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Diet-induced obesity (DIO) is a contributor to co-morbidities, resulting in alterations in hormones, lipids, and low-grade inflammation, with the cannabinoid type 2 receptor (CB2) contributing to the inflammatory response. The effects of modulating CB2 with pharmacological treatments on inflammation and adaptations to the obese state are not known. Therefore, we aimed to investigate the molecular mechanisms in adipose tissue of CB2 agonism and CB2 antagonism treatment in a DIO model. Male Sprague Dawley rats were placed on a high-fat diet (HFD) (21% fat) for 9 weeks, then received daily intraperitoneal injections with a vehicle, AM630 (0.3 mg/kg), or AM1241 (3 mg/kg), for a further 6 weeks. AM630 or AM1241 treatment in DIO rats did not alter their body weight, food intake, or liver weight, and it had no effect on their numerous circulating cytokines or peri-renal fat pad mass. AM1241 decreased heart weight and BAT weight; both treatments (AM630 or AM1241) decreased plasma leptin levels, while AM630 also decreased plasma ghrelin and GLP-1 levels. Both treatments decreased Adrb3 and TNF-α mRNA levels in eWAT and TNF-α levels in pWAT. AM630 treatment also decreased the mRNA levels of Cnr2, leptin, and Slc2a4 in eWAT. In BAT, both treatments decreased leptin, UCP1, and Slc2a4 mRNA levels, with AM1241 also decreasing Adrb3, IL1β, and PRDM16 mRNA levels, and AM630 increasing IL6 mRNA levels. In DIO, CB2 agonist and CB2 antagonist treatment reduces circulating leptin in the absence of weight loss and modulates the mRNA responsible for thermogenesis. [ABSTRACT FROM AUTHOR]

Diet-induced obesity (DIO) is a contributor to co-morbidities, resulting in alterations in hormones, lipids, and low-grade inflammation, with the cannabinoid type 2 receptor (CB2) contributing to the inflammatory response. The effects of modulating CB2 with pharmacological treatments on inflammation and adaptations to the obese state are not known. Therefore, we aimed to investigate the molecular mechanisms in adipose tissue of CB2 agonism and CB2 antagonism treatment in a DIO model. Male Sprague Dawley rats were placed on a high-fat diet (HFD) (21% fat) for 9 weeks, then received daily intraperitoneal injections with a vehicle, AM630 (0.3 mg/kg), or AM1241 (3 mg/kg), for a further 6 weeks. AM630 or AM1241 treatment in DIO rats did not alter their body weight, food intake, or liver weight, and it had no effect on their numerous circulating cytokines or peri-renal fat pad mass. AM1241 decreased heart weight and BAT weight; both treatments (AM630 or AM1241) decreased plasma leptin levels, while AM630 also decreased plasma ghrelin and GLP-1 levels. Both treatments decreased Adrb3 and TNF-α mRNA levels in eWAT and TNF-α levels in pWAT. AM630 treatment also decreased the mRNA levels of Cnr2, leptin, and Slc2a4 in eWAT. In BAT, both treatments decreased leptin, UCP1, and Slc2a4 mRNA levels, with AM1241 also decreasing Adrb3, IL1β, and PRDM16 mRNA levels, and AM630 increasing IL6 mRNA levels. In DIO, CB2 agonist and CB2 antagonist treatment reduces circulating leptin in the absence of weight loss and modulates the mRNA responsible for thermogenesis.

Objective: The aim of this study is to prove whether or not the cannabinoid (CB)2 receptor agonist, which is known to be effective in anti-inflammatory effects and tried in various organ and/or tissue ischemia/reperfusion (I/R) injuries, works in the treatment of I/R injury, which is a replication of the damage caused by clinical ovarian torsion.Materials and Methods: Rats were divided into five groups (n=6). After anesthesia, an approximately 2-cm incision was made in the lower abdominal region of the rats and both ovaries, uterine horns, and adnexa were occluded with a clamp for 30 min, except for the sham control group. After 3 h, both ovaries were surgically removed. Blood was collected for the measurement of cytokine levels in the serum.Results: The induction of ovaries by I/R injury resulted in an increase in interleukin 1 beta, tumor necrosis factor alpha, and malondialdehyde levels and decrease in glutathione (GSH) levels in ovarian tissues and serum. The pretreatment of the CB2 receptor agonist decreased these cytokines levels in both ovarian tissues and serum. The GSH level in both was reduced by I/R injury, while the agonist increased the GSH level reduced by I/R injury. The administration of the antagonist reversed the curative effect of the agonist. Conclusion: The results of this study support that the CB2 receptor agonist can be used to treat I/R injury, which is an imitation of ovarian torsion. However, no the clinical trial is a limitation of this study.

We have previously shown that cannabinoid CB1 and CB2 receptor antagonists, AM251 and AM630, respectively, modulate cardiostimulatory effects of isoprenaline in atria of Wistar rats. The aim of the present study was to examine whether such modulatory effects can also be observed (a) in the human atrium and (b) in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Inotropic effects of isoprenaline and/or CGP12177 (that activate the high‐ and low‐affinity site of β1‐adrenoceptors, respectively) were examined in paced human atrial trabeculae and rat left atria; chronotropic effects were studied in spontaneously beating right rat atria. AM251 modified cardiostimulatory effects more strongly than AM630. Therefore, AM251 (1 μM) enhanced the chronotropic effect of isoprenaline in WKY and SHR as well as inotropic action of isoprenaline in WKY and in human atria. It also increased the inotropic influence of CGP12177 in SHR. AM630 (1 μM) decreased the inotropic effect of isoprenaline and CGP12177 in WKY, but enhanced the isoprenaline‐induced inotropic effect in SHR and human atria. Furthermore, AM251 (0.1 and 3 μM) and AM630 (0.1 μM) reduced the inotropic action of isoprenaline in human atria. In conclusion, cannabinoid receptor antagonists have potentially harmful and beneficial effects through their amplificatory effects on β‐adrenoceptor‐mediated positive chronotropic and inotropic actions, respectively. [ABSTRACT FROM AUTHOR]

Cannabidiol (CBD), a phytocannabinoid compound, presents antidepressant and anxiolytic-like effects in the type-1 diabetes mellitus(DM1) animal model. Although the underlying mechanism remains unknown, the type-1A serotonin receptor (5-HT1A) and cannabinoids type-1 (CB1) and type-2 (CB2) receptors seem to play a central role in mediating the beneficial effects on emotional responses. We aimed to study the involvement of these receptors on an antidepressant- and anxiolytic-like effects of CBD and on some parameters of the diabetic condition itself. After 2 weeks of the DM1 induction in male Wistar rats by streptozotocin (60 mg/kg; i.p.), animals were treated continuously for 2-weeks with the 5-HT1A receptor antagonist WAY100635 (0.1 mg/kg, i.p.), CB1 antagonist AM251 (1 mg/kg i.p.) or CB2 antagonist AM630 (1 mg/kg i.p.) before the injection of CBD (30 mg/kg, i.p.) or vehicle (VEH, i.p.) and then, they were submitted to the elevated plus-maze and forced swimming tests. Our findings show the continuous treatment with CBD improved all parameters evaluated in these diabetic animals. The previous treatment with the antagonists − 5-HT1A, CB1, or CB2 - blocked the CBD-induced antidepressant-like effect whereas only the blockade of 5-HT1A or CB1 receptors was able to inhibit the CBD-induced anxiolytic-like effect. Regarding glycemic control, only the blockade of CB2 was able to inhibit the beneficial effect of CBD in reducing the glycemia of diabetic animals. These findings indicated a therapeutic potential for CBD in the treatment of depression/anxiety associated with diabetes pointing out a complex intrinsic mechanism in which 5-HT1A, CB1, and/or CB2 receptors are differently recruited. [ABSTRACT FROM AUTHOR]

Leptin is an adipokine predominantly secreted by adipocytes and has many physiological roles, including in energy homeostasis. We identified that AM630, a cannabinoid receptor 2 (CB2) antagonist, down-regulated leptin expression in mature adipocytes differentiated from either stromal vascular fractions isolated from inguinal fat pads of C57BL/6J mice or 3T3-L1 preadipocytes. However, the leptin-suppressive effects of AM630 preserved in CB2-deficient adipocytes indicated the off-target activity of AM630 in leptin expression. Pharmacological and genetic studies, cheminformatics, and docking simulation were applied to identify the potential protein target of AM630 that modulates leptin expression in differentiated primary preadipocytes. Screening of the reported off-targets of AM630 identified a synthetic cannabinoid WIN55212-2 exerting the same function. Target deconvolution and docking simulation suggested that AM630 and WIN55212-2 were both inhibitors of lipocalin-type prostaglandin D2 synthase (L-PGDS). Further studies showed that L-PGDS positively regulates leptin expression. Although glucocorticoid and aldosterone were previously reported to induce expression of both L-PGDS and leptin, our data demonstrated that L-PGDS mediates only glucocorticoid-induced leptin expression in differentiated primary preadipocytes. No effect was observed after aldosterone treatment. This newly discovered glucocorticoid – L-PGDS – leptin pathway may provide insights into current clinical use of glucocorticoid and management of their undesired effects such as obesity. [ABSTRACT FROM AUTHOR]

Endocannabinoids (eCBs) mediate their effects through actions on several receptors including the cannabinoid receptors CB1R and CB2R. The role played by eCBs in the development of locomotor systems is not fully understood. In this study we investigated the roles of the eCB system in zebrafish development by pharmacologically inhibiting the CB1R and CB2Rs (with AM251 and AM630 respectively) in either the first or second day of development. We examined the morphology of motor neurons and we determined neuromuscular outputs by quantifying the amount of swimming in 5 dpf larva. Blocking CB2R during the first day of development resulted in gross morphological deficits and reductions in heart rate that were greater than that following treatment with the CB1R blocker AM251. Blocking CB1Rs from 0 to 24 hpf resulted in an increase in the number of secondary and tertiary branches of primary motor neurons, whereas blocking CB2Rs had the opposite effect. Both treatments manifested in reduced levels of swimming. Additionally, blocking CB1Rs resulted in greater instances of non-inflated and partially inflated swim bladders compared with AM630, suggesting that at least some of the deficits in locomotion may result from an inability to adjust buoyancy. Together these findings indicate that the endocannabinoid system is pivotal to the development of the locomotor system in zebrafish, and that perturbations of the eCB system early in life may have detrimental effects. [ABSTRACT FROM AUTHOR]

The cannabinoid type 2 receptor (CB 2) has recently emerged as an important therapeutic target for cancer as well as cardiovascular diseases. The CB 2 receptor downregulation has been reported in solid tumors and cardiovascular diseases, therefore the CB 2 receptor activation has been considered as a viable strategy for chemotherapy as well as cardioprotection. Doxorubicin (DOX) is an important drug that continues to be the mainstay of chemotherapy in solid tumors, leukemia, and lymphoma. However, the use of DOX is often limited due to its lethal cardiotoxicity. Considering the role of CB 2 receptors in cardiovascular diseases and cancer, the activation of CB 2 receptors may protect against DOX-induced chronic cardiotoxicity in rats. In the present study, we investigated the cardioprotective effect of a selective CB 2 receptor agonist; β-Caryophyllene (BCP), a natural bicyclic sesquiterpene, against DOX-induced chronic cardiotoxicity in rats. AM630, a CB 2 receptor antagonist was administered as a pharmacological challenge prior to BCP treatment to demonstrate CB 2 receptor mediated cardioprotective mechanism of BCP. DOX (2.5 mg/kg) was injected intraperitoneally once a week for five weeks to induce chronic cardiotoxicity in rats. BCP was also injected into rats six days a week for a total duration of five weeks. DOX induced a significant decline in cardiac function and oxidative stress evidenced by the depletion of antioxidant enzymes, glutathione, and increased lipid peroxidation. DOX also triggered activation of nuclear factor kappa B (NF-κB) and increased the levels of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) and expression of the inflammatory mediators (iNOS and COX-2) in the heart. Furthermore, DOX also upregulated the expression of pro-apoptotic markers such as Bax, p53, cleaved PARP, active caspase-3 and downregulated anti-apoptotic marker Bcl-2 in the myocardium. BCP treatment exerted significant cardioprotective effect by salvaging the heart tissues, improving cardiac function, mitigating oxidative stress, inflammation, and apoptosis. The histological and ultrastructural studies also appear in line with our findings of biochemical and molecular parameters. The CB 2 receptor-mediated cardioprotective mechanism was further confirmed by the abrogation of the beneficial effects of BCP with prior administration of the CB 2 receptor antagonist; AM630. Our study revealed the novel mechanism of BCP in cardioprotection against DOX-induced chronic cardiotoxicity by the activation of CB 2 receptors. • BCP, a natural CB2 receptor agonist activates CB2 and PPARγ receptors in the heart. • CB2 receptor activation inhibits oxidative stress, inflammation, and apoptosis in the heart. • AM630, a CB2 receptor antagonist abrogates the beneficial effects of BCP. • This study has revealed the CB2 receptor-mediated cardioprotective effects of BCP. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The endocannabinoid system plays a pivotal role in the regulation of ethanol reinforcing and motivational actions. The pharmacological manipulation of cannabinoid CB1 receptor (CB 1 r) in alcoholic patients provided discouraging results, so researchers have recently turned their attention to the cannabinoid CB2 receptor (CB 2 r). In this regard, the present study aims to characterise CB 2 r-mediated effects on ethanol self-administration and to describe the neurochemical mechanisms that may be involved. We performed an oral ethanol self-administration (OEA) experiment to analyse the effects of repeated administration of AM630 (1 mg kg−1, i.p.) or JWH133 (1 mg kg−1, i.p.) on the number of reinforced responses, the 8% ethanol intake and the breaking point values in male C57BL/6J mice. By means of real-time polymerase chain reaction (PCR), we also analysed relative gene expression of tyrosine hydroxylase (TH) in the ventral tegmental area (VTA), and of mu-opioid receptor (OPRM1), CNR1 and CNR2 in the nucleus accumbens (NAcc). AM630-induced blockade of CB 2 r significantly increased the number of reinforced responses, 8% ethanol consumption and breaking point, whereas JWH133 treatment induced the opposite effect. Interestingly, the administration of AM630 significantly increased TH gene expression in the VTA, as well as OPRM1 and CNR1 gene expression in the NAcc, whereas administration with JWH133 decreased gene expression of these targets. In addition, CNR2 gene expression was unchanged with AM630 treatment but increased in animals treated with JWH133. The therapeutic implications of our results hold promise for CB 2 r as a means to manage alcohol use disorder and significantly contribute to improving understanding of the underlying neurobiological mechanisms involved. [ABSTRACT FROM AUTHOR]

In the present research, we examined the possible interaction between the hippocampal CB2 and GABA A receptors on modulation of memory consolidation. In this research, step-down passive a . voidance task was used to evaluate memory consolidation in adult male NMRI mice. The results showed that post-training intra-CA1 administration of muscimol (0.05 and 0.1 μg/mouse) impaired memory consolidation as evidenced by a decrease in step-down latency on the test day, which was suggestive of drug-produced amnesia. However co-administration of different doses of muscimol (0.01, 0.05 and 0.1 μg/mouse) along with a not-effect dose of AM630 (1 μg/mouse) or GP1a (1 μg/mouse) had no significant effect on impairment of memory consolidation induced by muscimol. Although post-training intra-CA1 administration of the cannabinoid CB2 receptor antagonist, AM630 (1, 10 and 100 μg/mouse) alone had no effect, its co-administration with an effective dose of muscimol (0.05 μg/mouse) impaired memory consolidation. Furthermore, post-training intra-CA1 microinjection of cannabinoid CB2 receptor agonist, GP1a (100 μg/mouse) impaired memory consolidation. Interestingly, post-training intra-CA1 co-injection of different doses of GP1a (1, 10 and 100 μg/mouse) along with an effect dose of muscimol (0.05 μg/mouse) significantly intensified impairment of memory consolidation induced by GP1a (10 μg/mouse). Moreover, all above doses of drugs did not significantly change locomotor activity. These findings suggest possible interaction between the CA1 cannabinoid CB2 and GABA A mechanisms on modulation of memory consolidation in mice. [ABSTRACT FROM AUTHOR]

Purpose: Renal cell carcinoma (RCC) is the most common malignancy of urogenital system, and patients with RCC may face a poor prognosis. However, limited curable therapeutic options are currently available. The aim of this study is to investigate the role of Cannabinoid receptor 2 (CB2) in RCC progression. Methods: Immunohistochemistry was to investigate the expression pattern of CB2 in 418 RCC tissues and explore its prognostic function in RCC patients. Furthermore, the role of used CB2 si-RNA knockdown and inhibited by AM630, a CB2 inverse agonist, on cell proliferation, migration, and cell cycle of RCC cell lines in vitro was also investigated. Results: We observed that CB2 was up-regulated in RCC tissues, and presented as an independent prognostic factor for overall survival of RCC patients and higher CB2 expression tends to have poor clinical outcomes in survival analyses. Moreover, we also observed that CB2, incorporated with pN stage, pathological grade, and recurrence or distant metastasis after surgery, could obviously enhance their prognostic accuracy in a predictive nomogram analysis. In addition, knockdown or inhibition by AM630 for the expression of CB2 in vitro could significantly decreased cell proliferation and migration, and obviously induced cell cycle arrest in G2/M of RCC cells. Conclusions: CB2 expression is functionally related to cellular proliferation, migration, and cell cycle of RCC cells. Our data suggest that CB2 might be a potential therapeutic target for RCC. [ABSTRACT FROM AUTHOR]

Rationale: CB receptors express constitutive activity and inverse agonists regulate receptor basal activity , which might be involved in death mechanisms. This study assessed the effects of a selective CB agonist (JWH133) and different CB inverse agonists (AM630, JTE907, raloxifene) on death pathways in brain. Objectives: The acute (JWH13) and the acute/chronic effects (AM630, JTE907, raloxifene) of CB ligands regulating pro-apoptotic c-Jun NH-terminal kinase (p-JNK/JNK ratio) and associated signaling of extrinsic (Fas receptor, Fas-Associated death domain protein, FADD) and intrinsic (Bax, cytochrome c) death pathways (nuclear poly (ADP-ribose) polymerase PARP) were investigated in mouse brain. Methods: Mice were treated with CB drugs and target protein contents were assessed by western blot analysis. Results: JWH133 reduced cortical JNK (−27-45%) whereas AM630 acutely increased JNK in cortex (+61-148%), cerebellum (+34-40%), and striatum (+33-42%). JTE907 and raloxifene also increased cortical JNK (+31%-57%). Acute AM630, but not JWH133, increased cortical FADD, Bax, cytochrome c, and PARP cleavage. Repeated treatments with the three CB inverse agonists were associated with a reversal of the acute effects resulting in decreases in cortical JNK (AM630: −36%; JTE907: −25%; raloxifene: −11%). Chronic treatments also induced a reversal with down-regulation (AM630) or only tolerance (JTE907 and raloxifene) on other apoptotic markers (FADD, Bax, cytochrome c, PARP). Conclusions: AM630 and JTE907 are CB protean ligands. Thus, chronic inverse agonists abolished CB constitutive activity and then the ligands behaved as agonists reducing (like JWH133) JNK activity. Acute and chronic treatments with CB inverse agonists regulate in opposite directions brain death markers. [ABSTRACT FROM AUTHOR]

Rationale: Convincing evidence has supported the pivotal role of N-methyl- d-aspartate receptors (NMDARs) and CB2Rs in the regulation of learning and memory. Objective: In this study, the role of hippocampal (CA1 region) CB2 receptors on aversive memory consolidation deficit induced by D-AP5, a NMDA receptor antagonist, was evaluated. Methods: Adult male Wistar rats received cannula implants that bilaterally targeted the CA1 region. Long-term memory was examined using the step-through type of passive avoidance task. Results: Post-training, intra-CA1 microinjection of D-AP5 (0.5 and 0.75 μg/rat), GP1a (CB2 receptor agonist at dose of 150 ng/rat) and AM630 (CB2 receptor antagonist at doses 75 and 100 ng/rat) impaired memory consolidation processes. Intra-CA1 microinjection of a lower dose of GP1a or AM630 restored memory impairment induced by D-AP5 at the two higher doses, while AM630 decreased D-AP5 memory response at the lower dose. The isobologram analysis showed that there is a synergistic effect between D-AP5 and AM630 on memory consolidation deficit. Conclusions: These results suggest that CA1 CB2 receptors modulate memory consolidation impairment induced by D-AP5. [ABSTRACT FROM AUTHOR]

The cannabinoid type two receptors (CB2), an important component of the endocannabinoid system, have recently emerged as neuromodulators and therapeutic targets for neurodegenerative diseases including Parkinson’s disease (PD). The downregulation of CB2 receptors has been reported in the brains of PD patients. Therefore, both the activation and the upregulation of the CB2 receptors are believed to protect against the neurodegenerative changes in PD. In the present study, we investigated the CB2 receptor-mediated neuroprotective effect of β-caryophyllene (BCP), a naturally occurring CB2 receptor agonist, in, a clinically relevant, rotenone (ROT)-induced animal model of PD. ROT (2.5 mg/kg BW) was injected intraperitoneally (i.p.) once daily for four weeks to induce PD in male Wistar rats. ROT injections induced a significant loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and DA striatal fibers, following activation of glial cells (astrocytes and microglia). ROT also caused oxidative injury evidenced by the loss of antioxidant enzymes and increased nitrite levels, and induction of proinflammatory cytokines: IL-1β, IL-6 and TNF-α, as well as inflammatory mediators: NF-κB, COX-2, and iNOS. However, treatment with BCP attenuated induction of proinflammatory cytokines and inflammatory mediators in ROT-challenged rats. BCP supplementation also prevented depletion of glutathione concomitant to reduced lipid peroxidation and augmentation of antioxidant enzymes: SOD and catalase. The results were further supported by tyrosine hydroxylase immunohistochemistry, which illustrated the rescue of the DA neurons and fibers subsequent to reduced activation of glial cells. Interestingly, BCP supplementation demonstrated the potent therapeutic effects against ROT-induced neurodegeneration, which was evidenced by BCP-mediated CB2 receptor activation and the fact that, prior administration of the CB2 receptor antagonist AM630 diminished the beneficial effects of BCP. The present study suggests that BCP has the potential therapeutic efficacy to elicit significant neuroprotection by its anti-inflammatory and antioxidant activities mediated by activation of the CB2 receptors.

We aimed to investigate the potential anti-emetic and anti-nausea properties of targeting the cannabinoid 2 (CB 2 ) receptor. We investigated the effect of the selective CB 2 agonist, HU-308, on lithium chloride- (LiCl) induced vomiting in Suncus murinus (S. murinus) and conditioned gaping (nausea-induced behaviour) in rats. Additionally, we determined whether these effects could be prevented by pretreatment with AM630 (a selective CB 2 receptor antagonist/inverse agonist). In S. murinus , HU-308 (2.5, 5 mg/kg, i.p.) reduced, but did not completely block, LiCl-induced vomiting; an effect that was prevented with AM630. In rats, HU-308 (5 mg/kg, i.p.) suppressed, but did not completely block, LiCl-induced conditioned gaping to a flavour; an effect that was prevented by AM630. These findings are the first to demonstrate the ability of a selective CB 2 receptor agonist to reduce nausea in animal models, indicating that targeting the CB 2 receptor may be an effective strategy, devoid of psychoactive effects, for managing toxin-induced nausea and vomiting. [ABSTRACT FROM AUTHOR]

The cannabinoid type two receptors (CB2), an important component of the endocannabinoid system, have recently emerged as neuromodulators and therapeutic targets for neurodegenerative diseases including Parkinson's disease (PD). The downregulation of CB2 receptors has been reported in the brains of PD patients. Therefore, both the activation and the upregulation of the CB2 receptors are believed to protect against the neurodegenerative changes in PD. In the present study, we investigated the CB2 receptor-mediated neuroprotective effect of β-caryophyllene (BCP), a naturally occurring CB2 receptor agonist, in, a clinically relevant, rotenone (ROT)-induced animal model of PD. ROT (2.5 mg/kg BW) was injected intraperitoneally (i.p.) once daily for 4 weeks to induce PD in male Wistar rats. ROT injections induced a significant loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and DA striatal fibers, following activation of glial cells (astrocytes and microglia). ROT also caused oxidative injury evidenced by the loss of antioxidant enzymes and increased nitrite levels, and induction of proinflammatory cytokines: IL-1β, IL-6 and TNF-α, as well as inflammatory mediators: NF-κB, COX-2, and iNOS. However, treatment with BCP attenuated induction of proinflammatory cytokines and inflammatory mediators in ROT-challenged rats. BCP supplementation also prevented depletion of glutathione concomitant to reduced lipid peroxidation and augmentation of antioxidant enzymes: SOD and catalase. The results were further supported by tyrosine hydroxylase immunohistochemistry, which illustrated the rescue of the DA neurons and fibers subsequent to reduced activation of glial cells. Interestingly, BCP supplementation demonstrated the potent therapeutic effects against ROT-induced neurodegeneration, which was evidenced by BCP-mediated CB2 receptor activation and the fact that, prior administration of the CB2 receptor antagonist AM630 diminished the beneficial effects of BCP. The present study suggests that BCP has the potential therapeutic efficacy to elicit significant neuroprotection by its anti-inflammatory and antioxidant activities mediated by activation of the CB2 receptors. [ABSTRACT FROM AUTHOR]

The present study investigated the potential protective effect of a selective Cannabinoid-2 (CB2) receptor agonist, 1-phenylisatin, in acute nephrotoxicity induced by cisplatin. Animals were arranged into 5 groups. Group I; normal saline, group II; 1-phenylisatin for 7 days, group III: received a single injection of cisplatin (20 mg/kg, i.p.) on day 5, group IV: 1-phenylisatin for 7 days and cisplatin on day 5 and group V: AM630, CB2 antagonist, 15 min before 1-phenylisatin for 7 days and a single injection of cisplatin on day 5. Mice were sacrificed 72 h after cisplatin injection. Kidneys were isolated for histopathological and biochemical analyses. Nephrotoxicity parameters including serum creatinine and urea were assessed as well as histopathological examination was done. Also, Oxidative stress markers; MDA and GSH, inflammatory markers; TNF-α, NF-κB (p65), MCP-1, MIP-2, and ICAM-1, along with apoptotic markers, Bax, Bcl2, and caspase-3 were studied. Further, CB2 receptor expression was investigated. Cisplatin injection increased serum creatinine and urea levels, and increased lipid peroxidation, decreased glutathione level and increased the renal expression of pro-inflammatory markers, TNF-α, NF-κB, MCP-1, MIP-2, and ICAM-1, along with increased apoptotic markers and significantly reduced the expression of the anti-apoptotic Bcl2. Pretreatment with 1-phenylisatin significantly counteracted these effects. The CB2 receptor antagonist; AM630, increased the renal expression of caspase-3 and Bax whereas Bcl2 expression decreased. 1-Phenylisatin protected against cisplatin-induced nephrotoxicity owing to its anti-apoptotic, anti-inflammatory, and antioxidant effects. These actions were mostly mediated through CB2 receptor. • 1-Phenylisatin is a selective cannabinoid-2 (CB2) receptor agonist. • 1-Phenylisatin protected against cisplatin-induced nephrotoxicity. • The nephroprotection is through its antioxidant, anti-inflammatory and anti-apoptotic effects. • This activity was mediated through its CB2 effect. [ABSTRACT FROM AUTHOR]

Painful neuropathy frequently develops as a consequence of commonly used chemotherapy agents for cancer treatment and is often a dose-limiting side effect. Currently available analgesic treatments are often ineffective on pain induced by neurotoxicity. Although peripheral administration of cannabinoids, endocannabinoids, and inhibitors of endocannabinoid hydrolysis has been effective in reducing hyperalgesia in models of peripheral neuropathy, including chemotherapy-induced peripheral neuropathy (CIPN), few studies have examined cannabinoid effects on responses of nociceptors in vivo. In this study we determined whether inhibition of fatty acid amide hydrolase (FAAH), which slows the breakdown of the endocannabinoid anandamide (AEA), reduced sensitization of nociceptors produced by chemotherapy. Over the course of a week of daily treatments, mice treated with the platinum-based chemotherapy agent cisplatin developed robust mechanical allodynia that coincided with sensitization of cutaneous C-fiber nociceptors as indicated by the development of spontaneous activity and increased responses to mechanical stimulation. Administration of the FAAH inhibitor URB597 into the receptive field of sensitized C-fiber nociceptors decreased spontaneous activity, increased mechanical response thresholds, and decreased evoked responses to mechanical stimuli. Cotreatment with CB1 (AM281) or CB2 (AM630) receptor antagonists showed that the effect of URB597 was mediated primarily by CB1 receptors. These changes following URB597 were associated with an increase in the endocannabinoid anandamide in the skin. Our results suggest that enhanced signaling in the peripheral endocannabinoid system could be utilized to reduce nociceptor sensitization and pain associated with CIPN. [ABSTRACT FROM AUTHOR]

This study assessed the effect of stimulation of CB 2 receptors or CB 1 blockade on fibrosis and apoptosis in rats subjected to bile duct ligation (BDL). It was performed in sham and BDL rats for four weeks. Fibrosis-induced rats received a CB 2 receptor agonist β-caryophyllene, CB 1 receptor antagonist, hemopressin, combination of β-caryophyllene and CB 2 antagonist, AM630 or vehicle daily during the last 2 weeks of the BDL ligation. Transaminases activity, bilirubin levels, hepatic collagen content, hydroxyproline level, Bcl2 positive hepatocytes, and mRNA expression of CB 1 , CB 2 receptors and matrix metalloproteinase-1 (MMP-1) genes were measured in all animals. Bile duct ligated rats showed increased bilirubin levels, elevated transaminases activity, increased hepatic collagen content, and hydroxyproline level, reduced Bcl2 positive hepatocytes and increased expression of the assessed messengers in comparison with sham rats. However, fibrotic rats treated with either β-caryophyllene or hemopressin had reduced hepatic collagen content, improved transaminase activity and reduced bilirubin level, ameliorated CB 1 gene expression, and increased MMP-1 gene expression compared with untreated fibrotic rats. These results were associated with attenuated apoptosis with only β-caryophyllene administration. CB 2 receptor blockade by AM630 prevents the effects of β-caryophyllene on CB 1 receptor and MMP-1 genes expression. This study points out that either stimulation of CB 2 receptors or CB 1 blockade can attenuate hepatic fibrosis in bile duct ligated rats. The mechanisms underlying these incidents may open new avenues for attenuating fibrosis and apoptosis of cholestasis- induced liver diseases. [ABSTRACT FROM AUTHOR]

Recent evidence suggests that the cannabinoid receptor subtype 2 (CB2) is implicated in anxiety and depression disorders, although few systematic studies in laboratory animals have been reported. The aim of the current experiments was to test the effects of the CB2 receptor potent-selective agonist β-caryophyllene (BCP) in animals subjected to models of anxiolytic- and antidepressant-like effects. Therefore effects of BCP (50mg/kg) on anxiety were assessed using the elevated plus maze (EPM), open field (OF), and marble burying test (MBT). However for depression, the novelty-suppressed feeding (NSF), tail suspension test (TST), and forced swim tests (FST) were used. Results indicated that adult mice receiving BCP showed amelioration of all the parameters observed in the EPM test. Also, BCP significantly increased the time spent in the center of the arena without altering the general motor activity in the OF test. This dose was also able to decrease the number of buried marbles and time spent digging in the MBT, suggesting an anti-compulsive-like effect. In addition, the systemic administration of BCP reduced immobility time in the TST and the FST. Finally, BCP treatment decreased feeding latency in the NSF test. Most importantly, pre-administration of the CB2 receptor antagonist AM630, fully abrogated the anxiolytic and the anti-depressant effects of BCP. Taken together, these preclinical results suggest that CB2 receptors may provide alternative therapeutic targets for the treatment of anxiety and depression. The possibility that BCP may ameliorate the symptoms of these mood disorders offers exciting prospects for future studies. [ABSTRACT FROM AUTHOR]

Addiction to major drugs of abuse, such as cocaine, has recently been linked to alterations in adult neurogenesis in the hippocampus. The endogenous cannabinoid system modulates this proliferative response as demonstrated by the finding that pharmacological activation/blockade of cannabinoid CB1 and CB2 receptors not only modulates neurogenesis but also modulates cell death in the brain. In the present study, we evaluated whether the endogenous cannabinoid system affects cocaine-induced alterations in cell proliferation. To this end, we examined whether pharmacological blockade of either CB1 (Rimonabant, 3 mg/kg) or CB2 receptors (AM630, 3 mg/kg) would affect cell proliferation [the cells were labeled with 5-bromo-2'-deoxyuridine (BrdU)] in the subventricular zone (SVZ) of the lateral ventricle and the dentate subgranular zone (SGZ). Additionally, we measured cell apoptosis (as monitored by the expression of cleaved caspase-3) and glial activation [by analyzing the expression of glial fibrillary acidic protein (GFAP) and Iba-1] in the striatum and hippocampus during acute and repeated (4 days) cocaine administration (20 mg/kg). The results showed that acute cocaine exposure decreased the number of BrdU-immunoreactive (ir) cells in the SVZ and SGZ. In contrast, repeated cocaine exposure reduced the number of BrdU-ir cells only in the SVZ. Both acute and repeated cocaine exposure increased the number of cleaved caspase-3-, GFAP- and Iba1-ir cells in the hippocampus, and this effect was counteracted by AM630 or Rimonabant, which increased the number of BrdU-, GFAP-, and Iba1-ir cells in the hippocampus. These results indicate that the changes in neurogenic, apoptotic and gliotic processes that were produced by repeated cocaine administration were normalized by pharmacological blockade of CB1 and CB2. The restorative effects of cannabinoid receptor blockade on hippocampal cell proliferation were associated with the prevention of the induction of conditioned locomotion but not with the prevention of cocaine-induced sensitization. [ABSTRACT FROM AUTHOR]

Highlights: [•] Tumor growth in mouse hind paw produced ongoing activity in C-fiber nociceptors. [•] The cannabinoid receptor agonist, WIN 55,212-2, reduced C-fiber activity. [•] Effects of WIN 55,212-2 were reduced by CB1 or CB2 receptor antagonists. [•] Further evidence that peripheral CB receptors may be targets to treat cancer pain. [Copyright &y& Elsevier]

Objective To investigate diabetes-associated changes in urinary bladder expression of cannabinoid receptors 1 and 2 ( CB1 and CB2) and the functional role of CB agonists and antagonists in mediating phasic contractions of isolated bladder strips using a streptozotocin-induced diabetic rat model., Materials and Methods The bladder and dorsal root ganglion ( DRG) were removed from diabetic rats and age-matched controls 8-10 weeks after diabetes induction., Expression of CB1 and CB2 m RNA was studied using quantitative real-time PCR and protein levels were determined by Western blot analysis., The effect of increasing concentrations (0.1-100 μM) of the mixed CB1/CB2 agonist R(+)- WIN 55,212-2 ( WIN), selective CB1 antagonist ( AM251) and selective CB2 antagonist ( AM630) on carbachol-evoked contraction of bladder strips from control and diabetic rats was investigated., WIN-induced alterations of bladder strip contraction were then studied after pre-incubation with AM251 and AM630., Results Diabetes induced decreased CB1 protein and m RNA expression in both the bladder and DRG ( P < 0.05), while decreased CB2 expression was observed in the bladder ( P < 0.05)., WIN decreased the amplitude, but not frequency, of carbachol-induced phasic contractions of bladder strips in a concentration-dependent manner and this effect was diminished in the diabetic state., AM630 and AM251 had no effect on isolated detrusor muscle function. Moreover, pre-incubation with AM251 partially counteracted the effect of WIN on detrusor muscle contraction., Conclusion The results indicate that CB1 and CB2 are responsible for the pathogenesis of bladder dysfunction in diabetes mellitus and represent a viable target for pharmacological treatment of bladder cystopathy. [ABSTRACT FROM AUTHOR]

Abstract: The G protein coupled receptors CB1 and CB2 are targets for the psychoactive constituents of cannabis, chief among them Δ9-THC. They are also key components of the multifunctional endogenous cannabinoid signaling system. CB1 and CB2 receptors modulate a wide variety of physiological systems including analgesia, memory, mood, reward, appetite and immunity. Identification and characterization of selective CB1 and CB2 receptor agonists and antagonists will facilitate understanding the precise physiological and pathophysiological roles of cannabinoid receptors in these systems. This is particularly necessary in the case of CB2 because these receptors are sparsely expressed and problematic to detect using traditional immunocytochemical approaches. 1-Propyl-2-methyl-3-(1-naphthoyl)indole (JWH015) is an aminoalkylindole that has been employed as a “CB2-selective” agonist in more than 40 published papers. However, we have found that JWH015 potently and efficaciously activates CB1 receptors in neurons. Using murine autaptic hippocampal neurons, which express CB1, but not CB2 receptors, we find that JWH015 inhibits excitatory postsynaptic currents with an EC50 of 216nM. JWH015 inhibition is absent in neurons from CB1 −/− cultures and is reversed by the CB1 antagonist, SR141716 [200nM]. Furthermore, JWH015 partially occludes CB1-mediated DSE (∼35% remaining), an action reversed by the CB2 antagonist, AM630 [1 and 3μM], suggesting that high concentrations of AM630 also antagonize CB1 receptors. We conclude that while JWH015 is a CB2-preferring agonist, it also activates CB1 receptors at experimentally encountered concentrations. Thus, CB1 agonism of JWH015 needs to be considered in the design and interpretation of experiments that use JWH015 to probe CB2-signaling. [Copyright &y& Elsevier]

Abstract: Objective: The aim of the present paper was to assess whether lipopolysaccharide (LPS)-induced inhibition of salivary secretion involves the activation of the endocannabinoid system and the participation of tumor necrosis factor (TNF)α in the submandibular gland. Design: Pharmacological approaches were performed by using CB1 and/or CB2 cannabinoid receptor antagonists, AM251 and AM630, respectively, injected into the submandibular gland, to study the participation of the endocannabinoid system in LPS inhibitory effects on metacholine-induced salivary secretion. To assess the participation of TNFα on LPS inhibitory effects, salivary secretion was studied in LPS treated rats after the intraglandular injection of etanercept, a soluble form of TNF receptor which blocks TNFα action. Finally, to evaluate the possible interplay between endocannabinoids and TNFα on the submandibular gland function reduced during LPS challenge, the salivary secretion was studied after the intraglandular injection of this cytokine alone or concomitantly with AM251 and AM630. Results: AM251 and AM630, injected separately or concomitantly, partially prevented LPS-induced inhibition of salivation. Also, anandamide synthase activity was increased in submandibular glands extracted from rats 3h after LPS injection, suggesting that the endocannabinoid system was activated in response to this challenge. On the other hand, etanercept, prevented the inhibitory effect of LPS on salivary secretion and moreover, TNFα injected intraglandularly inhibited salivary secretion, being this effect prevented by AM251 and AM630 injected concomitantly. Conclusion: The present results demonstrate the participation of the endocannabinoid system and TNFα on salivary responses during systemic inflammation induced by LPS. [Copyright &y& Elsevier]

Abstract: Oleamide (cis-9-octadecenamide) is an endogenous sleep-inducing fatty acid amide that accumulates in the cerebrospinal fluid of the sleep-deprived animals. Microglia are the major immune cells involved in neuroinflammation causing brain damage during infection, ischemia, and neurodegenerative disease. In this study, we examined the effects of oleamide on LPS-induced production of proinflammatory mediators and the mechanisms involved in BV2 microglia. Oleamide inhibited LPS-induced production of NO and prostaglandin E2 as well as expression of iNOS and COX-2. We showed that oleamide blocked LPS-induced NF-κB activation and phosphorylation of inhibitor κB kinase (IKK). We also showed that oleamide inhibited LPS-induced phosphorylation of Akt, p38 MAPK, and ERK, activation of PI 3-kinase, and accumulation of reactive oxygen species (ROS). Finally, we showed that a specific antagonist of the CB2 receptor, AM630, blocked the inhibitory effects of oleamide on LPS-induced production of proinflammatory mediators and activation of NF-κB. Taken together, our results suggest that oleamide shows an anti-inflammatory effect through inhibition of NF-κB activation in LPS-stimulated BV2 microglia. [Copyright &y& Elsevier]

Abstract: Osteolysis and subsequent aseptic loosening are the most common causes of failure of total joint arthroplasty. Osteolysis is initiated by inflammatory response to wear debris, resulting in localized, osteoclastic peri-implant bone loss. However, there were no effective measures for prevention and treatment of periprosthetic osteolysis. The aim of the current study was to determine whether CB2 selective antagonist (AM630) inhibits wear debris-induced osteolysis in a murine osteolysis model. Titanium (Ti) particles were introduced into established air pouches on BALB/c mice, followed by implantation of calvaria bone from syngeneic littermates. AM630 was given to mice intraperitoneally 2 days before Ti particles introduction and maintained until the sacrifice of the mice. Mice without drug treatment, as well as mice injected with saline alone, were included. Each group contains 10 mice. Pouch tissues were harvested 14 days after bone implantation for histological and molecular analysis. Ti particles stimulation significantly increased CB2 expression. However, less CB2 was observed in AM630 treatment group. AM630 inhibited Ti particle-induced osteolysis associated gene activity of RANK, RANKL and CPK, and diminished RANKL expression in Ti particle stimulated pouches. AM630 markedly reduced the number of TRAP+ cells in pouch tissues. In conclusion, this study provides the evidence that blockage of CB2 with AM630 can markedly reduce Ti particle induced osteolysis in a murine air pouch model. This finding points to the possibility that CB2 selective antagonists like AM630 may have potential value for prevention and treatment of wear particle induced osteolysis. [Copyright &y& Elsevier]

We have recently proposed that an endogenous cannabinoid may be an endothelium-derived hyperpolarizing factor (EDHF), and we have now characterized the cannabinoid receptors mediating these responses. EDHF-mediated vasorelaxations to carbachol (ED50=3.26±0.57 nmol; the maximum relaxation, R max=87.0±2.5%) were opposed by the selective cannabinoid CB1 antagonist, LY320135: at 2 µM ED50 for carbachol was 10.4±2.6 nmol and R max was 66.9±6.2%, at 10 µM ED50 was 15.9±4.0 nmol and R max was 34.0±4.3%. However, these responses were unaffected by another putative CB1 ligand, AM630 (10 µM), or a CB2 selective antagonist, SR144528 (100 nM–1 µM). None of the antagonists influenced vasorelaxation to either the potassium channel activator levcromakalim or sodium nitroprusside. Coupled to our previous observation that the CB1 receptor antagonist SR141716A opposes EDHF-mediated relaxation, the present observations point to the involvement of a cannabinoid receptor, which may be CB1 or CB1-like, in EDHF-mediated vasorelaxation. [ABSTRACT FROM AUTHOR]

We have previously shown that cannabinoid CB 1 and CB 2 receptor antagonists, AM251 and AM630, respectively, modulate cardiostimulatory effects of isoprenaline in atria of Wistar rats. The aim of the present study was to examine whether such modulatory effects can also be observed (a) in the human atrium and (b) in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Inotropic effects of isoprenaline and/or CGP12177 (that activate the high- and low-affinity site of β 1 -adrenoceptors, respectively) were examined in paced human atrial trabeculae and rat left atria; chronotropic effects were studied in spontaneously beating right rat atria. AM251 modified cardiostimulatory effects more strongly than AM630. Therefore, AM251 (1 μM) enhanced the chronotropic effect of isoprenaline in WKY and SHR as well as inotropic action of isoprenaline in WKY and in human atria. It also increased the inotropic influence of CGP12177 in SHR. AM630 (1 μM) decreased the inotropic effect of isoprenaline and CGP12177 in WKY, but enhanced the isoprenaline-induced inotropic effect in SHR and human atria. Furthermore, AM251 (0.1 and 3 μM) and AM630 (0.1 μM) reduced the inotropic action of isoprenaline in human atria. In conclusion, cannabinoid receptor antagonists have potentially harmful and beneficial effects through their amplificatory effects on β-adrenoceptor-mediated positive chronotropic and inotropic actions, respectively., (© 2021 John Wiley & Sons Australia, Ltd.)

The fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) enzymes are the predominant catabolic regulators of the major endocannabinoids (eCBs) anadamide (AEA) and 2-arachidonoylglycerol (2-AG), respectively. The expression and roles of eCBs during early embryogenesis remain to be fully investigated. Here, we inhibited FAAH and MAGL in zebrafish embryos during the first 24 h of life and examined motor neuron and locomotor development at 2 and 5 days post fertilization (dpf). Application of the dual FAAH/MAGL inhibitor, JZL195 (2 µmol l-1), resulted in a reduction in primary and secondary motor neuron axonal branching. JZL195 also reduced nicotinic acetylcholine receptor (nAChR) expression at neuromuscular junctions. Application of URB597 (5 µmol l-1), a specific inhibitor of the FAAH enzyme, also decreased primary motor neuron branching but did not affect secondary motor neuron branching and nAChR expression. Interestingly, JZL184 (5 µmol l-1), a specific inhibitor of MAGL, showed no effects on motor neuron branching or nAChR expression. Co-treatment of the enzyme inhibitors with the CB1R inhibitor AM251 confirmed the involvement of CB1R in motor neuron branching. Disruption of FAAH or MAGL reduced larval swimming activity, and AM251 attenuated the JZL195- and URB597-induced locomotor changes, but not the effects of JZL184. Together, these findings indicate that inhibition of FAAH, or augmentation of AEA acting through CB1R during early development, may be responsible for locomotor deficiencies., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

Introduction: Acute central nervous system (CNS) injury, such as stroke, spinal cord injury, or traumatic brain injury can result in dysregulated immune response, and the condition is known as CNS injury-induced immunodeficiency syndrome (CIDS). The endocannabinoid system is an important homeostatic regulator in the CNS and immune system. Activation of cannabinoid 2 receptors (CB2R) on immune cells has been reported to dampen inflammation, suggesting a potential role of CB2R in the peripheral immune response following CNS injury. In this study, we have investigated the effect of CB2R modulation on the peripheral immune response during CIDS. Materials and Methods: Experimental CNS injury was induced in C57BL/6 mice through intracerebral injection of the vasopressor peptide, endothelin-1. A selective CB2R agonist (HU308) was used as an early treatment before the onset of CIDS and AM630, a selective CB2R antagonist, was administered as a later-phase therapy to combat the systemic immunodeficiency following the CNS injury. The peripheral immune response to endotoxin was studied 24 h after the CNS injury using intravital microscopy to examine leukocyte activation within the intestinal microcirculation in mice. Brain infarct size, and plasma levels of cytokines and soluble adhesion molecules were measured as additional parameters for the assessment of treatment outcomes. Results: Our results showed that early CB2R activation with HU308 reduced brain injury size and restored leukocyte response to endotoxin in the peripheral microcirculation. Late CB2R inhibition with AM630 also improved the peripheral leukocyte response to endotoxin and did not exacerbate the extent of brain injury. Discussion: CB2R activation has the potential to mitigate CNS injury as an early treatment by limiting neuroinflammation and preventing the development of CIDS. At the later stage with already-established CIDS, treatment may require dampening CB2R activation to improve the patient's outcome.

• JWH133 increases activity of conventional antidepressant drugs. • AM630 potentiates activity of conventional antidepressant drugs. • Interplay between CB 2 receptor ligands and antidepressants is pharmacodynamic in nature. Although a lot of information can be found on the specific dual role of the endocannabinoid system in the emotional-related responses, little is known whether stimulation or inhibition of the cannabinoid (CB) receptors may affect the activity of the frequently prescribed antidepressant drugs. Our interests have been particularly focused on the potential influence of the CB 2 receptors, as the ones whose central effects are relatively poorly documented when compared to the central effects of the CB 1 receptors. Therefore, we evaluated the potential interaction between the CB 2 receptor ligands (i.e., JWH133 – CB 2 receptor agonist and AM630 – CB 2 receptor inverse agonist) and several common antidepressant drugs that influence the monoaminergic system (i.e., imipramine, escitalopram, reboxetine). In order to assess the antidepressant-like effects we used two widely recognized behavioural tests, the mouse forced swim test (FST) and the tail suspension test (TST). Brain concentrations of the tested antidepressants were evaluated by the HPLC method. Intraperitoneal co-administration of per se ineffective doses of JWH133 (0.25 mg/kg) or AM630 (0.25 mg/kg) with imipramine (15 mg/kg), escitalopram (2 mg/kg), and reboxetine (2.5 mg/kg) significantly shortened the immobility time of mice in the FST and the TST, whereas it did not disturb their spontaneous locomotor activity. Furthermore, the brain levels of antidepressants were not changed. Summarizing, the results of the present study revealed that both activation and inhibition of the CB 2 receptor function have a potential to strengthen the antidepressant activity of drugs targeting the monoaminergic system. Most probably, the described interaction has a pharmacodynamic background. [ABSTRACT FROM AUTHOR]

Available data support the notion that cannabinoids, whose therapeutic value is limited due to severe adverse reactions, could be beneficial as adjunctive agents in the management of mood disorders. Polytherapy, which is superior to monotherapy in the terms of effectiveness, usually requires lower doses of the individual components. Therefore, the main objective of our study was to determine whether administration of cannabinoid (CB) receptor ligands would enhance the antidepressant activity of atypical antidepressant drugs, i.e. agomelatine and tianeptine. To evaluate the antidepressant-like potential of the tested combinations, the mouse forced swim test (FST) and the tail suspension test (TST) were used. The HPLC method was applied to assess the brain levels of agomelatine and tianeptine. Both behavioural tests demonstrated that per se an ineffective intraperitoneal dose of oleamide (CB 1 receptor agonist, 5 mg/kg) potentiated the anti-immobility activity of tianeptine (15 mg/kg), whereas AM251 (CB 1 receptor inverse agonist/antagonist, 0.25 mg/kg) enhanced the antidepressant effects of tianeptine and agomelatine (20 mg/kg). Intraperitoneal co-administration of per se inactive doses of AM630 (CB 2 receptor inverse agonist/antagonist) and agomelatine or tianeptine significantly reduced the immobility time of animals only in the FST. CB receptor ligands did not affect the brain levels of the tested atypical antidepressants. In summary, the outcomes of the present study showed that activation and inhibition of CB 1 receptors as well as inhibition of CB 2 receptors may increase the antidepressant activity of tianeptine, whereas only inhibition of CB 1 and CB 2 receptors has a potential to augment the antidepressant activity of agomelatine. • CB 1 receptor ligands potentiate the activity of tianeptine. • CB 1 receptor antagonist but not an agonist augments the activity of agomelatine • CB 2 receptor agonist does not increase activity of agomelatine and tianeptine. • CB 2 inverse agonist/antagonist enhances activity of agomelatine and tianeptine in the FST. • Interaction between CB receptor ligands and atypical antidepressants has a pharmacodynamic nature. [ABSTRACT FROM AUTHOR]

Endocannabinoids (eCBs) mediate their effects through actions on several receptors, including the cannabinoid receptors CB 1 R and CB 2 R. The role played by eCBs in the development of locomotor systems is not fully understood. In this study, we investigated the roles of the eCB system in zebrafish development by pharmacologically inhibiting CB 1 R and CB 2 R (with AM251 and AM630, respectively) in either the first or second day of development. We examined the morphology of motor neurons and we determined neuromuscular outputs by quantifying the amount of swimming in 5 days post-fertilization larvae. Blocking CB 2 R during the first day of development resulted in gross morphological deficits and reductions in heart rate that were greater than those following treatment with the CB 1 R blocker AM251. Blocking CB 1 Rs from 0 to 24 h post-fertilization resulted in an increase in the number of secondary and tertiary branches of primary motor neurons, whereas blocking CB 2 Rs had the opposite effect. Both treatments manifested in reduced levels of swimming. Additionally, blocking CB 1 Rs resulted in greater instances of non-inflated and partially inflated swim bladders compared with AM630 treatment, suggesting that at least some of the deficits in locomotion may result from an inability to adjust buoyancy. Together, these findings indicate that the eCB system is pivotal to the development of the locomotor system in zebrafish, and that perturbations of the eCB system early in life may have detrimental effects., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2019. Published by The Company of Biologists Ltd.)

The cannabinoid type two receptors (CB2), an important component of the endocannabinoid system, have recently emerged as neuromodulators and therapeutic targets for neurodegenerative diseases including Parkinson's disease (PD). The downregulation of CB2 receptors has been reported in the brains of PD patients. Therefore, both the activation and the upregulation of the CB2 receptors are believed to protect against the neurodegenerative changes in PD. In the present study, we investigated the CB2 receptor-mediated neuroprotective effect of β-caryophyllene (BCP), a naturally occurring CB2 receptor agonist, in, a clinically relevant, rotenone (ROT)-induced animal model of PD. ROT (2.5 mg/kg BW) was injected intraperitoneally (i.p.) once daily for 4 weeks to induce PD in male Wistar rats. ROT injections induced a significant loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and DA striatal fibers, following activation of glial cells (astrocytes and microglia). ROT also caused oxidative injury evidenced by the loss of antioxidant enzymes and increased nitrite levels, and induction of proinflammatory cytokines: IL-1β, IL-6 and TNF-α, as well as inflammatory mediators: NF-κB, COX-2, and iNOS. However, treatment with BCP attenuated induction of proinflammatory cytokines and inflammatory mediators in ROT-challenged rats. BCP supplementation also prevented depletion of glutathione concomitant to reduced lipid peroxidation and augmentation of antioxidant enzymes: SOD and catalase. The results were further supported by tyrosine hydroxylase immunohistochemistry, which illustrated the rescue of the DA neurons and fibers subsequent to reduced activation of glial cells. Interestingly, BCP supplementation demonstrated the potent therapeutic effects against ROT-induced neurodegeneration, which was evidenced by BCP-mediated CB2 receptor activation and the fact that, prior administration of the CB2 receptor antagonist AM630 diminished the beneficial effects of BCP. The present study suggests that BCP has the potential therapeutic efficacy to elicit significant neuroprotection by its anti-inflammatory and antioxidant activities mediated by activation of the CB2 receptors.

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., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Several recent studies have suggested that brain CB2 cannabinoid receptors play a major role in alcohol reward. In fact, the implication of cannabinoid neurotransmission in the reinforcing effects of ethanol (EtOH) is becoming increasingly evident. The CB2 receptor agonist, β-caryophyllene (BCP) was used to investigate the role of the CB2 receptors in mediating alcohol intake and ethanol-induced conditioned place preference (EtOH-CPP) and sensitivity in mice. The effect of BCP on alcohol intake was evaluated using the standard two-bottle choice drinking method. The mice were presented with increasing EtOH concentrations and its consumption was measured daily. Consumption of saccharin and quinine solutions was measured following the EtOH preference tests. Finally, the effect of BCP on alcohol reward and sensitivity was tested using an unbiased EtOH-CPP and loss of righting-reflex (LORR) procedures, respectively. BCP dose-dependently decreased alcohol consumption and preference. Additionally, BCP-injected mice did not show any difference from vehicle mice in total fluid intake in a 24-hour paradigm nor in their intake of graded concentrations of saccharin or quinine, suggesting that the CB2 receptor activation did not alter taste function. More importantly, BCP inhibited EtOH-CPP acquisition and exacerbated LORR duration. Interestingly, these effects were abrogated when mice were pre-injected with a selective CB2 receptor antagonist, AM630. Overall, the CB2 receptor system appears to be involved in alcohol dependence and sensitivity and may represent a potential pharmacological target for the treatment of alcoholism., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Addiction to major drugs of abuse, such as cocaine, has recently been linked to alterations in adult neurogenesis in the hippocampus. The endogenous cannabinoid system modulates this proliferative response as demonstrated by the finding that pharmacological activation/blockade of cannabinoid CB1 and CB2 receptors not only modulates neurogenesis but also modulates cell death in the brain. In the present study, we evaluated whether the endogenous cannabinoid system affects cocaine-induced alterations in cell proliferation. To this end, we examined whether pharmacological blockade of either CB1 (Rimonabant, 3 mg/kg) or CB2 receptors (AM630, 3 mg/kg) would affect cell proliferation [the cells were labeled with 5-bromo-2'-deoxyuridine (BrdU)] in the subventricular zone (SVZ) of the lateral ventricle and the dentate subgranular zone (SGZ). Additionally, we measured cell apoptosis (as monitored by the expression of cleaved caspase-3) and glial activation [by analyzing the expression of glial fibrillary acidic protein (GFAP) and Iba-1] in the striatum and hippocampus during acute and repeated (4 days) cocaine administration (20 mg/kg). The results showed that acute cocaine exposure decreased the number of BrdU-immunoreactive (ir) cells in the SVZ and SGZ. In contrast, repeated cocaine exposure reduced the number of BrdU-ir cells only in the SVZ. Both acute and repeated cocaine exposure increased the number of cleaved caspase-3-, GFAP- and Iba1-ir cells in the hippocampus, and this effect was counteracted by AM630 or Rimonabant, which increased the number of BrdU-, GFAP-, and Iba1-ir cells in the hippocampus. These results indicate that the changes in neurogenic, apoptotic and gliotic processes that were produced by repeated cocaine administration were normalized by pharmacological blockade of CB1 and CB2. The restorative effects of cannabinoid receptor blockade on hippocampal cell proliferation were associated with the prevention of the induction of conditioned locomotion but not with the prevention of cocaine-induced sensitization.