am-630 and Disease-Models--Animal

The endocannabinoid system modulates a wide variety of pain conditions. Systemically administered AM404, an endocannabinoid reuptake inhibitor, exerts antinociceptive effects via activation of the endocannabinoid system. However, the mechanism and site of AM404 action are not fully understood. Here, we explored the effect of AM404 on neuropathic pain at the site of the spinal cord.. Male Sprague-Dawley rats were subjected to chronic constriction injury (CCI) of the sciatic nerve. The effects of intrathecal administration of AM404 on mechanical and cold hyperalgesia were examined using the electronic von Frey test and cold plate test, respectively. Motor coordination was assessed using the rotarod test. To understand the mechanisms underlying the action of AM404, we tested the effects of pretreatment with the cannabinoid type 1 (CB. AM404 attenuated mechanical and cold hyperalgesia with minimal effects on motor coordination. AM251 significantly inhibited the antihyperalgesic action of AM404, whereas capsazepine showed a potentiating effect.. These results indicate that AM404 exerts antihyperalgesic effects primarily via CB

Topics: Animals; Arachidonic Acids; Capsaicin; Constriction; Disease Models, Animal; Endocannabinoids; Hyperalgesia; Indoles; Male; Neuralgia; Pain Measurement; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Rotarod Performance Test; Spinal Cord; TRPV Cation Channels

Cannabinoid receptor 2 (CB2), whose activities are upregulated during sepsis, may be related to the regulation of inflammatory programmed cell death called pyroptosis. The aim of this study is to investigate the role of CB2 activation in attenuation of inflammation through inhibiting pyroptosis in cecal ligation puncture (CLP)-induced sepsis andlipopolysaccharide (LPS) + ATP-stimulated macrophages.. C57BL/6 mice were subjected to CLP procedure and treated with CB2 agonist HU308 and CB2 antagonist AM630. Lung tissues were collected for analyses of lung W/D ratio, inflammatory factors levels, and pyroptosis-related protein expression. Murine bone-marrow-derived macrophages (BMDM) were treated with LPS and ATP to construct a septic model in vitro in the presence of HU308 and AM630 for assessment of cell injury, cytokine levels and pyroptosis-related protein expression accordingly. To verify the relationship between CB2 receptors and pyroptosis in the process of inflammatory response, BMDM were transduced with CB2 receptors knockdown lentiviral vectors in the presence of HU308 and AM630 for assessment of pyroptosis-related protein expression.. CB2 activation ameliorated the release of inflammatory mediators. The results showed that CLP-induced pyroptosis was elevated, and CB2 agonist HU308 treatment inhibited the pyroptosis activity through a decrease of the protein levels of NLRP3 as well as caspase-1 and GSDMD activation. Similar results were obtained in BMDM after LPS and ATP treatment. Treatment with CB2 knockdown lentiviral particles prevented the HU308-induced decreases in cell pyroptosis, demonstrating that endogenous CB2 receptors are required for the cannabinoid-induced cell protection.. CB2 receptors activation plays a protective role in sepsis through inhibition of pyroptosis. The effect of CB2 receptors against pyroptosis depends on the existence of endogenous CB2 receptors.

Topics: Adenosine Triphosphate; Animals; Cannabinoids; Cecum; Disease Models, Animal; Indoles; Inflammation; Ligation; Lipopolysaccharides; Lung; Macrophages; Male; Mice, Inbred C57BL; Primary Cell Culture; Punctures; Pyroptosis; Receptor, Cannabinoid, CB2; Sepsis

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

The endocannabinoid 2-arachidonoylglycerol (2-AG) is an anti-nociceptive lipid, which is inactivated through cellular uptake and subsequent catabolism by monoacylglycerol lipase (MAGL). The present study aimed to explore the effects of inhibition of MAGL on intestinal permeability. We first tested it in differentiated CaCO2 cells after 21 days' culture. The rat model of water avoidance stress (WAS) was established, and rats were divided into four groups according to intervention. Rats received intraperitoneal injection (i.p.) of an MAGL inhibitor (JZL184) alone, JZL184 and a the cannabinoid receptor 1 (CB1) receptor antagonist (SR141716A), JZL184 and a cannabinoid receptor 2 (CB2) receptor antagonist (AM630) or vehicle alone (control). We analyzed the fluorescein isothiocyanate-dextran (FD4) permeability and 2-AG level. Expression of MAGL and tight-junction-associated proteins were detected by western blot. Compared with the control group, MAGL expression was higher and 2-AG levels lower among WAS rats. Intestinal permeability was increased following administration of JZL184 which occurred due to up-regulation of tight-junction-associated proteins Claudin-1, Claudin-2, Claudin-5 and Occludin. The effects of MAGL inhibition were mediated by CB1, indicating that MAGL may represent a novel target for the treatment of reduced intestinal permeability in the context of chronic stress.

Topics: Animals; Arachidonic Acids; Benzodioxoles; Caco-2 Cells; Claudin-1; Claudin-2; Claudin-5; Disease Models, Animal; Endocannabinoids; Glycerides; Humans; Indoles; Intestinal Mucosa; Intestines; Male; Monoacylglycerol Lipases; Occludin; Permeability; Piperidines; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Stress, Physiological

Toxoplasmosis is an infectious disease caused by the intracellular parasite Toxoplasma gondii that harms the brain and increases the risk of epilepsy acquisition. It is well known that cannabinoid (CB) signaling is activated following brain insults and protects the neurons from excitotoxicity and inflammation. We examined the role of CB neurotransmission in the proconvulsant effect of Toxoplasmosis in mice. Toxoplasmosis was established in mice by intraperitoneal injection of T. gondii cysts. The mice with acute and/or chronic Toxoplasma infection were pretreated (through intracerebroventricular injection) with CB1 and CB2 receptor agonists (ACEA and HU308) and antagonists (AM251 and AM630), as well as JZL184 (the irreversible inhibitor of mono acyl glycerol lipase, enzyme degrading the endogenous cannabinoid 2-Acyl glycerol). The seizure threshold was then measured by tail vein infusion of pentylenetetrazole. In healthy uninfected mice JZL184, ACEA, and AM630 increased the seizure threshold in a dose-dependent manner, whereas AM251 and HU308 showed dose-dependent proconvulsant effect. Mice with acute and/or chronic infection had a substantial lower seizure threshold than the uninfected mice. JZL 184, ACEA and AM630 inhibited proconvulsant effect of Toxoplasmosis, while AM251 and HU308 intensified proconvulsant effect of Toxoplasmosis. CB receptors play a role in proconvulsant effect of Toxoplasmosis in mice.

Topics: Animals; Benzodioxoles; Cannabinoids; Disease Models, Animal; Indoles; Male; Mice; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Receptors, Cannabinoid; Toxoplasma; Toxoplasmosis

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Capsaicin; Disease Models, Animal; Dopaminergic Neurons; Humans; Indoles; Mice; Mice, Inbred C57BL; Neurogenic Inflammation; Neuroglia; Neuroprotection; Parkinson Disease; Piperidines; Pyrazoles; Receptor Cross-Talk; Receptors, Cannabinoid; Substantia Nigra; TRPV Cation Channels

Protocatechuic acid is an antioxidant which is shown to have analgesic activity in limited studies. However, the mechanisms of action remain unclear.. It is aimed to investigate the possible contribution of cannabinoid system that supresses the nociceptive process by the activation of CB1 and CB2 receptors in central and peripheral levels of pain pathways, to the analgesic activity of protocatechuic acid.. The analgesic activity of protocatechuic acid was determined at the doses of 75, 150 and 300 mg/kg (i.p.) by acetic acid-induced writhing and tail-immersion tests in mice. The results were compared to the analgesic effect of 300 mg/kg (i.p.) dipyrone and non-specific CB receptor agonist 5 mg/kg (i.p.) WIN 55,212-2. For investigating the contribution of cannabinoid system to protocatechuic acid analgesia; pre-treatment with 8 mg/kg (i.p.) CB1 antagonist AM251 and 8 mg/kg (i.p.) CB2 antagonist AM630 were performed separately before 300 mg/kg protocatechuic acid administration.. It was determined that protocatechuic acid has dose-dependent analgesic effect independently from locomotor activity and is comparable with effects of dipyrone and WIN 55,212-2. Pre-treatment with CB1 receptor antagonist AM251 significantly antagonized the protocatechuic acid-induced analgesia in the tail-immersion and writhing tests, whereas pre-treatment of CB2 receptor antagonist AM630 was found to be effective only in the tail-immersion test.. It is concluded that cannabinoid modulation contributes to the analgesic effect of protocatechuic acid in spinal level rather than peripheral. CB1 receptor stimulation rather than CB2 receptor stimulation mediates the analgesic effect of protocatechuic acid in both levels, especially peripheral. Graphical abstract Protocatechuic acid inhibits pain response via cannabinoidergic system.

Topics: Acetic Acid; Analgesics; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Hydroxybenzoates; Indoles; Male; Mice; Pain; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Receptors, Cannabinoid

Cannabinoids (CBs) play important roles in pain modulation. Recently, VD-hemopressin(β) [VD-Hpβ], a 12-residue β-hemoglobin-derived peptide, was reported to activate both CB

Topics: Acetic Acid; Analgesics; Animals; Area Under Curve; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Routes; Indoles; Male; Mice; Mice, Inbred Strains; Oligopeptides; Pain; Pain Measurement; Piperidines; Pyrazoles; Rotarod Performance Test; Spinal Cord

CB2 cannabinoid receptor (CB2R) gene is associated with depression. We investigated the gene-environment interaction between CB2R function and diverse stressors. First, anxiety-like behavior during chronic-mild-stress (CMS) was evaluated in C57BL/6JJmsSlc mice following treatment with CB2R agonist JWH015 or inverse-agonist AM630. Second, locomotor activity and anxiety-like behavior were measured following exposure to an immune poly I:C stressor. Gene expressions of HPA axis related molecules,

Topics: Animals; Anxiety; Brain-Derived Neurotrophic Factor; Cannabinoid Receptor Agonists; Corticotropin-Releasing Hormone; Depression; Disease Models, Animal; Gene Expression Regulation; Gene-Environment Interaction; Hippocampus; Hypothalamo-Hypophyseal System; Immunologic Factors; Indoles; Interleukin-1beta; Locomotion; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Pituitary-Adrenal System; Poly I-C; Receptor, Cannabinoid, CB2; Receptors, Glucocorticoid; Signal Transduction; Tacrolimus Binding Proteins

Chronic pain and hyperalgesia, as well as pain resulting from episodes of vaso-occlusion, are characteristic features of sickle cell disease (SCD) and are difficult to treat. Since there is growing evidence that increasing local levels of endocannabinoids can decrease hyperalgesia, we examined the effects of URB597, a fatty acid amide hydrolase (FAAH) inhibitor, which blocks the hydrolysis of the endogenous cannabinoid anandamide, on hyperalgesia and sensitization of cutaneous nociceptors in a humanized mouse model of SCD. Using homozygous HbSS-BERK sickle mice, we determined the effects of URB597 on mechanical hyperalgesia and on sensitization of C-fiber nociceptors in vivo. Intraplantar administration of URB597 (10 μg in 10 μL) decreased the frequency of withdrawal responses evoked by a von Frey monofilament (3.9 mN bending force) applied to the plantar hind paw. This was blocked by the CB1 receptor antagonist AM281 but not by the CB2 receptor antagonist AM630. Also, URB597 decreased hyperalgesia in HbSS-BERK/CB2R sickle mice, further confirming the role of CB1 receptors in the effects produced by URB597. Electrophysiological recordings were made from primary afferent fibers of the tibial nerve in anesthetized mice. The proportion of Aδ- and C-fiber nociceptors that exhibited spontaneous activity and responses of C-fibers to mechanical and thermal stimuli were greater in HbSS-BERK sickle mice as compared to control HbAA-BERK mice. Spontaneous activity and evoked responses of nociceptors were decreased by URB597 via CB1 receptors. It is suggested that enhanced endocannabinoid activity in the periphery may be beneficial in alleviating chronic pain associated with SCD.

Topics: Anemia, Sickle Cell; Animals; Arachidonic Acids; Benzamides; Carbamates; Disease Models, Animal; Endocannabinoids; Enzyme Inhibitors; Evoked Potentials; Hemoglobins; Humans; Hydrolysis; Hyperalgesia; Indoles; Male; Mice; Mice, Transgenic; Morpholines; Nerve Fibers, Unmyelinated; Nociceptors; Pain Threshold; Polyunsaturated Alkamides; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2

Neuroinflammation plays a major role in postoperative cognitive dysfunction (POCD). Accumulated evidence indicates that cannabinoid receptor type 2 (CB2R) can mediate anti-inflammatory and immunomodulatory effects in part by controlling microglial activity. However, the impact of CB2R on postoperative cognition has not been investigated. We hypothesized that CB2R is involved in surgery-induced cognitive impairment in adult mice.. Adult C57BL/6 mice were subjected to intramedullary fixation surgery for tibial fracture under isoflurane anesthesia and CB2R agonist (JWH133) or CB2R antagonist (AM630) treatment. The mice were trained 24 h prior to surgery using a fear conditioning protocol and assessed in a novel context on postoperative days 1, 3, and 7 to evaluate cognitive function. Open-field testing was performed to evaluate the locomotor activity of the mice. The expression levels of IL-1β, TNF-α, MCP-1, and CB2R in the hippocampus and prefrontal cortex were assessed by Western blotting; the expression of microglial marker CD11b in the CA1 area of the hippocampus and medial prefrontal cortex was assessed by immunostaining.. The mice displayed no changes in locomotor activity after surgery and drug treatments. The mice exhibited impaired hippocampal-dependent memory accompanied by an increased expression of proinflammatory factors in the hippocampus and prefrontal cortex 1, 3, and 7 days after surgery, while hippocampal-independent memory remained unaffected at the same time points. JWH133 treatment attenuated surgery-induced memory loss, while AM630 treatment aggravated surgery-induced memory loss, paralleled by a decreased or increased expression of proinflammatory factors in the hippocampus and prefrontal cortex. The expression of CB2R in the hippocampus and prefrontal cortex was upregulated following surgery; however, it was downregulated by postoperative treatment with JWH133. Similarly, the expression of CD11b in the CA1 area of the hippocampus and medial prefrontal cortex was upregulated following surgery and downregulated by postoperative treatment with JWH133.. These findings indicate that CB2R may modulate the neuroinflammatory and cognitive impairment in a mouse model of orthopedic surgery, and the activation of CB2R may effectively ameliorate the hippocampal-dependent memory loss of mice in the early postoperative stage.

Topics: Animals; Anti-Inflammatory Agents; Brain; Cannabinoids; Cognition Disorders; Cytokines; Disease Models, Animal; Encephalitis; Exploratory Behavior; Fracture Fixation, Intramedullary; Indoles; Mice; Mice, Inbred C57BL; Postoperative Complications; Receptor, Cannabinoid, CB2; Tibial Fractures; Time Factors

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antineoplastic Agents, Phytogenic; Cannabinoid Receptor Modulators; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Hyperalgesia; Indoles; Male; Neuralgia; Paclitaxel; Pain Threshold; Peripheral Nervous System Diseases; Piperidines; Polycyclic Sesquiterpenes; Pyrazoles; Random Allocation; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Sesquiterpenes; Spinal Cord

Morphine is widely used as an analgesic to treat moderate to severe pain, but chronic morphine use is associated with development of tolerance and dependence, which limits its analgesic efficacy. Our previous research has showed that nonanalgetic dose of a cannabinoid type 2 (CB2) receptor agonist reduced morphine tolerance in cancer pain. A previous study showed the colocalization of CB2 and transient receptor potential vanilloid 1 (TRPV1) in human and rat dorsal root ganglia (DRG) sensory neurons. Whether coadministration of a CB2 receptor agonist and morphine could reduce TRPV1 expression in morphine‑induced antinociception and tolerance in cancer pain is unclear. Therefore, we investigated the effects of coadministration of a CB2 receptor agonist AM1241 and morphine on TRPV1 expression and tolerance in cancer pain. Coadministration of AM1241 and morphine for 8 days significantly reduced morphine tolerance, as assessed by measuring paw withdrawal latency to a radiant heat stimulation, in Walker 256 tumor‑bearing rats. Repeated morphine treatment for a period of 8 days induced upregulation of the TRPV1 protein expression levels in the DRG in the tumor‑bearing rats, although no change in mRNA expression. Pretreatment with AM1241 reduced this morphine‑induced upregulation of TRPV1 and the effect was reversed by the CB2 receptor antagonist AM630. Our findings suggest that coadministration of a CB2 receptor agonist AM1241 and morphine reduced morphine tolerance possibly through regulation of TRPV1 protein expression in the DRG in cancer pain.

Topics: Analgesics, Opioid; Animals; Cancer Pain; Cannabinoid Receptor Agonists; Cannabinoids; Disease Models, Animal; Down-Regulation; Drug Tolerance; Ganglia, Spinal; Indoles; Male; Morphine; Rats; Rats, Wistar; TRPV Cation Channels

There are no pharmacological treatments for obstructive sleep apnea syndrome, but dronabinol showed promise in a small pilot study. In anesthetized rats, dronabinol attenuates reflex apnea via activation of cannabinoid (CB) receptors located on vagal afferents; an effect blocked by cannabinoid type 1 (CB1) and/or type 2 (CB2) receptor antagonists. Here, using a natural model of central sleep apnea, we examine the effects of dronabinol, alone and in combination with selective antagonists in conscious rats chronically instrumented to stage sleep and measure cessation of breathing.. Adult male Sprague-Dawley rats were anesthetized and implanted with bilateral stainless steel screws into the skull for electroencephalogram recording and bilateral wire electrodes into the nuchal muscles for electromyogram recording. Each animal was recorded by polysomnography on multiple occasions separated by at least 3 days. The study was a fully nested, repeated measures crossover design, such that each rat was recorded following each of 8 intraperitoneal injections: vehicle; vehicle and CB1 antagonist (AM 251); vehicle and CB2 antagonist (AM 630); vehicle and CB1/CB2 antagonist; dronabinol; dronabinol and CB1 antagonist; dronabinol and CB2 antagonist; and dronabinol and CB1/CB2 antagonist.. Dronabinol decreased the percent time spent in rapid eye movement (REM) sleep. CB receptor antagonists did not reverse this effect. Dronabinol also decreased apneas during sleep, and this apnea suppression was reversed by CB1 or CB1/CB2 receptor antagonism.. Dronabinol's effects on apneas were dependent on CB1 receptor activation, while dronabinol's effects on REM sleep were CB receptor-independent.

Topics: Animals; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Disease Models, Animal; Dronabinol; Electroencephalography; Electromyography; Indoles; Male; Piperidines; Polysomnography; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Respiration; Sleep; Sleep Apnea, Central; Sleep, REM; Vagus Nerve

Remote ischemic preconditioning (RIPC) has protective effects on spinal cord ischemia reperfusion (I/R) injury, but the potential mechanisms remain unclear. In our study, the effects and underlying mechanisms of RIPC on blood-spinal cord barrier (BSCB) breakdown following I/R injury were investigated.. animals underwent intraperitoneal administration with cannabinoid-1 (CB1) receptor antagonist AM251, cannabinoid-2 (CB2) receptor antagonist AM630 or vehicle 15 minutes before three 3-minute occlusion-reperfusion cycles on the right femoral artery or a sham operation. 30 minutes after the preconditioning, aortic arch was exposed with or without 14-minute occlusion. Neurological function was assessed with Tarlov scoring system. The disruption of BSCB was assessed by measuring Evans Blue (EB) extravasation. The expression of tight junction protein occludin was determined by western blot analyses. The expression and localization of CB1 and CB2 receptors were assessed by western blot and immunofluorescence.. RIPC attenuated the motor dysfunction, BSCB disruption and downregulation of occludin after I/R injury, which were impaired by blocking CB1 and CB2 receptors. Moreover, RIPC upregulated the elevated perivascular expression of CB1 and CB2 receptors following I/R injury.. These results indicated that RIPC, through activation and upregulation of CB1 and CB2 receptors, was involved in preserving the integrity of BSCB after spinal cord I/R injury.

Topics: Animals; Disease Models, Animal; Down-Regulation; Femoral Artery; Indoles; Ischemic Preconditioning; Male; Permeability; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Reperfusion Injury; Spinal Cord; Up-Regulation

Proliferative vitreoretinopathy (PVR) can develop after ocular trauma or inflammation and is a common complication of surgery to correct retinal detachment. Currently, there are no pharmacological treatments for PVR. Cannabinoids acting at cannabinoid 2 receptor (CB2R) can decrease inflammation and fibrosis. The objective of this study was to examine the anti-inflammatory actions of CB2R as a candidate novel therapeutic target in experimental PVR. PVR was induced by intravitreal injection of dispase in wild-type (WT) and CB2R genetic knockout (CB2R

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cannabinoid Receptor Modulators; Cannabinoids; Disease Models, Animal; Dose-Response Relationship, Drug; Endopeptidases; Endothelial Cells; Indoles; Leukocytes; Lipopolysaccharides; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Receptor, Cannabinoid, CB2; Retina; Vitreoretinopathy, Proliferative

Social isolation stress (SIS) paradigm is a chronic stress procedure able to induce profound behavioral and neurochemical changes in rodents and evokes depressive and anxiety-like behaviors. Recent studies demonstrated that the cannabinoid system plays a key role in behavioral abnormalities such as depression through different pathways; however, there is no evidence showing a relation between SIS and the cannabinoid system. This study investigated the role of the cannabinoid system in depressive-like behavior and anxiety-like behavior of IC animals. For this purpose, NMRI mice were treated with WIN55, 212-2 (non-selective cannabinoid receptor agonist) and AM-251 (cannabinoid receptor type 1 antagonist) and AM-630 (cannabinoid receptor type 2 antagonist). We found that behavioral abnormality followed by SIS was mitigated after administration of WIN55, 212-2. Also, depressive-like effects induced by SIS were significantly increased following administration of AM-251 and AM-630. Co-administration of cannabinoid receptor antagonists (AM-251 and AM-630), significantly reversed the antidepressant effect of WIN55, 212-2 in IC animals. Our findings suggest that the cannabinoid system is involved in depressive-like behaviors induced by SIS. We showed that activation of cannabinoid receptors (type 1 and 2) could mitigate depression-like behavior induced by SIS in a mouse model.

Topics: Animals; Antidepressive Agents; Anxiety; Behavior, Animal; Benzoxazines; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Depression; Disease Models, Animal; Indoles; Male; Mice; Morpholines; Naphthalenes; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Social Isolation; Stress, Psychological

Studies have shown that cannabinoid CB2 receptors are involved in wound repair, however, its physiological roles in fibrogenesis remain to be elucidated. In the present study, the capacity of cannabinoid CB2 receptors in the regulation of skin fibrogenesis during skin wound healing was investigated. To assess the function of cannabinoid CB2 receptors, skin excisional BALB/c mice were treated with either the cannabinoid CB2 receptor selective agonist, GP1a, or antagonist, AM630. Skin fibrosis was assessed by histological analysis and profibrotic cytokines were determined by immunohistochemistry, immunofluorescence staining, reverse transcription‑quantitative polymerase chain reaction and immunoblotting in these animals. GP1a decreased collagen deposition, reduced the levels of transforming growth factor (TGF)‑β1, TGF‑β receptor I (TβRI) and phosphorylated small mothers against decapentaplegic homolog 3 (P‑Smad3), but elevated the expression of its inhibitor, Smad7. By contrast, AM630 increased collagen deposition and the expression levels of TGF‑β1, TβRI and P‑Smad3. These results indicated that cannabinoid CB2 receptors modulate fibrogenesis and the TGF‑β/Smad profibrotic signaling pathway during skin wound repair in the mouse.

Topics: Actins; Animals; Blotting, Western; Collagen Type I; Collagen Type III; Cytokines; Disease Models, Animal; Fibrosis; Indoles; Male; Mice; Mice, Inbred BALB C; Microscopy, Fluorescence; Protein Serine-Threonine Kinases; Real-Time Polymerase Chain Reaction; Receptor, Cannabinoid, CB2; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta; Skin Diseases; Smad3 Protein; Transforming Growth Factor beta1; Wound Healing

This study was designed to evaluate the effects of CP55,940 on normal bladder function in vivo and examine whether it suppresses urinary frequency induced by nociceptive stimuli in the bladder. Cannabinoid receptor (CBR) activity may be involved in the regulation of bladder function. However, the role of CBR subtypes in micturition has yet to be established. CP55,940 is a synthetic analogue of tetrahydrocannabidiol, which is a psychoactive ingredient of the Cannabis plant.. Cystometry under urethane anaesthesia was performed to evaluate the effect of intravesical delivery of CP55,940 with or without administration of CB1 antagonist AM251 or CB2 antagonist AM630 on bladder function in female rats. The effects of CP55,940 were also examined in rats with urinary irritation induced by intravesical infusion of acetic acid.. Infusion of CP55,940 significantly (p < 0.05) increased micturition interval (MI) and bladder capacity (BC) by 52 % and decreased maximal voiding pressure (MP) by 25 %. Pretreatment with AM251 or AM630 before CP55,940 administration prevented CP55,940-induced increases in MI, BC and reduced MP. Acetic acid induced urinary frequency as evidenced by a reduction in MI and was suppressed by CP55,940.. CP55,940 decreases bladder activity and urinary frequency induced by nociceptive stimuli, probably by suppression of bladder afferent activity. Effects of CP55,940 were abolished by both CBR antagonists. This data implicates a role for the endocannabinoid system in bladder mechanoafferent function in rats. In addition, our results show that CP55,940 reverses urinary frequency exemplified in an overactive bladder model, suggesting it could be an effective treatment for patients with lower urinary tract symptoms.

Topics: Acetic Acid; Administration, Intravesical; Animals; Cannabinoid Receptor Agonists; Cyclohexanols; Disease Models, Animal; Female; Indoles; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Treatment Outcome; Urinary Bladder; Urinary Bladder, Overactive; Urination; Urodynamics

Mixed cannabinoid receptor 1 and 2 (CB1 and CB2) agonists such as Δ(9)-tetrahydrocannabinol (Δ(9)-THC) can produce tolerance, physical withdrawal, and unwanted CB1-mediated central nervous system side effects. Whether repeated systemic administration of a CB2-preferring agonist engages CB1 receptors or produces CB1-mediated side effects is unknown.. We evaluated antiallodynic efficacy, possible tolerance, and cannabimimetic side effects of repeated dosing with a CB2-preferring agonist AM1710 in a model of chemotherapy-induced neuropathy produced by paclitaxel using CB1 knockout (CB1KO), CB2 knockout (CB2KO), and wild-type (WT) mice. Comparisons were made with the prototypic classic cannabinoid Δ(9)-THC. We also explored the site and possible mechanism of action of AM1710.. Paclitaxel-induced mechanical and cold allodynia developed to an equivalent degree in CB1KO, CB2KO, and WT mice. Both AM1710 and Δ(9)-THC suppressed established paclitaxel-induced allodynia in WT mice. In contrast to Δ(9)-THC, chronic administration of AM1710 did not engage CB1 activity or produce antinociceptive tolerance, CB1-mediated cannabinoid withdrawal, hypothermia, or motor dysfunction. Antiallodynic efficacy of systemic administration of AM1710 was absent in CB2KO mice and WT mice receiving the CB2 antagonist AM630, administered either systemically or intrathecally. Intrathecal administration of AM1710 also attenuated paclitaxel-induced allodynia in WT mice, but not CB2KO mice, implicating a possible role for spinal CB2 receptors in AM1710 antiallodynic efficacy. Finally, both acute and chronic administration of AM1710 decreased messenger RNA levels of tumor necrosis factor-α and monocyte chemoattractant protein 1 in lumbar spinal cord of paclitaxel-treated WT mice.. Our results highlight the potential of prolonged use of CB2 agonists for managing chemotherapy-induced allodynia with a favorable therapeutic ratio marked by sustained efficacy and absence of tolerance, physical withdrawal, or CB1-mediated side effects.

Topics: Animals; Antineoplastic Agents, Phytogenic; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Chemokine CCL2; Chromones; Disease Models, Animal; Dronabinol; Female; Hyperalgesia; Indoles; Male; Mice, Inbred C57BL; Mice, Knockout; Paclitaxel; Random Allocation; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; RNA, Messenger; Spinal Cord; Tumor Necrosis Factor-alpha

Water immersion is widely used in physiotherapy and might relieve pain, probably by activating several distinct somatosensory modalities, including tactile, pressure, and thermal sensations. However, the endogenous mechanisms behind this effect remain poorly understood. This study examined whether warm water immersion therapy (WWIT) produces an antiallodynic effect in a model of localized inflammation and whether peripheral opioid, cannabinoid, and adenosine receptors are involved in this effect. Mice were injected with complete Freund's adjuvant (CFA; intraplantar; i.pl.). The withdrawal frequency to mechanical stimuli (von Frey test) was used to determine 1) the effect of WWIT against CFA-induced allodynia and 2) the effect of i.pl. preadministration of naloxone (a nonselective opioid receptor antagonist; 5 µg/paw), caffeine (a nonselective adenosine receptor antagonist; 150 nmol/paw), 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; a selective adenosine A1 receptor antagonist; 10 nmol/paw), and AM630 (a selective cannabinoid receptor type 2 antagonist; 4 µg/paw) on the antiallodynic effect of WWIT against CFA-induced allodynia. Moreover, the influence of WWIT on paw inflammatory edema was measured with a digital micrometer. WWIT produced a significant time-dependent reduction of paw inflammatory allodynia but did not influence paw edema induced by CFA. Naloxone, caffeine, DPCPX, and AM630 injected in the right, but not in the left, hind paw significantly reversed the antiallodynic effect of WWIT. This is the first study to demonstrate the involvement of peripheral receptors in the antiallodynic effect of WWIT in a murine model of persistent inflammatory pain.

Topics: Adenosine; Animals; Benzoxazines; Disease Models, Animal; Edema; Freund's Adjuvant; Hyperalgesia; Immersion; Indoles; Inflammation; Male; Mice; Morpholines; Naloxone; Naphthalenes; Narcotic Antagonists; Neurobiology; Pain Measurement; Receptor, Adenosine A1; Receptor, Cannabinoid, CB2; Receptors, Opioid; Water Purification

The purpose of the experiments was to explore the role of the endocannabinoid system, through cannabinoid (CB) receptor ligands, nicotine and scopolamine, in the depression-related responses using the forced swimming test (FST) in mice. Our results revealed that acute injection of oleamide (10 and 20 mg/kg), a CB1 receptor agonist, caused antidepressant-like effect in the FST, while AM 251 (0.25-3 mg/kg), a CB1 receptor antagonist, did not provoke any effect in this test. Moreover, acute administration of both CB2 receptor agonist, JWH 133 (0.5 and 1 mg/kg) and CB2 receptor antagonist, AM 630 (0.5 mg/kg), exhibited antidepressant action. Antidepressant effects of oleamide and JWH 133 were attenuated by acute injection of both non-effective dose of AM 251, as well as AM 630. Among the all CB compounds used, only the combination of non-effective dose of oleamide (2.5 mg/kg) with non-effective dose of nicotine (0.5 mg/kg) caused an antidepressant effect. However, none of the CB receptor ligands, had influence on the antidepressant effects provoked by nicotine (0.2 mg/kg) injection. In turn, the combination of non-effective dose of oleamide (2.5 mg/kg); JWH (2 mg/kg) or AM 630 (2 mg/kg), but not of AM 251 (0.25 mg/kg), with non-effective dose of scopolamine (0.1 mg/kg), exhibited antidepressant properties. Indeed, all of the CB compounds used, intensified the antidepressant-like effects induced by an acute injection of scopolamine (0.3 mg/kg). Our results provide clear evidence that the endocannabinoid system participates in the depression-related behavior and through interactions with cholinergic system modulate these kind of responses.

Topics: Animals; Antidepressive Agents; Cannabinoids; Depressive Disorder; Disease Models, Animal; Indoles; Ligands; Male; Mice; Motor Activity; Nicotine; Oleic Acids; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Scopolamine; Swimming

Microglia accumulation plays detrimental roles in the pathology of germinal matrix hemorrhage (GMH) in the immature preterm brain. However, the underlying mechanisms remain poorly defined. Here, we investigated the effects of a cannabinoid receptor 2 (CB2R) agonist on microglia proliferation and the possible involvement of the mitogen-activated protein kinase (MAPK) family pathway in a collagenase-induced GMH rat model and in thrombin-induced rat microglia cells. We demonstrated that activation of CB2R played a key role in attenuating brain edema, neuronal degeneration, microglial accumulation and the phosphorylated extracellular signal-regulated kinase (p-ERK) protein level 24 h following GMH. In vitro, Western blot analysis and immunostaining indicated that ERK and P38 phosphorylation levels in microglia stimulated by thrombin were decreased after JWH-133 (CB2R selective agonist) treatment in a concentration-dependent manner. Microglia proliferation (EDU + microglia) and inflammatory and oxidative stress responses were attenuated by UO126 (ERK pathway inhibitor) 24 h after thrombin stimulation, an activity that was prevented by AM630 (CB2R selective antagonist). Overall, these findings suggest that activation of the endocannabinoid system might attenuate inflammation-induced secondary brain injury after GMH in rats by reducing microglia accumulation through a mechanism involving ERK dephosphorylation. Enhancing CB2R activation is a potential treatment to slow down the course of GMH in preterm newborns.

Topics: Animals; Brain; Brain Edema; Butadienes; Cannabinoids; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Extracellular Signal-Regulated MAP Kinases; Indoles; Intracranial Hemorrhages; Male; Microglia; Nerve Degeneration; Neuroimmunomodulation; Nitriles; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Protein Kinase Inhibitors; Random Allocation; Receptor, Cannabinoid, CB2; Thrombin

The cannabinoid receptors CB1 and CB2 are localized in the urinary bladder and play a role in the regulation of its function. We investigated the pathomechanisms through which hyperosmolarity induces detrusor overactivity (DO). We compared urinary bladder activity in response to blockade of CB1 and CB2 receptors using AM281 and AM630, respectively, in normal rats and after hyperosmolar stimulation. Experiments were performed on 44 rats. DO was induced by intravesical instillation of hyperosmolar saline. Surgical procedures and cystometry were performed under urethane anaesthesia. The measurements represent the average of 5 bladder micturition cycles. We analysed basal, threshold, and micturition voiding pressure; intercontraction interval; compliance; functional bladder capacity; motility index; and detrusor overactivity index. The blockage of CB1 and CB2 receptors diminished the severity of hyperosmolar-induced DO. In comparison with naïve animals the increased frequency of voiding with no significant effect on intravesical voiding pressure profile was observed as a result of the blockage of CB1 and CB2 receptors. These results demonstrate that hyperosmolar-induced DO is mediated by CB1 and CB2 receptors. Therefore, the cannabinoid pathway could potentially be a target for the treatment of urinary bladder dysfunction.

Topics: Administration, Intravesical; Animals; Cannabinoid Receptor Antagonists; Cannabinoids; Disease Models, Animal; Female; Indoles; Morpholines; Osmolar Concentration; Pyrazoles; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Saline Solution, Hypertonic; Signal Transduction; Urinary Bladder; Urinary Bladder, Overactive; Urination; Urodynamics

Cannabidiol (CBD), a major non-psychotomimetic constituent of Cannabis sativa, has therapeutic potential for certain psychiatric and neurological disorders. Studies in laboratory animals and limited human trials indicate that CBD has anticonvulsant and neuroprotective properties. Its effects against cocaine neurotoxicity, however, have remained unclear. Thus, the present study tested the hypothesis that CBD protects against cocaine-induced seizures and investigated the underlying mechanisms. CBD (30 mg/kg) pre-treatment increased the latency and reduced the duration of cocaine (75 mg/kg)-induced seizures in mice. The CB1 receptor antagonist, AM251 (1 and 3mg/kg), and the CB2 receptor antagonist, AM630 (2 and 4 mg/kg), failed to reverse this protective effect, suggesting that alternative mechanisms are involved. Synaptosome studies with the hippocampus of drug-treated animals revealed that cocaine increases glutamate release, whereas CBD induces the opposite effect. Finally, the protective effect of this cannabinoid against cocaine-induced seizure was reversed by rapamycin (1 and 5mg/kg), an inhibitor of the mammalian target of rapamycin (mTOR) intracellular pathway. In conclusion, CBD protects against seizures in a model of cocaine intoxication. These effects possibly occur through activation of mTOR with subsequent reduction in glutamate release. CBD should be further investigated as a strategy for alleviating psychostimulant toxicity.

Topics: Anesthetics, Local; Animals; Antiemetics; Cannabidiol; Cocaine; Disease Models, Animal; Dose-Response Relationship, Drug; Glutamic Acid; Immunosuppressive Agents; Indoles; Male; Mice; Seizures; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Transcriptional dysregulation is a major pathological feature of Huntington's disease (HD). The goal of this study was to understand how p65/RelA co-regulated genes, specifically those of the cytokine and endocannabinoid systems, were affected in HD. p65/RelA levels were lower in human HD tissue and R6/2 HD mice, as were the levels of the type 1 cannabinoid receptor (CB1), IL-1β, IL-8, CCL5, GM-CSF, MIP-1β, and TNFα, all of which may be regulated by p65/RelA. Activation of p65/RelA restored CB1 and CCL5 expression in STHdh cell models of HD. Therefore, p65/RelA activation may normalize the expression of some genes in HD.

Topics: Adult; Age Factors; Aged; Amidohydrolases; Animals; Arachidonic Acids; Cannabinoids; Cells, Cultured; Corpus Striatum; Cytokines; Disease Models, Animal; Endocannabinoids; Enzyme Inhibitors; Female; Gene Expression Regulation; Humans; Huntingtin Protein; Huntington Disease; Indoles; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Middle Aged; Nerve Tissue Proteins; Neurons; NF-kappa B; Nuclear Proteins; Receptor, Cannabinoid, CB1; Transcription Factor RelA; Trinucleotide Repeats; Young Adult

Pharmacological treatment and/or maintenance of remission in inflammatory bowel diseases (IBD) is currently one of the biggest challenge in the field of gastroenterology. Available therapies are mostly limited to overcoming the symptoms, but not the cause of the disease. Recently, the endocannabinoid system has been proposed as a novel target in the treatment of IBD. Here we aimed to assess the anti-inflammatory action of the novel fatty acid amide hydrolase (FAAH) inhibitor PF-3845 and its effect on the endocannabinoid and related lipid metabolism during the course of experimental colitis.. We used two models of experimental colitis in mice (TNBS- and DSS-induced) and additionally, we employed LC/MS/MS spectrometry to determine the changes in biolipid levels in the mouse colon during inflammation.. We showed that the FAAH inhibitor PF-3845 reduced experimental TNBS-induced colitis in mice and its anti-inflammatory action is associated with altering the levels of selected biolipids (arachidonic and oleic acid derivatives, prostaglandins and biolipids containing glycine in the mouse colon).. We show that FAAH is a promising pharmacological target and the FAAH-dependent biolipids play a major role in colitis. Our results highlight and promote therapeutic strategy based on targeting FAAH-dependent metabolic pathways in order to alleviate intestinal inflammation.

Topics: Amidohydrolases; Animals; Cannabinoids; Colitis, Ulcerative; Disease Models, Animal; Dose-Response Relationship, Drug; Indoles; Injections, Intraperitoneal; Male; Mice; Mice, Inbred C57BL; Piperidines; Pyrazoles; Pyridines; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Treatment Outcome

Cisplatin has been used effectively to treat a variety of cancers but its use is limited by the development of painful peripheral neuropathy. Because the endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG) is anti-hyperalgesic in several preclinical models of chronic pain, the anti-hyperalgesic effect of JZL184, an inhibitor of 2-AG hydrolysis, was tested in a murine model of cisplatin-induced hyperalgesia. Systemic injection of cisplatin (1mg/kg) produced mechanical hyperalgesia when administered daily for 7 days. Daily peripheral administration of a low dose of JZL184 in conjunction with cisplatin blocked the expression of mechanical hyperalgesia. Acute injection of a cannabinoid (CB)-1 but not a CB2 receptor antagonist reversed the anti-hyperalgesic effect of JZL184 indicating that downstream activation of CB1 receptors suppressed the expression of mechanical hyperalgesia. Components of endocannabinoid signaling in plantar hind paw skin and lumbar dorsal root ganglia (DRGs) were altered by treatments with cisplatin and JZL184. Treatment with cisplatin alone reduced levels of 2-AG and AEA in skin and DRGs as well as CB2 receptor protein in skin. Combining treatment of JZL184 with cisplatin increased 2-AG in DRGs compared to cisplatin alone but had no effect on the amount of 2-AG in skin. Evidence that JZL184 decreased the uptake of [(3)H]AEA into primary cultures of DRGs at a concentration that also inhibited the enzyme fatty acid amide hydrolase, in conjunction with data that 2-AG mimicked the effect of JZL184 on [(3)H]AEA uptake support the conclusion that AEA most likely mediates the anti-hyperalgesic effect of JZL184 in this model.

Topics: Amides; Analgesics; Animals; Antineoplastic Agents; Arachidonic Acids; Benzodioxoles; Cells, Cultured; Cisplatin; Disease Models, Animal; Endocannabinoids; Ethanolamines; Ganglia, Spinal; Glycerides; Hyperalgesia; Indoles; Male; Mesencephalon; Mice; Mice, Inbred C3H; Monoacylglycerol Lipases; Morpholines; Neuralgia; Palmitic Acids; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Skin; Spinal Cord

This study aimed at providing an insight on the possible role of cannabinoid (CB) type 2 receptors (CB2R) and cGMP pathway in the antiepileptic activity of WIN 55,212-2, (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl) pyrrolo[1,2,3-de]-1,4-benzoxazin-6-Yl]-1-naphthalenylmethanone, a non-selective CB agonist, in the maximal dentate activation (MDA) model of partial epilepsy in adult male rats. We evaluated the activity of a CB2 antagonist/inverse agonist AM630, [6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indol-3-yl](4-methoxyphenyl)methanone or 6-iodopravadoline, alone or in co-administration with WIN 55,212-2. Also, in the MDA model it was investigated the co-treatment of WIN 55,212-2 and 1H-[1,2,4]Oxadiazole[4,3-a]quinoxalin-1-one (ODQ), a specific inhibitor of the nitric oxide (NO)-activated soluble guanylyl cyclase (sGC), the cGMP producing enzyme. The WIN 55,212-2-dependent (21mg/kg) antiepileptic effects were significantly increased by the co-administration with AM630 and by the co-treatment with ODQ (10mg/kg). Whereas, the administration of AM630 (2mg/kg), alone exerts no effects on hippocampal hyperexcitability. Our data show that pharmacological blockade of CB2 receptors and of sGC seems to cooperate with WIN in its antiepileptic action. These findings shed light on CB signaling mechanisms, hinting that the modulation of the effects of CB agonist in the hyperexcitability phenomena may be exerted both by targeting CB receptors and their possible downstream effectors, such as nitrergic-dependent cGMP pathway.

Topics: Animals; Anticonvulsants; Benzoxazines; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Cyclic GMP; Disease Models, Animal; Electric Stimulation; Epilepsies, Partial; Guanylate Cyclase; Hippocampus; Indoles; Male; Morpholines; Naphthalenes; Rats, Wistar; Receptor, Cannabinoid, CB2

The endocannabinoid, N-arachidonoylethanolamine (AEA), is degraded by the enzyme fatty acid amide hydrolase (FAAH). This study examined whether the FAAH inhibitor, URB597, increases retinal ganglion cell (RGC) survival following optic nerve axotomy in young and aged animals. URB597 alone, or together with either a CB1 or CB2 receptor antagonist, was administered daily for 1 or 2 weeks post-axotomy. Histological assessment of retinas indicated that URB597 increased RGC survival in young retina at 1 and 2 weeks post-axotomy. The increase in RGC survival at 2 weeks was accompanied by a reduction in phagocytic microglia. The CB1 antagonist, AM281, but not the CB2 antagonist, AM630, ablated URB597-mediated RGC neuroprotection. CB1 or CB2 antagonism increased phagocytic microglia in URB597 and vehicle-treated animals. In aged animals, URB597 increased RGC survival at 1 week, but not at 2 weeks post-axotomy and had no effect on microglia. Retinal Iba-1 positive microglia were also decreased in URB597-treated axotomized young animals and this decrease was mitigated by CB1 but not CB2 antagonism. As seen with phagocytotic microglia, the CB2 antagonist, AM630, increased Iba-1 positive microglia in the absence of URB597 treatment. Measurement of retinal endocannabinoid levels in URB597-treated animals at 2 weeks post-axotomy revealed a significant increase in AEA levels, accompanied by a decrease in the AEA metabolite, N-arachidonoyl glycine, in young animals but not aged animals. 2-arachidonoylglycerol levels were similar across all experimental groups. These data demonstrate that URB597-mediated retinal neuroprotective effects are mediated primarily through CB1 receptors and that URB597 neuroprotective efficacy declines with age.

Topics: Age Factors; Amidohydrolases; Animals; Axotomy; Benzamides; Carbamates; Cell Count; Disease Models, Animal; Endocannabinoids; Indoles; Microglia; Morpholines; Neural Pathways; Neuroprotective Agents; Optic Nerve Diseases; Pyrazoles; Rats; Rats, Inbred F344; Retina; Retinal Ganglion Cells; Stilbamidines

Opioids do not effectively manage pain in many patients with advanced cancer. Because anandamide (AEA) activation of cannabinoid type-1 receptors (CB1R) on nociceptors reduces nociception, manipulation of AEA metabolism in the periphery may be an effective alternative or adjuvant therapy in the management of cancer pain. AEA is hydrolyzed by the intracellular enzyme fatty acid amide hydrolase (FAAH), and this enzyme activity contributes to uptake of AEA into neurons and to reduction of AEA available to activate CB1R. We used an in vitro preparation of adult murine dorsal root ganglion (DRG) neurons co-cultured with fibrosarcoma cells to investigate how tumors alter the uptake of AEA into neurons. Evidence that the uptake of [(3)H]AEA into dissociated DRG cells in the co-culture model mimicked the increase in uptake that occurred in DRG cells from tumor-bearing mice supported the utility of the in vitro model to study AEA uptake. Results with the fluorescent AEA analog CAY10455 confirmed that an increase in uptake in the co-culture model occurred in neurons. One factor that contributed to the increase in [(3)H]AEA uptake was an increase in total cellular cholesterol in the cancer condition. Treatment with the FAAH inhibitor URB597 reduced CAY10455 uptake in the co-culture model to the level observed in DRG neurons maintained in the control condition (i.e., in the absence of fibrosarcoma cells), and this effect was paralleled by OMDM-1, an inhibitor of AEA uptake, at a concentration that had no effect on FAAH activity. Maximally effective concentrations of the two drugs together produced a greater reduction than was observed with each drug alone. Treatment with BMS309403, which competes for AEA binding to fatty acid binding protein-5, mimicked the effect of OMDM-1 in vitro. Local injection of OMDM-1 reduced hyperalgesia in vivo in mice with unilateral tumors in and around the calcaneous bone. Intraplantar injection of OMDM-1 (5μg) into the tumor-bearing paw reduced mechanical hyperalgesia through a CB1R-dependent mechanism and also reduced a spontaneous nocifensive behavior. The same dose reduced withdrawal responses evoked by suprathreshold mechanical stimuli in naive mice. These data support the conclusion that OMDM-1 inhibits AEA uptake by a mechanism that is independent of inhibition of FAAH and provide a rationale for the development of peripherally restricted drugs that decrease AEA uptake for the management of cancer pain.

Topics: Animals; Arachidonic Acids; Benzamides; Brain Neoplasms; Cannabinoid Receptor Antagonists; Carbamates; Cells, Cultured; Coculture Techniques; Disease Models, Animal; Endocannabinoids; Enzyme Inhibitors; Fibrosarcoma; Fluorescent Dyes; Ganglia, Spinal; Hyperalgesia; Indoles; Lactones; Male; Mice; Mice, Inbred C3H; Pain; Pain Threshold; Polyunsaturated Alkamides; Sensory Receptor Cells; Statistics, Nonparametric; Tritium

Anandamide and 2-arachidonoylglycerol (2-AG) are the two main endocannabinoids, exerting their effects by activating type 1 (CB1r) and type 2 (CB2r) cannabinoid receptors. Anandamide inhibits anxiety-like responses through the activation of CB1r in certain brain regions, including the dorsolateral periaqueductal gray (dlPAG). 2-AG also attenuates anxiety-like responses, although the neuroanatomical sites for these effects remained unclear. Here, we tested the hypothesis that enhancing 2-AG signaling in the dlPAG would induce anxiolytic-like effects. The mechanisms involved were also investigated. Male Wistar rats received intra-dlPAG injections of 2-AG, URB602 (inhibitor of the 2-AG hydrolyzing enzyme, mono-acylglycerol lipase--MGL), AM251 (CB1r antagonist) and AM630 (CB2r antagonist). The behavior was analyzed in the elevated plus maze after the following treatments. Exp. 1: vehicle (veh) or 2-AG (5 pmol, 50 pmol, and 500 pmol). Exp. 2: veh or URB602 (30 pmol, 100 pmol or 300 pmol). Exp. 3: veh or AM251 (100 pmol) followed by veh or 2-AG (50 pmol). Exp. 4: veh or AM630 (1000 pmol) followed by veh or 2-AG. Exp. 5: veh or AM251 followed by veh or URB602 (100 pmol). Exp. 6: veh or AM630 followed by veh or URB602. 2-AG (50 pmol) and URB602 (100 pmol) significantly increased the exploration of the open arms of the apparatus, indicating an anxiolytic-like effect. These behavioral responses were prevented by CB1r (AM251) or CB2r (AM630) antagonists. Our results showed that the augmentation of 2-AG levels in the dlPAG induces anxiolytic-like effects. The mechanism seems to involve both CB1r and CB2r receptors.

Topics: Analysis of Variance; Animals; Anxiety; Arachidonic Acids; Biphenyl Compounds; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Disease Models, Animal; Dose-Response Relationship, Drug; Endocannabinoids; Glycerides; Indoles; Male; Maze Learning; Periaqueductal Gray; Piperidines; Pyrazoles; Rats; Rats, Wistar

Recently, we demonstrated that peripheral antinociception induced by δ opioid receptor is dependent of Ca(2+)-activated Cl(-) channels (CaCCs). Because opioid and cannabinoid receptors share some common mechanisms of action, our objective was to identify a possible relationship between CaCCs and the endocannabinoid system.. To induce hyperalgesia, rat paws were treated with intraplantar prostaglandin E2 (PGE2, 2μg). Nociceptive thresholds to pressure (grams) were measured using an algesimetric apparatus 3h following injection. Probabilities were calculated using ANOVA/Bonferroni's test, and values that were less than 5% were considered to be statistically significant.. Administration of the cannabinoid agonist CB1 anandamide (12.5, 25 and 50μg/paw) and the cannabinoid agonist CB2 PEA (5, 10 and 20μg/paw) decreased the PGE2-induced hyperalgesia in a dose-dependent manner. The possibility of the higher doses of anandamide (50μg) and PEA (20μg) having a central or systemic effect was excluded because the administration of the drug into the contralateral paw did not elicit antinociception in the right paw. As expected, the antinociceptive effects induced by anandamide and PEA were blocked by the CB1 and CB2 receptor antagonists AM251 and AM630, respectively. The peripheral antinociception was induced by anandamide but not PEA and was dose-dependently inhibited by the CaCC blocker niflumic acid (8, 16 and 32μg).. These results provide the first evidence for the involvement of CaCCs in the peripheral antinociception induced by activation of the CB1 cannabinoid receptor.

Topics: Amides; Analysis of Variance; Animals; Arachidonic Acids; Calcium Channel Blockers; Cannabinoid Receptor Agonists; Chloride Channels; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Endocannabinoids; Ethanolamines; Hyperalgesia; Indoles; Male; Niflumic Acid; Palmitic Acids; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2

Changes in leukocyte-endothelial and microvascular perfusion are hallmark events in inflammation. Thus, protection of the intestinal microcirculation represents a pivotal therapeutic target in systemic inflammation and sepsis. The endocannabinoid system (ECS) modulates a number of critical homeostatic functions and has been associated with anti-inflammatory responses. Our study aimed to examine intestinal leukocyte adhesion and capillary perfusion following selective inhibition of the endocannabinoid degradation enzyme, fatty acid amide hydrolase (FAAH), in experimental sepsis (endotoxemia).. Five groups of rats were used: controls, endotoxemia [lipopolysaccharide (LPS)], FAAH inhibitor URB597 (0.3 mg/kg)+LPS, URB597 (0.6 mg/kg)+LPS, and URB597 (0.6 mg/kg)+cannabinoid 2 receptor (CB2R) antagonist (AM630)+LPS. After 2 h, intravital microscopy was performed to quantify intestinal leukocyte recruitment and functional capillary density (FCD), as well as macrohemodynamic monitoring and histological examinations.. LPS induced a significant increase in leukocyte adhesion in collecting and postcapillary submucosal venules and a decrease in intestinal FCD. URB597 pretreatment prevented the LPS-induced increase in leukocyte adhesion in intestinal venules and a decrease in intestinal FCD. The administration of the CB2R inhibitor, AM630, with URB597 reversed the protective effects of URB597 on the LPS-induced increase in leukocyte adhesion in intestinal venules, but not URB597's effect on the intestinal FCD.. FAAH inhibition prevents the LPS-induced increase in leukocyte adhesion and improves the capillary perfusion of the gut. This might be mediated in part by CB2R activation. Our study encourages further investigation into the therapeutic potential of drugs targeting the ECS in sepsis.

Topics: Amidohydrolases; Animals; Benzamides; Cannabinoid Receptor Antagonists; Capillaries; Carbamates; Cell Adhesion; Disease Models, Animal; Endocannabinoids; Endotoxemia; Indoles; Intestinal Mucosa; Intestines; Leukocytes; Lipopolysaccharides; Male; Rats; Rats, Inbred Lew; Receptor, Cannabinoid, CB2

Endocannabinoid system is reported to be activated during myocardial ischemia-reperfusion (IR) injury and protects against heart injury. We, therefore, observed changes in endocannabinoids levels during acute myocardial infarction (AMI) and myocardial IR injury and evaluated the role of cannabinoid-2 (CB2) receptor in infarct and IR heart injury. In contrast to 16 control patients with normal coronary artery angiogram, the endocannabinoid 2-arachidonoylglycerol level in the infarct-side coronary artery of 23 AMI patients increased significantly, with increased reactive oxygen species and tumor necrosis factor-α levels in both infarct-side coronary artery and radial artery. Then, 35 C57BL/6J mice were made into SHAM, AMI, or IR models. AMI and IR groups were treated with CB2-selective agonist HU308 ((+)-(1aH,3H,5aH)-4-[2,6-dimethoxy-4-(1,1-dimethylheptyl)phenyl]-6,6-dimethylbicyclo[3.1.1]hept-2-ene-2-carbinol), with or without CB2-selective antagonist AM630 [6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indol-3-yl](4-methoxyphenyl)methanone through intraperitoneal injection. Compared with the SHAM, expressions of cannabinoid CB1/CB2 receptor proteins in AMI/IR animals were upregulated; production of 2-arachidonoylglycerol and anandamide and release of reactive oxygen species and tumor necrosis factor-α also increased. HU308 significantly decreased the infarct size and the levels of reactive oxygen species and tumor necrosis factor-α in AMI/IR animals. However, these effects were blocked by AM630. In conclusion, the endocannabinoid system was activated during AMI and IR, and CB2 receptor activation produces a protective role, thus offering a novel pharmaceutical target for treating these diseases.

Topics: Animals; Arachidonic Acids; Cannabinoid Receptor Modulators; Cannabinoids; Case-Control Studies; Coronary Angiography; Coronary Vessels; Disease Models, Animal; Endocannabinoids; Glycerides; Humans; Indoles; Injections, Intraperitoneal; Male; Mice; Mice, Inbred C57BL; Myocardial Infarction; Myocardial Reperfusion Injury; Radial Artery; Reactive Oxygen Species; Receptor, Cannabinoid, CB2; Tumor Necrosis Factor-alpha

Periodontitis is an infectious disease leading to inflammation and destruction of tissue surrounding and supporting the tooth. The progress of the inflammatory response depends on the host's immune system and risk factors such as stress. The aim of the present study was to investigate the role of the endocannabinoid anandamide (AEA) in experimental periodontitis with restraint stress, since the endocannabinoid system is known to modulate the hypothalamo-pituitary-adrenal axis as well as immune functions and has been found in human gingival tissues.. Experimental periodontitis was induced by ligature around first inferior molars and immobilization stress for 2 h twice daily for 7 days in a rat model.. Corticosterone plasma levels, locomotor activity, adrenal gland weight and bone loss were increased in periodontitis and stress groups, and there was also less weight gain. The inflammatory parameters such as prostaglandin E(2) (radioimmunoassay), nitric oxide (radioconversion of (14)C-arginine), tumor necrosis factor (TNF)-α (ELISA) and interleukin (IL)-1β (Western blot) measured in the gingival tissue were significantly increased in the periodontitis groups compared to the control group. Local injection of AEA (10(-8)M, 30 µl) decreased corticosterone plasma levels and the content of the cytokines TNF-α and IL-1β in gingival tissue in periodontitis-stress groups. These AEA-induced inhibitions were mediated by CB(1) and CB(2) cannabinoid receptors since the injection of both antagonists together, AM251 (10(-6)M) and AM630 (10(-6)M) in 30 µl, prevented these effects.. The endocannabinoid AEA diminishes the inflammatory response in periodontitis even during a stressful situation.

Topics: Alveolar Bone Loss; Animals; Anti-Inflammatory Agents; Arachidonic Acids; Body Weight; Cannabinoid Receptor Agonists; Corticosterone; Disease Models, Animal; Endocannabinoids; Enzyme-Linked Immunosorbent Assay; Exploratory Behavior; Indoles; Interleukin-1beta; Male; Nitric Oxide Synthase; Periodontitis; Piperidines; Polyunsaturated Alkamides; Prostaglandins E; Pyrazoles; Rats; Rats, Wistar; Statistics, Nonparametric; Stress, Psychological; Tumor Necrosis Factor-alpha

Peripheral nerve injury generally results in spinal neuronal and glial plastic changes associated with chronic behavioral hypersensitivity. Spinal mitogen-activated protein kinases (MAPKs), eg, p38 or extracellular signal-regulated kinases (ERKs), are instrumental in the development of chronic allodynia in rodents, and new p38 inhibitors have shown potential in acute and neuropathic pain patients. We have previously shown that the cannabinoid type 2 receptor agonist JWH015 inhibits ERK activity by inducing MAPK phosphatase (MKP)-1 and MKP-3 (the major regulators of MAPKs) in vitro in microglial cells. Therefore, we decided to investigate the role of these phosphatases in the mechanisms of action of JWH015 in vivo using the rat L5 nerve transection model of neuropathic pain. We observed that peripheral nerve injury reduced spinal MKP-1/3 expression and activity and that intrathecal JWH015 reduced established L5 nerve injury-induced allodynia, enhanced spinal MKP-1/3 expression and activity, and reduced the phosphorylated form of p38 and ERK-1/2. Triptolide, a pharmacological blocker of MKP-1 and MKP-3 expression, inhibited JWH015's effects, suggesting that JWH015 exerts its antinociceptive effects by modulating MKP-1 and MKP-3. JWH015-induced antinociception and MKP-1 and MKP-3 expression were inhibited by the cannabinoid type 2 receptor antagonist AM630. Our data suggest that MKP-1 and MKP-3 are potential targets for novel analgesic drugs.. MAPKs are pivotal in the development of chronic allodynia in rodent models of neuropathic pain. A cannabinoid type 2 receptor agonist, JWH015, reduced neuropathic allodynia in rats by reducing MAPK phosphorylation and inducing spinal MAPK phosphatases 1 and 3, the major regulators of MAPKs.

Topics: 4-Nitrophenylphosphatase; Animals; Disease Models, Animal; Diterpenes; Dual Specificity Phosphatase 1; Dual Specificity Phosphatase 6; Epoxy Compounds; Gene Expression Regulation; Hyperalgesia; Immunosuppressive Agents; Indoles; Male; Mitogen-Activated Protein Kinase Phosphatases; Nerve Tissue Proteins; Neuralgia; Phenanthrenes; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB2; Signal Transduction; Spinal Cord; Time Factors

Chemotherapeutic agents produce dose-limiting peripheral neuropathy through mechanisms that remain poorly understood. We previously showed that AM1710, a cannabilactone CB₂ agonist, produces antinociception without producing central nervous system (CNS)-associated side effects. The present study was conducted to examine the antinociceptive effect of AM1710 in rodent models of neuropathic pain evoked by diverse chemotherapeutic agents (cisplatin and paclitaxel). A secondary objective was to investigate the potential contribution of alpha-chemokine receptor (CXCR4) signaling to both chemotherapy-induced neuropathy and CB₂ agonist efficacy.. AM1710 (0.1, 1 or 5 mg/kg i.p.) suppressed the maintenance of mechanical and cold allodynia in the cisplatin and paclitaxel models. Anti-allodynic effects of AM1710 were blocked by the CB₂ antagonist AM630 (3 mg/kg i.p.), but not the CB1 antagonist AM251 (3 mg/kg i.p.), consistent with a CB₂-mediated effect. By contrast, blockade of CXCR4 signaling with its receptor antagonist AMD3100 (10 mg/kg i.p.) failed to attenuate mechanical or cold hypersensitivity induced by either cisplatin or paclitaxel. Moreover, blockade of CXCR4 signaling failed to alter the anti-allodynic effects of AM1710 in the paclitaxel model, further suggesting distinct mechanisms of action.. Our results indicate that activation of cannabinoid CB₂ receptors by AM1710 suppresses both mechanical and cold allodynia in two distinct models of chemotherapy-induced neuropathic pain. By contrast, CXCR4 signaling does not contribute to the maintenance of chemotherapy-induced established neuropathy or efficacy of AM1710. Our studies suggest that CB₂ receptors represent a promising therapeutic target for the treatment of toxic neuropathies produced by cisplatin and paclitaxel chemotherapeutic agents.

Topics: Animals; Benzylamines; Chromones; Cisplatin; Cryopyrin-Associated Periodic Syndromes; Cyclams; Disease Models, Animal; Heterocyclic Compounds; Hyperalgesia; Indoles; Male; Paclitaxel; Peripheral Nervous System Diseases; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB2; Receptors, CXCR4; Signal Transduction; Time Factors; Treatment Outcome

The present study examined whether enhancement of endogenous cannabinoid levels by administration of the fatty acid amide hydrolase inhibitor URB597 could modulate joint nociception in 2 rodent models of osteoarthritis (OA). OA-like changes were induced in male Wistar rats by intra-articular injection of monoiodoacetate, while Dunkin-Hartley guinea pigs (age 9-12 months) develop OA naturally and were used as a model of spontaneous OA. Joint nociception was measured by recording electrophysiologically from knee joint primary afferents in response to noxious hyper-rotation of the joint before and after close intra-arterial injection of URB597 (0.03 mg; 0.1 mL bolus); the CB(1) receptor antagonist AM251 (1 mg/kg intraperitoneally) or the CB(2) receptor antagonist AM630 (1 mg/kg intraperitoneally). The effect of systemic URB597 administration (5 mg/kg) on joint pain perception in the monoiodoacetate model was determined by hindlimb incapacitance. Peripheral injection of URB597 caused afferent firing rate to be significantly reduced by up to 56% in the rat OA model and by up to 69% in the guinea pig OA model. Systemic co-administration of AM251, but not AM630, abolished the antinociceptive effect of URB597 in both models. URB597 had no effect in saline-injected control rat joints or in nonarthritic guinea pigs. Systemic URB597 administration significantly reduced hindlimb incapacitance in monoiodoacetate joints and co-administration of the CB(1) antagonist abolished this effect. Local injection of URB597 into OA knee joints reduces mechanonociception and pain, and this response is mediated by CB(1) receptors. Targeting endocannabinoid-metabolizing enzymes in the peripheral nervous system could offer novel therapeutic approaches for the treatment of OA pain.

Topics: Action Potentials; Afferent Pathways; Age Factors; Animals; Arthralgia; Benzamides; Carbamates; Diclofenac; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Guinea Pigs; Indoles; Iodoacetic Acid; Male; Nociceptors; Osteoarthritis; Piperidines; Pyrazoles; Rats; Rats, Wistar; Time Factors; Weight-Bearing

Inflammatory bowel diseases (IBDs) are chronic inflammatory conditions for which new therapeutic approaches are needed. Genetic and pharmacological data point to a protective role of CB(1) and CB(2) cannabinoid receptor activation in IBD experimental models. Therefore, increasing the endogenous levels of 2-arachidonoylglycerol, the main full agonist of these receptors, should have beneficial effects on colitis. 2-Arachidonoylglycerol levels were raised in the trinitrobenzene sulfonic acid (TNBS)-induced colitis mouse model by inhibiting monoacylglycerol lipase (MAGL), the primary enzyme responsible for hydrolysis of 2-arachidonoylglycerol, using the selective inhibitor JZL184. MAGL inhibition in diseased mice increased 2-arachidonoylglycerol levels, leading to a reduction of macroscopic and histological colon alterations, as well as of colonic expression of proinflammatory cytokines. The restored integrity of the intestinal barrier function after MAGL inhibition resulted in reduced endotoxemia as well as reduced peripheral and brain inflammation. Coadministration of either CB(1) (SR141716A) or CB(2) (AM630) selective antagonists with JZL184 completely abolished the protective effect of MAGL inhibition on TNBS-induced colon alterations, thus demonstrating the involvement of both cannabinoid receptors. In conclusion, increasing 2-arachidonoylglycerol levels resulted in a dramatic reduction of colitis and of the related systemic and central inflammation. This could offer a novel pharmacological approach for the treatment of IBD based on the new protective role of 2-arachidonoylglycerol described here.

Topics: Animals; Arachidonic Acids; Benzodioxoles; Colitis; Disease Models, Animal; Endocannabinoids; Endotoxemia; Enzyme Inhibitors; Glycerides; Humans; Indoles; Inflammation; Inflammation Mediators; Inflammatory Bowel Diseases; Male; Mice; Mice, Inbred C57BL; Monoacylglycerol Lipases; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Rimonabant; Trinitrobenzenesulfonic Acid

The present study evaluated the role of CB(2) receptors in the regulation of depressive-like behaviours. Transgenic mice overexpressing the CB(2) receptor (CB2xP) were challenged with different types of acute and chronic experimental paradigms to evaluate their response in terms of depressive-like behaviours.. Tail suspension test (TST), novelty-suppressed feeding test (NSFT) and unpredictable chronic mild stress tests (CMS) were carried out in CB2xP mice. Furthermore, acute and chronic antidepressant-like effects of the CB(2) receptor-antagonist AM630 were evaluated by means of the forced swimming test (FST) and CMS, respectively, in wild-type (WT) and CB2xP mice. CB(2) gene expression, brain-derived neurotrophic factor (BDNF) gene and protein expressions were studied in mice exposed to CMS by real-time PCR and immunohistochemistry, respectively.. Overexpression of CB(2) receptors resulted in decreased depressive-like behaviours in the TST and NSFT. CMS failed to alter the TST and sucrose consumption in CB2xP mice. In addition, no changes in BDNF gene and protein expression were observed in stressed CB2xP mice. Interestingly, acute administration of AM630 (1 and 3 mg x kg(-1), i.p.) exerted antidepressant-like effects on the FST in WT, but not in CB2xP mice. Chronic administration of AM630 for 4 weeks (1 mg x kg(-1); twice daily, i.p.) blocked the effects of CMS on TST, sucrose intake, CB(2) receptor gene, BDNF gene and protein expression in WT mice.. Taken together, these results suggest that increased CB(2) receptor expression significantly reduced depressive-related behaviours and that the CB(2) receptor could be a new potential therapeutic target for depressive-related disorders.

Topics: Animals; Antidepressive Agents; Anxiety; Behavior, Animal; Brain-Derived Neurotrophic Factor; Depression; Disease Models, Animal; Feeding Behavior; Gene Expression; Hippocampus; Immunohistochemistry; Indoles; Male; Mice; Mice, Inbred ICR; Mice, Transgenic; Receptor, Cannabinoid, CB2; Restraint, Physical; Stress, Psychological; Swimming

Peripheral cannabinoid receptors exert a powerful inhibitory control over pain initiation, but the endocannabinoid signal that normally engages this intrinsic analgesic mechanism is unknown. To address this question, we developed a peripherally restricted inhibitor (URB937) of fatty acid amide hydrolase (FAAH), the enzyme responsible for the degradation of the endocannabinoid anandamide. URB937 suppressed FAAH activity and increased anandamide levels outside the rodent CNS. Despite its inability to access brain and spinal cord, URB937 attenuated behavioral responses indicative of persistent pain in rodent models of peripheral nerve injury and inflammation and prevented noxious stimulus-evoked neuronal activation in spinal cord regions implicated in nociceptive processing. CB₁ cannabinoid receptor blockade prevented these effects. These results suggest that anandamide-mediated signaling at peripheral CB₁ receptors controls the access of pain-related inputs to the CNS. Brain-impenetrant FAAH inhibitors, which strengthen this gating mechanism, might offer a new approach to pain therapy.

Topics: Amidohydrolases; Animals; Arachidonic Acids; Cannabinoid Receptor Modulators; Cannabinoids; Carrageenan; Chromatography, Liquid; Disease Models, Animal; Drug Administration Routes; Drug Administration Schedule; Endocannabinoids; Enzyme Inhibitors; Escape Reaction; Ethylene Glycols; Feeding Behavior; Formaldehyde; Gene Expression Regulation; Hyperalgesia; Indoles; Male; Mass Spectrometry; Mice; Mice, Inbred C57BL; Mice, Knockout; Monoacylglycerol Lipases; Motor Activity; Oncogene Proteins v-fos; Pain; Pain Measurement; Pain Threshold; Peripheral Nervous System Diseases; Piperidines; Polyunsaturated Alkamides; PPAR alpha; Pyrazoles; Rats; Rats, Sprague-Dawley; Rimonabant; Sciatica; Spinal Cord; Statistics, Nonparametric; Time Factors; Tissue Distribution; Tritium

Activation of cannabinoid (CB)(1) receptors results in attenuation of experimental colitis. Our aim was to examine the role of CB(2) receptors in experimental colitis using agonists (JWH133, AM1241) and an antagonist (AM630) in trinitrobenzene sulfonic acid (TNBS)-induced colitis in wildtype and CB(2) receptor-deficient (CB(2) (-/-)) mice.. Mice were treated with TNBS to induce colitis and then given intraperitoneal injections of the CB(2) receptor agonists JWH133, AM1241, or the CB(2) receptor antagonist AM630. Additionally, CB(2) (-/-) mice were treated with TNBS and injected with JWH133 or AM1241. Animals were examined 3 days after the induction of colitis. The colons were removed for macroscopic and microscopic evaluation, as well as the determination of myeloperoxidase activity. Quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) for CB(2) receptor was also performed in animals with TNBS and dextran sodium sulfate colitis.. Intracolonic installation of TNBS caused severe colitis. CB(2) mRNA expression was significantly increased during the course of experimental colitis. Three-day treatment with JWH133 or AM1241 significantly reduced colitis; AM630 exacerbated colitis. The effect of JWH133 was abolished when animals were pretreated with AM630. Neither JWH133 nor AM1241 had effects in CB(2) (-/-) mice.. We show that activation of the CB(2) receptor protects against experimental colitis in mice. Increased expression of CB(2) receptor mRNA and aggravation of colitis by AM630 suggests a role for this receptor in normally limiting the development of colitis. These results support the idea that the CB(2) receptor may be a possible novel therapeutic target in inflammatory bowel disease.

Topics: Animals; Cannabinoids; Colitis; Disease Models, Animal; Female; Gene Expression; Indoles; Inflammatory Bowel Diseases; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Receptor, Cannabinoid, CB2

Although participation of opioids in antinociception induced by cannabinoids has been documented, there is little information regarding the participation of cannabinoids in the antinociceptive mechanisms of opioids. The aim of the present study was to determine whether endocannabinoids could be involved in peripheral antinociception induced by activation of mu-, delta- and kappa-opioid receptors.. Nociceptive thresholds to mechanical stimulation of rat paws treated with intraplantar prostaglandin E2 (PGE2, 2 microg) to induce hyperalgesia were measured 3 h after injection using an algesimetric apparatus. Opioid agonists morphine (200 microg), (+)-4-[(alphaR)-alpha-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide (SNC80) (80 microg), bremazocine (50 microg); cannabinoid receptor antagonists N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251) (20-80 microg), 6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indol-3-yl(4-methoxyphenyl) methanone (AM630) (12.5-100 microg); and an inhibitor of methyl arachidonyl fluorophosphonate (MAFP) (1-4 microg) were also injected in the paw.. The CB1-selective cannabinoid receptor antagonist AM251 completely reversed the peripheral antinociception induced by morphine in a dose-dependent manner. In contrast, the CB2-selective cannabinoid receptor antagonist AM630 elicited partial antagonism of this effect. In addition, the administration of the fatty acid amide hydrolase inhibitor, MAFP, enhanced the antinociception induced by morphine. The cannabinoid receptor antagonists AM251 and AM630 did not modify the antinociceptive effect of SNC80 or bremazocine. The antagonists alone did not cause any hyperalgesic or antinociceptive effect.. Our results provide evidence for the involvement of endocannabinoids, in the peripheral antinociception induced by the mu-opioid receptor agonist morphine. The release of cannabinoids appears not to be involved in the peripheral antinociceptive effect induced by kappa- and delta-opioid receptor agonists.

Topics: Amidohydrolases; Analgesics, Opioid; Animals; Arachidonic Acids; Benzamides; Benzomorphans; Cannabinoid Receptor Modulators; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Hyperalgesia; Indoles; Male; Morphine; Organophosphonates; Pain; Pain Measurement; Piperazines; Piperidines; Pyrazoles; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Receptors, Opioid, delta; Receptors, Opioid, kappa; Receptors, Opioid, mu

Trigeminal neuralgia is a disorder of paroxysmal and severely disabling facial pain and continues to be a real therapeutic challenge. At present there are few effective drugs. Here we have evaluated the effects of the synthetic cannabinoid WIN 55,212-2 on mechanical allodynia and thermal hyperalgesia in a rat model of trigeminal neuropathic pain produced by a chronic constriction injury (CCI) of the infraorbital branch of the trigeminal nerve (ION). Relative to sham operation controls, rats with the CCI-ION consistently displayed hyperresponsiveness to von Frey filament and heat stimulation of the vibrissal pad. Both mechanical allodynia and thermal hyperalgesia are seen both ipsilateral and contralateral to the side of nerve injury, but is significantly more severe ipsilaterally. Administration of WIN 55,212-2 (0.3-5 mg/kg i.p.) dose-dependently increased the mechanical and heat withdrawal thresholds. WIN 55,212-2 (0.3-3 mg/kg i.p.) produced no significant motor deficits in animals using the rotarod test. The effect of WIN 55,212-2 was mimicked by cannabinoid CB1 receptor agonist HU 210 and was antagonized by CB1 receptor antagonist AM 251, but not by CB2 receptor antagonist AM 630 or vanilloid receptor 1 antagonist capsazepine, suggesting the involvement of CB1 receptors. CCI-ION also induced a time-dependent upregulation of CB1 receptors primarily within the ipsilateral superficial laminae of the trigeminal caudal nucleus revealed by both Western blot and immunohistochemistry. Taken together, these results suggest that cannabinoids may be a useful therapeutic approach for the clinical management of trigeminal neuropathic pain disorders.

Topics: Analgesics; Analysis of Variance; Animals; Benzoxazines; Cannabinoids; Disease Models, Animal; Dose-Response Relationship, Drug; Functional Laterality; Hyperalgesia; Hyperesthesia; Indoles; Male; Morpholines; Naphthalenes; Pain Measurement; Pain Threshold; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Reaction Time; Receptor, Cannabinoid, CB1; Time Factors; Trigeminal Nerve Diseases

Paracetamol analgesic mechanism of action is still poorly defined but mainly involves central inhibition of cyclooxygenases. Here we tested the peripheral antinociceptive effects of paracetamol (intraplantar injections) in a rat model of neuropathic pain. Paracetamol dose-dependently decreased mechanical allodynia and lowered nociceptive scores associated with hyperalgesia testing. These effects were inhibited by the administration of cannabinoid CB(1) (AM251) and CB(2) (AM630) receptor antagonists. The participation of the peripheral cannabinoid system in paracetamol analgesia is suggested.

Topics: Acetaminophen; Analgesics, Non-Narcotic; Animals; Arachidonic Acids; Cannabinoid Receptor Antagonists; Disease Models, Animal; Dose-Response Relationship, Drug; Hindlimb; Hot Temperature; Hyperalgesia; Indoles; Male; Neuralgia; Pain Measurement; Piperidines; Pyrazoles; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Receptors, Cannabinoid; Sciatic Nerve

Anandamide, an endocannabinoid, is degraded by the enzyme fatty acid amide hydrolase which can be inhibited by nonsteroidal anti-inflammatory drugs (NSAIDs). The present work was designed to study the peripheral interactions between anandamide and ibuprofen (a non-specific cyclooxygenase inhibitor) in the rat formalin test. We first determined the ED50 for anandamide (0.018 microg +/- 0.009), ibuprofen (0.18 microg +/- 0.09), and their combination (0.006 microg +/- 0.002). Drugs were given 15 min before a 2.5% formalin injection into the dorsal surface of the right hind paw. Results were analyzed using isobolographic analysis. The antinociceptive interaction between anandamide and ibuprofen was synergistic. To further investigate the mechanisms by which the combination of anandamide with ibuprofen produced their antinociceptive effects, we used specific antagonists for the cannabinoid CB1 (AM251; 80 microg) and CB2 (AM630; 25 microg) receptors. We demonstrated that the antinociceptive effects of ibuprofen were not antagonized by either AM251 or AM630 and that those of anandamide were antagonized by AM251 but not by AM630. The synergistic antinociceptive effects of the combination of anandamide with ibuprofen were completely antagonized by AM251 but only partially inhibited by AM630. In conclusion, locally (hind paw) injected anandamide, ibuprofen or combination thereof decreased pain behavior in the formalin test. The combination of anandamide with ibuprofen produced synergistic antinociceptive effects involving both cannabinoid CB1 and CB2 receptors. Comprehension of the mechanisms involved needs further investigation.

Topics: Acute Disease; Analysis of Variance; Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acids; Area Under Curve; Cannabinoid Receptor Modulators; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Combinations; Drug Interactions; Endocannabinoids; Ibuprofen; Indoles; Inflammation; Male; Pain; Pain Measurement; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Random Allocation; Rats

Hyperdynamic circulation and mesenteric hyperaemia are found in cirrhosis. To delineate the role of endocannabinoids in these changes, we examined the cardiovascular effects of anandamide, AM251 (CB(1) antagonist), AM630 (CB(2) antagonist) and capsazepine (VR1 antagonist), in a rat model of cirrhosis.. Cirrhosis was induced by bile duct ligation. Controls underwent sham operation. Four weeks later, diameters of mesenteric arteriole and venule (intravital microscopy), arterial pressure, cardiac output, systemic vascular resistance and superior mesenteric artery (SMA) flow were measured after anandamide, AM251 (with or without anandamide), AM630 and capsazepine administration. CB(1), CB(2) and VR1 receptor expression in SMA was assessed by western blot and RT-PCR.. Anandamide increased mesenteric vessel diameter and flow, and cardiac output in cirrhotic rats, but did not affect controls. Anandamide induced a triphasic arterial pressure response in controls, but this pattern differed markedly in cirrhotic rats. Pre-administration of AM251 blocked the effects of anandamide. AM251 (without anandamide) increased arterial pressure and systemic vascular resistance, constricted mesenteric arterioles, decreased SMA flow and changed cardiac output in a time-dependent fashion in cirrhotic rats. Capsazepine decreased cardiac output and mesenteric arteriolar diameter and flow, and increased systemic vascular resistance in cirrhotic rats, but lacked effect in controls. Expression of CB(1) and VR1 receptor proteins were increased in cirrhotic rats. AM630 did not affect any cardiovascular parameter in either group.. These data suggest that endocannabinoids contribute to hyperdynamic circulation and mesenteric hyperaemia in cirrhosis, via CB(1)- and VR1-mediated mechanisms.

Topics: Animals; Arachidonic Acids; Bile Ducts; Blood Flow Velocity; Blood Pressure; Blotting, Western; Capsaicin; Cardiac Output; Disease Models, Animal; Endocannabinoids; Hyperemia; Indoles; Liver Circulation; Liver Cirrhosis, Biliary; Male; Mesenteric Artery, Superior; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Splanchnic Circulation; Time Factors; TRPV Cation Channels; Vascular Resistance; Vasodilation; Vasodilator Agents

Accumulating evidence suggests that cannabinoids can produce antinociception through peripheral mechanisms. In the present study, we determined whether cannabinoids attenuated existing hyperalgesia produced by a mild heat injury to the glabrous hindpaw and whether the antihyperalgesia was receptor-mediated. Anesthetized rats received a mild heat injury (55 degrees C for 30 s) to one hindpaw. Fifteen minutes after injury, animals exhibited hyperalgesia as evidenced by lowered withdrawal latency to radiant heat and increased withdrawal frequency to a von Frey monofilament (200 mN force) delivered to the injured hindpaw. Separate groups of animals were then treated with an intraplantar (i.pl.) injection of vehicle or the cannabinoid receptor agonist WIN 55,212-2 at doses of 1, 10, or 30 microg in 100 microl. WIN 55,212-2 attenuated both heat and mechanical hyperalgesia dose-dependently. The inactive enantiomer WIN 55,212-3 did not alter mechanical or heat hyperalgesia, suggesting the effects of WIN 55,212-2 were receptor-mediated. The CB1 receptor antagonist AM 251 (30 microg) co-injected with WIN 55,212-2 (30 microg) attenuated the antihyperalgesic effects of WIN 55,212-2. The CB2 receptor antagonist AM 630 (30 microg) co-injected with WIN 55,212-2 attenuated only the early antihyperalgesic effects of WIN 55,212-2. I.pl. injection of WIN 55,212-2 into the contralateral paw did not alter the heat-injury induced hyperalgesia, suggesting that the antihyperalgesia occurred through a peripheral mechanism. These data demonstrate that cannabinoids primarily activate peripheral CB1 receptors to attenuate hyperalgesia. Activation of this receptor in the periphery may attenuate pain without causing unwanted side effects mediated by central CB1 receptors.

Topics: Animals; Benzoxazines; Burns; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Disease Models, Animal; Hot Temperature; Hyperalgesia; Indoles; Male; Morpholines; Naphthalenes; Nerve Fibers, Myelinated; Nerve Fibers, Unmyelinated; Nociceptors; Pain; Pain Measurement; Physical Stimulation; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Receptors, Cannabinoid; Reflex; Skin