Smooth Muscle Motility Research Articles

Immunohistochemical characterization of interstitial cells and their relationship to motor neurons within the mouse esophagus.

Interstitial cells of Cajal (ICC) and PDGFRα+ cells regulate smooth muscle motility in the gastrointestinal (GI) tract. However, their role(s) in esophageal motility are still unclear. The mouse esophagus has traditionally been described as almost entirely skeletal muscle in nature though ICC have been identified along its entire length. The current study evaluated the distribution of skeletal and smooth muscle within the esophagus using a mouse selectively expressing eGFP in smooth muscle cells (SMCs). The relationship of SMCs to ICC and PDGFRα+ cells was also examined. SMCs declined in density in the oral direction however SMCs represented ~ 25% of the area in the distal esophagus suggesting a likeness to the transition zone observed in humans. ANO1+ intramuscular ICC (ICC-IM) were distributed along the length of the esophagus though like SMCs, declined proximally. ICC-IM were closely associated with SMCs but were also found in regions devoid of SMCs. Intramuscular and submucosal PDGFRα+ cells were densely distributed throughout the esophagus though only intramuscular PDGFRα+ cells within the LES and distal esophagus highly expressed SK3. ICC-IM and PDGFRα+ cells were closely associated with nNOS+, VIP+, VAChT+ and TH+ neurons throughout the LES and distal esophagus. GFAP+ cells resembling intramuscular enteric glia were observed within the muscle and were closely associated with ICC-IM and PDGFRα+ cells, occupying a similar location to c. These data suggest that the mouse esophagus is more similar to the human than thought previously and thus set the foundation for future functional and molecular studies using transgenic mice.

Luteolin Attenuates Oxidative Stress and Colonic Hypermobility in Water Avoidance Stress Rats by Activating the Nrf2 Signaling Pathway.

Irritable bowel syndrome (IBS) is an intestinal disorder, whose symptoms can be alleviated by certain dietary phytochemicals. This study explores the role and potential mechanisms of a natural flavonoid luteolin (LUT) in alleviating the excessive motility of colonic smooth muscles and reducing oxidative stress in IBS with diarrhea (IBS-D) rats. LUT reduces excessive intestinal motility and lowers reactive oxygen species (ROS) levels in a water avoidance stress (WAS) rat model. Moreover, LUT increases the protein expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), activates the nuclear translocation of Nrf2, and greatly reduces the hydrogen peroxide (H2 O2 )-induced oxidative damage in intestinal epithelial cells. LUT, a phyto-active component, protects against excessive intestinal motility and diarrhea by regulating the Nrf2 signaling pathway and effectively reduces oxidative stress damage in the colon.

Age-dependent effects of the β3 adrenoceptor agonist CL316,243 on human and rat detrusor muscle strips

Motility of detrusor smooth muscle includes adrenergic relaxation and cholinergic contraction. Since the latter may be deregulated in overactive bladder (OAB) pathophysiology, anticholinergics are the standard therapy but occasionally less tolerated due to side effects such as dry mouth and constipation. β3 adrenoceptor agonists also alleviate OAB symptoms by relaxing the detrusor muscle. Their age dependence, however, is far from understood. To address this issue, we induced contractions with KCl (60 mM) and carbachol (from 10 nM to 100 μM) in the presence of the β3 adrenoceptor agonist CL316,243 (from 0.1 to 10 μM) in both human and rat muscle strips. Our results confirmed that both contractions were attenuated by β3 adrenoceptor activation in both species, but with differing age dependence. In humans, specimens from mid-life subjects showed a significantly more pronounced effect of CL316,243 in attenuating carbachol-induced contractions than those from aged subjects (Cohen’s d of maximal attenuation: 1.82 in mid-life versus 0.13 in aged) without altering EC50. Conversely, attenuation of KCl responses by CL316,243 increased during ageing (Spearman correlation coefficient = -0.584, P<0.01). In rats, both KCl- and carbachol-induced contractions were significantly more attenuated by CL316,243 in samples from adolescent as compared to aged samples. Immunohistochemistry in human detrusor sections proved β3 adrenoreceptor abundance to remain unaltered during ageing. In conclusion, our findings suggest differential age-dependent changes in human β3 adrenoceptor-dependent attenuation of detrusor contraction in terms of electromechanical versus pharmacomechanical coupling; they may help understand the differential responsiveness of OAB patients to β3 agents.

Flavonoids in Amomum tsaoko Crevost et Lemarie Ameliorate Loperamide-Induced Constipation in Mice by Regulating Gut Microbiota and Related Metabolites.

Amomum tsaoko (AT) is a dietary botanical with laxative properties; however, the active ingredients and mechanisms are still unclear. The active fraction of AT aqueous extract (ATAE) for promoting defecation in slow transit constipation mice is the ethanol-soluble part (ATES). The total flavonoids of ATES (ATTF) were the main active component. ATTF significantly increased the abundance of Lactobacillus and Bacillus and reduced the dominant commensals, such as Lachnospiraceae, thereby changing the gut microbiota structure and composition. Meanwhile, ATTF changed the gut metabolites mainly enriched in pathways such as the serotonergic synapse. In addition, ATTF increased the serum serotonin (5-HT) content and mRNA expression of 5-hydroxytryptamine receptor 2A (5-HT2A), Phospholipase A2 (PLA2), and Cyclooxygenase-2 (COX2), which are involved in the serotonergic synaptic pathway. ATTF increased Transient receptor potential A1 (TRPA1), which promotes the release of 5-HT, and Myosin light chain 3(MLC3), which promotes smooth muscle motility. Notably, we established a network between gut microbiota, gut metabolites, and host parameters. The dominant gut microbiota Lactobacillus and Bacillus, prostaglandin J2 (PGJ2) and laxative phenotypes showed the most significant associations. The above results suggest that ATTF may relieve constipation by regulating the gut microbiota and serotonergic synaptic pathway and has great potential for laxative drug development in the future.

Case Report on Achalasia Cardia

Motor dysphagia has a number of frequent causes, including achalasia. The failure of the lower esophageal sphincter to relax results in achalasia, a condition of esophageal smooth muscle motility. The gastroesophageal junction becomes functionally blocked as a result of this disease. The actual pathophysiology of this disorder is still unknown, despite the fact that the disease was originally recorded more than 300 years ago. Loss of the inhibitory ganglion in the myenteric plexus of the oesophagus can be the pathophysiological aetiology of achalasia cardia. In the esophageal myenteric plexus, there is a loss of inhibitory neurons that produce VIP and nitric oxide synthase, but in extreme situations, it also affects cholinergic neurons. Despite numerous possibilities being put forth, the specific cause of this deterioration remains unknown. The autoimmune phenomenon, viral infection, and genetic predisposition are some of these hypotheses. Read more...

Motor Dysfunction of Gastric Antral Smooth Muscle in Diabetic Rats: Contribution of ATP-Dependent Potassium Channels.

The goal of the current research was to further elucidate the role of adenosine triphosphate (ATP)-sensitive potassium (KATP) channels in the motility and contractility force of gastric smooth muscle of diabetic rats. Male Wistar rats (190-230 g) were grouped into control and streptozotocin (STZ)-induced diabetes (55 mg/kg) rats. Thirty days later, gastric muscle contractility was measured using a myograph and a force transducer of antral segments immersed in a tissue bath. Gastric emptying response was measured through feeding of standard pellet. Furthermore, the expression of KATP channel subunits in antral smooth muscle was determined by western blot technique. The amplitude of KCl-evoked twitch contractions of diabetic antral strips was about 25% more than control (P < 0.05). Application of minoxidil, a KATP channel opener, dose dependently decreased the force of twitch contractions in both normal and diabetic antral strips. Application of 10 μM glibenclamide, a KATP channel blocker, did not antagonize the minoxidil-induced relaxation of antral strips. Diabetic gastric emptying was faster than normal, although not significant. Despite the relaxant effect of minoxidil on gastric emptying rate in normal rats (P < 0.05), this effect was not observed in diabetic rats. Also, glibenclamide increased gastric emptying and antagonized minoxidil-induced relaxation in normal rats (P < 0.05). Furthermore, the expression of KATP Kir6.1 and SUR2B subunits was substantially reduced in antral smooth muscle in diabetic condition (P < 0.01). These results propose that KATP channels may contribute to the development of gastric motility disorders in diabetes.

LncRNA PCA3 Suppressed Carotid Artery Stenosis and Vascular Smooth Muscle Cell Function via Negatively Modulating the miR-124-3p/ITGB1 Axis.

Due to the hidden pathogen, carotid artery stenosis (CAS) always occurred at an advanced stage leading to serious sequelae and even deaths. The significance of long noncoding RNA (lncRNA) prostate cancer antigen 3 (PCA3) in CAS incidence and progression were evaluated aiming to explore a potential target for its therapy. Serum samples were collected from 83 asymptomatic CAS patients and 52 healthy individuals and PCA3 was compared using polymerase chain reaction (PCR). The PCA3 levels were compared between stable and unstable plaque in CAS patients. The effect of PCA3 on vascular smooth muscle cells (VSMCs) proliferation and motility was assessed by CCK8 and transwell assay. PCA3 was downregulated in CAS patients and their unstable plaque tissues compared with healthy individuals and stable plaque, respectively. Reduced PCA3 could discriminate CAS patients with relatively high sensitivity and specificity and were associated with higher total cholesterol level and stenosis degree, unstable plaque, and complications. PCA3 downregulation predicted the adverse outcomes of CAS patients. In VSMCs, overexpressing PCA3 significantly suppressed cell proliferation, migration, and invasion, which was alleviated by miR-124-3p/ITGB1 axis. PCA3 served as a biomarker of CAS and regulates the function of VSMCs through sponging miR-124-3p/ITGB1 and indirectly influence the stability of plaque.

Wernicke's Encephalopathy in Type 2 Achalasia: Case Report and Literature Review.

Achalasia is primarily a smooth muscle motility disorder of the esophagus driven by aberrant peristalsis and failure of sphincter relaxation. Notably, achalasia is a heterogeneous disease with primarily 3 possible pattern subtypes. According to the review of current cases and literature regarding achalasia, patients primarily present with dysphagia, usually to solids and, if progressed, to solids and liquids. Rarely, untreated achalasia may result in thiamine deficiency and present as Wernicke-Korsakoff syndrome (WKS). This acute neurologic condition primarily affects the central and peripheral nervous system and is known by the triad of ataxia, ophthalmoplegia, and confusion. Individuals who present with WKS typically have a notable history of chronic alcohol abuse with decreased thiamine intake and metabolism. Although less common, individuals with WKS may have a pertinent history of starvation, anorexia nervosa, and malnutrition. This case highlights a unique presentation of Wernicke's encephalopathy (WE) in a 30-year-old woman with severe type II achalasia complicated by a 60-pound weight loss in a span of 2 months. According to our literature review, there have only been 2 previously reported cases of severe achalasia leading to the development of WE. Considering the limited number of case reports available, WE must be in the differentials in patients with underlying achalasia, and our case report highlights this unusual presentation with corresponding brain imaging and manometry testing.

Downexpression of miR-200c-3p Contributes to Achalasia Disease by Targeting the PRKG1 Gene.

Achalasia is an esophageal smooth muscle motility disorder with unknown pathogenesis. Taking into account our previous results on the downexpression of miR-200c-3p in tissues of patients with achalasia correlated with an increased expression of PRKG1, SULF1, and SYDE1 genes, our aim was to explore the unknown biological interaction between these genes and human miR-200c-3p and if this relation could unravel their functional role in the etiology of achalasia. To search for putative miR-200c-3p binding sites in the 3'-UTR of PRKG1, SULF1 and SYDE1, a bioinformatics tool was used. To test whether PRKG1, SULF1, and SYDE1 are targeted by miR-200c-3p, a dual-luciferase reporter assay and quantitative PCR on HEK293 and fibroblast cell lines were performed. To explore the biological correlation between PRKG1 and miR-200c-3p, an immunoblot analysis was carried out. The overexpression of miR-200c-3p reduced the luciferase activity in cells transfected with a luciferase reporter containing a fragment of the 3'-UTR regions of PRKG1, SULF1, and SYDE1 which included the miR-200c-3p seed sequence. The deletion of the miR-200c-3p seed sequence from the 3'-UTR fragments abrogated this reduction. A negative correlation between miR-200c-3p and PRKG1, SULF1, and SYDE1 expression levels was observed. Finally, a reduction of the endogenous level of PRKG1 in cells overexpressing miR-200c-3p was detected. Our study provides, for the first time, functional evidence about the PRKG1 gene as a direct target and SULF1 and SYDE1 as potential indirect substrates of miR-200c-3p and suggests the involvement of NO/cGMP/PKG signaling in the pathogenesis of achalasia.

The efficacy of exogenous melatonin supplement in ameliorating irritable bowel syndrome severity: A meta-analysis of randomized controlled trials

Irritable bowel syndrome (IBS) was found in 11% of the general population worldwide. The current pharmacologic management of IBS was unsatisfactory, and it was accompanied by a number of adverse events. Melatonin was found to play an important role in gastrointestinal smooth muscle motility. Dysregulation of endogenous melatonin secretion has been found in IBS patients. Exogenous melatonin supplement has become one alternative treatment for IBS, but the evidence is inconclusive. The current meta-analysis sought to determine the efficacy of exogenous melatonin supplement in improving IBS severity in IBS patients. We included randomized controlled trials (RCTs) that investigated the efficacy of exogenous melatonin supplement in ameliorating IBS severity in IBS patients. This meta-analysis was conducted using a random effects model. The primary target outcomes were changes in IBS severity associated with melatonin or placebo. This meta-analysis of 4 RCTs and 115 participants revealed that exogenous melatonin supplement was associated with significantly better improvement in overall IBS severity than placebo (k=4, Hedges' g=0.746, 95% confidence intervals=0.401-1.091, p<0.001). The subgroup without concurrent medication had the same result (p<0.001). In addition, exogenous melatonin supplement was also associated with significantly better improvement in IBS pain severity (p<0.001) and quality of life (p=0.007) than placebo, but not in abdominal distension (p=0.111) or sleep quality (p=0.142). Finally, melatonin was associated with similar safety profiles with placebo. This meta-analysis provides evidence for the use of exogenous melatonin in IBS patients to ameliorate overall IBS severity, IBS pain severity, and quality of life. PROSPERO CRD42021269451.

Localization of substance P (SP)-immunoreactivity in the myenteric plexus of the rat esophagus.

The present immunohistochemical study was performed to examine the number, distribution, and chemical coding of intrinsic substance P (SP) neurons and nerve fibers within the esophagus and discuss their functional roles. Many SP neurons and nerve fibers were found in the myenteric plexus, and the SP neurons gradually decreased from the oral side toward the aboral side of the esophagus. Double-immunolabeling showed that most SP neurons were cholinergic (positive for choline acetyltransferase), and few were nitrergic (positive for nitric oxide synthase). Some cholinergic SP nerve terminals surrounded cell bodies of several myenteric neurons. In the muscularis mucosa and lower esophageal sphincter, and around blood vessels, numerous SP nerve endings were present, and many of them were cholinergic. Also, SP nerve endings were found on only a few motor endplates of the striated muscles, and most of them were calcitonin gene-related peptide (CGRP)-positive. Retrograde tracing using Fast Blue (FB) showed that numerous sensory neurons in the dorsal root ganglia (DRGs) and nodose ganglion (NG) projected to the esophagus, and most FB-labeled SP neurons were CGRP-positive. These results suggest that the intrinsic SP neurons in the rat esophagus may play roles as, at least, motor neurons, interneurons, and vasomotor neurons, which are involved in local regulation of smooth muscle motility, neuronal transmission, and blood circulation, respectively. Moreover, SP nerve endings on only a minority of motor endplates may be extrinsic, derived from DRGs or NG, and possibly detect chemical circumstances within motor endplates to modulate esophageal motility.

The effects of acetylcholine on intracellular calcium fluorescence in smooth muscle cells of human esophagogastric junction cultured in vitro.

Most esophageal motility studies are based on animals. It is necessary to explore smooth muscle motility in the human esophagus. This study was undertaken to explore the feasibility of in vitro culture of smooth muscle cells (SMCs) from human esophagogastric junction (EGJ) and to determine changes of intracellular calcium (Ca2+ ) fluorescence ([Ca2+ ]i ) in SMCs stimulated by acetylcholine (ACh). Primary cells of EGJ (Clasp, Sling, esophageal circular muscle (ECM), and longitudinal muscle (ELM)) were obtained by enzymatic digestion (ED) and explant culture with tissues (EC-T) from 9 upper esophageal carcinoma patients. Cells were cultured in smooth muscle cell medium (SMCM) and DMEM/F-12medium containing 10% newborn bovine serum (10%-F12), respectively, and then identified by α-SMA staining. After incubation with 5μM Fluo-3/am, the effect of 10-6 mM ACh on [Ca2+ ]i in Ca2+ -containing and Ca2+ -free buffers was evaluated by confocal microscopy. Cultured cells from ED and EC-T were identified as SMCs by α-SMA with spindle surface and "hills and valleys" morphology. Cells cultured in 10%-F12showed better morphology. The main characteristic of [Ca2+ ]i in Clasp-, Sling- and ECM-SMCs was the release of intracellular Ca2+ stores; the main characteristic in ELM-SMCs was extracellular Ca2+ influx. However, these cells seemed not to rely on a unique Ca2+ activity, instead combining the two activities to maintain [Ca2+ ]i . It was feasible to culture human EGJ SMCs in vitro; moreover, Ach-induced changes of [Ca2+ ]i in EGJ SMCs represent a complex interaction of intracellular Ca2+ release and extracellular Ca2+ influx.

Arecoline Hydrobromide Enhances Jejunum Smooth Muscle Contractility via Voltage-Dependent Potassium Channels in W/Wv Mice

Gastrointestinal motility was disturbed in W/Wv, which were lacking of interstitial cells of Cajal (ICC). In this study, we have investigated the role of arecoline hydrobromide (AH) on smooth muscle motility in the jejunum of W/Wv and wild-type (WT) mice. The jejunum tension was recorded by an isometric force transducer. Intracellular recording was used to identify whether AH affects slow wave and resting membrane potential (RMP) in vitro. The whole-cell patch clamp technique was used to explore the effects of AH on voltage-dependent potassium channels for jejunum smooth muscle cells. AH enhanced W/Wv and WT jejunum contractility in a dose-dependent manner. Atropine and nicardipine completely blocked the excitatory effect of AH in both W/Wv and WT. TEA did not reduce the effect of AH in WT, but was sufficient to block the excitatory effect of AH in W/Wv. AH significantly depolarized the RMP of jejunum cells in W/Wv and WT. After pretreatment with TEA, the RMP of jejunum cells indicated depolarization in W/Wv and WT, but subsequently perfused AH had no additional effect on RMP. AH inhibited the voltage-dependent K+ currents of acutely isolated mouse jejunum smooth muscle cells. Our study demonstrate that AH enhances the contraction activity of jejunum smooth muscle, an effect which is mediated by voltage-dependent potassium channels that acts to enhance the excitability of jejunum smooth muscle cells in mice.

Mfge8 attenuates human gastric antrum smooth muscle contractions

Coordinated gastric smooth muscle contraction is critical for proper digestion and is adversely affected by a number of gastric motility disorders. In this study we report that the secreted protein Mfge8 (milk fat globule-EGF factor 8) inhibits the contractile responses of human gastric antrum muscles to cholinergic stimuli by reducing the inhibitory phosphorylation of the MYPT1 (myosin phosphatase-targeting subunit (1) subunit of MLCP (myosin light chain phosphatase), resulting in reduced LC20 (smooth muscle myosin regulatory light chain (2) phosphorylation. Mfge8 reduced the agonist-induced increase in the F-actin/G-actin ratios of β-actin and γ-actin1. We show that endogenous Mfge8 is bound to its receptor, α8β1 integrin, in human gastric antrum muscles, suggesting that human gastric antrum muscle mechanical responses are regulated by Mfge8. The regulation of gastric antrum smooth muscles by Mfge8 and α8 integrin functions as a brake on gastric antrum mechanical activities. Further studies of the role of Mfge8 and α8 integrin in regulating gastric antrum function will likely reveal additional novel aspects of gastric smooth muscle motility mechanisms.

Fibrin and Transforming Growth Factor Alpha Affect Prostatic Smooth Muscle Cell's Phenotype and Motility.

Smooth muscle cells (SMCs) are dynamic and transition from a contractile to a synthetic phenotype under different circumstances. Plasma factors (fibrin and transforming growth factors, TGFs) are possible components affecting SMCs differentiation and behavior. Thus, the objective of this work was to investigate how the fibrin matrix and TGFs affect SMCs differentiation and motility behavior. SMCs invaded the fibrin gel and adopted a stellate phenotype while reducing the expression of differentiation markers (Acta2, Myh11, and Smtn). At the ultrastructural level, SMCs did not assemble a basal lamina and showed numerous blebs along the entire cell surface. This transition was not associated with changes in focal adhesion kinase (FAK) content and phosphorylation status but reflected a marked change in FAK distribution in the cytoplasm. After 48 h in culture, SMCs caused an active degradation of the fibrin gel. Additionally, we tested the SMCs response to TGFs in a cell layer wound repair assay. TGFα, but not TGFβ1 or TGFβ3, had significantly increased motility. In conclusion, prostatic SMCs present a phenotypical transition when cultured on fibrin, adopting a micro-blebbing based motility behavior and increasing migration in response to TGFα.

7,8-Dihydroxyflavone Enhanced Colonic Cholinergic Contraction and Relieved Loperamide-Induced Constipation in Rats.

Whether 7,8-dihydroxyflavone (7,8-DHF), a tyrosine kinase receptor B (TrkB) agonist, modulates colonic smooth muscle motility and/or alleviates constipation has not yet been studied. Here, we aimed to determine how 7,8-DHF influences carbachol (CCh)-stimulated contraction of colonic strips and the in vivo effect of 7,8-DHF on constipation. Muscle strips were isolated from rat colons for recording contractile tension and performing western blotting. Constipation was induced in rats with loperamide. Although it specifically activated TrkB, 7,8-DHF applied alone neither activated PLCγ1 in the colonic strips nor induced colonic strip contraction. However, 7,8-DHF enhanced CCh-stimulated PLCγ1 activation and strip contraction. The PLCγ1 antagonist U73122 suppressed both CCh-stimulated and 7,8-DHF-enhanced/CCh-stimulated contraction. While clarifying the underlying mechanism, we revealed that 7,8-DHF augmented muscarinic M3 receptor expression in the colonic strips. The M3-selective antagonist tarafenacin specifically inhibited the 7,8-DHF-enhanced/CCh-stimulated contraction of the colonic strips. Since 7,8-DHF increased Akt phosphorylation, and LY294002 (an antagonist of PI3K upstream of Akt) dramatically inhibited both 7,8-DHF-augmented M3 expression and 7,8-DHF-enhanced/CCh-stimulated contractions, we assumed that 7,8-DHF/TrkB/Akt was associated with the modulation of M3 expression in the colonic strips. ANA-12, a specific TrkB antagonist, not only inhibited TrkB activation by 7,8-DHF but also suppressed 7,8-DHF-enhanced cholinergic contraction, 7,8-DHF/CCh-mediated activation of PLCγ1/Akt, and M3 overexpression in colonic strips. In vivo 7,8-DHF, also by promoting intestinal motility and M3 expression, significantly alleviated loperamide-induced functional constipation in rats. Our results suggest that 7,8-DHF regulates colonic motility possibly via a TrkB/Akt/M3 pathway and may be applicable for alleviating constipation.

The endocannabinoid system in the adipose organ.

The endocannabinoid system is found in most, if not all, mammalian organs and is involved in a variety of physiological functions, ranging from the control of synaptic plasticity in the brain to the modulation of smooth muscle motility in the gastrointestinal tract. This signaling complex consists of G protein-coupled cannabinoid receptors, endogenous ligands for those receptors (endocannabinoids) and enzymes/transporters responsible for the formation and deactivation of these ligands. There are two subtypes of cannabinoid receptors, CB1 and CB2, and two major endocannabinoids, arachidonoylethanolamide (anandamide) and 2-arachidonoyl-sn-glycerol (2-AG), which are produced upon demand through cleavage of distinct phospholipid precursors. All molecular components of the endocannabinoid system are represented in the adipose organ, where endocannabinoid signals are thought to regulate critical homeostatic processes, including adipogenesis, lipogenesis and thermogenesis. Importantly, obesity was found to be associated with excess endocannabinoid activity in visceral fat depots, and the therapeutic potential of normalizing such activity by blocking CB1 receptors has been the focus of substantial preclinical and clinical research. Results have been mixed thus far, mostly owing to the emergence of psychiatric side effects rooted in the protective functions served by brain endocannabinoids in mood and affect regulation. Further studies about the roles played by the endocannabinoid system in the adipose organ will offer new insights into the pathogenesis of obesity and might help identify new ways to leverage this signaling complex for therapeutic benefit.

MiR-223/NFAT5 signaling suppresses arterial smooth muscle cell proliferation and motility in vitro.

Aberrant proliferation and migration of vascular smooth muscle cells contributes to cardiovascular diseases (CVDs), including atherosclerosis. MicroRNA-223 (miR-223) protects against atherosclerotic CVDs. We investigated the contribution of miR-223 to platelet-derived growth factor-BB (PDGF-BB)-induced proliferation and migration of human aortic smooth muscle cells (HASMCs). We found that miR-223 was downregulated in PDGF-BB-treated HASMCs in a dose- and time-dependent manner, while nuclear factor of activated T cells 5 (NFAT5) was upregulated. Gain- and loss-of-function studies demonstrated that miR-223 treatment reduced PDGF-BB-induced HASMC proliferation and motility, whereas miR-223 inhibitor enhanced these processes. Moreover, NFAT5 was identified as a direct target of miR-223 in HASMC. The inhibitory effects of miR-223 on HASMC proliferation and migration were partly rescued by NFAT5 restoration. Overall, these findings suggest that miR-223 inhibits the PDGF-BB-induced proliferation and motility of HASMCs by targeting NFAT5 and that miR-223 and NFAT5 may be potential therapeutic targets for atherosclerosis.

Assessment of Polygonum odoratum Lour. Leaf Extract on Rat's Ileum Contraction and the Mechanisms Involved.

Vietnamese coriander (Polygonum odoratum Lour.) is a plant native to northern Thailand. The biological activities of P. odoratum Lour. extract (POE) include antibacterial, antiviral, and expectorant. However, the effect of POE on intestinal smooth muscle motility is unclear. The aim of this study was to evaluate the relaxant effects of POE on isolated rat ileum. Propranolol (1 μM), calcium chloride (1-20 mM), and Nω-nitro-l-arginine methylester (l-NAME, 100 μM) were used to investigate the mechanisms of action. The results showed that POE (0.01-5 mg/mL) reduced KCl-induced contraction. In addition, POE (1 mg/mL) reduced the contraction by propranolol and l-NAME and attenuated CaCl2-induced contractions. Our results indicate that the relaxation effect of POE on ileum contractions seems to involve nitric oxide and β-adrenergic pathways, and blockade of calcium influx. These findings provide a pharmacological basis for the traditional use of POE to treat gastrointestinal disorders such as irritable bowel syndrome or diarrhea.

Luteolin suppresses colonic smooth muscle motility via inhibiting L-type calcium channel currents in mice.

As a naturally occurring flavone, luteolin has received much attention due to its antioxidant, anti-inflammatory and anticancer functions. In the present study, we investigated the effect of luteolin on colonic motility and its mechanism using isometric muscle recording and the whole-cell patch-clamp technique in mice. Luteolin dose-dependently inhibited colonic smooth muscles motility and CMMC significantly. BayK8644, an L-type Ca2+ channel agonist, significantly attenuated the luteolin-induced inhibition. Moreover, the calcium currents recorded in colonic smooth muscle cells were dramatically inhibited by luteolin. However, no significant changes were found in the luteolin-induced inhibitory effect in the presence of TEA, a nonselective K+ channel blocker, glibenclamide, an ATP-dependent K+ channel blocker, and apamin, a small-conductance Ca2+-activated K+ channel blocker. Additionally, luteolin did not affect potassium currents. Furthermore, TTX, a Na+ channel blocker, L-NAME, an inhibitor of nitric oxide (NO) synthase, ODQ, an inhibitor of NO-sensitive guanylyl cyclase, and Ani9, a specific ANO1 channels blocker, had no effect on the luteolin-induced suppression. These results suggest that luteolin inhibited colonic smooth muscle motility by inhibiting L-type calcium channels in mice but not through potassium channels, the enteric nervous system (ENS), NO signaling pathways or ANO1 channels of interstitial cells of Cajal (ICCs).