail damping, stimulation, and forced exercise with fatigue. Change in weight, rate of gastric emptying and intestinal propulsion, and serum levels of leptin, motilin, vasoactive intestinal peptide (VIP), gastrin, calcitonin gene-related peptide (CGRP), ghrelin, and cholecystokinin were compared between the groups. RESULTS In the FD model group, weight, rate of gastric emptying and intestinal propulsion significantly decreased, the expression of leptin, VIP and CGRP increased, and expression of motilin, gastrin, ghrelin, and cholecystokinin significantly decreased. Treatment with low-dose Fructus aurantii with stir-fried wheat bran significantly reversed these effects. CONCLUSIONS In the rat model of FD, low-dose Fructus aurantii with stir-fried wheat bran increased gastrointestinal motility and gastrointestinal hormone levels.

Maillard Reaction Products of Stir Fried Hordei Fructus Germinatus Are Important for Its Efficacy in Treating Functional Dyspepsia

Hordei Fructus Germinatus (HFG) has been used as a traditional medicine to treat functional dyspepsia (FD) in China. Stir fried HFG (F-HFG) containing Maillard reaction products (MRPs) is used more widely than the raw HFG (R-HFG). However, the exact mechanisms in its functionality remain unclear. This article investigated the effect of R-HFG, F-HFG, and MRPs on brain-gut peptides, gut microbiota, and digestive enzymes using an FD animal mode. After administration of R-HFG, F-HFG, and MRPs, higher mRNA expression level of gastrin (GAS) and lower mRNA expression level of vasoactive intestinal peptide (VIP) were exhibited in F-HFG and MRPs rats than R-HFG rats (P < .05). Furthermore, compared with the R-HFG group, the contents of motilin (MTL) and GAS showed an upward tendency, whereas the contents of VIP and chokcystokinin (CCK) showed a downward tendency in the F-HFG group. In addition, bacterial communities in the control, F-HFG, and MRPs groups clustered closely to one another, and bacterial communities in the model and recovery groups clustered together, whereas the bacterial communities in the R-HFG group were clustered into a category. Moreover, there were no apparent differences in brain-gut peptides and gut microbiota between the F-HFG and MRPs groups. However, after the oral administration of R-HFG, F-HFG, and MRPs, the level of digestive enzyme did not show a significant change as compared with the recovery group. These results indicated that the stronger effect of F-HFG could be attributed to the MRPs produced during stir frying, and MRPs possessed the effect of regulating brain-gut peptides and gut microbiota.

Electroacupuncture Upregulated Ghrelin in Rats with Functional Dyspepsia via AMPK/TSC2/Rheb-Mediated mTOR Inhibition

BACKGROUND

Gastrointestinal motility disorder is an important pathological basis for functional dyspepsia (FD). Epigastric ache and discomfort are the main symptoms of FD, and ghrelin deficiency is closely related to the occurrence and development of FD. While electroacupuncture (EA) alleviated the symptoms of FD patients and improved their quality of life, there is a lack of sufficient mechanistic evidence to support these beneficial effects.

METHODS

An in vivo FD model was established in wild-type and mammalian target of rapamycin (mTOR) knockout (-/-) rats. FD rats were subjected to EA with or without mTOR agonists or inhibitors. Gastric emptying and intestinal propulsion were assessed, and pathological changes in the hypothalamus, gastric antrum, and small intestine were examined histologically. In addition, ghrelin expression and AMPK/TSC2/Rheb/mTOR activation were detected by quantitative reverse transcription polymerase chain reaction and western blot.

RESULTS

EA alone or in combination with mTOR inhibitors improved gastrointestinal function in FD rats by increasing the rates of intestinal propulsion and gastric emptying, and pathological changes in the hypothalamus, gastric antrum, and small intestine were alleviated. This may be related to the significant upregulation of ghrelin expression and the effective activation of the AMPK/TSC2/Rheb/mTOR signaling pathway. Interestingly, EA also improved gastrointestinal function and ghrelin expression in mTOR (-/-) KO FD rats.

CONCLUSION

Altering the level of ghrelin by regulating AMPK/TSC2/Rheb-mediated mTOR inhibition is an important way through which EA treats FD. The complex EA-mediated regulatory mechanisms of the brain-gut axis still require further exploration.