The non-euphoric phytocannabinoid cannabidivarin counteracts intestinal inflammation in mice and cytokine expression in biopsies from UC pediatric patients.

Patients with ulcerative colitis (UC) using marijuana have been reported to experience symptomatic benefit. Cannabidivarin (CBDV) is a safe non-psychoactive phytocannabinoid able to activate and desensitize TRPA1, a member of the TRP channels superfamily, which plays a pivotal role in intestinal inflammation. Here, we have investigated the potential intestinal anti-inflammatory effect of CBDV in mice and in biopsies from pediatric patients with active UC. Colonic inflammation was induced in mice by dinitrobenzenesulfonic acid (DNBS). The effect of orally administered CBDV on macroscopic and microscopic damage, inflammatory parameters (i.e. myeloperoxidase activity, intestinal permeability and cytokine production) and faecal microbiota composition, was evaluated 3 days after DNBS administration. TRPA1 expression was studied by RT-PCR in inflamed colons of mice as well as in mucosal colonic biopsies of children with active UC, whose response to incubation with CBDV was also investigated. CBDV attenuates, in a TRPA1-antagonist sensitive manner, DNBS-induced signs of inflammation including neutrophil infiltration, intestinal permeability, and cytokine (i.e. IL-1ß, IL-6 and the chemokine MCP-1) production. CBDV also alters the dysregulation of gut microbiota associated to colitis. Finally, CBDV lessens cytokine expression in colonic biopsies from pediatric patients with ulcerative colitis, a condition in which TRPA1 was up-regulated. Our preclinical study shows that CBDV exerts intestinal anti-inflammatory effects in mice via TRPA1, and in children with active UC. Since CBDV has a favorable safety profile in humans, it may be considered for possible clinical trials in patients with UC.

Targeting fatty acid amide hydrolase and transient receptor potential vanilloid-1 simultaneously to modulate colonic motility and visceral sensation in the mouse: A pharmacological intervention with N-arachidonoyl-serotonin (AA-5-HT).

BACKGROUND: Endocannabinoid anandamide (AEA) inhibits intestinal motility and visceral pain, but it may also be proalgesic through transient receptor potential vanilloid-1 (TRPV1). AEA is degraded by fatty acid amide hydrolase (FAAH). This study explored whether dual inhibition of FAAH and TRPV1 reduces diarrhea and abdominal pain. METHODS: Immunostaining was performed on myenteric plexus of the mouse colon. The effects of the dual FAAH/TRPV1 inhibitor AA-5-HT on electrically induced contractility, excitatory junction potential (EJP) and fast (f) and slow (s) inhibitory junction potentials (IJP) in the mouse colon, colonic propulsion and visceromotor response (VMR) to rectal distension were studied. The colonic levels of endocannabinoids and fatty acid amides were measured. KEY RESULTS: CB1-positive neurons exhibited TRPV1; only some TRPV1 positive neurons did not express CB1. CB1 and FAAH did not colocalize. AA-5-HT (100 nM-10 µM) decreased colonic contractility by ~60%; this effect was abolished by TRPV1 antagonist 5'-IRTX, but not by CB1 antagonist, SR141716. AA-5-HT (1 µM-10 µM) inhibited EJP by ~30% and IJPs by ~50%. The effects of AA-5-HT on junction potentials were reversed by SR141716 and 5`-IRTX. AA-5-HT (20 mg/kg; i.p.) inhibited colonic propulsion by ~30%; SR141716 but not 5`-IRTX reversed this effect. AA-5-HT decreased VMR by ~50%-60%; these effects were not blocked by SR141716 or 5`-IRTX. AA-5-HT increased AEA in the colon. CONCLUSIONS AND INFERENCES: The effects of AA-5-HT on visceral sensation and colonic motility are differentially mediated by CB1, TRPV1 and non-CB1/TRPV1 mechanisms, possibly reflecting the distinct neuromodulatory roles of endocannabinoid and endovanilloid FAAH substrates in the mouse intestine.

Prokinetic effect of a standardized yarrow (Achillea millefolium) extract and its constituent choline: studies in the mouse and human stomach.

BACKGROUND: Functional dyspepsia (FD) is a highly prevalent gastrointestinal disorder characterized by alterations in gastric motility. Yarrow (Achillea millefolium L., Fam Asteraceae) preparations are traditional remedies used to treat dyspeptic complaints. Herein, we investigated the effect of a standardized dry water extract obtained from A. millefolium flowering tops (AME) on gastric motility. METHODS: The effect of AME on motility was evaluated on the resting tone of the isolated gastric antrum and on gastric emptying in vivo (phenol red meal method) both in control mice and in the model of cancer chemotherapy (cisplatin)-induced gastric abnormalities. KEY RESULTS: The AME contracted mouse and human gastric strips and this action was unaffected by hexamethonium and tetrodotoxin, but strongly reduced by atropine. Among various chemical ingredients in yarrow, choline, but not the flavonoids rutin and apigenin, mimicked the action of AME. Furthermore, AME deprived of choline did not exert a contractile effect. In vivo, AME stimulated gastric emptying both in control and in cisplatin-treated mice, being more active in pathological states. CONCLUSIONS & INFERENCES: It is concluded that (i) AME exerts a direct spasmogenic effect on gastric antrum; (ii) choline is the chemical ingredient responsible of such effect; (iii) the prokinetic effect of AME observed in vivo could provide the pharmacological basis underlying its traditional use in the treatment of dyspepsia.

Cannabinoid actions at TRPV channels: effects on TRPV3 and TRPV4 and their potential relevance to gastrointestinal inflammation.

AIM: Plant cannabinoids, like Δ(9)-tetrahydrocannabinol (THC) and cannabidiol (CBD), activate/desensitize thermosensitive transient receptor potential (TRP) channels of vanilloid type-1 or -2 (TRPV1 or TRPV2). We investigated whether cannabinoids also activate/desensitize two other 'thermo-TRP's', the TRP channels of vanilloid type-3 or -4 (TRPV3 or TRPV4), and if the TRPV-inactive cannabichromene (CBC) modifies the expression of TRPV1-4 channels in the gastrointestinal tract. METHODS: TRP activity was assessed by evaluating elevation of [Ca(2+)](i) in rat recombinant TRPV3- and TRPV4-expressing HEK-293 cells. TRP channel mRNA expression was measured by quantitative RT-PCR in the jejunum and ileum of mice treated with vehicle or the pro-inflammatory agent croton oil. RESULTS: (i) CBD and tetrahydrocannabivarin (THCV) stimulated TRPV3-mediated [Ca(2+)](i) with high efficacy (50-70% of the effect of ionomycin) and potency (EC(50∼) 3.7 µm), whereas cannabigerovarin (CBGV) and cannabigerolic acid (CBGA) were significantly more efficacious at desensitizing this channel to the action of carvacrol than at activating it; (ii) cannabidivarin and THCV stimulated TRPV4-mediated [Ca(2+)](i) with moderate-high efficacy (30-60% of the effect of ionomycin) and potency (EC(50) 0.9-6.4 µm), whereas CBGA, CBGV, cannabinol and cannabigerol were significantly more efficacious at desensitizing this channel to the action of 4-α-phorbol 12,13-didecanoate (4α-PDD) than at activating it; (iii) CBC reduced TRPV1ß, TRPV3 and TRPV4 mRNA in the jejunum, and TRPV3 and TRPV4 mRNA in the ileum of croton oil-treated mice. CONCLUSIONS: Cannabinoids can affect both the activity and the expression of TRPV1-4 channels, with various potential therapeutic applications, including in the gastrointestinal tract.

Inhibitory effects of bromelain, a cysteine protease derived from pineapple stem (Ananas comosus), on intestinal motility in mice.

BACKGROUND: Bromelain (BR) is a cysteine protease with inhibitory effects on intestinal secretion and inflammation. However, its effects on intestinal motility are largely unexplored. Thus, we investigated the effect of this plant-derived compound on intestinal contractility and transit in mice. METHODS: Contractility in vitro was evaluated by stimulating the mouse isolated ileum, in an organ bath, with acetylcholine, barium chloride, or electrical field stimulation. Motility in vivo was measured by evaluating the distribution of an orally administered fluorescent marker along the small intestine. Transit was also evaluated in pathophysiologic states induced by the pro-inflammatory compound croton oil or by the diabetogenic agent streptozotocin. KEY RESULTS: Bromelain inhibited the contractions induced by different spasmogenic compounds in the mouse ileum with similar potency. The antispasmodic effect was reduced or counteracted by the proteolytic enzyme inhibitor, gabexate (15 × 10(-6) mol L(-1) ), protease-activated receptor-2 (PAR-2) antagonist, N(1) -3-methylbutyryl-N(4) -6-aminohexanoyl-piperazine (10(-4) mol L(-1) ), phospholipase C (PLC) inhibitor, neomycin (3 × 10(-3) mol L(-1) ), and phosphodiesterase 4 (PDE4) inhibitor, rolipram (10(-6) mol L(-1) ). In vivo, BR preferentially inhibited motility in pathophysiologic states in a PAR-2-antagonist-sensitive manner. CONCLUSIONS & INFERENCES: Our data suggest that BR inhibits intestinal motility - preferentially in pathophysiologic conditions - with a mechanism possibly involving membrane PAR-2 and PLC and PDE4 as intracellular signals. Bromelain could be a lead compound for the development of new drugs, able to normalize the intestinal motility in inflammation and diabetes.

Cannabinoids and gastrointestinal motility: animal and human studies.

The plant Cannabis has been known for centuries to be beneficial in a variety of gastrointestinal diseases, including emesis, diarrhea, inflammatory bowel disease and intestinal pain. delta9-tetrahydrocannabinol, the main psychotropic component of Cannabis, acts via at least two types of cannabinoid receptors, named CB1 and CB2 receptors. CB1 receptors are located primarily on central and peripheral neurons (including the enteric nervous system) where they modulate neurotransmitter release, whereas CB2 receptors are concerned with immune function, inflammation and pain. The discovery of endogenous ligands [i.e. anandamide and 2-arachidonoyl glycerol (2-AG)] for these receptors indicates the presence of a functional endogenous cannabinoid system in the gastrointestinal tract. Anatomical and functional evidence suggests the presence of CB1 receptors in the myenteric plexus, which are associated with cholinergic neurons in a variety of species, including in humans. Activation of prejunctional CB1 receptors reduces excitatory enteric transmission (mainly cholinergic transmission) in different regions of the gastrointestinal tract. Consistently, in vivo studies have shown that cannabinoids reduce gastrointestinal transit in rodents through activation of CB1, but not CB2, receptors. However, in pathophysiological states, both CB1 and CB2 receptors could reduce the increase of intestinal motility induced by inflammatory stimuli. Cannabinoids also reduce gastrointestinal motility in randomized clinical trials. Overall, modulation of the gut endogenous cannabinoid system may provide a useful therapeutic target for disorders of gastrointestinal motility.

Inhibitory effect of salvinorin A, from Salvia divinorum, on ileitis-induced hypermotility: cross-talk between kappa-opioid and cannabinoid CB(1) receptors.

BACKGROUND AND PURPOSE: Salvinorin A, the active component of the hallucinogenic herb Salvia divinorum, inhibits intestinal motility through activation of kappa-opioid receptors (KORs). However, this compound may have target(s) other than the KORs in the inflamed gut. Because intestinal inflammation upregulates cannabinoid receptors and endogenous cannabinoids, in the present study we investigated the possible involvement of the endogenous cannabinoid system in salvinorin A-induced delay in motility in the inflamed gut. EXPERIMENTAL APPROACH: Motility in vivo was measured by evaluating the distribution of a fluorescent marker along the small intestine; intestinal inflammation was induced by the irritant croton oil; direct or indirect activity at cannabinoid receptors was evaluated by means of binding, enzymic and cellular uptake assays. KEY RESULTS: Salvinorin A as well as the KOR agonist U-50488 reduced motility in croton oil treated mice. The inhibitory effect of both salvinorin A and U-50488 was counteracted by the KOR antagonist nor-binaltorphimine and by the cannabinoid CB(1) receptor antagonist rimonabant. Rimonabant, however, did not counteract the inhibitory effect of salvinorin A on motility in control mice. Binding experiments showed very weak affinity of salvinorin A for cannabinoid CB(1) and CB(2) and no inhibitory effect on 2-arachidonoylglycerol and anandamide hydrolysis and cellular uptake. CONCLUSIONS AND IMPLICATIONS: The inhibitory effect of salvinorin A on motility reveals a functional interaction between cannabinoid CB(1) receptors and KORs in the inflamed--but not in the normal--gut in vivo.

Gastrointestinal regulation of food intake: general aspects and focus on anandamide and oleoylethanolamide.

The gastrointestinal tract plays a pivotal role in the regulation of food intake and energy balance. Signals from the gastrointestinal tract generally function to limit ingestion in the interest of efficient digestion. These signals may be released into the bloodstream or may activate afferent neurones that carry information to the brain and its cognitive centres, which regulates food intake. The rate at which nutrients become systemically available is also influenced by gastrointestinal motility: a delay in gastric emptying may evoke a satiety effect. Recent evidence suggests that the endocannabinoid anandamide and the related acylethanolamide oleoylethanolamide are produced in the intestine and might regulate feeding behaviour by engaging sensory afferent neurones that converge information to specific areas of the brain. The intestinal levels of these acylethanolamides are inversely correlated to feeding, as food deprivation increases intestinal levels of anandamide (which acts in the gut as a 'hunger signal'), while it decreases the levels of oleoylethanolamide (which acts in the gut as a 'satiety signal'). Additionally, these acylethanolamides, whose gastric levels change in response to diet-induced obesity, alter gastrointestinal motility, which might contribute to their effect on food intake and nutrient absorption.

Cannabidiol, extracted from Cannabis sativa, selectively inhibits inflammatory hypermotility in mice.

BACKGROUND AND PURPOSE: Cannabidiol is a Cannabis-derived non-psychotropic compound that exerts a plethora of pharmacological actions, including anti-inflammatory, neuroprotective and antitumour effects, with potential therapeutic interest. However, the actions of cannabidiol in the digestive tract are largely unexplored. In the present study, we investigated the effect of cannabidiol on intestinal motility in normal (control) mice and in mice with intestinal inflammation. EXPERIMENTAL APPROACH: Motility in vivo was measured by evaluating the distribution of an orally administered fluorescent marker along the small intestine; intestinal inflammation was induced by the irritant croton oil; contractility in vitro was evaluated by stimulating the isolated ileum, in an organ bath, with ACh. KEY RESULTS: In vivo, cannabidiol did not affect motility in control mice, but normalized croton oil-induced hypermotility. The inhibitory effect of cannabidiol was counteracted by the cannabinoid CB1 receptor antagonist rimonabant, but not by the cannabinoid CB2 receptor antagonist SR144528 (N-[-1S-endo-1,3,3-trimethyl bicyclo [2.2.1] heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide), by the opioid receptor antagonist naloxone or by the alpha2-adrenergic antagonist yohimbine. Cannabidiol did not reduce motility in animals treated with the fatty acid amide hydrolase (FAAH) inhibitor N-arachidonoyl-5-hydroxytryptamine, whereas loperamide was still effective. In vitro, cannabidiol inhibited ACh-induced contractions in the isolated ileum from both control and croton oil-treated mice. CONCLUSIONS AND IMPLICATIONS: Cannabidiol selectively reduces croton oil-induced hypermotility in mice in vivo and this effect involves cannabinoid CB1 receptors and FAAH. In view of its low toxicity in humans, cannabidiol may represent a good candidate to normalize motility in patients with inflammatory bowel disease.

Emerging role of cannabinoids in gastrointestinal and liver diseases: basic and clinical aspects.

A multitude of physiological effects and putative pathophysiological roles have been proposed for the endogenous cannabinoid system in the gastrointestinal tract, liver and pancreas. These range from effects on epithelial growth and regeneration, immune function, motor function, appetite control, fibrogenesis and secretion. Cannabinoids have the potential for therapeutic application in gut and liver diseases. Two exciting therapeutic applications in the area of reversing hepatic fibrosis as well as antineoplastic effects may have a significant impact in these diseases. This review critically appraises the experimental and clinical evidence supporting the clinical application of cannabinoid receptor-based drugs in gastrointestinal, liver and pancreatic diseases. Application of modern pharmacological principles will most probably expand the selective modulation of the cannabinoid system peripherally in humans. We anticipate that, in addition to the approval in several countries of the CB(1) antagonist, rimonabant, for the treatment of obesity and associated metabolic dysfunctions, other cannabinoid modulators are likely to have an impact on human disease in the future, including hepatic fibrosis and neoplasia.

Immune response induced by three Mycobacterium bovis BCG substrains with diverse regions of deletion in a C57BL/6 mouse model.

This study was performed to examine the adaptive immune response generated by three Mycobacterium bovis bacillus Calmette-Guérin (BCG) substrains to determine if the number of genomic regions of deletion played a significant role in determining the magnitude of the immune response or affected their ability to reduce the bacterial burden following low-dose aerosol challenge with a virulent M. tuberculosis strain. BCG Connaught, Pasteur, and Sweden were chosen as representative substrains, as they possessed many, intermediate, and few regions of deletion, respectively, as a result of changes in the genome in various regions. Mice were vaccinated subcutaneously and were then examined at 14, 21, and 42 days postvaccination. BCG was observed in the spleen, lung, and lymph nodes. BCG Connaught induced a greater pulmonary T-cell response than the other two substrains at day 14 postvaccination, although by 42 days postvaccination activated T-cell levels dropped to the levels observed in control mice for all three substrains. Among the three substrains, BCG Connaught induced significantly greater levels of interleukin-12 in bone marrow-derived macrophage cultures. Mice challenged at days 14, 21, and 42 postvaccination displayed an equal capacity to reduce the bacterial burden in the lungs and spleen. The data provide evidence that although the BCG substrains generated qualitatively and quantitatively different immune responses, they induced similar reductions in the bacterial burden against challenge with a virulent M. tuberculosis strain in the mouse model of tuberculosis. The data raise questions about the assessment of vaccine immune responses and the relationship to a vaccine's ability to reduce the bacterial burden.

The role of endocannabinoids in the regulation of gastric emptying: alterations in mice fed a high-fat diet.

BACKGROUND AND PURPOSE: Endocannabinoids (via cannabinoid CB(1) receptor activation) are physiological regulators of intestinal motility and food intake. However, their role in the regulation of gastric emptying is largely unexplored. The purpose of the present study was to investigate the involvement of the endocannabinoid system in the regulation of gastric emptying in mice fed either a standard diet (STD) or a high-fat diet (HFD) for 14 weeks. EXPERIMENTAL APPROACH: Gastric emptying was evaluated by measuring the amount of phenol red recovered in the stomach after oral challenge; CB(1) expression was analysed by quantitative reverse transcription-PCR; endocannabinoid (anandamide and 2-arachidonoyl glycerol) levels were measured by liquid chromatography-mass spectrometry. KEY RESULTS: Gastric emptying was reduced by anandamide, an effect counteracted by the CB(1) receptor antagonist rimonabant, but not by the CB(2) receptor antagonist SR144528 or by the transient receptor potential vanilloid type 1 (TRPV1) antagonist 5'-iodoresiniferatoxin. The fatty acid amide hydrolase (FAAH) inhibitor N-arachidonoyl-5-hydroxytryptamine (but not the anandamide uptake inhibitor OMDM-2) reduced gastric emptying in a way partly reduced by rimonabant. Compared to STD mice, HFD mice exhibited significantly higher body weight and fasting glucose levels, delayed gastric emptying and lower anandamide and CB(1) mRNA levels. N-arachidonoylserotonin (but not rimonabant) affected gastric emptying more efficaciously in HFD than STD mice. CONCLUSIONS AND IMPLICATIONS: Gastric emptying is physiologically regulated by the endocannabinoid system, which is downregulated following a HFD leading to overweight.

The hallucinogenic herb Salvia divinorum and its active ingredient salvinorin A reduce inflammation-induced hypermotility in mice.

The hallucinogenic plant Salvia divinorum has been used for medical treatments of gastrointestinal disorders. Here, we evaluated the effect of a standardized extract from the leaves of Salvia divinorum (SDE) and of its active ingredient salvinorin A on motility in vivo, both in physiological states and during croton oil-induced intestinal inflammation. SDE (1-100 mg kg(-1)) significantly inhibited motility only in inflamed, but not in control, mice. In control mice, salvinorin A (0.01-10 mg kg(-1)) significantly inhibited motility only at the highest doses tested (3 and 10 mg kg(-1)) and this effect was not counteracted by naloxone or by the kappa-opioid receptor (KOR) antagonist nor-binaltorphimine. Inflammation significantly increased the potency of salvinorin A (but not of the KOR agonist U-50488) in reducing motility. The inhibitory effects of both salvinorin A and U-50488 in inflamed mice were counteracted by naloxone or by nor-binaltorphimine. We conclude that salvinorin A may reduce motility through activation of different targets. In physiological states, salvinorin A, at high doses, inhibited motility through a non-KOR mediated mechanism. Gut inflammation increased the potency of salvinorin A; this effect was mediated by KOR, but it was not shared by U-50488, thus suggesting that salvinorin A may have target(s) other than KOR in the inflamed gut.

Role and regulation of acylethanolamides in energy balance: focus on adipocytes and beta-cells.

The endocannabinoid, arachidonoylethanolamide (AEA), and the peroxisome proliferator-activated receptor (PPAR)-alpha ligand, oleylethanolamide (OEA) produce opposite effects on lipogenesis. The regulation of OEA and its anti-inflammatory congener, palmitoylethanolamide (PEA), in adipocytes and pancreatic beta-cells has not been investigated. We report here the results of studies on acylethanolamide regulation in these cells during obesity and hyperglycaemia, and provide an overview of acylethanolamide role in metabolic control. We analysed by liquid chromatography-mass spectrometry OEA and PEA levels in: 1) mouse 3T3F442A adipocytes during insulin-induced differentiation, 2) rat insulinoma RIN m5F beta-cells kept in 'low' or 'high' glucose, 3) adipose tissue and pancreas of mice with high fat diet-induced obesity (DIO), and 4) in visceral fat or blood of obese or type 2 diabetes (T2D) patients. In adipocytes, OEA levels remain unchanged during differentiation, whereas those of PEA decrease significantly, and are under the negative control of both leptin and PPAR-gamma. PEA is significantly downregulated in subcutaneous adipose tissue of DIO mice. In RIN m5F insulinoma beta-cells, OEA and PEA levels are inhibited by 'very high' glucose, this effect being enhanced by insulin, whereas in cells kept for 24 h in 'high' glucose, they are stimulated by both glucose and insulin. Elevated OEA and PEA levels are found in the blood of T2D patients. Reduced PEA levels in hypertrophic adipocytes might play a role in obesity-related pro-inflammatory states. In beta-cells and human blood, OEA and PEA are down- or up-regulated under conditions of transient or chronic hyperglycaemia, respectively.

The cannabinoid CB(2) receptor: a good friend in the gut.

Mammalian tissues express the cannabinoid 1 (CB(1)) receptor and the cannabinoid 2 (CB(2)) receptor, the latter being involved in inflammation and pain. In somatic nerve pathways, the analgesic effects of CB(2) agonism are well documented. Two papers published in the Journal have provided evidence that CB(2) receptor activation inhibits visceral afferent nerve activity in rodents. These exciting findings are discussed in the context of recent data highlighting the emerging role of CB(2) receptor as a critical target able to counteract hypermotility in pathophysiological states, gut inflammation and possibly colon cancer.

Endocannabinoid overactivity and intestinal inflammation.

Cannabinoid receptors of type 1 and 2 (CB(1) and CB(2)), endogenous ligands that activate them (endocannabinoids), and mechanisms for endocannabinoid biosynthesis and inactivation have been identified in the gastrointestinal system. Activation of CB(1 )receptors by endocannabinoids produces relaxation of the lower oesophageal sphincter and inhibition of gastric acid secretion, intestinal motility, and fluid stimulated secretion. However, stimulation of cannabinoid receptors impacts on gastrointestinal functions in several other ways. Recent data indicate that the endocannabinoid system in the small intestine and colon becomes over stimulated during inflammation in both animal models and human inflammatory disorders. The pathological significance of this "endocannabinoid overactivity" and its possible exploitation for therapeutic purposes are discussed here.

The hallucinogenic herb Salvia divinorum and its active ingredient salvinorin A inhibit enteric cholinergic transmission in the guinea-pig ileum.

Salvia divinorum is a widespread hallucinogenic herb traditionally employed for divination, as well as a medicament for several disorders including disturbances of gastrointestinal motility. In the present study we evaluated the effect of a standardized extract from the leaves of S. divinorum (SDE) on enteric cholinergic transmission in the guinea-pig ileum. SDE reduced electrically evoked contractions without modifying the contractions elicited by exogenous acetylcholine, thus suggesting a prejunctional site of action. The inhibitory effect of SDE on twitch response was abolished by the opioid receptor antagonist naloxone and by the kappa-opioid antagonist nor-binaltorphimine, but not by naltrindole (a delta-opioid receptor antagonist), CTOP (a mu-opioid receptor antagonist), thioperamide (a H(3) receptor antagonist), yohimbine (an alpha(2)-receptor antagonist), methysergide (a 5-hydroxytryptamine receptor antagonist), N(G)-nitro-L-arginine methyl ester (an inhibitor of NO synthase) or apamin (a blocker of Ca(2+)-activated K(+) channels). Salvinorin A, the main active ingredient of S. divinorum, inhibited in a nor-binaltorphimine- and naloxone-sensitive manner electrically induced contractions. It is concluded that SDE depressed enteric cholinergic transmission likely through activation of kappa-opioid receptors and this may provide the pharmacological basis underlying its traditional antidiarrhoeal use. Salvinorin A might be the chemical ingredient responsible for this activity.

Senna and the formation of aberrant crypt foci and tumors in rats treated with azoxymethane.

Chronic use of anthraquinone laxatives has been blamed for the induction of habituation and the development of colonic cancer, but there are no definitive studies which have demonstrated this. To evaluate the carcinogenic potential of anthraquinones, the effect of long-term senna pod extract (SE) treatment on either healthy rats or rats treated with an initiating tumor agent (azoxymethane--AOM) has been studied. SE (30 and 60mg/kg), administered for 110 weeks, did not induce the development of aberrant crypt foci (ACF) and tumors in healthy rats. The development of ACF and tumors in rats treated with AOM were significantly reduced by SE (30 and 60 mg/kg). These results suggest that a chronic SE use does not predispose to colon cancer. By contrast, SE might exert an anti-tumoral activity on rat colon carcinogenesis.

Cannabinoids and the digestive tract.

In the digestive tract there is evidence for the presence of high levels of endocannabinoids (anandamide and 2-arachidonoylglycerol) and enzymes involved in the synthesis and metabolism of endocannabinoids. Immunohistochemical studies have shown the presence of CB1 receptors on myenteric and submucosal nerve plexuses along the alimentary tract. Pharmacological studies have shown that activation of CB1 receptors produces relaxation of the lower oesophageal sphincter, inhibition of gastric motility and acid secretion, as well as intestinal motility and secretion. In general, CB1-induced inhibition of intestinal motility and secretion is due to reduced acetylcholine release from enteric nerves. Conversely, endocannabinoids stimulate intestinal primary sensory neurons via the vanilloid VR1 receptor, resulting in enteritis and enhanced motility. The endogenous cannabinoid system has been found to be involved in the physiological control of colonic motility and in some pathophysiological states, including paralytic ileus, intestinal inflammation and cholera toxin-induced diarrhoea. Cannabinoids also possess antiemetic effects mediated by activation of central and peripheral CB1 receptors. Pharmacological modulation of the endogenous cannabinoid system could provide a new therapeutic target for the treatment of a number of gastrointestinal diseases, including nausea and vomiting, gastric ulcers, secretory diarrhoea, paralytic ileus, inflammatory bowel disease, colon cancer and gastro-oesophageal reflux conditions.

A matrix metalloproteinase inhibitor promotes granuloma formation during the early phase of Mycobacterium tuberculosis pulmonary infection.

OBJECTIVE: The host response to pulmonary Mycobacterium tuberculosis (Mtb) infection results in granuloma formation in an effort to limit infection, but the host immune cells also provide an environment in which Mtb persists. Granuloma formation requires immune cell infiltration and concurrent extensive remodeling of pulmonary tissue which we hypothesize to be the result of increased matrix metalloproteinases (MMP) activity. DESIGN: C57BL/6 mice infected with virulent Mtb (H37Rv) via intratracheal inoculation were treated with a synthetic inhibitor of MMP activity (BB-94). Mice were assessed for colony forming units, granuloma morphology, leukocyte recruitment and cytokine levels over 90 days of infection. RESULTS: BB-94 treated mice had significantly decreased numbers of pulmonary and blood-borne Mtb early during disease, increased collagen deposition within early granulomas and significantly decreased pulmonary leukocyte recruitment when compared to vehicle-treated, Mtb-infected mice. Cytokine expression did not differ significantly between groups. CONCLUSION: Events of early granuloma formation can be modified by inhibiting MMP activity, by decreasing leukocyte recruitment, a major source of MMPs during infection, enhancing the establishment of granulomas and decreasing blood-borne dissemination of Mtb.