Cannabinoid Antagonist Research Articles

Xie2-64, a novel CB2 receptor inverse agonist, reduces cocaine abuse-related behaviors in rodents

Cocaine abuse remains a public health threat around the world. There are no pharmacological treatments approved for cocaine use disorder. Cannabis has received growing attention as a treatment for many conditions, including addiction. Most cannabis-based medication development has focused on cannabinoid CB1 receptor (CB1R) antagonists (and also inverse agonists) such as rimonabant, but clinical trials with rimonabant have failed due to its significant side-effects. Here we sought to determine whether a novel and selective CB2R inverse agonist, Xie2-64, has similar therapeutic potential for cocaine use disorder. Computational modeling indicated that Xie2-64 binds to CB2R in a way similar to SR144528, another well-characterized but less selective CB2R antagonist/inverse agonist, suggesting that Xie2-64 may also have CB2R antagonist profiles. Unexpectedly, systemic administration of Xie2-64 or SR144528 dose-dependently inhibited intravenous cocaine self-administration and shifted cocaine dose-response curves downward in rats and wild-type, but not in CB2R-knockout, mice. Xie2-64 also dose-dependently attenuated cocaine-enhanced brain-stimulation reward maintained by optical stimulation of ventral tegmental area dopamine (DA) neurons in DAT-Cre mice, while Xie2-64 or SR144528 alone inhibited optical brain-stimulation reward. In vivo microdialysis revealed that systemic or local administration of Xie2-64 into the nucleus accumbens reduced extracellular dopamine levels in a dose-dependent manner in rats. Together, these results suggest that Xie2-64 has significant anti-cocaine reward effects likely through a dopamine-dependent mechanism, and therefore, deserves further study as a new pharmacotherapy for cocaine use disorder.

Simultaneous Inhibition of Peripheral CB1R and iNOS Mitigates Obesity-Related Dyslipidemia Through Distinct Mechanisms.

Diabetic dyslipidemia, characterized by increased plasma triglycerides and decreased HDL cholesterol levels, is a major factor contributing to nonalcoholic steatohepatitis and cardiovascular risk in type 2 diabetes. Activation of the cannabinoid-1 receptor (CB1R) and activation of inducible nitric oxide synthase (iNOS) are associated with nonalcoholic steatohepatitis progression. Here, we tested whether dual-targeting inhibition of hepatic CB1R and iNOS improves diabetic dyslipidemia in mice with diet-induced obesity (DIO mice). DIO mice were treated for 14 days with (S)-MRI-1867, a peripherally restricted hybrid inhibitor of CB1R and iNOS. (R)-MRI-1867, the CB1R-inactive stereoisomer that retains iNOS inhibitory activity, and JD-5037, a peripherally restricted CB1R antagonist, were used to assess the relative contribution of the two targets to the effects of (S)-MRI-1867. (S)-MRI-1867 reduced hepatic steatosis and the rate of hepatic VLDL secretion, upregulated hepatic LDLR expression, and reduced the circulating levels of proprotein convertase subtilisin/kexin type 9 (PCSK9). The decrease in VLDL secretion could be attributed to CB1R blockade, while the reduction of PCSK9 levels and the related increase in LDLR resulted from iNOS inhibition via an mTOR complex 1-dependent mechanism. In conclusion, this approach based on the concomitant inhibition of CB1R and iNOS represents a promising therapeutic strategy for the treatment of dyslipidemia.

Cannabinoid 1 Receptor Antagonists Play a Neuroprotective Role in Chronic Alcoholic Hippocampal Injury Related to Pyroptosis Pathway.

Alcohol use disorders affect millions of people worldwide, and there is growing evidence that excessive alcohol intake causes severe damage to the brain of both humans and animals. Numerous studies on chronic alcohol exposure in animal models have identified that many functional impairments are associated with the hippocampus, which is a structure exhibiting substantial vulnerability to alcohol exposure. However, the precise mechanisms that lead to structural and functional impairments of the hippocampus are poorly understood. Herein, we report a novel cell death type, namely pyroptosis, which accounts for alcohol neurotoxicity in mice. For this study, we used an in vivo model to induce alcohol-related neurotoxicity in the hippocampus. Adult male C57BL/6 mice were treated with 95% alcohol vapor either alone or in combination with selective cannabinoid receptor antagonists or agonists, and VX765 (Belnacasan), which is a selective caspase-1 inhibitor. Alcohol-induced in vivo pyroptosis occurs because of an increase in the levels of pyroptotic proteins such as nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3), caspase-1, gasdermin D (GSDMD), and amplified inflammatory response. Our results indicated that VX765 suppressed the expression of caspase-1 and inhibited the maturation of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18. Additionally, chronic alcohol intake created an imbalance in the endocannabinoid system and regulated 2 cannabinoid receptors (CB1R and CB2R) in the hippocampus. Specific antagonists of CB1R (AM251 and AM281) significantly ameliorated alcohol-induced pyroptosis signaling and inactivated the inflammatory response. Alcohol induces hippocampal pyroptosis, which leads to neurotoxicity, thereby indicating that pyroptosis may be an essential pathway involved in chronic alcohol-induced hippocampal neurotoxicity. Furthermore, cannabinoid receptors are regulated during this process, which suggests promising therapeutic strategies against alcohol-induced neurotoxicity through pharmacologic inhibition of CB1R.

The effect of multiple simulation parameters on MM/PBSA performance for binding affinity prediction of CB1 cannabinoid receptor agonists and antagonists.

Both the inactive- and active-state CB1 receptor crystal structures have now been solved, allowing their application in various structure-based drug design methods. One potential method utilizing these crystal structures is the Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) method of predicting relative binding free.

High-intensity swimming exercise reduces inflammatory pain in mice by activation of the endocannabinoid system.

As exercise intervention solely for pain reduction is relatively new, the available research still leaves an incomplete picture of responsible mechanisms and pathways. Nonetheless, evidence indicates that exercise-induced analgesia involves activation of the endocannabinoid (eCB) system. The present study investigated the role of the eCB system on the antihyperalgesic effect of high-intensity swimming exercise (HISE) in an animal model of peripheral persistent inflammation. Male Swiss mice were allocated to non-exercised and exercised groups and subjected to subcutaneous intraplantar injection (i.pl.) of a single dose of complete Freund's adjuvant (CFA) to induce inflammatory pain. Cumulative HISE was performed once a day, and mechanical hyperalgesia and edema were evaluated 0.5hour after HISE for seven consecutive days. To investigate the role of the eCB system on the antihyperalgesic effect of HISE, non-exercised and exercised mice received intraperitoneal (ip), intrathecal (i.t.) or i.pl. injections of vehicle, AM281 (a CB1 cannabinoid receptor antagonist) or AM630 (a CB2 cannabinoid receptor antagonist) from the 3rd to 5th day after CFA injection. Mechanical hyperalgesia was evaluated 0.5hour after HISE. In addition, the effect of the fatty acid amide hydrolase [FAAH] inhibitor or monoacylglycerol lipase [MAGL] inhibitor on the antihyperalgesic action of HISE was investigated. HISE reduced mechanical hyperalgesia with effects prevented by AM281 or AM630 pretreatment in all delivery routes tested. The inhibition of FAAH and MAGL prolonged the antihyperalgesic effect of HISE. These data demonstrate evidence for the role of the eCB system upon exercise-induced analgesia in a murine model of inflammatory pain.

β-Caryophyllene Reduces the Inflammatory Phenotype of Periodontal Cells by Targeting CB2 Receptors.

Human gingival fibroblasts (GF) and human oral mucosa epithelial cells (EC) with an inflammatory phenotype represent a valuable experimental paradigm to explore the curative activity of agents to be used in oral mucositis. The role of cannabinoid receptor 2 (CB2) has not yet been investigated in oral mucositis. The aim of this study was to evaluate the therapeutic potential of β-Caryophyllene (BCP), a CB2 agonist, in an in vitro model of oral mucositis. GF and EC were stimulated with LPS (2 µg/mL) alone or in combination with BCP; a group of LPS challenged GF and EC were treated with BCP and AM630, a CB2 antagonist. LPS increased the inflammatory cytokines TNF-α, IL-1β, IL-6 and IL-17A whereas it decreased the anti-inflammatory cytokine IL-13. The upstream signals were identified in an augmented expression of NF-κB and STAT-3 and in reduced mRNA levels of PPARγ and PGC-1α. BCP blunted the LPS-induced inflammatory phenotype and this effect was reverted by the CB2 antagonist AM630. These results suggest that CB2 receptors are an interesting target to develop innovative strategies for oral mucositis and point out that BCP exerts a marked curative effect in a preclinical model of oral mucositis which deserves to be confirmed in a clinical setting.

Opioid-enhancing antinociceptive effects of delta-9-tetrahydrocannabinol and amitriptyline in rhesus macaques.

Cannabinoids can enhance the antinociceptive effects of opioids in a synergistic manner, potentially reducing the analgesic dosage of opioids and improving pain therapy. This strategy has also been used as a rationale to combine certain antidepressants and opioids. In this experiment, opioid-induced thermal antinociception was assessed in rhesus macaques using a warm-water tail-withdrawal procedure with 3 water temperatures (40, 50, and 55 °C). In general, the acute antinociceptive effects of intramuscular (i.m.) cumulative doses of heroin were studied alone or in combination with i.m. (-)-trans-delta-9-tetrahydrocannabinol (THC), cannabinol (CBN), or the tricyclic antidepressant amitriptyline. A nonantinociceptive dose of THC (1 mg/kg) shifted the ED50 for the heroin dose-effect curve 3.6-fold leftward at 50 °C and 1.9-fold leftward at 55 °C compared with heroin alone. When the cannabinoid type-1 receptor (CB1R) antagonist, rimonabant, was administered prior to the most effective THC-heroin combination, rimonabant blocked the THC enhancement of heroin antinociception. When CBN (1-3.2 mg/kg) was administered prior to heroin, or 1 mg/kg of CBN was administered prior to a combination of 0.32 mg/kg of THC and heroin, no shifts were evident in the heroin dose-effect curves at either temperature. However, similar to THC, amitriptyline (0.32-1 mg/kg) administered prior to heroin significantly shifted the heroin dose-effect curve leftward. Heroin produced both dose- and temperature-dependent thermal antinociception in nonhuman primates and THC produced opioid-enhancing effects in a CB1R-dependent manner. These effects of THC were not shared by cannabinol, but were quantitatively similar to that of amitriptyline. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Functional role for preoptic CB1 receptors in breathing and thermal control

The anteroventral preoptic region (AVPO) of the hypothalamus is involved in both temperature and breathing regulation. This area densely express cannabinoid receptors type 1 (CB1) that modulate both excitatory and inhibitory synaptic transmission. However, it is still unknown if the endocannabinoid system located in the AVPO participates in breathing control and thermoregulation. Therefore, we tested the participation of CB1 in the AVPO in the modulation of ventilation and thermal control during normoxia and hypoxia. To this end, body temperature (Tb) of Wistar rats was monitored by datallogers and ventilation (VE) by whole body plethysmography before and after intra-AVPO microinjection of AM-251 (CB1 antagonist, 50 and 100 pmol) followed by 60 min of hypoxia exposure (7% O2). Intra-AVPO microinjection of the higher dose of AM-251 increased VE but did not change Tb under resting conditions. Exposure of rats to 7% of inspired oxygen evoked typical hypoxia-induced anapyrexia and hyperventilation after vehicle microinjection. The higher dose of the cannabinoid antagonist increased the hypoxia-induced hyperventilation, in the same magnitude as observed under normoxic condition, whereas the drop in Tb elicited by hypoxia was attenuated. Therefore, the present results demonstrate that the endocannabinoid system acting on CB1 receptors in the AVPO exerts a tonic inhibitory modulation on breathing but seem not be involved in thermoregulation during resting conditions. In addition, activation of CB1 receptors in the AVPO stimulate thermal response during hypoxia, reducing energetically expensive responses, such as the hypoxic hyperventilation.

Discovery of a NAPE-PLD inhibitor that modulates emotional behavior in mice.

N-acylethanolamines (NAEs), which include the endocannabinoid anandamide, represent an important family of signaling lipids in the brain. The lack of chemical probes that modulate NAE biosynthesis in living systems hamper the understanding of the biological role of these lipids. Using a high-throughput screen, chemical proteomics and targeted lipidomics, we report here the discovery and characterization of LEI-401 as a CNS-active N-acylphosphatidylethanolamine phospholipase D (NAPE-PLD) inhibitor. LEI-401 reduced NAE levels in neuroblastoma cells and in the brain of freely moving mice, but not in NAPE-PLD KO cells and mice, respectively. LEI-401 activated the hypothalamus-pituitary-adrenal axis and impaired fear extinction, thereby emulating the effect of a cannabinoid CB1 receptor antagonist, which could be reversed by a fatty acid amide hydrolase inhibitor. Our findings highlight the distinctive role of NAPE-PLD in NAE biosynthesis in the brain and suggest the presence of an endogenous NAE tone controlling emotional behavior.

SUN-LB137 Endocannabinoids Induce Endoplasmic Reticulum Stress in Hepatocytes and Human Coronary Artery Endothelial Cells

Obesity and diabetes are important risk factors for the development of coronary heart disease and stroke. Plasma endocannabinoid (EC) levels are inappropriately elevated in obesity and diabetes, and are hypothesized to play a causal role in central regulation of weight gain. Importantly, it was recently demonstrated that cannabinoid receptor 1 (CNR1) triggers cell stress and induces apoptosis in kidney tubule cells exposed to palmitic acid and high-glucose (HG). HepG2 and human coronary artery endothelial cells (HCAEC) were treated with tunicamycin (TM), thapsigargin (TG), high-glucose (HG), anandamide (AN), and 2-arachondonyl glycerol (2-AG), and endoplasmic reticulum (ER) stress was measured. In cells treated with TM, AM, and 2-AG and the UPR inhibitors 4-phenylbutyrate (4-PB) and taurodeoxycholic acid (TUDCA), both 4-PB and TUDCA prevented AN and 2-AG from promoting ER stress. ER stress in cells treated with AN and 2-AG, but not TM, was inhibited by the CNR1 antagonist rimonabant. Similar results were obtained with HCAEC. Furthermore, treatment with AN and 2-AG induced inositol requiring enzyme 1α and protein kinase R-like endoplasmic reticulum kinase phosphorylation but had no effect on their expression, while activating transcription factor 6 and binding immunoglobulin protein expression were also induced by AN and 2-AG in both HepG2 and HCAEC. Finally, AN and 2-AG treatment induced CNR1 expression in both cell lines. These results strongly suggest that EC’s promote ER stress and potentially induce liver and endothelial cell dysfunction.

CB1 cannabinoid receptor-mediated plasticity of GABAergic synapses in the mouse insular cortex

The insular cortex plays pivotal roles in taste learning. As cellular mechanisms of taste learning, long-term potentiation (LTP) at glutamatergic synapses is well studied. However, little is known about long-term changes of synaptic efficacy at GABAergic synapses in the insular cortex. Here, we examined the synaptic mechanisms of long-term plasticity at GABAergic synapses in layer V pyramidal neurons of the mouse insular cortex. In response to a prolonged high-frequency stimulation (HFS), GABAergic synapses displayed endocannabinod (eCB)-mediated long-term depression (LTDGABA). When cannabinoid 1 receptors (CB1Rs) were blocked by a CB1R antagonist, the same stimuli caused LTP at GABAergic synapses (LTPGABA) which was mediated by production of nitric oxide (NO) via activation of NMDA receptors. Intriguingly, NO signaling was necessary for the induction of LTDGABA. In the presence of leptin which blocks CB1 signaling, the prolonged HFS caused LTPGABA which was mediated by NO signaling. These results indicate that long-term plasticity at GABAergic synapses in the insular cortex can be modulated by combined effects of eCB and NO signaling. These forms of GABAergic synaptic plasticity in the insular cortex may be crucial synaptic mechanisms in taste learning.

β-Caryophyllene Inhibits Cell Proliferation through a Direct Modulation of CB2 Receptors in Glioblastoma Cells.

Glioblastomas are aggressive cancers characterized by uncontrolled proliferation and inflammation. b-caryophyllene (BCP) is a cannabinoid receptor 2 (CB2) agonist that showed an important anti-inflammatory effect through the interaction of CB2 and peroxisome proliferator-activated receptor gamma (PPARg) receptors. BCP effects were investigated in an in vitro model of glioblastoma. U-373 and U87, derived from a human glioblastoma, and human glioma stem-like cells (GSCs) were treated with BCP at different doses and time-points. AM360, a specific CB2 antagonist, was added 2 h before BCP treatment. BCP showed a significant anti-proliferative effect, reducing cell viability, inhibiting cell cycle, and increasing apoptosis, as demonstrated by Tunel assay, caspase-3 and caspase -9 activation. In addition, the pro-apoptotic BAX expression was increased, whereas the anti-apoptotic Bcl-2 expression was reduced. Treatment with BCP decreased Beclin-1, LC3 and p62/SQSTM1 expression, indicating a possible switch of autophagy to apoptosis. BCP’s anti-inflammatory effect was demonstrated by NF-κB reduction, PPARg activation and TNF-a decrease; BCP significantly reduced Jun N-Terminal Kinase (JNK) expression as a consequence of TNF-α inhibition. AM360 abrogated BCP effects, thus demonstrating the BCP mechanism of action through the CB2 receptor. These findings let us hypothesize that BCP may act as a tumor suppressor in glioblastoma, acting on CB2 receptor and modulating JNK.

Drug Therapy in Obesity: A Review of Current and Emerging Treatments.

Whilst the prevalence of obesity continues to increase at an alarming rate worldwide, the personal and economic burden of obesity-related complications becomes ever more important. Whilst dietary and lifestyle measures remain the fundamental focus of the patient to counter obesity, more frequently pharmacological and/or surgical interventions are required. Nevertheless, these therapies are often limited by weight loss efficacy, side effects, surgical risks and frequently obesity relapse. Currently, only five drug therapies are approved for the specific treatment of obesity. However, our understanding of the pathophysiology of obesity and of gut hormones has developed precipitously over the last 20–30 years. As a result, there has been a recent movement to create and use analogues that manipulate these gut hormones to support weight loss. In this article we review the efficacy of the currently approved drug therapies and discuss future potential drug mechanisms and early clinical trial results exploring these budding avenues. We discuss the use of glucagon-like peptide-1 (GLP-1) analogues as monotherapy and unimolecular dual or triple agonists that exploit the GLP-1 receptor and/or the gastric inhibitory peptide (GIP) receptor and/or the glucagon receptor. We also explore the use of sodium-glucose co-transporter-2 (SGLT-2) inhibitors, amylin mimetics, leptin analogues, ghrelin antagonists and centrally acting agents to suppress appetite [neuropeptide Y (NPY) antagonists, melanocortin-4 receptor (MC4R) agonists and cannabinoid-1 receptor antagonists]. Whilst further evidence is required to support their clinical use, preclinical and early clinical trial results are encouraging.

Nausea-Induced Conditioned Gaping Reactions in Rats Produced by High-Dose Synthetic Cannabinoid, JWH-018.

Introduction: Cannabinoid hyperemesis syndrome is becoming a more prominently reported side effect of cannabis containing high-dose Δ9-tetrahydrocannabinol (THC) and designer cannabinoid drugs such as "Spice." One active ingredient that has been found in "Spice" is 1-pentyl-3-(1-naphthoyl)indole (JWH-018), a synthetic full agonist of the cannabinoid 1 (CB1) receptor. In this study, we evaluated the potential of different doses of JWH-018 to produce conditioned gaping in rats, an index of nausea. Materials and Methods: Rats received 3 daily conditioning trials in which saccharin was paired with JWH-018 (0.0, 0.1, 1, and 3 mg/kg, intraperitoneal [i.p.]). Then the potential of pretreatment with the CB1 antagonist, rimonabant (SR), to prevent JWH-018-induced conditioned gaping was determined. To begin to understand the potential mechanism underlying JWH-018-induced nausea, serum collected from trunk blood was subjected to a corticosterone (CORT) analysis in rats receiving three daily injections with vehicle (VEH) or JWH-018 (3 mg/kg). Results: At doses of 1 and 3 mg/kg (i.p.), JWH-018 produced nausea-like conditioned gaping reactions. The conditioned gaping produced by 3 mg/kg JWH-018 was reversed by pretreatment with rimonabant, which did not modify gaping on its own. Treatment with JWH-018 elevated serum CORT levels compared to vehicle-treated rats. Conclusions: As we have previously reported with high-dose THC, JWH-018 produced conditioned gaping in rats, reflective of a nausea effect mediated by its action on CB1 receptors and accompanied by elevated CORT, reflective of hypothalamic-pituitary-adrenal (HPA) activation.

Role of Cannabinoid Receptors in Crocin-Induced Hypoalgesia in Neuropathic Pain in Rats.

PurposeNeuropathic pain involves injury or alteration of the normal sensory and modulatory nervous systems to produce a set of symptoms that are often difficult to treat. Previous study indicates that crocin has anti-inflammatory properties that may be mediated by the neurotransmitter system. In this study, we determine if there is an interaction between crocin and the cannabinoid system on chronic constriction injury (CCI)-induced neuropathic pain in male rats.Materials and MethodsIn this experimental study, adult male Wistar rats (220–250 g) were used. CCI was induced by setting four loose ligatures around the sciatic nerve. In part 1, after nerve lesion, vehicle, crocin (60 mg/kg) or Win 55-212-2 (0.1 mg/kg) as an agonist and AM 251 (0.1 mg/kg) as an antagonist of cannabinoid receptors were injected intraperitoneally daily in separate groups for 2 weeks. In part 2, two weeks after nerve lesion, vehicle (5 µL), crocin (6 µg/5 µL), Win 55-212-2 (0.1 µg/5 µL), AM 251 (0.1 µg/5 µL) were administered intracerebroventricularly (ICV) in separate groups. Mechanical allodynia and thermal hyperalgesia were measured using Von Frey filaments and plantar test device, respectively, at day 14. Data were analyzed by two-way ANOVA and Sidak’s multiple comparisons post-test.ResultsResults indicated that centrally administered crocin significantly decreased thermal hyperalgesia and mechanical allodynia. Also, peripheral injection of crocin significantly decreased mechanical allodynia but not thermal hyperalgesia. Central or peripheral administration of Win 55-212-2 or AM 251 modulates the analgesic effect of crocin significantly.ConclusionOur findings showed that crocin has significant analgesic effects that are probably mediated by an endocannabinoid mechanism.

The Sigma1 Receptor Antagonist CM304 Potentiates the Antinociceptive but not the Discriminative Stimulus Effects of the Cannabinoid Receptor Agonist THC in Rats

Opioid overdose is one of the leading causes of death in the United States in people under 50 years, which has resulted in a decline in life expectancy in the United States. Thus, there is a need for an alternative to prescription mu‐opioid agonists for pain treatment. Delta (9)‐tetrahydrocannabinol (THC), a cannabinoid (CB) agonist, has been shown to produce antinociceptive effects albeit less effectively than mu‐opioid receptor agonists. Sigma1 receptor (σ1R) antagonists in combination with THC may provide a viable and safe pharmacological alternative to prescription opioids for pain treatment. The present study compared the pharmacological effects of the σ1R antagonist CM304 alone and in combination with THC in Sprague Dawley rats. Hotplate latency was determined at 52°C followed by rectal temperature measurement and the drugs were administered intravenously (i.v.) and in cumulative doses every 5 min. THC dose‐dependently increased maximum possible effects (MPEs) up to 84% which were reversed by 10 mg/kg rimonabant (cannabinoid CB1 receptor antagonist). CM304 alone up to a dose of 10 mg/kg did not produce significant antinociceptive or hypothermic effects, but CM304 (1.0 and 3.2 mg/kg, i.v.) dose‐dependently left‐shifted the dose‐effect functions of the antinociceptive (7.3‐fold at 3.2 mg/kg CM304) and hypothermic effects of THC. In rats discriminating 3.2 mg/kg THC i.p. from vehicle under a fixed ratio (FR) 10 schedule of food delivery, the cannabinoid CB1 receptor agonist CP55,940 fully substituted for THC, whereas CM304 i.p. produced a maximum of 27 % THC‐lever responding at 17.8 mg/kg. CM304, at doses of 32 and 56 mg/kg, decreased response rate to 24 and 9 %, respectively. No dose of BD1063 (σ1R antagonist), rimonabant, SR144528 (cannabinoid CB2 receptor antagonist), morphine (μ‐opioid receptor agonist), or naltrexone (opioid antagonist) produced greater than 30% THC‐lever responding. Pretreatment with rimonabant (1.78 mg/kg) produced a rightward shift in the dose effect curve of THC (4.5‐fold) and CP55940 (4.5‐fold) while pretreatment with CM304, BD1063, SR144528, and naltrexone had no significant effect on the dose effect curve of THC. The present results may support the development of a σ1R antagonist as an adjunct to cannabinoids for treatment of acute pain without enhancing an undesirable side effect of THC.Support or Funding InformationThis work was supported by National Institute on Drug Abuse grants DA23205 and DA48353.

Inhibition of fatty acid amide hydrolase in the CNS prevents and reverses morphine tolerance in male and female mice.

Fatty acid amide hydrolase (FAAH) is an intracellular serine amidase that terminates the signalling of various lipid messengers involved in pain regulation, including anandamide and palmitoylethanolamide. Here, we investigated the effects of pharmacological or genetic FAAH removal on tolerance to the anti-nociceptive effects of morphine. We induced tolerance in male and female mice by administering twice-daily morphine for 7 days while monitoring nociceptive thresholds by the tail immersion test. The globally active FAAH inhibitor URB597 (1 and 3 mg·kg-1 , i.p.) or the peripherally restricted FAAH inhibitor URB937 (3 mg·kg-1 , i.p.) were administered daily 30 min prior to morphine, alone or in combination with the cannabinoid CB1 receptor antagonist AM251 (3 mg·kg-1 , i.p.), the CB2 receptor antagonist AM630 (3 mg·kg-1 , i.p.), or the PPAR-α antagonist GW6471 (4 mg·kg-1 , i.p.). Spinal levels of FAAH-regulated lipids were quantified by LC/MS-MS. Gene transcription was assessed by RT-qPCR. URB597 prevented and reversed morphine tolerance in both male and female mice. This effect was mimicked by genetic FAAH deletion, but not by URB937. Treatment with AM630 suppressed, whereas treatment with AM251 or GW6471, attenuated the effects of URB597. Anandamide mobilization was enhanced in the spinal cord of morphine-tolerant mice. mRNA levels of the anandamide-producing enzyme N-acyl-phosphatidylethanolamine PLD (NAPE-PLD) and the palmitoylethanolamide receptor PPAR-α, but not those for CB2 , CB1 receptors or FAAH, were elevated in spinal cord CONCLUSION AND IMPLICATIONS: FAAH-regulated lipid signalling in the CNS modulated opiate tolerance, suggesting FAAH as a potential target for opiate-sparing medications.

Pharmacological and molecular docking assessment of cryptotanshinone as natural-derived analgesic compound

Medicinal plants from traditional chinese medicine are used increasingly worldwide for their benefits to health and quality of life for the relevant clinical symptoms related to pain. Among them, Salvia miltiorrhiza Bunge is traditionally used in asian countries as antioxidant, anticancer, anti-inflammatory and analgesic agent. In this context, several evidences support the hypothesis that some tanshinones, in particular cryptotanshinone (CRY), extracted from the roots (Danshen) of this plant exhibit analgesic actions. However, it is surprisingly noted that no pharmacological studies have been carried out to explore the possible analgesic action of this compound in terms of modulation of peripheral and/or central pain.Therefore, in the present study, by using peripheral and central pain models of nociception, such as tail flick and hot plate test, the analgesic effect of CRY in mice was evaluated. Successively, by the aim of a computational approach, we have evaluated the interaction mode of this diterpenoid on opioid and cannabinoid system. Finally, CRY was dosed in mice serum by an HPLC method validated according to European Medicines Agency guidelines validation rules.Here, we report that CRY displayed anti-nociceptive activity on both hot plate and tail flick test, with a prominent long-lasting peripheral analgesic effect. These evidences were indirectly confirmed after the daily administration of the tanshinone for 7 and 14 days. In addition, the analgesic effect of CRY was reverted by naloxone and cannabinoid antagonists and amplified by arginine administration. These findings were finally supported by HPLC and docking studies, that revealed a noteworthy presence of CRY on mice serum 1 h after its intraperitoneal administration and a possible interaction of tested compound on μ and k receptors.Taken together, these results provide a new line of evidences showing that CRY can produce analgesia against various phenotypes of nociception with a mechanism that seems to be related to an agonistic activity on opioid system.

Effect of (m)RVD-hemopressin against Aβ1-42-induced apoptosis and inhibition of neurite outgrowth in SH-SY5Y cells

Alzheimer's disease (AD) is a serious neurodegenerative disease. Senile plaques (SPs) in the extracellular space and neurofibrillary tangles (NFTs) in the intracellular areas of the brain are two typical features of AD. SPs and NFTs are composed of amyloid-β (Aβ) aggregates and hyperphosphorylated Tau, respectively. (m)RVD-hemopressin (RVD), which is derived from mouse brain peptide, binds to the cannabinoid 1 receptor (CB1R) as an agonist. Our previous study indicated that RVD reversed Aβ1–42-induced memory impairment in mice. Here, we investigated the underlying molecular mechanism of RVD on Aβ1–42-induced neurotoxicity in retinoic acid-differentiated human neuroblastoma SH-SY5Y cells. Cell viability and neurite outgrowth were investigated by live cell imaging and analysis instrument. We found that RVD reversed Aβ1–42-induced Tau phosphorylation, apoptosis and suppression of neurite outgrowth and the synapse-associated protein postsynaptic density protein 95 (PSD-95) by inhibiting the activity of protein kinase A (PKA) and glycogen synthase kinase 3β (GSK-3β). Combined treatment with AM251 (a CB1R antagonist) blocked the effects of RVD. In conclusion, RVD may be a potential therapeutic agent for the treatment of cognitive dysfunctions, such as Alzheimer's disease.

Novel CB1 receptor antagonist BAR-1 modifies pancreatic islet function and clinical parameters in prediabetic and diabetic mice

BackgroudsCannabinoid receptor antagonists have been suggested as a novel treatment for obesity and diabetes. We have developed a synthetic cannabinoid receptor antagonist denominated BAR-1. As the function and integrity of a β-cell cellular structure are important keys for diabetes onset, we evaluated the effects of pharmacological administration of BAR-1 on prediabetic and diabetic rodents.MethodsCD-1 mice fed a hypercaloric diet or treated with streptozotocin were treated with 10 mg/kg BAR-1 for 2, 4 or 8 weeks. Body weight, oral glucose tolerance test, HbA1c, triglycerides and insulin in serum were measured. In isolated islets, we evaluated stimulated secretion and mRNA expression, and relative area of islets in fixed pancreases. Docking analysis of BAR-1 was complemented.ResultsBAR-1 treatment slowed down weight gain in prediabetic mice. Fasting glucose–insulin relation also decreased in BAR-1-treated mice and glucose-stimulated insulin secretion was increased in isolated islets, without effects in oral test. Diabetic mice treated with BAR-1 showed a reduced glucose and a partial recovery of islet integrity. Gene expression of insulin and glucagon showed biphasic behaviour, increasing after 4 weeks of BAR-1 administration; however, after 8 weeks, mRNA abundance decreased significantly. Administration of BAR-1 also prevents changes in endocannabinoid element expression observed in prediabetic mice. No changes were detected in other parameters studied, including the histological structure. A preliminary in-silico study suggests a close interaction with CB1 receptor.ConclusionsBAR-1 induces improvement of islet function, isolated from both prediabetic and diabetic mice. Effects of BAR-1 suggest a possible interaction with other cannabinoid receptors.