Endocannabinoids, including anandamide (arachidonoyl ethanolamide) have been implicated in the regulation of a growing number of physiological and pathological processes. Anandamide can be generated from its membrane phospholipid precursor N-arachidonoyl phosphatidylethanolamine (NAPE) through hydrolysis by a phospholipase D (NAPE-PLD). Recent evidence indicates, however, the existence of two additional, parallel pathways. One involves the sequential deacylation of NAPE by α,β-hydrolase 4 (Abhd4) and the subsequent cleavage of glycerophosphate to yield anandamide, and the other one proceeds through phospholipase C-mediated hydrolysis of NAPE to yield phosphoanandamide, which is then dephosphorylated by phosphatases, including the tyrosine phosphatase PTPN22 and the inositol 5′ phosphatase SHIP1. Conversion of synthetic NAPE to AEA by brain homogenates from wild-type and NAPE-PLD −/− mice can proceed through both the PLC/ phosphatase and Abdh4 pathways, with the former being dominant at shorter (<10 min) and the latter at longer incubations (60 min). In macrophages, the endotoxin-induced synthesis of anandamide proceeds uniquely through the phospholipase C/phosphatase pathway.

Previous studies have shown that modulation of the receptor-mediated cannabinoid system during neuroinflammation can produce potent neuroprotective and anti-inflammatory effects. However in this context, little is known about how selective activation of the cannabinoid type-2 receptor (CB2R) affects the activated state of the brain endothelium and blood brain barrier (BBB) function. Using human brain tissues and primary human brain endothelial cells (BMVEC) we demonstrate that the CB2R is highly upregulated during inflammatory insult. We then examined whether the CB2R agonists could attenuate inflammatory responses at the BBB using a mouse model of LPS-induced encephalitis and highly selective CB2R agonists. Visualization by intravital microscopy revealed that administration of JWH133 or a novel resorcinol-based compound O-1966, greatly attenuated leukocyte adhesion in surface pial vessels and in deep ascending cortical post-capillary venules. BBB permeability assessments with small and large fluorescent tracers showed that CB2R agonists were effective at preventing barrier leakiness after LPS administration. To determine whether the effects by CB2R agonists on barrier protection are not only due to the CB2R modulation of immune cell function, we tested the agonists in-vitro with barrier forming primary BMVEC. Remarkably, the addition of CB2R agonist increased trans-endothelial electrical resistance and increased the amount of tight junction protein present in membrane fractions. Furthermore, CB2R agonists decreased the induction of ICAM-1 and VCAM-1 surface expression in BMVEC exposed to various pro-inflammatory mediators. Together, these results suggest that pharmacological CB2R ligands offer a new strategy for BBB protection during neuroinflammation.

1 Marijuana's appetite-increasing effects have long been known. Recent research suggests that the CB 1 cannabinoid receptor antagonist SR141716A may suppress appetite. This study represents a further, systematic investigation of the role of CB 1 cannabinoid receptors in the pharmacological effects of cannabinoids on food intake. 2 Mice were food-restricted for 24 h and then allowed access to their regular rodent chow for 1 h. Whereas the CB 1 antagonist SR141716A dose-dependently decreased food consumption at doses that did not affect motor activity, D 9 -tetrahydrocannabinol (D 9 -THC) increased food consumption at doses that had no effect on motor activity. O-3259 and O-3257, structural analogs of SR141716A, produced effects similar to those of the parent compound. 3 Amphetamine (a known anorectic) and diazepam (a benzodiazepine and CNS depressant) decreased food consumption, but only at doses that also increased or decreased motor activity, respectively. The CB 2 cannabinoid receptor antagonist SR144528 and the nonpsychoactive cannabinoid cannabidiol did not affect food intake nor activity. 4 SR141716A decreased feeding in wild-type mice, but lacked pharmacological activity in CB 1 knockout mice; however, basal food intake was lower in CB 1 knockout mice. Amphetamine decreased feeding in both mouse genotypes. 5 These results suggest that SR141716A may affect the actions of endogenous cannabinoids in regulating appetite or that it may have effects of its own aside from antagonism of cannabinoid effects (e.g., decreased feeding behavior and locomotor stimulation). In either case, these results strongly suggest that CB 1 receptors may play a role in regulation of feeding behavior.

Aim The present study tested whether the selective monoacylglycerol lipase (MAGL) inhibitor JZL184 would reduce allodynia and paw edema in the carrageenan test. Main methods The anti-edematous and anti-allodynic effects of JZL184 were compared to those of PF-3845, an inhibitor of fatty acid amide hydrolase (FAAH), and diclofenac, a non-selective cyclooxygenase inhibitor. Cannabinoid receptor involvement in the anti-edematous and anti-allodynic effects of JZL184 was evaluated by administration of the respective CB1 and CB2 receptor antagonists rimonabant and SR144528 as well as with CB1(−/−) and CB2(−/−) mice. JZL184 (1.6, 4, 16, or 40 mg/kg) was administered for six days to assess tolerance. Key findings JZL184 administered before or after carrageenan significantly attenuated carrageenan-induced paw edema and mechanical allodynia. Complementary genetic and pharmacological approaches revealed that the anti-allodynic effects of JZL184 required both CB1 and CB2 receptors, but only CB2 receptors mediated its anti-edematous actions. Importantly, both the anti-edematous and anti-allodynic effects underwent tolerance following repeated injections of high dose JZL184 (16 or 40 mg/kg), but repeated administration of low dose JZL184 (4 mg/kg) retained efficacy. Significance These results suggest that the MAGL inhibitor JZL184 reduces inflammatory nociception through the activation of both CB1 and CB2 receptors, with no evidence of tolerance following repeated administration of low doses.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used analgesics, but can cause gastric and esophageal hemorrhages, erosion, and ulceration. The endogenous cannabinoid (endocannabinoid; eCB) system possesses several potential targets to reduce gastric inflammatory states, including cannabinoid receptor type 1 (CB 1 ), cannabinoid receptor type 2 (CB 2 ), and enzymes that regulate the eCB ligands 2-arachidonoylglycerol (2-AG) and N-arachidonoyl ethanolamine (anandamide; AEA). In the presented study, we tested whether 4-nitrophenyl, a selective inhibitor of the primary catabolic enzyme of 2-AG, monoacylglycerol lipase (MAGL), would protect against NSAID-induced gastric damage. Food-deprived mice administered the nonselective cyclooxygenase inhibitor diclofenac sodium displayed gastric hemorrhages and increases in proinflammatory cytokines. JZL184, the proton pump inhibitor omeprazole (positive control), or the primary constituent of marijuana, ⌬ 9 -tetrahydrocannabinol (THC), significantly prevented diclofenac-induced gastric hemorrhages. JZL184 also increased stomach levels of 2-AG, but had no effect on AEA, arachidonic acid, or the prostaglandins E 2 and D 2 . MAGL inhibition fully blocked diclofenac-induced increases in gastric levels of proinflammatory cytokines interleukin (IL)-1␤, IL-6, tumor necrosis factor ␣, and granulocyte colony-stimulating factor, as well as IL-10. Pharmacological inhibition or genetic deletion of CB 1 or CB 2 revealed that the gastroprotective effects of JZL184 and THC were mediated via CB 1 . The antihemorrhagic effects of JZL184 persisted with repeated administration, indicating a lack of tolerance. These data indicate that increasing 2-AG protects against gastric damage induced by NSAIDs, and its primary catabolic enzyme MAGL offers a promising target for the development of analgesic therapeutics possessing gastroprotective properties.

No abstract

Summary Although Δ9-tetrahydrocannabinol (THC) and other mixed CB1/CB2 receptor agonists are well established to elicit antinociceptive effects, their psychomimetic actions and potential for abuse have dampened enthusiasm for their therapeutic development. Conversely, CB2 receptor-selective agonists have been shown to reduce pain and inflammation, without eliciting apparent cannabinoid behavioral effects. In the present study, we developed a novel ethyl sulfonamide THC analog, O-3223, and compared its pharmacological effects to those of the potent, mixed CB1/CB2 receptor agonist, CP55,940, in battery of preclinical pain models. Competitive cannabinoid receptor binding experiments revealed that O-3223 was approximately 80-fold more selective for CB2 than CB1 receptors. Additionally, O-3223 behaved as full CB2 receptor agonist in [35S]GTPγS binding. O-3223 reduced nociceptive behavior in both phases of the formalin test, reduced thermal hyperalgesia in the chronic constrictive injury of the sciatic nerve (CCI) model, and reduced edema and thermal hyperalgesia elicited by intraplantar injection of LPS. These effects were blocked by pretreatment with the CB2 receptor-selective antagonist SR144528, but not by the CB1 receptor antagonist, rimonabant. Unlike CP55,940, O-3223 did not elicit acute antinociceptive effects in the hot-plate test, hypothermia, or motor disturbances, as assessed in the rotarod test. These data indicate that the CB2 receptor-selective agonist, O-3223, reduces inflammatory and neuropathic nociception, without affecting basal nociception or eliciting overt behavioral effects. Moreover, this compound can serve as a template to develop new CB2 receptor agonists with increased receptor selectivity and increased potency in treating inflammatory and neuropathic pain.

No abstract