Pellino3 ubiquitinates RIP2 and mediates Nod2-induced signaling and protective effects in colitis.

Mutations that result in loss of function of Nod2, an intracellular receptor for bacterial peptidoglycan, are associated with Crohn's disease. Here we found that the E3 ubiquitin ligase Pellino3 was an important mediator in the Nod2 signaling pathway. Pellino3-deficient mice had less induction of cytokines after engagement of Nod2 and had exacerbated disease in various experimental models of colitis. Furthermore, expression of Pellino3 was lower in the colons of patients with Crohn's disease. Pellino3 directly bound to the kinase RIP2 and catalyzed its ubiquitination. Loss of Pellino3 led to attenuation of Nod2-induced ubiquitination of RIP2 and less activation of the transcription factor NF-κB and mitogen-activated protein kinases (MAPKs). Our findings identify RIP2 as a substrate for Pellino3 and Pellino3 as an important mediator in the Nod2 pathway and regulator of intestinal inflammation.

ABIN2 Function Is Required To Suppress DSS-Induced Colitis by a Tpl2-Independent Mechanism.

The A20-binding inhibitor of NF-κB 2 (ABIN2) interacts with Met1-linked ubiquitin chains and is an integral component of the tumor progression locus 2 (Tpl2) kinase complex. We generated a knock-in mouse expressing the ubiquitin-binding-defective mutant ABIN2[D310N]. The expression of Tpl2 and its activation by TLR agonists in macrophages or by IL-1ß in fibroblasts from these mice was unimpaired, indicating that the interaction of ABIN2 with ubiquitin oligomers is not required for the stability or activation of Tpl2. The ABIN2[D310N] mice displayed intestinal inflammation and hypersensitivity to dextran sodium sulfate-induced colitis, an effect that was mediated by radiation-resistant cells rather than by hematopioetic cells. The IL-1ß-dependent induction of cyclooxygenase 2 (COX2) and the secretion of PGE2 was reduced in mouse embryonic fibroblasts and intestinal myofibroblasts (IMFs) from ABIN2[D310N] mice. These observations are similar to those reported for the Tpl2 knockout (KO) mice (Roulis et al. 2014. Proc. Natl. Acad. Sci. USA 111: E4658-E4667), but the IL-1ß-dependent production of COX2 and PGE2 in mouse embryonic fibroblasts or IMFs was unaffected by pharmacological inhibition of Tpl2 in wild-type mice. The expression of ABIN2 is decreased drastically in Tpl2 KO mice. These and other lines of evidence suggest that the hypersensitivity of Tpl2 KO mice to dextran sodium sulfate-induced colitis is not caused by the loss of Tpl2 catalytic activity but by the loss of ABIN2, which impairs COX2 and PGE2 production in IMFs by a Tpl2 kinase-independent pathway.

Schistosoma mansoni Worm Infection Regulates the Intestinal Microbiota and Susceptibility to Colitis.

Infection with parasite helminths induces potent modulation of the immune system of the host. Epidemiological and animal studies have shown that helminth infections can suppress or exacerbate unrelated autoimmune, allergic, and other inflammatory disorders. There is growing evidence that helminth infection-mediated suppression of bystander inflammatory responses is influenced by alterations in the intestinal microbiome modulating metabolic and immune functions of the infected host. We analyzed the fecal microbiota of mice infected with adult male Schistosoma mansoni worms, which are less susceptible to experimental colitis, and male- and female-worm-infected mice, which are highly sensitive to colitis. While both groups of infected mice developed a disrupted microbiota, there were marked alterations in mice with male and female worm infections. Antibiotic-treated recipients that were cohoused with both types of S. mansoni worm-infected mice acquired a colitogenic microbiome, leading to increased susceptibility to experimental colitis. Following anthelmintic treatment to remove worms from worm-only-infected mice, the mice developed exacerbated colitis. This study provides evidence that adult male S. mansoni worm infection modulates the host's immune system and suppresses bystander colitis while limiting dysbiosis of the host's intestinal microbiome during infection.

Pharmacological inhibition of MAGL attenuates experimental colon carcinogenesis.

Colorectal cancer (CRC) is a major health problem in Western countries. The endocannabinoid 2-arachidonoyl-glycerol (2-AG) exerts antiproliferative actions in a number of tumoral cell lines, including CRC cells. Monoacylglycerol lipase (MAGL), a serine hydrolase that inactivates 2-AG, is highly expressed in aggressive human cancer cells. Here, we investigated the role of MAGL in experimental colon carcinogenesis. The role of MAGL was assessed in vivo by using the xenograft and the azoxymethane models of colon carcinogenesis; MAGL expression was evaluated by RT-PCR and immunohistochemistry; 2-AG levels were measured by liquid chromatography mass spectrometry; angiogenesis was evaluated in tumor tissues [by microvessel counting and by investigating the expression of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) proteins] as well as in human umbilical vein endothelial cells (HUVEC); cyclin D1 was evaluated by RT-PCR. MAGL and 2-AG were strongly expressed in tumor tissues. The MAGL inhibitor URB602 reduced xenograft tumor volume, this effect being associated to down-regulation of VEGF and FGF-2, reduction in the number of vessels and down-regulation of cyclin D1. In HUVEC, URB602 exerted a direct antiangiogenic effect by inhibiting FGF-2 induced proliferation and migration, and by modulating pro/anti-angiogenic agents. In experiments aiming at investigating the role of MAGL in chemoprevention, URB602 attenuated azoxymethane-induced preneoplastic lesions, polyps and tumors. MAGL, possibly through modulation of angiogenesis, plays a pivotal role in experimental colon carcinogenesis. Pharmacological inhibition of MAGL could represent an innovative therapeutic approach to reduce colorectal tumor progression.

Cellular ROS imaging with hydro-Cy3 dye is strongly influenced by mitochondrial membrane potential.

BACKGROUND: Hydrocyanines are widely used as fluorogenic probes to monitor reactive oxygen species (ROS) generation in cells. Their brightness, stability to autoxidation and photobleaching, large signal change upon oxidation, pH independence and red/near infrared emission are particularly attractive for imaging ROS in live tissue. METHODS: Using confocal fluorescence microscopy we have examined an interference of mitochondrial membrane potential (ΔΨm) with fluorescence intensity and localisation of a commercial hydro-Cy3 probe in respiring and non-respiring colon carcinoma HCT116 cells. RESULTS: We found that the oxidised (fluorescent) form of hydro-Cy3 is highly homologous to the common ΔΨm-sensitive probe JC-1, which accumulates and aggregates only in 'energised' negatively charged mitochondrial matrix. Therefore, hydro-Cy3 oxidised by hydroxyl and superoxide radicals tends to accumulate in mitochondrial matrix, but dissipates and loses brightness as soon as ΔΨm is compromised. Experiments with mitochondrial inhibitor oligomycin and uncoupler FCCP, as well as a common ROS producer paraquat demonstrated that signals of the oxidised hydro-Cy3 probe rapidly and strongly decrease upon mitochondrial depolarisation, regardless of the rate of cellular ROS production. CONCLUSIONS: While analysing ROS-derived fluorescence of commercial hydrocyanine probes, an accurate control of ΔΨm is required. GENERAL SIGNIFICANCE: If not accounted for, non-specific effect of mitochondrial polarisation state on the behaviour of oxidised hydrocyanines can cause artefacts and data misinterpretation in ROS studies.

Protective role for caspase-11 during acute experimental murine colitis.

Activation of the noncanonical inflammasome, mediated by caspase-11, serves as an additional pathway for the production of the proinflammatory cytokines IL-1ß and IL-18. Noncanonical inflammasome activity occurs during host defense against Gram-negative bacteria and in models of acute septic shock. We propose that the noncanonical inflammasome is activated in mice during acute intestinal inflammation elicited by dextran sodium sulfate (DSS), a model of experimental colitis. We find that caspase-11(-/-) mice display enhanced susceptibility to DSS, because of impaired IL-18 production. The impaired IL-18 levels observed are shown to result in reduced intestinal epithelial cell proliferation and increased cell death. We also suggest that a novel type II IFN-dependent, type I IFN-TRIF-independent signaling pathway is required for in vivo caspase-11 production in intestinal epithelial cells during DSS colitis. Collectively, these data suggest that IFN-γ-mediated caspase-11 expression has a key role maintaining intestinal epithelial barrier integrity in vivo during experimentally induced acute colitis.

Farnesoid X receptor agonists attenuate colonic epithelial secretory function and prevent experimental diarrhoea in vivo.

OBJECTIVE: Bile acids are important regulators of intestinal physiology, and the nuclear bile acid receptor, farnesoid X receptor (FXR), is emerging as a promising therapeutic target for several intestinal disorders. Here, we investigated a role for FXR in regulating intestinal fluid and electrolyte transport and the potential for FXR agonists in treating diarrhoeal diseases. DESIGN: Electrogenic ion transport was measured as changes in short-circuit current across voltage-clamped T84 cell monolayers or mouse tissues in Ussing chambers. NHE3 activity was measured as BCECF fluorescence in Caco-2 cells. Protein expression was measured by immunoblotting and cell surface biotinylation. Antidiarrhoeal efficacy of GW4064 was assessed using two in vivo mouse models: the ovalbumin-induced diarrhoea model and cholera toxin (CTX)-induced intestinal fluid accumulation. RESULTS: GW4064 (5 µmol/L; 24 h), a specific FXR agonist, induced nuclear translocation of the receptor in T84 cells and attenuated Cl(-) secretory responses to both Ca(2+) and cAMP-dependent agonists. GW4064 also prevented agonist-induced inhibition of NHE3 in Caco-2 cells. In mice, intraperitoneal administration of GW4064 (50 mg/mL) also inhibited Ca(2+) and cAMP-dependent secretory responses across ex vivo colonic tissues and prevented ovalbumin-induced diarrhoea and CTX-induced intestinal fluid accumulation in vivo. At the molecular level, FXR activation attenuated apical Cl(-) currents by inhibiting expression of cystic fibrosis transmembrane conductance regulator channels and inhibited basolateral Na(+)/K(+)-ATPase activity without altering expression of the protein. CONCLUSIONS: These data reveal a novel antisecretory role for the FXR in colonic epithelial cells and suggest that FXR agonists have excellent potential for development as a new class of antidiarrheal drugs.

MyD88 adaptor-like (Mal) regulates intestinal homeostasis and colitis-associated colorectal cancer in mice.

Toll-like receptors (TLRs) play a central role in the recognition and response to microbial pathogens and in the maintenance and function of the epithelial barrier integrity in the gut. The protein MyD88 adaptor-like (Mal/TIRAP) serves as a bridge between TLR2/TLR4- and MyD88-mediated signaling to orchestrate downstream inflammatory responses. Whereas MyD88 has an essential function in the maintenance of intestinal homeostasis, a role for Mal in this context is less well described. Colitis was induced in wild-type (WT) and Mal-deficient (Mal(-/-)) mice by administration of dextran sodium sulfate (DSS). Colitis-associated cancer was induced by DSS and azoxymethane (AOM) treatment. Chimeric mice were generated by total body gamma irradiation followed by transplantation of bone marrow cells. In the DSS model of colon epithelial injury, Mal(-/-) mice developed increased inflammation and severity of colitis relative to WT mice. Mal(-/-) mice demonstrated the presence of inflammatory cell infiltrates, increased crypt proliferation, and presence of neoformations. Furthermore, in the AOM/DSS model, Mal(-/-) mice had greater incidence of tumors. Mal(-/-) and WT bone marrow chimeras demonstrated that nonhematopoietic cell expression of Mal had an important protective role in the control of intestinal inflammation and inflammation-associated cancer. Mal is essential for the maintenance of intestinal homeostasis and expression of Mal in nonhematopoietic cells prevents chronic intestinal inflammation that may predispose to colon neoplasia.

A mineral extract from red algae ameliorates chronic spontaneous colitis in IL-10 deficient mice in a mouse strain dependent manner.

Inflammatory bowel disease is an urgent public health problem with a high incidence in developed countries. Alterations of lifestyle or dietary interventions may attenuate the disease progression and increase the efficacy of current therapies. Here we tested the effect of chronic supplementation with a mineral extract from red marine algae - rich in calcium (34%), magnesium, phosphorus, selenium and other trace minerals - in a clinically relevant model of spontaneous enterocolitis, interleukin (IL)-10(-/-) mice. The mineral extract was administered in the drinking water of Il10(-/-) mice on C57BL/6 J and BALB/c strain backgrounds for 25 weeks commencing from 3 to 4 weeks of age. The mineral extract ameliorated the spontaneous development of colitis and severity of disease in Il10(-/-) mice on a C57BL/6 J background. Mineral extract-treated Il10(-/-) C57BL/6 J strain mice had significantly reduced mortality, circulating levels of serum Amyloid A and reduced colonic tissue damage. In contrast, comparable treatment of Il10(-/-) mice on a BALB/c background with the mineral extract did not alter the course of colitis. These data demonstrate that chronic supplementation with a natural mineral extract selectively ameliorates spontaneous mild-moderate colitis in Il10(-/-) mice on a C57BL/6 J, but does not attenuate more moderate-severe colitis in BALB/c strain animals.

Salvinorin A reduces mechanical allodynia and spinal neuronal hyperexcitability induced by peripheral formalin injection.

BACKGROUND: Salvinorin A (SA), the main active component of Salvia Divinorum, is a non-nitrogenous kappa opioid receptor (KOR) agonist. It has been shown to reduce acute pain and to exert potent antinflammatory effects. This study assesses the effects and the mode of action of SA on formalin-induced persistent pain in mice. Specifically, the SA effects on long-term behavioural dysfuctions and changes in neuronal activity occurring at spinal level, after single peripheral formalin injection, have been investigated. Moreover, the involvement of microglial and glial cells in formalin-induced chronic pain condition and in SA-mediated effects has been evaluated. RESULTS: Formalin induced a significant decrease of mechanical withdrawal threshold at the injected and contralateral paw as well as an increase in the duration and frequency, and a rapid decrease in the onset of evoked activity of the nociceptive neurons 7 days after formalin injection. SA daily treatment significantly reduced mechanical allodynia in KOR and cannabinoid receptor 1 (CB1R) sensitive manner. SA treatment also normalized the spinal evoked activity. SA significantly reduced the formalin-mediated microglia and astrocytes activation and modulated pro and anti-inflammatory mediators in the spinal cord. CONCLUSION: SA is effective in reducing formalin-induced mechanical allodynia and spinal neuronal hyperactivity. Our findings suggest that SA reduces glial activation and contributes in the establishment of dysfunctions associated with chronic pain with mechanisms involving KOR and CB1R. SA may provide a new lead compound for developing anti-allodynic agents via KOR and CB1R activation.

Therapeutic management of a symptomatic Kaposi's sarcoma patient with renal failure undergoing haemodialysis: A case report.

Kaposi's sarcoma (KS) is a rare inflammation- based vascular cancer involving the skin. The viral aetiology of KS is the Human Herpesvirus 8. KS may be frequently diagnosed in immunosuppressed kidneytransplanted patients, while is less common in patients with dialysis. It is known that various immunological abnormalities can lead to impaired immune status in uremic patients. It is noteworthy that despite the incidence of KS in patients with renal impairment, only few cases have reported efficacy and safety profile of KS targeting anti-cancer drugs in this kidney disease population. Herein, we report the first case of a symptomatic KS patient with renal disease in haemodialysis and focus on its therapeutic management. We also review the main data available from literature regarding the safety of KS therapy in dialysis patients.

Anorectic and aversive effects of GLP-1 receptor agonism are mediated by brainstem cholecystokinin neurons, and modulated by GIP receptor activation.

OBJECTIVE: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective medications to reduce appetite and body weight. These actions are centrally mediated; however, the neuronal substrates involved are poorly understood. METHODS: We employed a combination of neuroanatomical, genetic, and behavioral approaches in the mouse to investigate the involvement of caudal brainstem cholecystokinin-expressing neurons in the effect of the GLP-1RA exendin-4. We further confirmed key neuroanatomical findings in the non-human primate brain. RESULTS: We found that cholecystokinin-expressing neurons in the caudal brainstem are required for the anorectic and body weight-lowering effects of GLP-1RAs and for the induction of GLP-1RA-induced conditioned taste avoidance. We further show that, while cholecystokinin-expressing neurons are not a direct target for glucose-dependent insulinotropic peptide (GIP), GIP receptor activation results in a reduced recruitment of these GLP-1RA-responsive neurons and a selective reduction of conditioned taste avoidance. CONCLUSIONS: In addition to disclosing a neuronal population required for the full appetite- and body weight-lowering effect of GLP-1RAs, our data also provide a novel framework for understanding and ameliorating GLP-1RA-induced nausea - a major factor for withdrawal from treatment.

Hypothalamic AgRP neurons exert top-down control on systemic TNF-α release during endotoxemia.

Loss of appetite and negative energy balance are common features of endotoxemia in all animals and are thought to have protective roles by reducing nutrient availability to host and pathogen metabolism. Accordingly, fasting and caloric restriction have well-established anti-inflammatory properties. However, in response to reduced nutrient availability at the cellular and organ levels, negative energy balance also recruits distinct energy-sensing brain circuits, but it is not known whether these neuronal systems have a role in its anti-inflammatory effects. Here, we report that hypothalamic AgRP neurons-a critical neuronal population for the central representation of negative energy balance-have parallel immunoregulatory functions. We found that when endotoxemia occurs in fasted mice, the activity of AgRP neurons remains sustained, but this activity does not influence feeding behavior and endotoxemic anorexia. Furthermore, we found that endotoxemia acutely desensitizes AgRP neurons, which also become refractory to inhibitory signals. Mimicking this sustained AgRP neuron activity in fed mice by chemogenetic activation-a manipulation known to recapitulate core behavioral features of fasting-results in reduced acute tumor necrosis factor alpha (TNF-α) release during endotoxemia. Mechanistically, we found that endogenous glucocorticoids play an important role: glucocorticoid receptor deletion from AgRP neurons prevents their endotoxemia-induced desensitization, and importantly, it counteracts the fasting-induced suppression of TNF-α release, resulting in prolonged sickness. Together, these findings provide evidence directly linking AgRP neuron activity to the acute response during endotoxemia, suggesting that these neurons are a functional component of the immunoregulatory effects associated with negative energy balance and catabolic metabolism.

Brain control of appetite during sickness.

Given the high-energy requirements to sustain immune responses and healing processes, it is intriguing that lack of appetite (i.e., anorexia) is a cardinal feature of sickness behaviour. While our understanding of the brain mechanisms that control appetite is rapidly growing, how inflammation affects these mechanisms is not fully understood. Here, we discuss advances in our understanding of discrete appetite controlling mechanisms and how inflammation influences their function. We further discuss the pathophysiological significance of anorexia and negative energy balance during the immune regulatory response. LINKED ARTICLES: This article is part of a themed issue on Cellular metabolism and diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.10/issuetoc.

Anti-proliferative effect of rhein, an anthraquinone isolated from Cassia species, on Caco-2 human adenocarcinoma cells.

In recent years, the use of anthraquinone laxatives, in particular senna, has been associated with damage to the intestinal epithelial layer and an increased risk of developing colorectal cancer. In this study, we evaluated the cytotoxicity of rhein, the active metabolite of senna, on human colon adenocarcinoma cells (Caco-2) and its effect on cell proliferation. Cytotoxicity studies were performed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), neutral red (NR) and trans-epithelial electrical resistance (TEER) assays whereas (3)H-thymidine incorporation and Western blot analysis were used to evaluate the effect of rhein on cell proliferation. Moreover, for genoprotection studies Comet assay and oxidative biomarkers measurement (malondialdehyde and reactive oxygen species) were used. Rhein (0.1-10 microg/ml) had no significant cytotoxic effect on proliferating and differentiated Caco-2 cells. Rhein (0.1 and 1 microg/ml) significantly reduced cell proliferation as well as mitogen-activated protein (MAP) kinase activation; by contrast, at high concentration (10 microg/ml) rhein significantly increased cell proliferation and extracellular-signal-related kinase (ERK) phosphorylation. Moreover, rhein (0.1-10 microg/ml): (i) did not adversely affect the integrity of tight junctions and hence epithelial barrier function; (ii) did not induce DNA damage, rather it was able to reduce H(2)O(2)-induced DNA damage and (iii) significantly inhibited the increase in malondialdehyde and reactive oxygen species (ROS) levels induced by H(2)O(2)/Fe(2+). Rhein was devoid of cytotoxic and genotoxic effects in colon adenocarcinoma cells. Moreover, at concentrations present in the colon after a human therapeutic dosage of senna, rhein inhibited cell proliferation via a mechanism that seems to involve directly the MAP kinase pathway. Finally, rhein prevents the DNA damage probably via an anti-oxidant mechanism.

NADPH oxidase 4 is protective and not fibrogenic in intestinal inflammation.

Dysregulated redox signaling and oxidative injury are associated with inflammatory processes and fibrosis. H2O2 generation by NOX4 has been suggested as a key driver in the development of fibrosis and a small molecule drug is under evaluation in clinical trials for idiopathic pulmonary fibrosis and primary biliary cholangitis. Fibrosis is a common complication in Crohn's disease (CD) leading to stricture formation in 35-40% of patients, who require surgical interventions in the absence of therapeutic options. Here we assess NOX4 expression in CD patients with inflammatory or stricturing disease and examine whether loss of NOX4 is beneficial in acute and fibrotic intestinal disease. NOX4 was upregulated in inflamed mucosal tissue of CD and ulcerative colitis (UC) patients, in CD ileal strictures, and in mice with intestinal inflammation. Nox4 deficiency in mice promoted pathogen colonization and exacerbated tissue injury in acute bacterial and chemical colitis. In contrast, in two chronic injury models aberrant tissue remodeling and fibrosis-related gene expression did not differ substantially between Nox4-/- mice and wildtype mice, suggesting that Nox4 is dispensable in TGF-ß1-driven intestinal fibrogenesis. While animal models do not recapitulate all the hallmarks of CD fibrosis, the tissue-protective role of Nox4 warrants a cautious approach to pharmacological inhibitors.

Analgesic and Anti-Inflammatory Effects of Perampanel in Acute and Chronic Pain Models in Mice: Interaction With the Cannabinergic System.

Pain conditions, such as neuropathic pain (NP) and persistent inflammatory pain are therapeutically difficult to manage. Previous studies have shown the involvement of glutamate receptor in pain modulation and in particular same of these showed the key role of the AMPA ionotropic glutamate receptor subtype. Antiseizure medications (ASMs) are often used to treat this symptom, however the effect of perampanel (PER), an ASM acting as selective, non-competitive inhibitor of the AMPA receptor on the management of pain has not well been investigated yet. Here we tested the potential analgesic and anti-inflammatory effects of PER, in acute and chronic pain models. PER was given orally either in acute (5 mg/kg) or repeated administration (3 mg/kg/d for 4 days). Pain response was assessed using models of nociceptive sensitivity, visceral and inflammatory pain, and mechanical allodynia and hyperalgesia induced by chronic constriction injury to the sciatic nerve. PER significantly reduced pain perception in all behavioral tests as well as CCI-induced mechanical allodynia and hyperalgesia in acute regimen (5 mg/kg). This effect was also observed after repeated treatment using the dose of 3 mg/kg/d. The antinociceptive, antiallodynic and antihyperalgesic effects of PER were attenuated when the CB1 antagonist AM251 (1 mg/kg/i.p.) was administered before PER treatment, suggesting the involvement of the cannabinergic system. Moreover, Ex vivo analyses showed that PER significantly increased CB1 receptor expression and reduced inflammatory cytokines (i.e. TNFα, IL-1ß, and IL-6) in the spinal cord. In conclusion, these results extend our knowledge on PER antinociceptive and antiallodynic effects and support the involvement of cannabinergic system on its mode of action.

Inhibitory effect of the anorexic compound oleoylethanolamide on gastric emptying in control and overweight mice.

Gastric emptying regulates food intake. Oleoylethanolamide (OEA), an endogenous acylethanolamide chemically related to the endocannabinoid anandamide, inhibits food intake, but its effect on gastric emptying is unknown. Here, we investigated the effect and the role of OEA on gastric emptying in mice fed either a standard (STD) or a high-fat diet (HFD) for 14 weeks. Gastric emptying was reduced by OEA, but not by its saturated analog, palmitoylethanolamide. The effect of OEA was unaffected by rimonabant (cannabinoid CB1 receptor antagonist), SR144528 (cannabinoid CB2 receptor antagonist), 5'-iodoresiniferatoxin (transient receptor potential vanilloid type 1 antagonist), or MK886 (peroxisome proliferator-activated receptor-alpha) antagonist. Compared to STD mice, HFD mice showed delayed gastric emptying and higher levels of gastric OEA. HFD-induced increase in OEA levels was accompanied by increased expression of the OEA-synthesizing enzyme N-acyl-phosphatidylethanolamine-selective phospholipase D and decreased expression of the OEA-degrading enzyme fatty acid amide hydrolase. These results might suggest that elevation of gastric OEA could possibly contribute to the delayed gastric emptying observed in HFD-fed animals. HFD regulates OEA levels in the stomach through an increase of its biosynthesis and a decrease of its enzymatic degradation. The inhibitory effect of OEA on gastric emptying here observed might underlie part of the anorexic effects of this compound previously reported.

Antispasmodic effects and structure-activity relationships of labdane diterpenoids from Marrubium globosum ssp. libanoticum.

Marrubium globosum ssp. libanoticum is a medicinal plant used in Lebanon to reduce pain and smooth muscle spasms. A chloroform extract obtained from M. globosum aerial parts reduced acetylcholine-induced contractions in the isolated mouse ileum. The purification of this extract identified, among 12 isolated labdane diterpenoids, four new compounds, named 13-epicyllenin A (4), 13,15-diepicyllenin A (5), marrulibacetal (9), and marrulactone (11). Their structures were determined by spectroscopic methods. Compound 9, which exerted antispasmodic activity, is likely the active ingredient of the extract. Preliminary structure-activity relationships for this class of compounds are suggested.

Inhibitory effect of quercetin on rat trachea contractility in vitro.

OBJECTIVES: The effect of quercetin, a naturally occurring flavonoid traditionally used to treat airway diseases such as bronchial asthma, on the contractile response elicited by electrical field stimulation or carbachol in rat isolated trachea was investigated. METHODS: Isolated tracheal tissue was subjected to contractions by an electrical field stimulation of 5 Hz for 30 s, 400 mA, and the responses in the presence of cumulative concentrations of quercetin (10(-6)-3x10(-4) M) were observed. The effect of quercetin was also evaluated after administration of phentolamine plus propranolol (to block alpha- and beta-adrenergic receptors), NG-nitro-L-arginine methyl ester (to block nitric oxide synthesis), capsaicin (to desensitise sensory C fibres), alpha-chymotrypsin (a proteolytic enzyme that rapidly degrades vasoactive intestinal peptide), SR140333 and SR48968 (tackykinin NK1 and NK2 receptor antagonists, respectively). KEY FINDINGS: Quercetin produced a concentration-dependent inhibition of contractions induced by both carbachol and electrical field stimulation. However, quercetin was more active in inhibiting the contractions produced by electrical field stimulation than those induced by carbachol, suggesting a presynaptic site of action (in addition to a postsynaptic effect, as revealed by the inhibitory action of quercetin on carbachol-induced contractions). The inhibitory effect of quercetin on contractions induced by electrical field stimulation was unaffected by phentolamine plus propranolol, SR 140333 and SR 48968, capsaicin treatment or by the proteolytic enzyme alpha-chymotrypsin. In contrast, the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester significantly reduced the inhibitory effect of quercetin on contractions induced by electrical field stimulation. CONCLUSIONS: Quercetin inhibits rat tracheal contractility through a presynaptic (involving nitric oxide) and a postsynaptic site of action.