Evaluation of fatty acid amides in the carrageenan-induced paw edema model

Carrageenan as a macromolecular crowding agent in human umbilical cord derived mesenchymal stromal cell culture

Cell sheet tissue engineering requires prolonged in vitro culture for the development of implantable devices. Unfortunately, lengthy in vitro culture is associated with cell phenotype loss and substantially higher cost of goods, which collectively hinder clinical translation and commercialisation of tissue engineered medicines. Although macromolecular crowding has been shown to enhance and accelerate extracellular matrix deposition, whilst maintaining cellular phenotype, the optimal macromolecular crowding agent still remains elusive. Herein, we evaluated the biophysical properties of seven different carrageenan molecules at five different concentrations and their effect on human umbilical cord-derived mesenchymal stromal cell morphology, viability, metabolic activity, proliferation, extracellular matrix deposition and surface marker expression. All types of carrageenan (CR) assessed demonstrated a hydrodynamic radius increase as a function of increasing concentration; high polydispersity; and negative charge. Two iota CRs were excluded from further analysis due to poor solubility in cell culture. Among the remaining five carrageenans, the lambda medium viscosity type at concentrations of 10 and 50 μg/ml did not affect cell morphology, viability, metabolic activity, proliferation and expression of surface markers and significantly increased the deposition of collagen types I, III and IV, fibronectin and laminin. Our data highlight the potential of lambda medium viscosity carrageenan as a macromolecular crowding agent for the accelerated development of functional tissue engineered medicines.

Anti-Inflammatory, Antioxidant, Chemical Characterization, and Safety Assessment of Argania spinosa Fruit Shell Extract from South-Western Morocco

Argania spinosa (L.) plays an important role in the Moroccan agroeconomy, providing both employment and export revenue. Argan oil production generates different by-products with functionalities that are not yet investigated, in particular, the shell fruit. The present study aims, for the first time, at evaluating the acute and subacute toxicity, anti-inflammatory, and antioxidant effects of argan fruit shell ethanol extract (AFSEE). The LD₅₀ of AFSEE was determined to be greater than the 5000 mg/kg body weight of mice. No significant variation in the body and organ weights was observed after 28 days of AFSEE treatment compared to that of the control group. Biochemical parameters and histopathological examination revealed no toxic effects of AFSEE. The AFSEE produced a significant inhibition of xylene-induced ear edema in mice. AFSEE reduced significantly the paw edema in mice after carrageenan injection. The chemical characterization showed that AFSEE contains a high level of total phenol content, flavonoids, condensed tannins, and flavanols. The obtained IC₅₀ of DPPH, ABTS, reducing power, and β-carotene demonstrates that AFSEE has a potential antioxidant effect. The results indicate that AFSEE was safe and nontoxic to mice even at higher doses. Furthermore, the present findings demonstrate that AFSEE has potential anti-inflammatory and antioxidant activities.

Palmitoylethanolamide and Related ALIAmides: Prohomeostatic Lipid Compounds for Animal Health and Wellbeing

Virtually every cellular process is affected by diet and this represents the foundation of dietary management to a variety of small animal disorders. Special attention is currently being paid to a family of naturally occurring lipid amides acting through the so-called autacoid local injury antagonism, i.e., the ALIA mechanism. The parent molecule of ALIAmides, palmitoyl ethanolamide (PEA), has being known since the 1950s as a nutritional factor with protective properties. Since then, PEA has been isolated from a variety of plant and animal food sources and its proresolving function in the mammalian body has been increasingly investigated. The discovery of the close interconnection between ALIAmides and the endocannabinoid system has greatly stimulated research efforts in this field. The multitarget and highly redundant mechanisms through which PEA exerts prohomeostatic functions fully breaks with the classical pharmacology view of “one drug, one target, one disease”, opening a new era in the management of animals’ health, i.e., an according-to-nature biomodulation of body responses to different stimuli and injury. The present review focuses on the direct and indirect endocannabinoid receptor agonism by PEA and its analogues and also targets the main findings from experimental and clinical studies on ALIAmides in animal health and wellbeing.

Anti-inflammatory Effect of Woodfordia fructicosa Leaves Ethanolic Extract on Adjuvant and Carragenan Treated Rats

BACKGROUND

Woodfordia fructicosa is used traditionally for the treatment of inflammation associated with arthritis.

METHODS

In the present study, the anti-inflammatory activity of W. fructicosa (WFE) leaves ethanolic extract was assessed in Sprague Dawley rats by giving 200 mg/kg dose orally. Inflammation was studied by using carrageenan induced paw edema, Freund's adjuvant (FA) and monosodium iodo acetate (MIA) induced arthritis as animal models. Serum tumor necrosis factor-alpha (TNF-α) was estimated in blood sample of animals treated with FA. The one way ANOVA followed by Bonferroni's test was used for statistical analysis.

RESULTS

WFE significantly decreased (P<0.05, P<0.001) paw thickness in carrageenan induced paw edema and FA induced arthritis. The significant decrease in knee diameter (P<0.001) in MIA induced arthritis as well as inhibitory effect (P<0.001) on elevated TNF- α was observed.

CONCLUSION

These results showed that the WFEexerted an inhibitory effect on TNF-α and carrageenan paw edema which may justify its traditional use in inflammatory conditions. Thus, the study shows that leaves of W. fruticose afford anti-inflammatory activity by preventing the inflammation in different animal models.

Safety and efficacy of a new micronized formulation of the ALIAmide palmitoylglucosamine in preclinical models of inflammation and osteoarthritis pain

Background

Osteoarthritis is increasingly recognized as the result of a complex interplay between inflammation, chrondrodegeneration, and pain. Joint mast cells are considered to play a key role in orchestrating this detrimental triad. ALIAmides down-modulate mast cells and more generally hyperactive cells. Here we investigated the safety and effectiveness of the ALIAmide N-palmitoyl-d-glucosamine (PGA) in inflammation and osteoarthritis pain.

Methods

Acute toxicity of micronized PGA (m-PGA) was assessed in rats following OECD Guideline No.425. PGA and m-PGA (30 mg/kg and 100 mg/kg) were orally administered to carrageenan (CAR)-injected rats. Dexamethasone 0.1 mg/kg was used as reference. Paw edema and thermal hyperalgesia were measured up to 6 h post-injection, when also myeloperoxidase activity and histological inflammation score were assessed. Rats subjected to intra-articular injection of sodium monoiodoacetate (MIA) were treated three times per week for 21 days with PGA or m-PGA (30 mg/kg). Mechanical allodynia and motor function were evaluated at different post-injection time points. Joint histological and radiographic damage was scored, articular mast cells were counted, and macrophages were immunohistochemically investigated. Levels of TNF-α, IL-1β, NGF, and MMP-1, MMP-3, and MMP-9 were measured in serum using commercial colorimetric ELISA kits. One- or two-way ANOVA followed by a Bonferroni post hoc test for multiple comparisons was used.

Results

Acute oral toxicity of m-PGA resulted in LD50 values in excess of 2000 mg/kg. A single oral administration of PGA and m-PGA significantly reduced CAR-induced inflammatory signs (edema, inflammatory infiltrate, and hyperalgesia), and m-PGA also reduced the histological score. Micronized PGA resulted in a superior activity to PGA on MIA-induced mechanical allodynia, locomotor disability, and histologic and radiographic damage. The MIA-induced increase in mast cell count and serum level of the investigated markers was also counteracted by PGA and to a significantly greater extent by m-PGA.

Conclusions

The results of the present study showed that PGA is endorsed with anti-inflammatory, pain-relieving, and joint-protective effects. Moreover, it proved that particle size reduction greatly enhances the activity of PGA, particularly on joint pain and disability. Given these results, m-PGA could be considered a valuable option in the management of osteoarthritis.

Micronized Palmitoylethanolamide-Polydatin Reduces the Painful Symptomatology in Patients with Interstitial Cystitis/Bladder Pain Syndrome

Aims

To assess the efficacy of a micronized-palmitoylethanolamide-polydatin (m-PEA-Pol) based product on chronic pelvic pain and severity of other symptoms in interstitial cystitis/bladder pain syndrome (IC/BPS) patients refractory to conventional therapies.

Methods

A pilot, open-label bicentric study was carried out involving 32 IC/BPS patients. Chronic, oral m-PEA-Pol treatment lasted 6 months. Bladder pain was evaluated using the visual analog scale, while changes from baseline in other urinary symptoms were evaluated by means of the O'Leary-Sant Interstitial Cystitis Symptom and Problem Index and the Pelvic Pain and Urgency/Frequency (PUF) symptom scale questionnaires. The generalized linear mixed model was used to evaluate significant mean changes across time.

Results

A significant and progressive reduction of pain intensity was observed during m-PEA-Pol treatment (p < 0.0001 for reduction over time). The effect was associated with a reduction in severity of patients' symptoms evaluated with the O'Leary-Sant questionnaire (p=0.0110 and p=0.0014 for cystitis symptoms and problem mean scores, respectively) and the PUF scale (p=0.0163 and p=0.0005 for symptom and bother mean scores, respectively). m-PEA-Pol therapy elicited a significant reduction over time in the urinary frequency evaluated with voiding diary (p=0.0005) and a small but not significant improvement of bladder capacity.

Conclusions

These data highlight the potential benefit of m-PEA-Pol in patients with rare pathology such as IC/BPS and confirm the good safety profile of micronized PEA-based products.

A double-blind randomized placebo controlled study assessing safety, tolerability and efficacy of palmitoylethanolamide for symptoms of knee osteoarthritis

BACKGROUND

The aim of the study was to assess the safety, tolerability and efficacy of palmitoylethanolamide (PEA) when dosed at 300 mg and 600 mg per day on symptoms of knee osteoarthritis.

METHODS

This was a single site, comparative, double-blind placebo controlled study in adults with mild to moderate knee osteoarthritis with 111 participants randomized to receive 300 mg PEA, 600 mg PEA or placebo each day, in divided doses b.i.d, for 8 weeks. The primary outcome was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The secondary outcomes were the Numerical Rating Scales (NRS) for pain, the Depression Anxiety Stress Scale (DASS), the Perceived Stress Scale (PSS), the Pittsburg Sleep Quality Index (PSQI), the Short Form Health Survey (SF-36), the use of rescue pain medication and clinical safety assessment.

RESULTS

There was a significant reduction in the total WOMAC score in the 300 mg PEA (p = 0.0372) and the 600 mg PEA (p = 0.0012) groups, the WOMAC pain score (300 mg PEA, p = 0.0074; 600 mg PEA, p =  < 0.001), the WOMAC stiffness score (PEA 300 mg, p < 0.0490; 600 mg PEA, p = 0.001) and in the WOMAC function score in the 600 mg PEA group (p = 0.033) compared to placebo. The NRS pain evaluations for "worst pain" and "least pain" were significantly reduced in the 300 mg PEA group (p < 0.001, p = 0.005) and the 600 mg PEA group (p < 0.001, p < 0.001) compared to placebo. There was a significant reduction in anxiety (DASS) in both active treatment groups (300 mg PEA, p = 0.042; 600 mg PEA group (p = 0.043) compared to placebo. There were no changes in the clinical markers and the product was well tolerated.

CONCLUSIONS

The study demonstrated that palmitoylethanolamide may be a novel treatment for attenuating pain and reducing other associated symptoms of knee osteoarthritis. Further studies on the pharmacological basis of this anti-inflammatory effect are now required.

Diuretic, Natriuretic, and Vasodepressor Activity of a Lipid Fraction Enhanced in Medium of Cultured Mouse Medullary Interstitial Cells by a Selective Fatty Acid Amide Hydrolase Inhibitor

The relationship between the endocannabinoid system in the renal medulla and the long-term regulation of blood pressure is not yet understood. To investigate the possible role of the endocannabinoid system in renomedullary interstitial cells, mouse medullary interstitial cells (MMICs) were obtained, cultured, and characterized for their responses to treatment with a selective inhibitor of fatty acid amide hydrolase, PF-3845 (N-3-pyridinyl-4-[[3-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenyl]methyl]-1-piperidinecarboxamide). Treatment of MMICs with PF-3845 increased cytoplasmic lipid granules detected by Sudan Black B staining and multilamellar bodies identified by transmission electron microscopy. High-performance liquid chromatography (HPLC) analyses of lipid extracts of MMIC culture medium revealed a 205-nm absorbing peak that showed responsiveness to PF-3845 treatment. The biologic activities of the PF-3845-induced product (PIP) isolated by HPLC were investigated in anesthetized, normotensive surgically instrumented mice. Intramedullary and intravenous infusion of PIP at low dose rates (0.5-1 area units under the peak/10 min) stimulated diuresis and natriuresis, whereas these parameters returned toward baseline at higher doses but mean arterial pressure (MAP) was lowered. Whereas intravenous bolus doses of PIP stimulated diuresis, the glomerular filtration rate, and medullary blood flow (MBF) and reduced or had no effect on MAP, an intraperitoneal bolus injection of PIP reduced MAP, increased MBF, and had no effect on urine parameters. These data support a model whereby PF-3845 treatment of MMICs results in increased secretion of a neutral lipid that acts directly to promote diuresis and natriuresis and indirectly through metabolites to produce vasodepression. Efforts to identify the structure of the PF-3845-induced lipid and its relationship to the previously proposed renomedullary antihypertensive lipids are ongoing.

The exogenous administration of CB2 specific agonist, GW405833, inhibits inflammation by reducing cytokine production and oxidative stress

The present study aimed to investigate the role of cannabinoid 2 (CB2) receptors in a rat model of acute inflammation. Therefore, the potential of anti-inflammatory effects of CB2 receptor agonist (GW405833), CB2 receptor antagonist (AM630), and diclofenac, were investigated in carrageenan induced paw oedema in rats: as were assessed by measuring paw oedema; myeloperoxidase (MPO) activity in paw tissue; malondialdehyde (MDA) concentration; glutathione (GSH) level in paw tissue for oxidant/antioxidant balance; cytokine (interleukin-1β, IL-1β; tumour necrosis factor-α, TNF-α) levels in serum; histopathology of paw tissue for inflammatory cell accumulations. The results showed that GW405833 or diclofenac significantly reduced carrageenan-induced paw oedema. GW405833 also inhibited the increase of MPO activity, the recruitment of total leukocytes and neutrophils, and MDA concentration during carrageenan-induced acute inflammation, along with reversed nearly to the normal levels the increased of TNF-α, and IL-1β in serum. AM630 did not affect inflammation alone however clearly reversed the effects of agonist when co-administered. The mechanism of GW405833's suppression of inflammation is supported by these results, which are achieved by the inhibition of neutrophil migration, which regulates the reduction of oxidative stress, TNF-α and IL-1β levels. Finally, the activation of CB2 receptor, by selective agonist, has a major role in peripheral inflammation, and in the near future, targeting the peripheral cannabinoid system as a promising alternative to treat inflammation diseases may be considered a novel pharmacologic approach.

The Endogenous Cannabinoid System: A Budding Source of Targets for Treating Inflammatory and Neuropathic Pain

A great need exists for the development of new medications to treat pain resulting from various disease states and types of injury. Given that the endogenous cannabinoid (that is, endocannabinoid) system modulates neuronal and immune cell function, both of which play key roles in pain, therapeutics targeting this system hold promise as novel analgesics. Potential therapeutic targets include the cannabinoid receptors, type 1 and 2, as well as biosynthetic and catabolic enzymes of the endocannabinoids N-arachidonoylethanolamine and 2-arachidonoylglycerol. Notably, cannabinoid receptor agonists as well as inhibitors of endocannabinoid-regulating enzymes fatty acid amide hydrolase and monoacylglycerol lipase produce reliable antinociceptive effects, and offer opioid-sparing antinociceptive effects in myriad preclinical inflammatory and neuropathic pain models. Emerging clinical studies show that 'medicinal' cannabis or cannabinoid-based medications relieve pain in human diseases such as cancer, multiple sclerosis, and fibromyalgia. However, clinical data have yet to demonstrate the analgesic efficacy of inhibitors of endocannabinoid-regulating enzymes. Likewise, the question of whether pharmacotherapies aimed at the endocannabinoid system promote opioid-sparing effects in the treatment of pain reflects an important area of research. Here we examine the preclinical and clinical evidence of various endocannabinoid system targets as potential therapeutic strategies for inflammatory and neuropathic pain conditions.

Anti-inflammatory and bronchodilatory constituents of leaf extracts of Anacardium occidentale L. in animal models

OBJECTIVE

Anacardium occidentale L. leaf is useful in the treatment of inflammation and asthma, but the bioactive constituents responsible for these activities have not been characterized. Therefore, this study was aimed at identifying the bioactive constituent(s) of A. occidentale ethanolic leaf extract (AOEL) and its solvent-soluble portions, and evaluating their effects on histamine-induced paw edema and bronchoconstriction.

METHODS

The bronchodilatory effect was determined by measuring the percentage protection provided by plant extracts in the histamine-induced bronchoconstriction model in guinea pigs. The anti-inflammatory effect of the extracts on histamine-induced paw edema in rats was determined by measuring the increase in paw diameter, after which the percent edema inhibition was calculated. The extracts were analyzed using gas chromatography-mass spectrometry to identify the bioactive constituents. Column chromatography and Fourier transform infrared spectroscopy were used respectively to isolate and characterize the constituents. The bronchodilatory and anti-inflammatory activities of the isolated bioactive constituent were evaluated.

RESULTS

Histamine induced bronchoconstriction in the guinea pigs and edema in the rat paw. AOEL, hexane-soluble portion of AOEL, ethyl acetate-soluble portion of AOEL, and chloroform-soluble portion of AOEL significantly increased bronchodilatory and anti-inflammatory activities (P < 0.05). Oleamide (9-octadecenamide) was identified as the most abundant compound in the extracts and was isolated. Oleamide significantly increased bronchodilatory and anti-inflammatory activities by 32.97% and 98.41%, respectively (P < 0.05).

CONCLUSION

These results indicate that oleamide is one of the bioactive constituents responsible for the bronchodilatory and anti-inflammatory activity of A. occidentale leaf, and can therefore be employed in the management of bronchoconstriction and inflammation.

A novel composite formulation of palmitoylethanolamide and quercetin decreases inflammation and relieves pain in inflammatory and osteoarthritic pain models

BACKGROUND

Osteoarthritis (OA) is a common progressive joint disease in dogs and cats. The goal of OA treatment is to reduce inflammation, minimize pain, and maintain joint function. Currently, non-steroidal anti-inflammatory drugs (e.g., meloxicam) are the cornerstone of treatment for OA pain, but side effects with long-term use pose important challenges to veterinary practitioners when dealing with OA pain. Palmitoylethanolamide (PEA) is a naturally-occurring fatty acid amide, locally produced on demand by tissues in response to stress. PEA endogenous levels change during inflammatory and painful conditions, including OA, i.e., they are typically increased during acute conditions and decreased in chronic inflammation. Systemic treatment with PEA has anti-inflammatory and pain-relieving effects in several disorders, yet data are lacking in OA. Here we tested a new composite, i.e., PEA co-ultramicronized with the natural antioxidant quercetin (PEA-Q), administered orally in two different rat models of inflammatory and OA pain, namely carrageenan paw oedema and sodium monoiodoacetate (MIA)-induced OA. Oral treatment with meloxicam was used as benchmark.

RESULTS

PEA-Q decreased inflammatory and hyperalgesic responses induced by carrageenan injection, as shown by: (i) paw oedema reduction, (ii) decreased severity in histological inflammatory score, (iii) reduced activity of myeloperoxidase, i.e., a marker of inflammatory cell infiltration, and (iv) decreased thermal hyperalgesia. Overall PEA-Q showed superior effects compared to meloxicam. In MIA-treated animals, PEA-Q exerted the following effects: (i) reduced mechanical allodynia and improved locomotor function, (ii) protected cartilage against MIA-induced histological damage, and (iii) counteracted the increased serum concentration of tumor necrosis factor alpha, interleukin 1 beta, metalloproteases 1, 3, 9 and nerve growth factor. The magnitude of these effects was comparable to, or even greater than, those of meloxicam.

CONCLUSION

The present findings shed new light on some of the inflammatory and nociceptive pathways and mediators targeted by PEA-Q and confirm its anti-inflammatory and pain-relieving effects in rodent OA pain models. The translatability of these observations to canine and feline OA pain is currently under investigation.

The endocannabinoid hydrolysis inhibitor SA-57: Intrinsic antinociceptive effects, augmented morphine-induced antinociception, and attenuated heroin seeking behavior in mice

Although opioids are highly efficacious analgesics, their abuse potential and other untoward side effects diminish their therapeutic utility. The addition of non-opioid analgesics offers a promising strategy to reduce required antinociceptive opioid doses that concomitantly reduce opioid-related side effects. Inhibitors of the primary endocannabinoid catabolic enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) show opioid-sparing effects in preclinical models of pain. As simultaneous inhibition of these enzymes elicits enhanced antinociceptive effects compared with single enzyme inhibition, the present study tested whether the dual FAAH-MAGL inhibitor SA-57 [4-[2-(4-chlorophenyl)ethyl]-1-piperidinecarboxylic acid 2-(methylamino)-2-oxoethyl ester] produces morphine-sparing antinociceptive effects, without major side effects associated with either drug class. SA-57 dose-dependently reversed mechanical allodynia in the constriction injury (CCI) of the sciatic nerve model of neuropathic pain and carrageenan inflammatory pain model. As previously reported, SA-57 was considerably more potent in elevating anandamide (AEA) than 2-arachidonyl glycerol (2-AG) in brain. Its anti-allodynic effects required cannabinoid (CB)₁ and CB₂ receptors; however, only CB₂ receptors were necessary for the anti-edematous effects in the carrageenan assay. Although high doses of SA-57 alone were required to produce antinociception, low doses of this compound, which elevated AEA and did not affect 2-AG brain levels, augmented the antinociceptive effects of morphine, but lacked cannabimimetic side effects. Because of the high abuse liability of opioids and implication of the endocannabinoid system in the reinforcing effects of opioids, the final experiment tested whether SA-57 would alter heroin seeking behavior. Strikingly, SA-57 reduced heroin-reinforced nose poke behavior and the progressive ratio break point for heroin. In conclusion, the results of the present study suggest that inhibition of endocannabinoid degradative enzymes represents a promising therapeutic approach to decrease effective doses of opioids needed for clinical pain control, and may also possess therapeutic potential to reduce opioid abuse.

Assessment of Phenolic Compounds and Anti-Inflammatory Activity of Ethyl Acetate Phase of Anacardium occidentale L. Bark

The bark of A. occidentale L. is rich in tannins. Studies have described various biological activities of the plant, including antimicrobial, antioxidant, antiulcerogenic and antiinflammatory actions. The objective of this study was to assess the activity of the ethyl acetate phase (EtOAc) of A. occidentale on acute inflammation and to identify and quantify its phenolic compounds by HPLC. The method was validated and shown to be linear, precise and accurate for catechin, epicatechin, epigallocatechin and gallic acid. Swiss albino mice (Mus musculus) were treated with saline, Carrageenan (2.5%), Indomethacin (10 mg/kg), Bradykinin (6 nmol) and Prostaglandine E2 (5 µg) at different concentrations of EtOAc - A. occidentale (12.5; 25; 50; and 100 mg/kg/weight p.o.) for the paw edema test. Challenge was performed with carrageenan (500 µg/mL i.p.) for the doses 50 and 100 mg/kg of EtOAc. Levels of cytokines IL-1, TNF-α, IL-6 and IL-10 were also measured. All EtOAc - A. occidentale concentrations reduced the edema. At 50 and 100 mg/kg, an anti-inflammatory response of the EtOAc was observed. Carrageenan stimulus produced a neutrophil count of 28.6% while 50 and 100 mg/kg of the phase reduced this to 14.5% and 9.1%, respectively. The EtOAc extract reduced levels of IL-1 and TNF-α. These results suggest that the EtOAc plays a modulatory role in the inflammatory response. The chromatographic method can be used for the analysis of the phenolic compounds of the EtOAc phase.

Mustard vesicants alter expression of the endocannabinoid system in mouse skin

Vesicants including sulfur mustard (SM) and nitrogen mustard (NM) are bifunctional alkylating agents that cause skin inflammation, edema and blistering. This is associated with alterations in keratinocyte growth and differentiation. Endogenous cannabinoids, including N-arachidonoylethanolamine (anandamide, AEA) and 2-arachidonoyl glycerol (2-AG), are important in regulating inflammation, keratinocyte proliferation and wound healing. Their activity is mediated by binding to cannabinoid receptors 1 and 2 (CB1 and CB2), as well as peroxisome proliferator-activated receptor alpha (PPARα). Levels of endocannabinoids are regulated by fatty acid amide hydrolase (FAAH). We found that CB1, CB2, PPARα and FAAH were all constitutively expressed in mouse epidermis and dermal appendages. Topical administration of NM or SM, at concentrations that induce tissue injury, resulted in upregulation of FAAH, CB1, CB2 and PPARα, a response that persisted throughout the wound healing process. Inhibitors of FAAH including a novel class of vanillyl alcohol carbamates were found to be highly effective in suppressing vesicant-induced inflammation in mouse skin. Taken together, these data indicate that the endocannabinoid system is important in regulating skin homeostasis and that inhibitors of FAAH may be useful as medical countermeasures against vesicants.

A Cannabinoid CB1 Receptor-Positive Allosteric Modulator Reduces Neuropathic Pain in the Mouse with No Psychoactive Effects

The CB1 receptor represents a promising target for the treatment of several disorders including pain-related disease states. However, therapeutic applications of Δ(9)-tetrahydrocannabinol and other CB1 orthosteric receptor agonists remain limited because of psychoactive side effects. Positive allosteric modulators (PAMs) offer an alternative approach to enhance CB1 receptor function for therapeutic gain with the promise of reduced side effects. Here we describe the development of the novel synthetic CB1 PAM, 6-methyl-3-(2-nitro-1-(thiophen-2-yl)ethyl)-2-phenyl-1H-indole (ZCZ011), which augments the in vitro and in vivo pharmacological actions of the CB1 orthosteric agonists CP55,940 and N-arachidonoylethanolamine (AEA). ZCZ011 potentiated binding of [(3)H]CP55,940 to the CB1 receptor as well as enhancing AEA-stimulated [(35)S]GTPγS binding in mouse brain membranes and β-arrestin recruitment and ERK phosphorylation in hCB1 cells. In the whole animal, ZCZ011 is brain penetrant, increased the potency of these orthosteric agonists in mouse behavioral assays indicative of cannabimimetic activity, including antinociception, hypothermia, catalepsy, locomotor activity, and in the drug discrimination paradigm. Administration of ZCZ011 alone was devoid of activity in these assays and did not produce a conditioned place preference or aversion, but elicited CB1 receptor-mediated antinociceptive effects in the chronic constriction nerve injury model of neuropathic pain and carrageenan model of inflammatory pain. These data suggest that ZCZ011 acts as a CB1 PAM and provide the first proof of principle that CB1 PAMs offer a promising strategy to treat neuropathic and inflammatory pain with minimal or no cannabimimetic side effects.

Esculin exhibited anti-inflammatory activities in vivo and regulated TNF-α and IL-6 production in LPS-stimulated mouse peritoneal macrophages in vitro through MAPK pathway

Esculin, a coumarinic derivative found in Aesculus hippocastanum L. (Horse-chestnut), has been reported to have potent anti-inflammatory properties. The present study is designed to investigate the protective effects of esculin on various inflammation models in vivo and in vitro and to clarify the possible mechanism. Induced-animal models of inflammation and lipopolysaccharide (LPS)-challenged mouse peritoneal macrophages were used to examine the anti-inflammatory activity of esculin. In present study, xylene-induced mouse ear edema, carrageenan-induced rat paw edema, and carrageenan-induced mouse pleurisy were attenuated by esculin. In vitro, the pro-inflammatory cytokine levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in supernatant were reduced by esculin. Meanwhile, we found that esculin significantly inhibited LPS-induced activation of mitogen-activated protein kinase (MAPK) pathway in peritoneal macrophages. These results suggest that esculin has potent anti-inflammatory activities in vivo and in vitro, which may involve the inhibition of the MAPK pathway. Esculin may be a promising preventive agent for inflammatory diseases in human.

Coptis chinensis and Myrobalan (Terminalia chebula) Can Synergistically Inhibit Inflammatory Response In Vitro and In Vivo

Objectives. To investigate the anti-inflammatory effect of Coptis chinensis plus myrobalan (CM) in vitro and in vivo. Methods. The inflammation in mouse peritoneal macrophages was induced by lipopolysaccharide (LPS). Animal models were established by using ear swelling and paw edema of mouse induced by xylene and formaldehyde, respectively. In vitro, cytotoxicity, the phagocytosis of macrophages, the levels of nitric oxide (NO), induced nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in cell supernatant were detected. In vivo, swelling rate and edema inhibitory rate of ear and paw were observed using CM-treated mice. Results. At 150–18.75 μg·mL⁻¹, CM had no cytotoxicity and could significantly promote the growth and the phagocytosis of macrophages and inhibit the overproduction of NO, iNOS, TNF-α, and IL-6 in macrophages induced by LPS. In vivo, pretreatment with CM, the ear swelling, and paw edema of mice could be significantly inhibited in a dose-dependent manner, and the antiedema effect of CM at high dose was better than dexamethasone. Conclusion. Our results demonstrated that Coptis chinensis and myrobalan possessed synergistically anti-inflammatory activities in vitro and in vivo, which indicated that CM had therapeutic potential for the prevention and treatment of inflammation-mediated diseases.

Attenuation of cystitis and pain sensation in mice lacking fatty acid amide hydrolase

Endocannabinoids, such as N-arachidonoylethanolamine (AEA, also called anandamide), exert potent analgesic and anti-inflammatory effects. Fatty acid amide hydrolase (FAAH) is primarily responsible for degradation of AEA, and deletion of FAAH increases AEA content in various tissues. Since FAAH has been shown to be present in the bladder of various species, we compared bladder function, severity of experimental cystitis, and cystitis-associated referred hyperalgesia in male wild-type (WT) and FAAH knock-out (KO) mice. Basal concentrations of AEA were greater, and the severity of cyclophosphamide (CYP)-induced cystitis was reduced in bladders from FAAH KO compared to WT mice. Cystitis-associated increased peripheral sensitivity to mechanical stimuli and enhanced bladder activity (as reflected by increased voiding frequency) were attenuated in FAAH KO compared to WT mice. Further, abundances of mRNA for several pro-inflammatory compounds were increased in the bladder mucosa after CYP treatment of WT mice, and this increase was inhibited in FAAH KO mice. These data indicate that endogenous substrates of FAAH, including the cannabinoid AEA, play an inhibitory role in bladder inflammation and subsequent changes in pain perception. Therefore, FAAH could be a therapeutic target to treat clinical symptoms of painful inflammatory bladder diseases.

Anti-inflammatory potential of zootherapeutics derived from animals used in Brazilian traditional medicine

CONTEXT

Animals are used for the treatment of diseases caused by inflammatory processes, although few studies evaluate their potential for these purposes.

OBJECTIVES

To evaluate the anti-inflammatory potential of zootherapeutic products derived from vertebrates used in Brazilian traditional medicine.

MATERIAL AND METHODS

The species analyzed were Tupinambis merianae, Iguana iguana, Crotalus durissus, Boa constrictor, and Euphractus sexcinctus. The methods used in anti-inflammatory assays were ear edema (topical) and paw (systemic).

RESULTS

With regard to topical anti-inflammatory activity, the fat from T. merianae, C. durissus, I. iguana, B. constrictor, and E. sexcinctus reduced inflammation, while for systemic anti-inflammatory activity, only the fat and the skin of C. durissus, the skin of I. iguana and the fat from B. constrictor reduced inflammation.

CONCLUSIONS

Studies should be conducted to evaluate the mechanisms of action for each product that demonstrated anti-inflammatory activity as well as against other inflammatory processes.

Colitis generates remote antinociception in rats: the role of the L-arginine/NO/cGMP/PKG/KATP pathway and involvement of cannabinoid and opioid systems

OBJECTIVE AND DESIGN

The aim of this study was to investigate the possible involvement of the NO/cGMP/PKG/KATP+ pathway, cannabinoids and opioids in remote antinociception associated with 2,4,6-trinitrobenzene sulph onic acid (TNBS)-induced colitis.

METHODS

TNBS-induced colitis was induced by intracolonic administration of 20 mg of TNBS in 50% ethanol. After induction, carrageenan (500 μg/paw) or prostaglandin (PG) E2 (100 ng/paw) was injected in the rat's plantar surface and hypersensitivity was evaluated by the electronic von Frey test. Rats were pre-treated with L-Noarg one hour before carrageenan injection. L-Arginine was given 10 min before L-Noarg injections. ODQ, KT 5823, glibenclamide (Glib), naloxone and AM 251 or AM 630 were administered 30 min prior to carrageenan or PGE2 treatments.

RESULTS

Colitis induction by TNBS reduced PGE2 or carrageenan-induced hypersensitivity. Antinociception produced by TNBS-induced colitis was reversed significantly (P<0.05) by L-Noarg, ODQ, KT 5823, glibenclamide, naloxone, AM251 and AM630 treatments.

CONCLUSIONS

TNBS-induced colitis causes antinociception in the rat paw. This disorder appears to be mediated by activation of the NO/cGMP/PKG/KATP pathway, endocannabinoids and endogenous opioids. This information may contribute to a better understanding of peripheral neurological dysfunctions occurring in Crohn's disease.

Anti-inflammatory and antioxidant activities of Costus afer Ker Gawl. hexane leaf fraction in arthritic rat models

ETHNOPHARMACOLOGICAL RELEVANCE

Costus afer Ker Gawl is an indigenous tropical African medicinal plant used as therapy in the treatment of inflammatory ailments such as rheumatoid arthritis. This study was designed to evaluate the anti-inflammatory and antioxidant activities of the hexane fraction of C. afer leaves (CAHLF).

MATERIALS AND METHODS

The anti-inflammatory effect of varying doses of CAHLF on carrageenan, arachidonic acid, and formaldehyde induced arthritis in male albino rats׳ models were investigated in order to study the acute inflammatory phase. Complete Freund׳s Adjuvant (CFA)-induced arthritis model was used to study the chronic inflammatory phase. Two known anti-inflammatory drugs, Diclofenac sodium (non-steroidal anti-inflammatory drug [NSAID]) and prednisolone (glucocorticoid [steroidal drug]) were used as standards for comparison. Various biochemical indices viz. superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), reduced glutathione (GSH) and malondialdehyde (MDA), aspartate amino transferase (AST), alanine amino transferase (ALT), alkaline phosphatase (ALP), total bilirubin (TB), total protein (TP), globulin and albumin levels were assayed using spectrophotometric methods.

RESULTS

Control animals in which arthritis have been induced using carrageenan, arachidonic acid, formaldehyde or CFA showed significant increases (P<0.05) in paw edema when compared with normal animals. Treatment of the arthritis induced rats with CAHLF significantly (P<0.05) suppressed the edema. in vivo antioxidant study showed that CAHLF treated animals had a significantly (P<0.05) elevated GSH level, SOD, CAT and GST activities while MDA levels were significantly (P<0.05) reduced in the plasma, liver, kidney and brain. CAHLF treated rats had a significantly (P<0.05) reduced plasma AST, ALT and ALP. Plasma TP, globulin, TB levels were reduced while albumin levels were elevated in CAHLF treated animals.

CONCLUSIONS

CAHLF possesses substantial anti-inflammatory and antioxidant activities against inflammatory diseases especially arthritis. It could be considered as a choice candidate in pharmaceutical anti-inflammatory drug development.

Harnessing the anti-inflammatory potential of palmitoylethanolamide

Palmitoylethanolamide (PEA) is a peroxisome proliferator-activated receptor alpha (PPAR-α) ligand that exerts anti-inflammatory, analgesic and neuroprotective actions. PEA is synthetized from phospholipids through the sequential actions of N-acyltransferase and N-acylphosphatidylethanolamine-preferring phospholipase D (NAPE-PLD), and its actions are terminated by its hydrolysis by two enzymes, fatty acid amide hydrolase (FAAH) and N-acylethanolamine-hydrolysing acid amidase (NAAA). Here, we review the impact of PEA administration in inflammatory and neurodegenerative settings and the differential role of FAAH and NAAA in controlling PEA levels. Recent studies with NAAA inhibitors put forth this enzyme as capable of increasing PEA levels in vivo in inflammatory processes, and identified it as an interesting target for drug discovery research. Thus, PEA hydrolysis inhibitors could constitute potential therapeutic alternatives in chronic inflammatory and neurodegenerative diseases.

Elevation of endogenous anandamide impairs LTP, learning, and memory through CB1 receptor signaling in mice

In rodents, many exogenous and endogenous cannabinoids, such as anandamide (AEA) and 2-arachidonyl glycerol (2-AG), have been shown to play an important role in certain hippocampal memory processes. However, the mechanisms by which endogenous AEA regulate this processes are not well understood. Here the effects of AEA on long-term potentiation (LTP), hippocampal-dependent learning and memory tasks, pERK1/2, pCaMKIV, and pCREB signaling events in both cannabinoid receptor type 1 (CB1R) wild-type (WT) and knockout (KO) mice were assessed following administration of URB597, an inhibitor of the fatty acid amide hydrolase (FAAH). Acute administration of URB597 enhanced AEA levels without affecting the levels of 2-AG or CB1R in the hippocampus and neocortex as compared to vehicle. In hippocampal slices, URB597 impaired LTP in CB1R WT but not in KO littermates. URB597 impaired object recognition, spontaneous alternation and spatial memory in the Y-maze test in CB1R WT mice but not in KO mice. Furthermore, URB597 enhanced ERK phosphorylation in WT without affecting total ERK levels in WT or KO mice. URB597 impaired CaMKIV and CREB phosphorylation in WT but not in KO mice. CB1R KO mice have a lower pCaMKIV/CaMKIV ratio and higher pCREB/CREB ratio as compared to WT littermates. Our results indicate that pharmacologically elevated AEA impair LTP, learning and memory and inhibit CaMKIV and CREB phosphorylation, via the activation of CB1Rs. Collectively, these findings also suggest that pharmacological elevation of AEA beyond normal concentrations is also detrimental for the underlying physiological responses.

Targeting inflammation: new therapeutic approaches in chronic kidney disease (CKD)

Chronic inflammation and oxidative stress, features that are closely associated with nuclear factor (NF-κB) activation, play a key role in the development and progression of chronic kidney disease (CKD). Several animal models and clinical trials have clearly demonstrated the effectiveness of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) therapy to improve glomerular/tubulointerstitial damage, reduce proteinuria, and decrease CKD progression, but CKD treatment still represents a clinical challenge. Bardoxolone methyl, a first-in-class oral Nrf-2 (nuclear factor erythroid 2-related factor 2) agonist that until recently showed considerable potential for the management of a range of chronic diseases, had been shown to improve kidney function in patients with advanced diabetic nephropathy (DN) with few adverse events in a phase 2 trial, but a large phase 3 study in patients with diabetes and CKD was halted due to emerging toxicity and death in a number of patients. Instead, palmitoylethanolamide (PEA) a member of the fatty acid ethanolamine family, is a novel non-steroidal, kidney friendly anti-inflammatory and anti-fibrotic agent with a well-documented safety profile, that may represent a potential candidate in treating CKD probably by a combination of pharmacological properties, including some activity at the peroxisome proliferator activated receptor alpha (PPAR-α). The aim of this review is to discuss new therapeutic approaches for the treatment of CKD, with particular reference to the outcome of two therapies, bardoxolone methyl and PEA, to improve our understanding of which pharmacological properties are responsible for the anti-inflammatory effects necessary for the effective treatment of renal disease.

In vivo characterization of the highly selective monoacylglycerol lipase inhibitor KML29: antinociceptive activity without cannabimimetic side effects

BACKGROUND AND PURPOSE

Since monoacylglycerol lipase (MAGL) has been firmly established as the predominant catabolic enzyme of the endocannabinoid 2-arachidonoylglycerol (2-AG), a great need has emerged for the development of highly selective MAGL inhibitors. Here, we tested the in vivo effects of one such compound, KML29 (1,1,1,3,3,3-hexafluoropropan-2-yl 4-(bis(benzo[d][1,3]dioxol-5-yl)(hydroxy)methyl)piperidine-1-carboxylate).

EXPERIMENTAL APPROACH

In the present study, we tested KML29 in murine inflammatory (i.e. carrageenan) and sciatic nerve injury pain models, as well as the diclofenac-induced gastric haemorrhage model. KML29 was also evaluated for cannabimimetic effects, including measurements of locomotor activity, body temperature, catalepsy, and cannabinoid interoceptive effects in the drug discrimination paradigm.

KEY RESULTS

KML29 attenuated carrageenan-induced paw oedema and completely reversed carrageenan-induced mechanical allodynia. These effects underwent tolerance after repeated administration of high-dose KML29, which were accompanied by cannabinoid receptor 1 (CB1 ) receptor desensitization. Acute or repeated KML29 administration increased 2-AG levels and concomitantly reduced arachidonic acid levels, but without elevating anandamide (AEA) levels in the whole brain. Furthermore, KML29 partially reversed allodynia in the sciatic nerve injury model and completely prevented diclofenac-induced gastric haemorrhages. CB1 and CB2 receptors played differential roles in these pharmacological effects of KML29. In contrast, KML29 did not elicit cannabimimetic effects, including catalepsy, hypothermia and hypomotility. Although KML29 did not substitute for Δ(9) -tetrahydrocannabinol (THC) in C57BL/6J mice, it fully and dose-dependantly substituted for AEA in fatty acid amide hydrolase (FAAH) (-/-) mice, consistent with previous work showing that dual FAAH and MAGL inhibition produces THC-like subjective effects.

CONCLUSIONS AND IMPLICATIONS

These results indicate that KML29, a highly selective MAGL inhibitor, reduces inflammatory and neuropathic nociceptive behaviour without occurrence of cannabimimetic side effects.

LINKED ARTICLES

This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.

Inhibitory effect of topical adelmidrol on antigen-induced skin wheal and mast cell behavior in a canine model of allergic dermatitis

BACKGROUND

Adelmidrol is a semisynthetic derivative of azelaic acid and analogue of the anti-inflammatory compound palmitoylethanolamide (PEA). Based upon its physicochemical properties, adelmidrol is suitable for topical application. The main objective of the present study was to evaluate the efficacy of a topical adelmidrol emulsion on early and late inflammatory responses in hypersensitive dogs. Repeated intradermal injections of Ascaris suum extract were performed in both lateral thoracic areas of six conscious hypersensitive Beagle dogs, topically treated during 8 consecutive days. Adelmidrol (2%) was applied to one side and vehicle to the other. 24 hours after the last antigen challenge, two biopsies (adelmidrol- and vehicle-treated side) were obtained for each dog at the antigen injection site.

RESULTS

A significant reduction in the antigen-induced wheal areas was observed on the 4th and 7th day of adelmidrol treatment. Moreover, cutaneous mast cell numbers were significantly decreased in biopsies obtained after 8 consecutive days of topical adelmidrol treatment.

CONCLUSIONS

The results obtained in the present study show that topical treatment with adelmidrol might represent a new therapeutic tool in controlling the early and late allergic inflammatory skin responses in companion animals.

Isofraxidin exhibited anti-inflammatory effects in vivo and inhibited TNF-α production in LPS-induced mouse peritoneal macrophages in vitro via the MAPK pathway

Isofraxidin (IF) is a Coumarin compound that can be isolated from medicinal plants, such as Sarcandra glabra (Thunb.). Nakai is widely used in Asian countries for the treatment of anti-bacterial, anti-inflammatory and anti-tumour action. The present investigation was designed to evaluate the effect of IF on inflammation and nociception. In addition, we investigated a potential novel mechanism to explain the anti-inflammatory properties of IF. In vivo, xylene-induced mouse ear edema, carrageenan-induced rat paw edema, LPS-induced mouse endotoxic shock, acetic acid-induced mice writhing and formalin-induced mouse pain models were used to evaluate the anti-inflammatory activity of IF. In vitro, we examined the effects of IF inhibition on TNF-α production and the regulation of ERK1/2 and p38 phosphorylation activity in LPS-induced mouse peritoneal macrophages. Our results demonstrated that IF can significantly decrease xylene-induced ear edema, carrageenan-induced paw edema, acetic acid-induced writhing and formalin-induced pain. Moreover, IF greatly inhibited the production of TNF-α in the serum of LPS-stimulated mice and peritoneal macrophages, and it decreased phospho-p38 and ERK1/2 protein expression in LPS-stimulated mouse peritoneal macrophages. Overall, our data suggest that IF possesses significant analgesic and anti-inflammatory activities that may be mediated through the regulation of pro-inflammatory cytokines, TNF-α and the phosphorylation of p38 and ERK1/2.

The monoacylglycerol lipase inhibitor JZL184 suppresses inflammatory pain in the mouse carrageenan model

AIM

The present study tested whether the selective monoacylglycerol lipase (MAGL) inhibitor JZL184 would reduce allodynia and paw edema in the carrageenan test.

MAIN METHODS

The anti-edematous and anti-allodynic effects of JZL184 were compared to those of PF-3845, an inhibitor of fatty acid amide hydrolase (FAAH), and diclofenac, a non-selective cyclooxygenase inhibitor. Cannabinoid receptor involvement in the anti-edematous and anti-allodynic effects of JZL184 was evaluated by administration of the respective CB1 and CB2 receptor antagonists rimonabant and SR144528 as well as with CB1(-/-) and CB2(-/-) mice. JZL184 (1.6, 4, 16, or 40mg/kg) was administered for six days to assess tolerance.

KEY FINDINGS

JZL184 administered before or after carrageenan significantly attenuated carrageenan-induced paw edema and mechanical allodynia. Complementary genetic and pharmacological approaches revealed that the anti-allodynic effects of JZL184 required both CB1 and CB2 receptors, but only CB2 receptors mediated its anti-edematous actions. Importantly, both the anti-edematous and anti-allodynic effects underwent tolerance following repeated injections of high dose JZL184 (16 or 40mg/kg), but repeated administration of low dose JZL184 (4mg/kg) retained efficacy.

SIGNIFICANCE

These results suggest that the MAGL inhibitor JZL184 reduces inflammatory nociception through the activation of both CB1 and CB2 receptors, with no evidence of tolerance following repeated administration of low doses.

Inhibiting fatty acid amide hydrolase normalizes endotoxin-induced enhanced gastrointestinal motility in mice

BACKGROUND AND PURPOSE

Gastrointestinal (GI) motility is regulated in part by fatty acid ethanolamides (FAEs), including the endocannabinoid (EC) anandamide (AEA). The actions of FAEs are terminated by fatty acid amide hydrolase (FAAH). We investigated the actions of the novel FAAH inhibitor AM3506 on normal and enhanced GI motility.

EXPERIMENTAL APPROACH

We examined the effect of AM3506 on electrically-evoked contractility in vitro and GI transit and colonic faecal output in vivo, in normal and FAAH-deficient mice treated with saline or LPS (100 µg·kg(-1), i.p.), in the presence and absence of cannabinoid (CB) receptor antagonists. mRNA expression was measured by quantitative real time-PCR, EC levels by liquid chromatography-MS and FAAH activity by the conversion of [(3)H]-AEA to [(3)H]-ethanolamine in intestinal extracts. FAAH expression was examined by immunohistochemistry.

KEY RESULTS

FAAH was dominantly expressed in the enteric nervous system; its mRNA levels were higher in the ileum than the colon. LPS enhanced ileal contractility in the absence of overt inflammation. AM3506 reversed the enhanced electrically-evoked contractions of the ileum through CB(1) and CB(2) receptors. LPS increased the rate of upper GI transit and faecal output. AM3506 normalized the enhanced GI transit through CB(1) and CB(2) receptors and faecal output through CB(1) receptors. LPS did not increase GI transit in FAAH-deficient mice.

CONCLUSIONS AND IMPLICATIONS

Inhibiting FAAH normalizes various parameters of GI dysmotility in intestinal pathophysiology. Inhibition of FAAH represents a new approach to the treatment of disordered intestinal motility.

CRSBP-1/LYVE-1 ligands disrupt lymphatic intercellular adhesion by inducing tyrosine phosphorylation and internalization of VE-cadherin

Cell-surface retention sequence (CRS) binding protein (CRSBP-1) is a membrane glycoprotein identified by its ability to bind PDGF-BB and VEGF-A via their CRS motifs (clusters of basic amino acid residues). CRSBP-1 is identical to LYVE-1 and exhibits dual ligand (CRS-containing proteins and hyaluronic acid) binding activity, suggesting the importance of CRSBP-1 ligands in lymphatic function. Here, we show that CRSBP-1 ligands induce disruption of VE-cadherin-mediated intercellular adhesion and opening of intercellular junctions in lymphatic endothelial cell (LEC) monolayers as determined by immunofluorescence microscopy and Transwell permeability assay. This occurs by interaction with CRSBP-1 in the CRSBP-1-PDGFβR-β-catenin complex, resulting in tyrosine phosphorylation of the complex, dissociation of β-catenin and p120-catenin from VE-cadherin, and internalization of VE-cadherin. Pretreatment of LECs with a PDGFβR kinase inhibitor abolishes ligand-stimulated tyrosine phosphorylation of VE-cadherin, halts the ligand-induced disruption of VE-cadherin intercellular adhesion and blocks the ligand-induced opening of intercellular junctions. These CRSBP-1 ligands also induce opening of lymphatic intercellular junctions that respond to PDGFβR kinase inhibitor in wild-type mice (but not in Crsbp1-null mice) as evidenced by increased transit of injected FITC-dextran and induced edema fluid from the interstitial space into lymphatic vessels. These results disclose a novel mechanism involved in the opening of lymphatic intercellular junctions.

Pharmacological elevation of anandamide impairs short-term memory by altering the neurophysiology in the hippocampus

In rodents, many exogenous cannabinoid agonists including Δ(9)-THC and WIN55,212-2 (WIN-2) have been shown to impair short-term memory (STM) by inhibition of hippocampal neuronal assemblies. However, the mechanisms by which endocannabinoids such as anandamide and 2-arachidonyl glycerol (2-AG) modulate STM processes are not well understood. Here the effects of anandamide on performance of a Delayed-Non-Match-to-Sample (DNMS) task (i.e. STM task) and concomitant hippocampal ensemble activity were assessed following administration of either URB597 (0.3, 3.0 mg/kg), an inhibitor of the Fatty Acid Amide Hydrolase (FAAH), AM404 (1.5, 10.0 mg/kg), a putative anandamide uptake/FAAH inhibitor, or R-methanandamide (3.0, 10.0 mg/kg), a stable analog of anandamide. Principal cells from hippocampal CA3/CA1 were recorded extracellularly by multi-electrode arrays in Long-Evans rats during DNMS task (1-30 s delays) performance and tracked throughout drug administration and recovery. Both R-methanandamide and URB597 caused dose- and delay-dependent deficits in DNMS performance with suppression of hippocampal ensemble activity during the encoding (sample) phase. R-methanandamide-induced effects were not reversed by capsaicin excluding a contribution of TRPV-1 receptors. AM404 produced subtle deficits at longer delay intervals but did not alter hippocampal neuronal activity during task-specific events. Collectively, these data indicate that endocannabinoid levels affect performance in a STM task and their pharmacological elevation beyond normal concentrations is detrimental also for the underlying physiological responses. They also highlight a specific window of memory processing, i.e. encoding, which is sensitive to cannabinoid modulation.

Fatty acid amide hydrolase blockade attenuates the development of collagen-induced arthritis and related thermal hyperalgesia in mice

Fatty acid amide hydrolase (FAAH) is the primary degradative enzyme of the endocannabinoid anandamide (N-arachidonoylethanolamine), which activates cannabinoid CB(1) and CB(2) receptors. FAAH disruption reduces nociception in a variety of acute rodent models of inflammatory pain. The present study investigated whether these actions extend to the chronic, collagen-induced arthritis (CIA) model. We investigated the anti-arthritic and anti-hyperalgesic effects of genetic deletion or pharmacological inhibition of FAAH in the CIA model. FAAH (-/-) mice, and FAAH-NS mice that express FAAH exclusively in nervous tissue, displayed decreased severity of CIA and associated hyperalgesia. These phenotypic anti-arthritic effects were prevented by repeated daily injections of the CB(2) receptor antagonist, SR144528, but not the CB(1) receptor antagonist rimonabant. Similarly, repeated administration of the FAAH inhibitor URB597 reduced CIA severity, and acute administration of rimonabant, but not SR144528, blocked the anti-hyperalgesic effects of prolonged FAAH inhibition, suggesting that prolonged CB(2) receptor activation reduces the severity of CIA, whereas acute CB(1) receptor activation reduces CIA-induced hyperalgesia. In contrast, acute administration of URB597 elicited a CB(1) receptor-dependent anti-hyperalgesic effect. The observed anti-arthritic and anti-hyperalgesic properties of FAAH inhibition, coupled with a lack of apparent behavioral alterations, suggest that endocannabinoid modulating enzymes offer a promising therapeutic target for the development of novel pharmacological approaches to treat rheumatoid arthritis and associated hyperalgesia.

The endogenous cannabinoid anandamide shares discriminative stimulus effects with ∆(9)-tetrahydrocannabinol in fatty acid amide hydrolase knockout mice

The endogenous cannabinoid system has been noted for its therapeutic potential, as well as the psychoactivity of cannabinoids such as Δ9-tetrahydrocannabinol (THC). However, less is known about the psychoactivity of anandamide (AEA), an endocannabinoid ligand. Thus, the goals of this study were to establish AEA as a discriminative stimulus in transgenic mice lacking fatty acid amide hydrolase (i.e., FAAH -/- mice unable to rapidly metabolize AEA), evaluate whether THC or oleamide, a fatty acid amide, produced AEA-like responding, and assess for CB(1) mediation of AEA's discriminative stimulus. Mice readily discriminated between 6mg/kg AEA and vehicle in a two-lever drug discrimination task. AEA dose-dependently generalized to itself. THC elicited full AEA-like responding, whereas oleamide failed to substitute. The CB(1) antagonist rimonabant attenuated AEA- and THC-induced AEA-appropriate responding, demonstrating CB(1) mediation of AEA's discriminative stimulus. These findings suggest that, in the absence of FAAH, AEA produces intoxication comparable to THC, and consequently to marijuana.

Synthesis of gold and silver nanoparticles stabilized with glycosaminoglycans having distinctive biological activities

Metal nanoparticles have been studied for their anticoagulant and anti-inflammatory efficacy in various models. Specifically, gold and silver nanoparticles exhibit properties that make these ideal candidates for biological applications. The typical synthesis of gold and silver nanoparticles incorporates contaminants that could pose further problems. Here we demonstrate a clean method of synthesizing gold and silver nanoparticles that exhibit biological functions. These nanoparticles were prepared by reducing AuCl(4) and AgNO(3) using heparin and hyaluronan as both reducing and stabilizing agents. The particles show stability under physiological conditions and narrow size distributions for heparin particles and wider distribution for hyaluronan particles. Studies show that the heparin nanoparticles exhibit anticoagulant properties. Additionally, either gold- or silver-heparin nanoparticles exhibit local anti-inflammatory properties without any significant effect on systemic hemostasis upon administration in carrageenan-induced paw edema models. In conclusion, gold and silver nanoparticles complexed with heparin demonstrated effective anticoagulant and anti-inflammatory efficacy, having potential in various local applications.

Fatty acid amide hydrolase and monoacylglycerol lipase inhibitors produce anti-allodynic effects in mice through distinct cannabinoid receptor mechanisms

The endocannabinoids anandamide and 2-arachidonoylglycerol are predominantly regulated by the respective catabolic enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). Inhibition of these enzymes elevates endocannabinoid levels and attenuates neuropathic pain. In the present study, CB₁ and CB₂ receptor-deficient mice were subjected to chronic constriction injury (CCI) of the sciatic nerve to examine the relative contribution of each receptor for the anti-allodynic effects of the FAAH inhibitor, PF-3845, and the MAGL inhibitor, JZL184. CCI caused marked hypersensitivity to mechanical and cold stimuli, which was not altered by deletion of either the CB₁ or CB₂ receptor, but was attenuated by gabapentin, as well as by each enzyme inhibitor. Whereas PF-3845 lacked anti-allodynic efficacy in both knockout lines, JZL184 did not produce anti-allodynic effects in CB₁ (-/-) mice, but retained its anti-allodynic effects in CB₂ (-/-) mice. These data indicate that FAAH and MAGL inhibitors reduce nerve injury-related hyperalgesic states through distinct cannabinoid receptor mechanisms of action. In conclusion, although endogenous cannabinoids do not appear to play a tonic role in long-term expression of neuropathic pain states, both FAAH and MAGL represent potential therapeutic targets for the development of pharmacological agents to treat chronic pain resulting from nerve injury.

PERSPECTIVE

This article presents data addressing the cannabinoid receptor mechanisms underlying the anti-allodynic actions of endocannabinoid catabolic enzyme inhibitors in the mouse sciatic nerve ligation model. Fatty acid amide hydrolase and monoacylglycerol lipase inhibitors reduced allodynia through distinct cannabinoid receptor mechanisms. These enzymes offer potential targets to treat neuropathic pain.

Individual and additive effects of the CNR1 and FAAH genes on brain response to marijuana cues

As previous work has highlighted the significance of the cannabinoid receptor 1 (CNR1) and fatty acid amide hydrolase (FAAH) genes with respect to cannabis dependence (CD), this study sought to characterize the neural mechanisms that underlie these genetic effects. To this end, we collected DNA samples and fMRI data using a cue-elicited craving paradigm in thirty-seven 3-day-abstinent regular marijuana users. The participants were grouped according to their genotype on two single-nucleotide polymorphisms (SNPs) earlier associated with CD phenotypes: rs2023239 in CNR1 and rs324420 in FAAH. Between-group comparisons showed that carriers of the CNR1 rs2023239 G allele had significantly greater activity in reward-related areas of the brain, such as the orbitofrontal cortex (OFC), inferior frontal gyrus (IFG), and anterior cingulate gyrus (ACG), during exposure to marijuana cues, as compared with those with the A/A genotype for this SNP. The FAAH group contrasts showed that FAAH rs324420 C homozygotes also had greater activation in widespread areas within the reward circuit, specifically in the OFC, ACG, and nucleus accumbens (NAc), as compared with the FAAH A-allele carriers. Moreover, there was a positive correlation between neural response in OFC and NAc and the total number of risk alleles (cluster-corrected p<0.05). These findings are in accord with earlier reported associations between CNR1 and FAAH and CD intermediate phenotypes, and suggest that the underlying mechanism of these genetic effects may be enhanced neural response in reward areas of the brain in carriers of the CNR1 G allele and FAAH C/C genotype in response to marijuana cues.

Effects of palmitoylethanolamide on immunologically induced histamine, PGD2 and TNFalpha release from canine skin mast cells

Palmitoylethanolamide (PEA) is an endocannabinoid-like compound and the parent molecule of the aliamide family, a group of fatty acid amides able to act through the down-regulation of mast cell degranulation. PEA has been proven to exert both analgesic and anti-inflammatory activity, and recent studies have shown its ability in reducing clinical symptoms of inflammatory skin diseases, both in humans and in animals. Although its pharmacological efficacy is well known, the mechanism of action of this family of compounds is still unclear. To better understand the cellular effects of aliamides in dogs, canine mast cells freshly isolated from skin biopsies were incubated with IgE-rich serum and were challenged with anti-canine IgE. Histamine, prostaglandin D(2) (PGD(2)) and tumour necrosis factor-alpha (TNFalpha) release was measured in the presence and absence of increasing concentrations of PEA, ranging from 10(-8)M to 10(-5)M. Histamine, PGD(2) and TNFalpha release, immunologically induced by canine anti-IgE, were significantly inhibited in the presence of PEA. The maximum inhibitory effect on histamine release was observed at 3x10(-6)M PEA concentration achieving an inhibition of 54.3+/-5.2%. PGD(2) release was significantly inhibited at 10(-5)M and 10(-6)M PEA concentrations with 25.5+/-10.2% and 14.6+/-5.6% of inhibition, respectively. Finally, PEA inhibited TNFalpha release to 29.2+/-2.0% and 22.1+/-7.2%, at concentrations of 10(-5)M and 3x10(-6)M, respectively. The results obtained in the present study showed the ability of the aliamide PEA to down-modulate skin mast cell activation. Therefore, our findings suggest that the beneficial effect of PEA, observed in inflammation and pain clinical studies, could be due, at least in part, to its ability to inhibit the release of both preformed and newly synthesised mast cell mediators.

In vivo pharmacology of endocannabinoids and their metabolic inhibitors: therapeutic implications in Parkinson's disease and abuse liability

This review focuses on the behavioral pharmacology of endogenous cannabinoids (endocannabinoids) and indirect-acting cannabinoid agonists that elevate endocannabinoid tone by inhibiting the activity of metabolic enzymes. Similarities and differences between prototype cannabinoid agonists, endocannabinoids and inhibitors of endocannabinoid metabolism are discussed in the context of endocannabinoid pharmacokinetics in vivo. The distribution and function of cannabinoid and non-CB(1)/CB(2) receptors are also covered, with emphasis on their role in disorders characterized by dopamine dysfunction, such as drug abuse and Parkinson's disease. Finally, evidence is presented to suggest that FAAH inhibitors lack the abuse liability associated with CB(1) agonists, although they may modify the addictive properties of other drugs, such as alcohol.

Fatty acid amide hydrolase as a potential therapeutic target for the treatment of pain and CNS disorders

BACKGROUND: Fatty acid amide hydrolase (FAAH) is an integral membrane enzyme that hydrolyzes the endocannabinoid anandamide and related amidated signaling lipids. Genetic or pharmacological inactivation of FAAH produces analgesic, anti-inflammatory, anxiolytic, and antidepressant phenotypes without showing the undesirable side effects of direct cannabinoid receptor agonists, indicating that FAAH may be a promising therapeutic target. OBJECTIVES: This review highlights advances in the development of FAAH inhibitors of different mechanistic classes and their in vivo efficacy. Also highlighted are advances in technology for the in vitro and in vivo selectivity assessment of FAAH inhibitors employing activity-based protein profiling (ABPP) and click chemistry-ABPP, respectively. Recent reports on structure-based drug design for human FAAH generated by protein engineering using interspecies active site conversion are also discussed. METHODS: The literature searches of Medline and SciFinder databases were used. CONCLUSIONS: There has been tremendous progress in our understanding in FAAH and development of FAAH inhibitors with in vivo efficacy, selectivity, and drug like pharmacokinetic properties.

Cannabinoids, endocannabinoids, and related analogs in inflammation

This review covers reports published in the last 5 years on the anti-inflammatory activities of all classes of cannabinoids, including phytocannabinoids such as tetrahydrocannabinol and cannabidiol, synthetic analogs such as ajulemic acid and nabilone, the endogenous cannabinoids anandamide and related compounds, namely, the elmiric acids, and finally, noncannabinoid components of Cannabis that show anti-inflammatory action. It is intended to be an update on the topic of the involvement of cannabinoids in the process of inflammation. A possible mechanism for these actions is suggested involving increased production of eicosanoids that promote the resolution of inflammation. This differentiates these cannabinoids from cyclooxygenase-2 inhibitors that suppress the synthesis of eicosanoids that promote the induction of the inflammatory process.

Targeting fatty acid amide hydrolase (FAAH) to treat pain and inflammation

The endogenous cannabinoid N-arachidonoyl ethanolamine (anandamide; AEA) produces most of its pharmacological effects by binding and activating CB(1) and CB(2) cannabinoid receptors within the CNS and periphery. However, the actions of AEA are short lived because of its rapid catabolism by fatty acid amide hydrolase (FAAH). Indeed, FAAH knockout mice as well as animals treated with FAAH inhibitors are severely impaired in their ability to hydrolyze AEA as well as a variety of noncannabinoid lipid signaling molecules and consequently possess greatly elevated levels of these endogenous ligands. In this mini review, we describe recent research that has investigated the functional consequences of inhibiting this enzyme in a wide range of animal models of inflammatory and neuropathic pain states. FAAH-compromised animals reliably display antinociceptive and anti-inflammatory phenotypes with a similar efficacy as direct-acting cannabinoid receptor agonists, such as Delta(9)-tetrahydrocannabinol (THC), the primary psychoactive constituent of Cannabis sativa. Importantly, FAAH blockade does not elicit any apparent psychomimetic effects associated with THC or produce reinforcing effects that are predictive of human drug abuse. The beneficial effects caused by FAAH blockade in these models are predominantly mediated through the activation of CB(1) and/or CB(2) receptors, though noncannabinoid mechanisms of actions can also play contributory or even primary roles. Collectively, the current body of scientific literature suggests that activating the endogenous cannabinoid system by targeting FAAH is a promising strategy to treat pain and inflammation but lacks untoward side effects typically associated with Cannabis sativa.

Inhibition of fatty acid amide hydrolase produces PPAR-alpha-mediated analgesia in a rat model of inflammatory pain

BACKGROUND AND PURPOSE

We have previously demonstrated antinociceptive effects of fatty acid amide hydrolase (FAAH) inhibition that were accompanied by increases in the levels of endocannabinoids (ECs) in the hind paw. Here, the effects of the FAAH inhibitor URB597 (3'-carbamoyl-biphenyl-3-yl-cyclohexylcarbamate) on responses of spinal neurons were studied.

EXPERIMENTAL APPROACH

Extracellular single-unit recordings of dorsal horn neurons were made in anaesthetized rats with hind paw inflammation induced by lambda-carrageenan. Effects of intraplantar pre-administration of URB597, or vehicle, on carrageenan-evoked expansion of peripheral receptive fields of spinal neurons and mechanically evoked responses of neurons were studied. The cannabinoid receptor type 1 (CB(1)) antagonist AM251 (N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide) and the peroxisome proliferator-activated receptor (PPAR)-alpha antagonist GW6471 ([(2S)-2-[[(1Z)-1-methyl-3-oxo-3-[4-(trifluoromethyl)phenyl]-1-propenyl]amino]-3-[4-[2-(5-methyl-2-phenyl-4-oxa zolyl)ethoxy]phenyl]propyl]-carbamic acid ethyl ester) were used to investigate the roles of these receptors in mediating the effects of URB597.

KEY RESULTS

URB597 (25 microg in 50 microL) pretreatment significantly inhibited carrageenan-evoked receptive field expansion and this was significantly reversed by co-administration of the PPAR-alpha antagonist but not the CB(1) antagonist. Pretreatment with the PPAR-alpha receptor agonist WY14643 ([[4-chloro-6-[(2,3-dimethylphenyl)amino]-2-pyrimidinyl]thio]acetic acid) also significantly inhibited receptive field expansion. URB597 (25 or 100 microg in 50 microL) had no significant effect on mechanically evoked responses of spinal neurons.

CONCLUSIONS AND IMPLICATIONS

URB597 inhibited receptive field expansions but not mechanically evoked responses of spinal neurons in rats with hind paw inflammation. These effects were blocked by PPAR-alpha receptor antagonism. These data support the contention that URB597 exerts its antinociceptive effects by indirect inhibition of sensitization of neuronal responses at least partly through PPAR-alpha activation due to enhanced EC levels.

Fatty acid amide hydrolase inhibition enhances the anti-allodynic actions of endocannabinoids in a model of acute pain adapted for the mouse

Cannabinoid ligands have been shown to be anti-nociceptive in animal models of acute and chronic pain by acting at the two known cannabinoid receptors, cannabinoid-1 receptor (CB-1) and cannabinoid-2 receptor (CB-2). A major concern with the use of cannabinoids for pain relief is that they activate receptors at sites other than those involved in the transmission of nociceptive stimuli. An alternative approach is to target the naturally occurring endocannabinoids, such as anandamide (AEA), 2-arachidonylglycerol (2-AG) and N-arachidonylglycine (N-AG). However in vivo results obtained with these compounds appear to be weak, most probably due to their rapid degradation and subsequent short half-life. The predominant enzyme responsible for the hydrolysis of anandamide (and some other endocannabinoids) in the brain is fatty acid amide hydrolase (FAAH). Recently, the alpha-ketoheterocycle OL135 has been synthesized and shown to be a highly potent and selective inhibitor of FAAH with efficacy in pain models in vivo. In the present study, we have adapted the mild thermal injury (MTI) model of acute pain for the mouse and pharmacologically characterized this model by showing significant reversal of the tactile allodynia by morphine (3, 5 and 10 mg kg(-1) s.c.), gabapentin (100 and 300 mg kg(-1) i.p.), ibuprofen (100 mg kg(-1) i.p.) and OL135 (10, 30 and 100 mg kg(-1) i.p.). Furthermore we have demonstrated, using this model, that a subtherapeutic dose of OL135 can enable the endocannabinoids AEA and 2-AG, but not N-AG to be active at doses where they are otherwise nonanalgesic (20 mg kg(-1) i.p.). The implications of this model in the study of pain in mice, and the therapeutic potential of FAAH inhibition to provide analgesia without the undesirable side effects of direct agonism of cannabinoid receptors are discussed.

Adelmidrol, a palmitoylethanolamide analogue, reduces chronic inflammation in a carrageenin-granuloma model in rats

Palmitoylethanolamide (PEA) and some of its analogues have shown great efficacy in the treatment of pain and inflammation. Adelmidrol – the International Nonproprietary Name (INN) of the di-amide derivative of azelaic acid – is one of these analogues. The anti-inflammatory and analgesic effects of PEA and adelmidrol are hypothesized to be mediated, at least in part, by mast cell down-modulation. Mast cell mediators released at early stage of the inflammatory process drive the inflammatory reaction to chronicity as it happens in X-carrageenin-induced granulomatous tissue formation. In the present study, the choice of testing adelmidrol depends upon the physicochemical properties of the compound, i.e. the amphipatic feature, that make it more easily soluble than PEA. In this study, we investigated the effect of adelmidrol on granuloma formation induced by λ-carrageenin-soaked sponge implant in rats. Our results show that the local administration of the compound under study significantly decreases weight and neo-angiogenesis in granulomatous tissue. The anti-inflammatory effect was due to the modulation of mast cells degranulation, as shown by histological analysis and by the inhibition of the release of several pro-inflammatory and pro-angiogenic enzymes (e.g. iNOS, chymase and metalloproteinase MMP-9), and mediators (e.g. nitric oxide and TNF-α). The results indicate that adelmidrol, given locally, may represent a potential therapeutic tool in controlling chronic inflammation.