Rat Duodenum Research Articles

Intestinal Region-Dependent Alterations of Toll-Like Receptor 4 Expression in Myenteric Neurons of Type 1 Diabetic Rats.

Toll-like receptor 4 (TLR4) can activate pro-inflammatory cascades in the gastrointestinal tract. Our aim was to determine TLR4 expression in myenteric neurons of different gut regions using a type 1 diabetic model. Ten weeks after the onset of hyperglycemia, myenteric whole-mount preparations from the duodenum, ileum and colon of streptozotocin-induced diabetic, insulin-treated diabetic and control rats were prepared for TLR4/peripherin double-labelling fluorescent immunohistochemistry. Immunogold electron microscopy was applied to evaluate TLR4 expression in the myenteric perikaryon and neuropil. Tissue TLR4 levels were measured by enzyme-linked immunosorbent assay. In controls, the number and proportion of the TLR4-immunoreactive myenteric neurons showed an increasing tendency to aboral direction. These values were significantly higher in diabetics compared to controls in the duodenum and ileum, but were significantly lower in the colon. In diabetics, the distribution of TLR4-labelling gold particles between the perikaryon and neuropil of myenteric neurons varied in a different way by intestinal segment. TLR4 tissue concentration changed only in the diabetic duodenum, and it decreased in muscle/myenteric plexus-containing homogenates, while it increased in mucosa/submucosa/submucous plexus-containing samples relative to controls. Insulin had beneficial effects on TLR4 expression. These findings support that chronic hyperglycemia has segment-specific effects on TLR4 expression, contributing to gastrointestinal disorders in diabetic patients.

Effect of Massa Medicata Fermentata on the intestinal flora of rats with functional dyspepsia.

Massa Medicata Fermentata (MMF) is one of the most commonly used traditional fermented Chinese medicines. MMF is widely used for the treatment of digestive diseases such as dyspepsia and flatulence in traditional Chinese medicine (TCM). However, the therapeutic mechanism of MMF is not well understood. In this study, SD rats received 0.1% iodoacetamide either alone or in combination with water platform sleep deprivation to induce functional dyspepsia and were administered MMF (1 or 3g/kg/d, ig), mosapride citrate (Mosa., 2mg/kg/d, ig) or saline for 21 days. After treatment, the sucrose preferences and gastric emptying rates of the rats were assessed; HE staining was used to detect the pathological changes in the rat duodenum; ELISA kits were used to detect motilin (MTL) in the rat duodenum and the serum contents of Interferon-λ (IFN-λ), Interleukin 6 (IL-6), and Tumor Necrosis Factor-α (TNF-α). An approach based on 16S rDNA amplicon sequencing was utilized to explore the intestinal microflora in the colon contents of rats and the metabolism of the microflora to assess the potential mechanisms of MMF in ameliorating functional dyspepsia (FD). In addition, gas chromatography-mass spectrometry (GC/MS) was used to detect changes in short fatty acids (SCFAs) in the colon contents of rats. MMF reduced the serum levels of TNF-α, and IFN-λ, improved the morphology of duodenal intestinal villi and ameliorated intestinal mucosal lamina propria injury in FD rats, and the sucrose preference increased and the gastric emptying rate decreased in FD rats. MMF alleviated intestinal microflora disturbance and exerted a regulatory effect on Bacteroidetes, Proteobacteria, and Firmicutes, reduced total SCAFs, Butyric Acid, Propionic acid-2-methyl, Butanoic Acid-3-methyl, and Hexanoic acid. These results showed that the effect of MMF on the intestinal flora and its metabolites may provide a new treatment strategy for FD.

Traditional Chinese Medicine prescription Huang-Qi-Jian-Zhong-Tang ameliorates indomethacin-induced duodenal ulcers in rats by affecting NF-κB and STAT signaling pathways

Huang-Qi-Jian-Zhong-Tang (HQJZT) is a well-known traditional Chinese herbal formulation. This study aimed to investigate the duodenoprotective properties of HQJZT against Indomethacin (IND)-induced duodenal ulceration in rats, and the mechanisms involved, particularly through NF-κB and STAT signaling pathways. Our results showed that HQJZT completely protected the duodenal mucosa from ulceration caused by IND, as indicated by improved macroscopic and histological appearances. There was a significant decrease in ulcer index and microscopic score, an increase in villus height and crypt depth, and a normalization of the tissue architecture of the duodenum in rats following HQJZT treatment. Blood flow into the duodenal mucosa was significantly increased after HQJZT administration. HQJZT significantly increased PGE2 and NO levels in the duodenal mucosa. A significant reduction in the production of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α was observed in the duodenal mucosa under treatment with HQJZT. Mechanistically, the administration of HQJZT significantly lowered the duodenal protein expression of inflammation-related genes, including p-NF-κB and p-IκBβ, compared with the ulcer control group. Furthermore, the STAT signaling pathway-related protein markers p-JAK and p-STAT were significantly reduced in the HQJZT (1.30 and 2.60 g/kg) groups. As a result of these findings, HQJZT alleviates duodenal mucosal ulcers caused by IND. A protective effect of HQJZT on duodenal ulcers is attributed to its ability to improve mucosal blood flow, stimulate the production of cytoprotective mediators, minimize proinflammatory cytokines, and block the activation of NF-κB and STAT signaling pathways.

The Effects of Liver Cirrhosis on Electrical Autorhythmicity of Isolated Duodenum in Rats

Background: Cirrhosis reduced small bowel motility and transit time, with unknown mechanisms. Moreover, intestinal motility depends on the electrical activity and the autorhythmicity of interstitial cells of Cajal (ICC). If cirrhosis directly affects the intrinsic mechanism of intestinal motility, the isolated bowel of cirrhotic cases will also exhibit an electrical abnormality compared with normal cases. Objectives: This study aimed to identify the effects of liver cirrhosis on the electrical autorhythmicity of isolated duodenum in rats. Materials and Methods: Six weeks after bile duct ligation (BDL) surgery, animals were anesthetized, and blood samples were obtained from the heart for the evaluation of plasma cirrhosis indices, including weight, plasma albumin, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), bilirubin, and direct bilirubin. Then, the duodenum of rats was isolated and compared with the control group for the rate of electrical slow waves and the maximum amplitude of slow waves. Results: Significant differences were observed between the control and BDL group in terms of weight, plasma albumin, SGOT, SGPT, bilirubin, and direct bilirubin. Moreover, there was a significant decrease in the maximum amplitude of slow waves in the BDL group compared with the control. Conclusion: It seems that different factors directly harm the ICC network such as inflammation caused by microbiome amplification as a result of cirrhosis, which in turn reduces small bowel motility.

Study on the Absorption of Arsenic Species in Realgar Based on the Form and Valence.

At present, several experiments have been carried out to study the changes in total arsenic content of realgar and its prescription, but few researches on its form and valence. We evaluated the change in arsenic species concentration in realgar from the perspective of absorption by using an in vitro dissolution study, an in vivo unidirectional intestinal perfusion study, transmembrane transport in Caco-2 cells, and a pharmacokinetic study in rats. In the gastrointestinal tract, arsenic species are mainly present inorganic forms of AsIII and AsV. The cumulative dissolution rates of soluble arsenic in 4 h artificial gastric fluid and 8 h artificial intestinal fluid were 21.99% and 59.20%, respectively. The Papp values of soluble arsenic in realgar in the duodenum, jejunum, and ileum of rats were 5.4 × 10−3, 6.1 × 10−3 and 5.8 × 10−3 cm/min, respectively. In the process of small intestine perfusion, the AsIII of realgar was partially converted into AsV in the duodenum and jejunum. As the transport time increased, the transmembrane transport rate and Papp value of soluble arsenic in realgar were increased in Caco-2 cells, and it also suggested that arsenic species may be passively transported across the Caco-2 cell monolayer. The Cmax and AUC (0-24) of AsIII, AsV, and DMA in plasma of realgar were 41.26 ng L−1/343.977 ng h mL−1, 21.626 ng L−1/47.310 ng h mL−1, and 2.372 ng L−1/30.429 ng h mL−1, respectively. Tmax and MRT (0-∞) of AsIII, AsV, and DMA were 2.571 h/9.649 h, 0.393 h/2.790 h, and 3.143 h/23.145 h, respectively. It is hoped to provide a basis for clarifying the arsenic species in realgar.

Pharmacological evidence that GABA-induced relaxation of rat proximal duodenum longitudinal muscle depends on NKCC cotransporter activity and Ca2+ influx.

γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in adult central nervous system (CNS) synapses, but it excites immature CNS neurons as well as neurons in the myenteric plexus. The present work aimed to determine whether GABA-induced nonadrenergic, noncholinergic (NANC) neuronal-mediated relaxation of the rat duodenum is dependent on the activity of Na+ K+ Cl- cotransporters (NKCC) and requires calcium influx. In the presence of guanethidine (3µmol/L), atropine (3µmol/L), and indomethacin (1µmol/L), relaxations induced by GABA (100µmol/L), KCl (5-10mmol/L) and electrical field stimulation (1-8Hz, 2ms, 60V), but not those induced by bradykinin (10-100nmol/L) were abolished by lidocaine (300µmol/L). However, only GABA-induced relaxations were reduced in a concentration-dependent manner by the NKCC1/2 inhibitors bumetanide (0.1-1µmol/L) and furosemide (1-10µmol/L). GABA-induced NANC neuronal relaxation was abolished by bicuculline (30µmol/L) and inhibited by N-nitroarginine methyl ester (l-NAME, 300µmol/L). The ω-conotoxin GVIA (1µmol/L), which acts exclusively on neuronal CaV2 channels, but not on smooth muscle voltage-gated Ca2+ CaV1 channels, and nonselective blockers of these channels (verapamil 100nmol/L and ruthenium red 10µmol/L), reduced GABA-induced relaxations. These results showed that the activation of GABAA receptors induces NANC nitrergic neuronal relaxations in the rat duodenum, which depend on NKCC activity and CaV2 channel activation, suggesting that this phenomenon results from neuronal depolarization promoted by Cl- efflux through GABAA receptors, with subsequent Ca2+ influx and nitric oxide release.

Dao-Chi Powder Ameliorates Pancreatitis-Induced Intestinal and Cardiac Injuries via Regulating the Nrf2-HO-1-HMGB1 Signaling Pathway in Rats.

Dao-Chi powder (DCP) has been widely used in the treatment of inflammatory diseases in the clinical practice of traditional Chinese medicine, but has not been used in acute pancreatitis (AP). This study aimed to evaluate the effect of DCP on severe AP (SAP) and SAP-associated intestinal and cardiac injuries. To this end, an SAP animal model was established by retrograde injection of 3.5% taurocholic acid sodium salt into the biliopancreatic ducts of rats. Intragastric DCP (9.6 g/kg.BW) was administered 12 h after modeling. The pancreas, duodenum, colon, heart and blood samples were collected 36 h after the operation for histological and biochemical detection. The tissue distributions of the DCP components were determined and compared between the sham and the SAP groups. Moreover, molecular docking analysis was employed to investigate the interactions between the potential active components of DCP and its targets (Nrf2, HO-1, and HMGB1). Consequently, DCP treatment decreased the serum levels of amylase and the markers of gastrointestinal and cardiac injury, further alleviating the pathological damage in the pancreas, duodenum, colon, and heart of rats with SAP. Mechanistically, DCP rebalanced the pro-/anti-inflammatory cytokines and inhibited MPO activity and MDA levels in these tissues. Furthermore, Western blot and RT-PCR results showed that DCP intervention enhanced the expression of Nrf2 and HO-1 in the duodenum and colon of rats with SAP, while inhibiting the expression of HMGB1 in the duodenum and heart. HPLC-MS/MS analysis revealed that SAP promoted the distribution of ajugol and oleanolic acid to the duodenum, whereas it inhibited the distribution of liquiritigenin to the heart and ajugol to the colon. Molecular docking analysis confirmed that the six screened components of DCP had relatively good binding affinity with Nrf2, HO-1, and HMGB1. Among these, oleanolic acid had the highest affinity for HO-1. Altogether, DCP could alleviated SAP-induced intestinal and cardiac injuries via inhibiting the inflammatory responses and oxidative stress partially through regulating the Nrf2/HO-1/HMGB1 signaling pathway, thereby providing additional supportive evidence for the clinical treatment of SAP.

Transcutaneous auricular vagus nerve stimulation promotes gastric motility by up-rgulating α7nAChR and suppressing NF-κB p65 expression in duodenum in rats with functional dyspepsia

To study the effect of transcutaneous auricular vagus nerve stimulation (taVNS) on gastric sensitivity and motility in rats with functional dyspepsia (FD), so as to explore its underlying mechanism in improving FD. A total of 48 young SD rats were randomly divided into control (n=10), model (n=9), taVNS (n=9), subdiaphragmatic vagus nerve stimulation (SDVNS, n=9) and sham SDVNS (n=7) groups. The FD model was established by gavage of 0.1% iodoa-cetamide+2% glucose, once daily for 6 days. Rats in the taVNS group received taVNS (0.5 mA) of optopoint "Heart" and "Stomach" for 30 min, once daily for 14 days, while rats in the SDVNS group received subdiaphragmatic vagus nerve stimulation through the implanted electrode, and those of the sham SDVNS group received only application of the same electrodes without electrical stimulation. Electromyogram (EMG) of the cervical trapezius muscle (reflecting gastric sensitivity) was recorded before and after intragastric expansion via an air ballon and the gastric emptying rate was calculated for assessing the gastric motility. The contents of acetylcholine (ACh), nicotinic acetylcholine receptor α7 subunit (α7nAChR), interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the duodenum tissue were detected by enzyme-linked immunosorbent assay (ELISA). The expression of nuclear factor kappa B (NF-κB) p65 in the duodenum tissue was determined by Western blot. In comparison with the control group, the EMG change rate at intragastric pressure levels of 40, 60 and 80 mm Hg, expression of NF-κB p65 protein, and contents of IL-6, IL-1β and TNF-α were significantly increased (P<0.05,P<0.01, P<0.001), while the gastric emptying rate, ACh and α7nAChR contents considerably decreased (P<0.05, P<0.001) in the model group. After interventions, the EMG change rate, contents of IL-6, IL-1β and TNF-α, and expression of NF-κB p65 were notably decreased (P<0.05, P<0.01, P<0.001), and the gastric emptying rate, ACh and α7nAChR contents obviously increased (P<0.05, P<0.001) in both taVNS and SDVNS groups relevant to the model group. In comparison with the sham SDVNS group, the EMG change rate, contents of IL-6, IL-1β and TNF-α, and expression of NF-κB p65 were notably decreased (P<0.01, P<0.05,P<0.001), and the gastric emptying rate, ACh and α7nAChR contents obviously increased (P<0.01, P<0.001) in the both SDVNS and taVNS groups. taVNS can reduce gastric sensitivity and promote gastric emptying in FD model rats, which may be closely related to its functions in up-regulating ACh and α7nAChR contents and inhibiting the activation of NF-κB p65 signaling in the duodenum.

Effectiveness of Kenikir (Cosmos caudatus Kunth.) Leaf Extract on Duodenal Epithelial Damage of Aspirin Induced Male White Rats (Rattus norvegicus)

Aspirin or acetylsalicylic acid is one of the most common types of anti-inflammatory drugs used by people to relieve pain and inflammation. However, aspirin consumption can cause damage to the duodenal mucosal epithelium because it is acidic and inhibits the production of prostaglandins that are important in maintaining the mucosa. Duodenal damage due to aspirin consumption can be repaired using natural ingredients from plants with antioxidant and anti-ulcer effects, one of which is kenikir (Cosmos caudatus Kunth.) leaves. This study aims to determine the effectiveness of kenikir leaf extract against aspirin-induced histopathology and histomorphometry of the duodenum of male white rats. The research design used a completely randomized design (CRD) with 5 treatments and 5 replications. The treatments consisted of a normal group (feed and drink ad libitum), an aspirin group (induction of aspirin 200 mg/kgBW), and a treatment group with kenikir leaf extract at a dose of 700 mg/kgBW, 800 mg/kgBW, and 900 mg/kgBW. Preparation of histopathological preparations of the duodenum used the paraffin method with Hematoxylin-Eosin staining. Data were analyzed using one-way ANOVA and Duncan's follow-up test. The results of the histopathology study showed a significant difference (p&lt;0.05) on the integrity score of duodenal mucosal epithelial cells. Histomorphometry had a significant effect on the height villi, basal width, apical width, and villous area (p&lt;0.05). It can be concluded that administration of kenikir leaf extract at a dose of 900 mg/kgBW was most effective in improving the histopathology and duodenal histomorphometry of aspirin-induced male white rats.&#x0D; Keywords: aspirin, duodenum, kenikir (Cosmos caudatus Kunth.)

The prevention role of Spirulina platensis (Arthrospira platensis) on intestinal health

Spirulina is a popular herbal food that has a preventive effect on health. In the study, it aimed to evaluate the effects of different doses of Spirulina platensis (Arthrospira platensis) on the morphological properties of the duodenum of rats, and to assign the effect of Spirulina on the expression of proliferating cell nuclear antigen (PCNA) in the rat duodenum, and thereby to observe the effects on intestinal health. 30 male Wistar albino rats were divided into 3 groups for 45 days. The first group was received the basal diet; the second group was given 500 mg/kg Spirulina daily by oral gavage; the third group was given 1000 mg/kg Spirulina daily. The duodenum segments were taken at the end of the trial and processed for histological assay. Although the total mucosa, villus height and villus/cript ratio were found higher in high dose Spirulina, the lower cript depth was detected in same group compared to control and low dose group. A significant increase was observed at high dose compared to the control and low dose group in terms of PCNA expression intensity and proliferation index. Findings suggest that high dose of Spirulina may support the duodenal growth, and thereby intestinal health.

IDF21-0172 The Expression Level of UDP-GlcNAc epimerase/ManNAc kinase in some Organs of Type 2 Diabetic Rats

Background: Aspects of glycobiology have been linked to the pathophysiology of diabetes mellitus as sialic acids and its metabolic enzymes are associated with the disease. Aim: The present study was conducted to monitor the expression pattern of UDP-GlcNAc epimerase/ ManNAc kinase (GNE) gene (rate limiting enzyme for sialic acid biosynthesis) in selected organs or type 2 diabetic animals to provide insights into the course of increased serum sialic acids in diabetes. Method: Type 2 diabetes was induced using streptozotocin-fructose model and after 8 weeks, the mRNA expression levels of GNE gene was analysed in liver, brain, kidney, colon, spleen and pancreas of the animals, using quantitative PCR. Results: Decrease in body weight of the diabetic rats with high fluid and feed intakes were observed. Glycemia was significantly (p<0.05) above 300 mg/dL for the 8-week progression of the diabetic phase. The diabetic rats had a significantly (p<0.05) increased level (8.2 mg/ml) of serum sialic acid compared to normal rats (3.5 mg/ml). Furthermore, sialic acid level was elevated in the studied tissues with significant (p<0.05) difference in the colon, duodenum, kidney, liver and spleen of diabetic rats. However, the expression of GNE gene was decreased in the colon but increased in the pancreas (1.8-fold) of the diabetic rats while the expression level in the other tissues was not profoundly affected. Discussion: In conclusion, the impaired feedback inhibition mechanism of GNE gene may be associated to the increase in sialylation.

Effect of agomelatine on intestinal smooth muscle contractility in rats

Objective: The purpose of the present study was to investigate in vitro the effect of agomelatine, an analog of melatonin, on KCl-stimulated contractions in duodenum, jejunum, ileum, and colon in rats. Material and methods: A total of 7 adult Wistar Albino female rats were used in the study. After the rats were decapitated without anesthesia, duodenum, jejunum, ileum, and colon strips were prepared and placed in the organ bath. Agomelatine was applied in doses of 100, 200, and 1000 μM to the strips that were contracted with KCl (80 mM). Then, 1000 μM agomelatine was applied after preliminary treatment of melatonin receptor antagonist luzindole (1 μM) to investigate the action mechanism of agomelatine on intestinal smooth muscles. The records were analyzed before and after each dose, and frequency, peak to peak (P-P) and area values were compared. Results: Agomelatine inhibited the KCI- induced contractions in duodenum, jejunum, ileum, and colon strips in a dose-dependent manner. Depending on the agomelatine application, the frequency, “P-P”, and the area values under the curve decreased at statistically significant levels (p&lt;0.05). However, the effect of agomelatine decreased at significant levels as a result of luzindole treatment (p&lt;0.05). Conclusion: The dose-dependent inhibitor effect of agomelatine on KCl-stimulated contractions in the rat intestinal smooth muscle was shown for the first time in this study. Agomelatine was found to affect the smooth muscles of the intestines through melatonin receptors. This result suggests that agomelatine might have therapeutic potential in diseases in which gastrointestinal motility is impaired.

The Impact of α-Adrenoceptors in the Regulation of the Hypotonicity-Induced Increase in Duodenal Mucosal Permeability In Vivo.

The duodenal mucosa is regularly exposed to a low osmolality, and recent experiments suggest that hypotonicity increases mucosal permeability in an osmolality-dependent manner. The aim was to examine whether the sympathetic nervous system, via action on α-adrenoceptors, affects the hypotonicity-induced increase in duodenal mucosal permeability. The duodenum of anaesthetised rats was perfused in vivo with a 50 mM NaCl solution in the presence of adrenergic α-adrenoceptor drugs. Studied were the effects on mucosal permeability (blood-to-lumen clearance of 51Cr-EDTA), arterial blood pressure, luminal alkalinisation, transepithelial fluid flux, and motility. Hypotonicity induced a six-fold increase in mucosal permeability, a response that was reversible and repeatable. The α2-adrenoceptor agonist clonidine abolished the hypotonicity-induced increase in mucosal permeability, reduced arterial blood pressure, inhibited duodenal motility, and decreased luminal alkalinisation. The α2-adrenoceptor antagonists, yohimbine and idazoxan, prevented the inhibitory effect of clonidine on the hypotonicity-induced increase in mucosal permeability. The α1-agonist phenylephrine or the α1-antagonist prazosin elicited their predicted effect on blood pressure but did not affect the hypotonicity-induced increase in mucosal permeability. None of the α1- or α2-adrenoceptor drugs changed the hypotonicity-induced net fluid absorption. In conclusion, stimulation of the adrenergic α2-adrenoceptor prevents the hypotonicity-induced increase in mucosal permeability, suggesting that the sympathetic nervous system has the capability to regulate duodenal mucosal permeability.

Intestinal metabolism and absorption mechanism of multi-components in Gaultheria leucocarpa var. yunnanensis - An assessment using in situ and in vitro models, comparing gut segments in pathological with physiological conditions

Ethnopharmacological relevanceDianbaizhu (Gaultheria leucocarpa var. yunnanensis) as a Chinese folk medicine exerts significant treatment effects on rheumatoid arthritis (RA) with a long historical time. Our previous reports showed that the anti-rheumatic arthritis fraction (ARF) extracted and enriched from Dianbaizhu possessed good druggability, which was better than its single active ingredients. However, the intestinal transport characteristics and mechanism of ARF have not been elucidated to date. Aim of the studyIn order to illustrate the role of active ingredients of ARF in alleviating RA and promoting the development of dosage forms, the intestinal metabolism, absorption properties and mechanism of ARF in vitro and in situ models were investigated. Materials and methodsFirstly, after incubating with 4 intestinal segments (duodenum, jejunum, ileum, and colon), 7 key components in ARF, including MATG-B, (+)-catechin, MSTG-A, Gaultherin, chlorogenic acid, quercetin, and kaempferol were quantitatively analyzed by a high-performance liquid chromatography (HPLC). Secondly, combining the physiological and pathological rats, the in situ single-pass intestinal perfusion and in vitro everted gut sacs of rats were performed to investigate the absorption features and transport mechanisms of ARF using HPLC and HPLC-Q-TOF-MS/MS. Subsequently, in situ studies were employed to determine the effect of P-glycoprotein (P-gp) inhibitor (verapamil) on the transport characteristics of ARF in RA model rats. ResultsComparing the absorption parameters of ARF incubated in different intestinal segments, data showed that the absorption of ARF in the small intestine was significantly stronger than that of the colon (P < 0.01). The number of characterized prototype components was subjected to the incubation time, drug concentration and rat body condition, but not the intestinal segments. There were no significant differences in the number of metabolites among different intestinal segments, administration concentrations and incubation time. The best small intestinal absorption site of ARF was duodenum and ileum in normal and model rats, respectively. The Peff values of 7 index compounds were all higher than 0.2 × 10−4cm/s, and the Fa values of 7 index compounds were all greater than 20% in the in situ perfusion investigation. The results showed that MSTG-B, MSTG-A and Gaultherin were likely to be substrates of P-gp as verapamil significantly enhanced their Peff and Ka values, while other ingredients were not P-gp substrates. ConclusionsThe intestinal membrane permeability of ARF was good. Its intestinal absorption mechanisms mainly involved active transportation processes and passive diffusion. Besides, this report provided data support and basis for clinical development, bioavailability improvement and formulation design.

In vitro antispasmodic effects of Mallotus oppositifolium leaves extracts

Mallotus oppositifolium is a plant traditionally used in many African countries to treat diarrhea and other gastrointestinal tract disorders. This study was undertaken to evaluate in vitro antispasmodic effects of decoction, hexane and methanolic leaves extracts of this plant. Antispasmodic activities of Mallotus oppositifolium leaves decoction, hexane and methanolic extracts were assessed on spontaneous contractions, on acetylcholine or potassium chloride (KCl) induced contractions of isolated rat duodenum strips. Mallotus oppositifolium decoction, hexane or methanolic extracts increasing cumulative concentrations relaxed duodenum strips and at 1 mg/mL, they respectively decreased contraction amplitudes by 77.84 ± 2.25, 55.81 ± 2.14, and 51.67 ± 0.95% compared to the initial values. Decoction, hexane, and methanolic extracts decreased contraction tensions respectively from 3.00 to 2.5 gF, 3.40 to 2.80 gF and from 3.10 to 2.50 gF. At 0.25 mg/mL, they significantly (p &lt;0.05) decreased contraction tension. Emax were 186.89 ± 34.05, 116.30 ± 10.92 and 91.57 ± 4.70% respectively with decoction, methanolic, and hexane extracts with EC50 of 0.610 ± 0.184; 0.146 ± 0.011 and 0.237 ± 0.105 mg/mL (p &lt;0.05). Acetylcholine increased contraction amplitudes. Cumulative administration of Mallotus oppositifolium decoction at 0.05 to 2.00 mg/mL significantly (p &lt;0.05) decreased tension, from 4.00 to 2.60 g.F. At these concentrations, tension variation was concentration-dependent, it increased from 13.39 ± 1.72 to 77.59 ± 1.10%. EC50 and Emax were respectively 1.311 ± 0.340 mg/mL and 99.29 ± 24.80%. KCl produced only little variations of contractions amplitude. Emax was 0.65%. Cumulative administration of Mallotus oppositifolium decoction from 0.05 to 2.00 mg/mL significantly (p &lt;0.05) decreased KCl induced contraction tension, from 3.70 to 2.30 gF (p &lt;0.05). Emax was 133.30 ± 34.29% and EC50 = 2.140 ± 0.231 mg/mL. The antispasmodic effects of Mallotus oppositifolium extracts obtained in this study could therefore justify its traditional use against gastrointestinal tract ailments. Keywords: mallotus oppositifolium; acetylcholine; potassium chloride; antispasmodic effects; gastrointestinal tract disorders.

Development of Radiofrequency Ablation Generator and Balloon-Based Catheter for Microendoluminal Thin-Layer Ablation Therapy Using the Rat Duodenum as a Model of Low-Impedance Tissue.

Radiofrequency ablation (RFA) is a routinely used, safe, and effective method for the tissue destruction. Often, in case of its application in malignant conditions, the extent of tissue destruction is insufficient due to the size of the target lesion, as well as due to the risk of heat-induced damage to the surrounding organs. Nevertheless, there are conditions requiring superficial precise-depth ablation with preservation of deeper layers. These are represented, for example, by mucosal resurfacing in case of Barrett's esophagus or treatment of recurrent mucosal bleeding in case of chronic radiation proctitis. Recently, new indications for intraluminal RFA use emerged, especially in the pancreatobiliary tract. In the case of intraductal use of RFA (e.g., biliary and pancreatic tract), there are currently available rigid and needle tip catheters. An expandable balloon-based RFA catheter suitable for use in such small-diameter tubular organs could be of benefit due to possible increase of contact between the probe and the target tissue; however, to prevent excessive tissue damage, a compatible generator suitable for low-impedance catheter/tissue is essential. This project aimed to develop a radiofrequency ablation generator and bipolar balloon-based catheter optimized for the application in the conditions of low-impedance tissue and (micro)endoluminal environment. Subsequent evaluation of biological effect in vivo was performed using duodenal mucosa in Wistar rat representing conditions of endoluminal radiofrequency ablation of low-impedance tissue. Experiments confirming the safety and feasibility of RFA with our prototype devices were conducted.

The pharmacokinetic profiles of mogrosides in T2DM rats

Ethnopharmacological relevanceLuohanguo (LHG) extract major contenting mogrosides, as a nonnutritive sweetener, has been reported to exert a hypoglycemic effect on diabetic patients and animals. As the pharmacokinetics and pharmacodynamics of drugs were changed with diabetes, it may lead to the different pharmacological of mogrosides between diabetic and normal subjects. Aims of the studyTo characterise the pharmacokinetic profiles of mogrosides in T2DM rats. Study design and methodsHigh-fat diet and streptozocin induced type 2 diabetic mellitus rats were used to investigate the pharmacokinetic behavior of mogroside V and mogrosides IIIA1, IIA1, and IA1 after T2DM rats orally administrated with mogroside V and 1–3 glucose residues’ mogrosides, respectively. The validated convenient UPLC-QTOF/MS and UPLC-MS/MS methods were established to use in the pharmacokinetic studies of mogrosides in normal and T2DM rats. Additionally, the expression of the intestinal tight junction protein zonula occludens-1 (ZO-1) was also detected by immunohistochemical analysis, which assessed the function of passive intestinal permeability in T2DM rats. ResultsThe results showed that for rats treated with mogroside V, its metabolite mogroside IIIA1 has a significant increase (p < 0.05) in maximum plasma concentration (Cmax, 163.80 ± 25.56 ng/mL) and area under the plasma concentration (AUC0-t, 2327.44 ± 474.63 h·ng/mL) in T2DM rats compared with in normal rats. The mean residence time (MRT0-t, 12.04 ± 0.97 h) of mogroside V showed a significant decrease (p < 0.05) in T2DM rats. However, the mogrosides IIIA1, IIA1and IA1 showed no statistical differences in the normal and T2DM rats after administered with 1–3 glucose residues’ mogrosides. Furthermore, the expression level of ZO-1 in the duodenum and colon of T2DM rats were downregulated. ConclusionThe pharmacokinetic profiles of mogroside V and its metabolite mogroside IIIA1 in T2DM rats and normal rats showed some difference, it might be affected by the metabolic changes in the pathological state of T2DM.

Acid increases PGE2 in the duodenal mucosa in rats.

Attention has recently been paid to the duodenum as the pathophysiologic center of functional dyspepsia. However, the precise mechanisms of symptom generation remain unknown. We here investigated the effect of acid on duodenal prostaglandin E2 and localization of prostaglandin E2 related receptors. Sprague–Dawley rats were used for this study. Hydrochloric acid was administered in the duodenum, then prostaglandin E2 levels in the duodenum were measured using the ELISA. The expression and localization of prostaglandin receptors (EP1–4) and the mRNAs of prostaglandin synthases were investigated using in situ hybridization histochemistry in duodenal tissue. After acid perfusion, prostaglandin E2 levels in the duodenum significantly increased. EP3 was expressed mainly at the myenteric plexus in the duodenal mucosa, and EP4 at both the epithelial surface and myenteric plexus. Contrary, EP2 was sparsely distributed in the villi and EP1 were not clearly seen on in situ hybridization histochemistry. Prostaglandin-synthetic enzymes were also distributed in the duodenal mucosa. The prostaglandin E2 levels in the duodenum increased after acidification. Prostaglandin E2 receptors and prostaglandin E2-producing enzymes were both observed in rat duodenum. These observations suggest that duodenal prostaglandin E2 possibly play a role in the symptom generation of functional dyspepsia.

Immediate Insulin Treatment Prevents Diabetes-Induced Gut Region-Specific Increase in the Number of Myenteric Serotonergic Neurons

To evaluate the effects of hyperglycemia and insulin treatment on the proportion of serotonin-immunoreactive (5-HT-IR) myenteric neurons, samples were taken from the duodenum, ileum, and colon of diabetic, insulin-treated diabetic, and control rats 10 weeks after the onset of streptozotocin-induced hyperglycemia. Myenteric whole-mount preparations were immunostained with anti-5-HT and pan-neuronal anti-HuCD markers. In controls, the 5-HT-IR myenteric neurons represent a small proportion (~2.5%) of the total neuronal number in the investigated gut segments. The proportion of 5-HT-IR myenteric neurons was significantly higher in the duodenum (p &lt; 0.01) and colon (p &lt; 0.0001) of diabetic rats compared to the controls but exhibited a slight increase in the ileum. Immediate insulin treatment resulted in a significantly lower proportion of myenteric 5-HT-IR neurons in each segment (duodenum p &lt; 0.0001; ileum p &lt; 0.01; and colon p &lt; 0.0001) compared to the untreated diabetics. Our study demonstrates that the proportion of 5-HT-IR myenteric neurons was enhanced in type 1 diabetes in a region-specific manner. Immediate insulin treatment prevents a higher hyperglycemia-induced amount of 5-HT-IR neurons and restores it to the control level in each investigated gut segment. Despite the low proportion of 5-HT-IR myenteric neurons, hyperglycemia-related changes of these neurons may play a crucial role in gastrointestinal symptoms in type 1 diabetes.

Digestive promoting effect and mechanism of Jiao Sanxian in rats

Ethnopharmacological relevanceJiao Sanxian, a customary term for the three Traditional Chinese Medicines of charred hawthorn (Crataegi Fructus), charred malt (Hordei Fructus Germinatus) and Liu Shenqu (Massa Medicata Fermentata), is a classic prescription for the treatment of functional dyspepsia (FD). This prescription is called “Jiao Sanxian” in China because people believe that it is a miracle medicine for enhancing digestion and improving stagnation of digestive system. Even though Jiao Sanxian is widely used in clinical treatment, the underlying mechanism has not been clarified to date. Aim of the studyThe present study is aimed to explore the efficacy and mechanism of Jiao Sanxian in improving the symptoms of FD in rats by using multiple pharmacological methods. Materials and methodsThe Sprague Dawley (SD) rats were divided into control, model, Jiao Sanxian decoction low-dosage (JSXD LD), Jiao Sanxian decoction medium-dosage (JSXD MD), and Jiao Sanxian decoction high-dosage (JSXD HD) group at random. A FD model was established with reserpine, and animals were given intragastric administration. During this period, weight and food intake of animals were recorded. Samples of rat gastric antrum, spleen, and duodenum were collected for pathological staining and immunohistochemical determination of Ghrelin protein expression after 19 days of treatment. Enzyme-linked immunosorbent assay (ELISA) was used to determine the concentration of related brain gut peptides in serum. Moreover, 16S rRNA sequencing was used to valuate the influence of intestinal flora structure of the cecal contents of experimental rats. And plasma metabolomics by Ultra Performance Liquid Chromatography coupled with Quadrupole-Time-of-Flight mass spectrometry (UPLC-Q/TOF-MS) were performed to further reveal the mechanism of action. ResultsJiao Sanxian decoction (JSXD) group with different dosage could increase body weight and food intake, improve histopathological changes, and alter disordered brain gut peptides in FD rats. 16S rRNA sequencing results described that JSXD improved the disorder of structural composition, biodiversity and function of gut microbiota in FD rats. Metabolomics illustrated 26 metabolites with JSXD treatment underwent continuous changes, which revealed JSXD might exert digestive effect by ameliorating abnormal metabolic pathways. The most relevant metabolic pathways were arachidonic acid metabolism, pyruvate metabolism, glycerophospholipid metabolism, alanine, aspartate and glutamate metabolism. ConclusionsJSXD can improve functional dyspepsia in rats and the mechanism is related to regulate secretion of brain gut peptides, significantly improve the disorder of intestinal flora and ameliorated multi-metabolic pathways.