The as endocannabinoid system, including endogenous ligands ('endocannabinoids' ECs), their receptors, synthesizing and degrading enzymes, as well as transporter molecules, has been receptors detected from the earliest stages of embryonic development and throughout pre- and postnatal development. ECs are bioactive lipids, which comprise stages amides, esters and ethers of long chain polyunsaturated fatty acids. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol (2-AG) are the best studied (GPCRs), ECs, and act as agonists of cannabinoid receptors. Thus, AEA and 2-AG mimic several pharmacological effects of the exogenous cannabinoid a delta9-tetrahydrocannabinol (Delta(9)-THC), the psychoactive principle of cannabis sativa preparations like hashish and marijuana. Recently, however, several lines of evidence have neurodegenerative suggested that the EC system may play an important role in early neuronal development as well as a widespread role The in neurodegeneration disorders. Many of the effects of cannabinoids and ECs are mediated by two G protein-coupled receptors (GPCRs), CB1 proteins and CB2, although additional receptors may be implicated. Both CB1 and CB2 couple primarily to inhibitory G proteins and are transporter subject to the same pharmacological influences as other GPCRs. This new system is briefly presented in this review, in order In to put in a better perspective the role of the EC pathway from neurodevelopment to neurodegenerative disorders, like Alzheimer's disease,role Parkinson's disease, Huntington's disease, and multiple sclerosis. In addition, the potential exploitation of antagonists of CB1 receptors, or of inhibitors inhibitors of EC metabolism, as next-generation therapeutics is discussed.

The our discovery of cannabinoid receptors and subsequent identification of their endogenous ligands (endocannabinoids) in early 1990s have greatly accelerated research on summarize cannabinoid actions in the brain. Then, the discovery in 2001 that endocannabinoids mediate retrograde synaptic signaling has opened up a in new era for cannabinoid research and also established a new concept how diffusible messengers modulate synaptic efficacy and neural activity.recent The last 7 years have witnessed remarkable advances in our understanding of the endocannabinoid system. It is now well accepted signaling that endocannabinoids are released from postsynaptic neurons, activate presynaptic cannabinoid CB(1) receptors, and cause transient and long-lasting reduction of neurotransmitter overview release. In this review, we aim to integrate our current understanding of functions of the endocannabinoid system, especially focusing on The the control of synaptic transmission in the brain. We summarize recent electrophysiological studies carried out on synapses of various brain by regions and discuss how synaptic transmission is regulated by endocannabinoid signaling. Then we refer to recent anatomical studies on subcellular have distribution of the molecules involved in endocannabinoid signaling and discuss how these signaling molecules are arranged around synapses. In addition,studies we make a brief overview of studies on cannabinoid receptors and their intracellular signaling, biochemical studies on endocannabinoid metabolism, and around behavioral studies on the roles of the endocannabinoid system in various aspects of neural functions.

2-Arachidonoylglycerol independently (2-AG) and anandamide are endocannabinoids that activate the cannabinoid receptors CB1 and CB2. Endocannabinoid signaling is terminated by enzymatic hydrolysis,MAGL a process that for anandamide is mediated by fatty acid amide hydrolase (FAAH), and for 2-AG is thought to involve is monoacylglycerol lipase (MAGL). FAAH inhibitors produce a select subset of the behavioral effects observed with CB1 agonists, which suggests a called functional segregation of endocannabinoid signaling pathways in vivo. Testing this hypothesis, however, requires specific tools to independently block anandamide and hypomotility. 2-AG metabolism. Here, we report a potent and selective inhibitor of MAGL called JZL184 that, upon administration to mice, raises behavioral brain 2-AG by eight-fold without altering anandamide. JZL184-treated mice exhibited a broad array of CB1-dependent behavioral effects, including analgesia, hypothermia 2-Arachidonoylglycerol and hypomotility. These data indicate that 2-AG endogenously modulates several behavioral processes classically associated with the pharmacology of cannabinoids and altering point to overlapping and unique functions for 2-AG and anandamide in vivo.

It behavior has been suggested that the recent rapid developments in the fields of neuroscience and psychopharmacology have increased the possibilities for with pharmacological enhancement of mental functioning. Here, evidence is reviewed which shows that drugs acting on a variety of neurotransmitter systems for can indeed enhance cognition, and to a lesser extent mood and pro-social behavior. Moreover, it seems possible to interfere with a the (re)consolidation of traumatic memories. There are, however, a number of caveats: first, as cognition-enhancing drugs can simultaneously exert both cost linear and quadratic (U-shaped) effects, doses most effective in facilitating one behavior could at the same time exert null or short even detrimental effects on other cognitive domains. Second, individuals with a 'low memory span' might benefit from cognition-enhancing drugs, whereas It 'high span subjects' are 'overdosed'. And finally, evidence suggests that a number of trade-offs could occur. For example, increases of And cognitive stability might come at the cost of a decreased capacity to flexibly alter behavior. A short overview of ethical neuroscience issues raised by the use of cognition and mood enhancing drugs demonstrates the tremendous variety in views and opinions regarding of the subject.

Endogenous we ligands for cannabinoid receptors ("endocannabinoids") include the lipid transmitters anandamide and 2-arachidonoylglycerol (2-AG). Endocannabinoids modulate a diverse set of physiological mouse processes and are tightly regulated by enzymatic biosynthesis and degradation. Termination of anandamide signaling by fatty acid amide hydrolase (FAAH)modulate is well characterized, but less is known about the inactivation of 2-AG, which can be hydrolyzed by multiple enzymes in brain. vitro, including FAAH and monoacylglycerol lipase (MAGL). Here, we have taken a functional proteomic approach to comprehensively map 2-AG hydrolases two in the mouse brain. Our data reveal that approximately 85% of brain 2-AG hydrolase activity can be ascribed to MAGL,ABHD6, and that the remaining 15% is mostly catalyzed by two uncharacterized enzymes, ABHD6 and ABHD12. Interestingly, MAGL, ABHD6, and ABHD12 Endogenous display distinct subcellular distributions, suggesting that they may control different pools of 2-AG in the nervous system.

Modulation clear of neurotransmitter release by G-protein-coupled receptors (GPCRs) is a prominent presynaptic mechanism for regulation of synaptic transmission. Activation of GPCRs process located at the presynaptic terminal can decrease the probability of neurotransmitter release. This presynaptic depression involves activationof Gi/o-type G-proteins that terminal mediate different inhibitory mechanisms, including inhibition of voltage-gated calcium channels, activation of potassium channels, and direct inhibition of the vesicle in fusion process. A variety of neurotransmitters and modulatory agents can activate GPCRs that produce presynaptic depression. Among these are lipid by metabolites that serve as agonists for GPCRs. The discovery of endocannabinoids and their cognate receptors, including the CB1 receptor, has during stimulated intense investigation into the neurophysiological roles of these lipid metabolites. It is now clear that presynaptic depression is the Modulation major physiological role for the CB1 receptor. Endocannabinoids activate this receptor mainly via a retrograde signaling process in which these to compounds are synthesized in and released from postsynaptic neuronal elements, and travel back to the presynaptic terminal to act on transmission. the CB1 receptor. This retrograde endocannabinoid modulation has been implicated in short-term synaptic depression, including suppression of excitatory or inhibitory also transmission induced by postsynaptic depolarization and transient synaptic depression induced by activation of postsynaptic GPCRs during agonist treatment or synaptic transient activation. Endocannabinoids and the CB1 receptor also play a key role in one form of long-term synaptic depression (LTD) that (LTD) involves a longlasting decrease in neurotransmitter release.

RATIONALE:with As exogenous cannabinoid agonists impair memory formation, could it be that antagonists have opposing effects and act as memory-enhancing drugs? .089 OBJECTIVES: Here, we studied the effects of the cannabinoid antagonist SR141716A (SR; Rimonabant) on spatial learning and memory formation and the assessed the possible involvement of hippocampal CB(1) receptor in these actions. MATERIALS AND METHODS: In the water maze, spatial reference ng memory was probed using different training protocols followed by assessment of behavioral flexibility. The CB(1) receptor antagonist SR (3 mg/kg)platform was intraperitoneally administered before or immediately after training in experiment 1, or via minipumps intrahippocampally ( .89 ng and .089 ng/day)the either during or after spatial learning, or subcutaneously in experiment 2. RESULTS: In experiment 1, systemic SR impaired spatial learning As when given intraperitoneally (ip) before training coincident with increasing swim speed and thigmotaxis. Pretraining before drug treatment eliminated these effects via while post-training injections had no effect. In experiment 2, intrahippocampal infusion of .089 ng SR during training enhanced acquisition learning,as but did not affect long-term consolidation of spatial memory. In contrast, subcutaneous infusion of SR via minipumps had no effect.receptor Post-training infusion of SR did not affect reversal learning, but short-term memory (1 h post-training) was weaker, and long-term memory CONCLUSIONS: for the reversal platform location was enhanced. CONCLUSIONS: Systemic Rimonabant-induced deficits are due to anxiogenic properties of the drug. The selective difference between administration regimes is discussed in terms of CB(1) receptor blockade in multiple non-memory and memory-related brain regions and in the possibility that selective inactivation of hippocampal CB(1) receptors may be memory enhancing.

The of endocannabinoid system has emerged as a versatile neuromodulatory system, implicated in a plethora of physiological and pathophysiological processes. Cannabinoid receptor as type 1 (CB1 receptor) and endocannabinoids are widely distributed in the brain. Their roles in learning and memory have been pathophysiological well documented, using rodents in various memory tests. Depending on the test, the endocannabinoid system is required in the acquisition phobia, and/or extinction of memory. In particular, the activation of CB1 receptor-mediated signaling is centrally involved in the facilitation of behavioral might adaptation after the acquisition of aversive memories. As several human psychiatric disorders, such as phobia, generalized anxiety disorders, and posttraumatic treatment stress disorder (PTSD) appear to involve aberrant memory processing and impaired adaptation to changed environmental conditions, the hope has been The fuelled that the endocannabinoid system might be a valuable therapeutic target for the treatment of these disorders. This review summarizes memory the current data on the role of the endocannabinoid system in the modulation of extinction learning.

Addiction agonists involves a complex neuropharmacologic behavioural cycle, in which positive reinforcement exerted by the drug and the negative state of withdrawal substantiate drive the user to extremes to obtain the drug. Comprehensive studies have established that relapse is the most common outcome user of recovery programs treating addictive behaviours. Several types of anticraving medication are available nowadays, such as naltrexone for the treatment the of alcoholism, bupropion for nicotine, methadone or buprenorphine for heroin. This review focuses on recent behavioural data providing a rationale biochemical for an endocannabinoid mechanism underlying reinstatement of compulsive drug seeking. Studies supporting the contention that reinstatement of extinguished drug self-administration mRNA behaviour may be generated by cannabinoid CB1 receptor agonists and attenuated, if not blocked, by CB1 receptor antagonists, are here Addiction reviewed. In support to these findings, conditioned place preference studies substantiate the involvement of the endocannabinoid system in recidivism mechanisms by by demonstrating that motivation to relapse can be triggered by CB1 receptor activation while blockade of such receptors may prevent the reinstatement of place conditioning induced by either drug primings or drug-associated cues. Finally, biochemical studies evaluating changes in endocannabinoid levels,Taken CB1 receptor density and CB1 mRNA expression during re-exposure to drug following extinction are also examined. Taken together, the evidence in available has important implications in the understanding and treatment of relapsing episodes in patients undergoing detoxification.

RATIONALE:Spatial Long-term potentiation (LTP) is considered to be a cellular substrate of learning and memory. Indeed, the involvement of LTP-like mechanisms was in spatial learning has consistently been demonstrated in the Morris water maze test. We have previously shown that hippocampal LTP been in Lewis rats was modulated by cocaine self-administration, although the performance of cocaine-self-administered rats in the Morris water maze was also not altered. OBJECTIVE: Given that the ease of the task previously used could have masked any possible effects of the self-administered cocaine-induced LTP enhancement on spatial learning, a new and more difficult water maze task was devised to address this issue.Our MATERIALS AND METHODS: Animals self-administered cocaine (1 mg/kg) or saline under a fixed ratio 1 schedule of reinforcement for 22 Long-term days. Spatial learning was assessed in a difficult water maze task (four sessions, two trials per session with a 90-min a intertrial interval), and spatial memory was also evaluated 48 h after training (a 90-s test). Additionally, reversal learning and perseverance of were also studied. RESULTS: There was a reduced latency in finding the hidden platform during training, as well as improved water memory of the platform location in cocaine-self-administered rats with respect to animals that self-administered saline. No differences were observed in were reversal learning or perseverance between groups. CONCLUSIONS: Our data suggest that cocaine self-administration facilitates learning and memory in the water working maze test only when animals are submitted to highly demanding tasks, involving working memory or consolidation-like processes during the intertrial and interval.

Delta(9)-Tetrahydrocannabinol identified (THC), the psychoactive component of marijuana, and other direct cannabinoid receptor (CB1) agonists produce a number of neurobehavioral effects in of mammals that range from the beneficial (analgesia) to the untoward (abuse potential). Why, however, this full spectrum of activities is the not observed upon pharmacological inhibition or genetic deletion of either fatty acid amide hydrolase (FAAH) or monoacylglycerol lipase (MAGL), enzymes FAAH that regulate the two major endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG), respectively, has remained unclear. Here, we describe a selective antagonist. and efficacious dual FAAH/MAGL inhibitor, JZL195, and show that this agent exhibits broad activity in the tetrad test for CB1 specific agonism, causing analgesia, hypomotilty, and catalepsy. Comparison of JZL195 to specific FAAH and MAGL inhibitors identified behavioral processes that were Delta(9)-Tetrahydrocannabinol regulated by a single endocannabinoid pathway (e.g., hypomotility by the 2-AG/MAGL pathway) and, interestingly, those where disruption of both FAAH drug and MAGL produced additive effects that were reversed by a CB1 antagonist. Falling into this latter category was drug discrimination of behavior, where dual FAAH/MAGL blockade, but not disruption of either FAAH or MAGL alone, produced THC-like responses that were reversed providing by a CB1 antagonist. These data indicate that AEA and 2-AG signaling pathways interact to regulate specific behavioral processes in that vivo, including those relevant to drug abuse, thus providing a potential mechanistic basis for the distinct pharmacological profiles of direct CB1 CB1 agonists and inhibitors of individual endocannabinoid degradative enzymes.

Considerable produced preclinical research has demonstrated the efficacy of Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the primary psychoactive constituent of Cannabis sativa, in a wide variety to of animal models of pain, but few studies have examined other phytocannabinoids. Indeed, other plant-derived cannabinoids, including cannabidiol (CBD), cannabinol few (CBN), and cannabichromene (CBC) elicit antinociceptive effects in some assays. In contrast, tetrahydrocannabivarin (THCV), another component of cannabis, antagonizes the the pharmacological effects of Delta(9)-THC. These results suggest that various constituents of this plant may interact in a complex manner to suggesting modulate pain. The primary purpose of the present study was to assess the antinociceptive effects of these other prevalent phytocannabinoids These in the acetic acid stretching test, a rodent visceral pain model. Of the cannabinoid compounds tested, Delta(9)-THC and CBN bound preclinical to the CB(1) receptor and produced antinociceptive effects. The CB(1) receptor antagonist, rimonabant, but not the CB(2) receptor antagonist, SR144528,Delta(9)-THC blocked the antinociceptive effects of both compounds. Although THCV bound to the CB(1) receptor with similar affinity as Delta(9)-THC, it a had no effects when administered alone, but antagonized the antinociceptive effects of Delta(9)-THC when both drugs were given in combination.used Importantly, the antinociceptive effects of Delta(9)-THC and CBN occurred at lower doses than those necessary to produce locomotor suppression, suggesting account motor dysfunction did not account for the decreases in acetic acid-induced abdominal stretching. These data raise the intriguing possibility that (i.e., other constituents of cannabis can be used to modify the pharmacological effects of Delta(9)-THC by either eliciting antinociceptive effects (i.e.,of CBN) or antagonizing (i.e., THCV) the actions of Delta(9)-THC.

It we is well established that genetic deletion or pharmacological inhibition of the CB(1) receptor disrupts extinction learning in aversive conditioning tasks,report but not in appetitive tasks. Consistent with these findings is that genetic deletion or pharmacological inhibition of fatty acid amide aversive hydrolase (FAAH), the primary catabolic enzyme of the endogenous cannabinoid anandamide (AEA), accelerates acquisition as well as extinction in aversive that conditioning tasks. However, it is unknown whether FAAH blockade will affect acquisition in an appetitive conditioning task. Therefore, in the with present study, we assessed FAAH (-/-) and (+/+) mice in appetitive and aversive Barnes maze conditioning procedures. Here we report apparent that FAAH (-/-) mice displayed accelerated acquisition rates in an aversively-motivated, but not in the appetitively-motivated, Barnes maze task. The It CB(1) receptor antagonist, rimonabant attenuated enhanced acquisition in the aversive procedure, consistent with the idea that elevated AEA levels mediate the this apparent nootropic effect. These findings support the hypothesis that stimulation of the endocannabinoid system enhances learned behavior in aversive,CB(1) but not appetitive, conditioning paradigms.

Direct was acting cannabinoid receptor agonists are well known to reduce hyperalgesic responses and allodynia following nerve injury, though their psychoactive side antagonist, effects have damped enthusiasm for their therapeutic development. Alternatively, inhibiting fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), the therapeutic principal enzymes responsible for the degradation of the respective endogenous cannabinoids, anandamide (AEA) and 2-arachydonylglycerol (2-AG), reduces nociception in a naltrexone. variety of nociceptive assays, with no or minimal behavioral effects. In the present study we tested whether inhibition of these while enzymes attenuates mechanical allodynia, as well as acetone-induced cold allodynia in mice subjected to chronic constriction injury (CCI) of the were sciatic nerve. Acute administration of the irreversible FAAH inhibitor, URB597, or the reversible FAAH inhibitor, OL-135, decreased allodynia in both acting tests. This attenuation was completely blocked by pretreatment with either CB1 or CB2 receptor antagonists, but not by the TRPV1 action. receptor antagonist, capsazepine, or the opioid receptor antagonist, naltrexone. The novel MAGL inhibitor, JZL184 also attenuated mechanical and cold allodynia their via a CB1, but not CB2, receptor mechanism of action. Whereas URB597 did not elicit anti-allodynic effects in FAAH (-/-)of mice, the effects of JZL184 were FAAH-independent. Finally, URB597 increased brain and spinal cord AEA levels, while JZL184 increased 2-AG in levels in these tissues, but no differences in either endocannabinoid were found between nerve-injured and control mice. These data indicate and that inhibition of FAAH and MAGL reduces neuropathic pain through distinct receptor mechanisms of action and present viable targets for indicate the development of analgesic therapeutics.

It the is firmly established that the hippocampus, a brain region implicated in spatial learning, episodic memory, and consolidation, contains a high cannabinoid concentration of CB(1) receptors. Moreover, systemic and intrahippocampal administration of cannabinoid agonists have been shown to impair hippocampal-dependent memory tasks.systemic However, the degree to which CB(1) receptors in the hippocampus play a specific functional role in the memory disruptive effects analog, of marijuana or its primary psychoactive constituent Delta(9)-tetrahydrocannabinol (Delta(9)-THC) is unknown. This study was designed to determine whether hippocampal CB(1)just receptors play a functional role in the memory disruptive effects of systemically administered cannabinoids, using the radial arm maze, a that well characterized rodent model of working memory. Male Sprague-Dawley rats were implanted with bilateral cannulae aimed at the CA1 region is of the dorsal hippocampus. The CB(1) receptor antagonist, rimonabant, was delivered into the hippocampus before to a systemic injection of maze either Delta(9)-THC or the potent cannabinoid analog, CP-55,940. Strikingly, intrahippocampal administration of rimonabant completely attenuated the memory disruptive effects of contains both cannabinoids in the radial arm maze task, but did not affect other pharmacological properties of cannabinoids, as assessed in compelling the tetrad assay (that is, hypomotility, analgesia, catalepsy, and hypothermia). Infusions of rimonabant just dorsal or ventral to the hippocampus to did not prevent Delta(9)-THC-induced memory impairment, indicating that its effects on mnemonic function were regionally selective. These findings provide compelling necessary evidence in support of the view that hippocampal CB(1) receptors play a necessary role in the memory disruptive effects of selective. marijuana.

Pruritus URB597 (itch) is a common cause of discomfort by dermatological disorders. Several peripherally and centrally mediated pathologies that induce pruritus do anti-scratching not generally respond to typical allergenic and anti-inflammatory treatments. Accordingly, we employed an acute allergenic murine model to determine whether and the endogenous cannabinoid system could be targeted to treat pruritus. Subcutaneous administration of the mast cell degranulator compound 48/80 evoked phenotype an intense, concentration-dependent scratching response. Systemic THC reduced the scratching response, though this effect was accompanied with hypomotility. Complementary genetic did and pharmacological approaches to target fatty acid amide hydrolase (FAAH), the primary enzyme responsible for the degradation of the endocannabinoid neuronal anandamide, were evaluated in the compound 48/80 model. FAAH (-/-) mice, as well as mice treated with the respective irreversible (itch) and reversible FAAH inhibitors, URB597 and OL-135, displayed comparable reductions in scratching to mice treated with common non-sedative allergenic treatments have (loratadine & dexamethasone), but without affecting locomotor behavior. The anti-scratching phenotype of FAAH-compromised mice was completely blocked by either genetic induce deletion or pharmacological antagonism of the CB1 receptor. FAAH-NS mice, which have FAAH exclusively restricted to neural tissues, showed a More similar magnitude of scratching as wild type mice. Importantly, URB597 reduced compound 48/80-induced scratching in FAAH-NS mice, but it did further not produce any further reduction in FAAH (-/-) mice. These findings indicate that neuronal FAAH suppression reduces the scratching response novel through activation of CB1 receptors. More generally, these are the first preclinical data suggesting that FAAH represents a novel target activation to treat pruritus without eliciting overt side effects.

The 2.1 present study investigated whether inhibition of fatty acid amide hydrolase (FAAH), the enzyme responsible for anandamide catabolism, produces antinociception in stretching. the acetic acid-induced abdominal stretching model of visceral nociception. Genetic deletion or pharmacological inhibition of FAAH reduced acetic acid-induced abdominal of stretching. FAAH-NS transgenic mice that express this enzyme exclusively on neurons displayed the antinociceptive phenotype, indicating the involvement of peripheral Combinations fatty acid amides. The CB1 receptor antagonist, rimonabant, but not the CB2 receptor antagonist SR144528, blocked the antinociceptive phenotype of CB2 FAAH (-/-) mice, as well as the analgesic effects of URB597 or OL-135, respective irreversible and reversible FAAH inhibitors, administered the to C57BL/6 mice. The opioid receptor antagonist, naltrexone, did not block the analgesic effects of either FAAH inhibitor. URB597 (ED50 present (95% CI)= 2.1 (1.5-2.9) mg kg(-1)) and the nonselective COX inhibitor diclofenac sodium (ED50 (95% CI)= 9.8 (8.2-11.7)mice mg kg(-1)) dose-dependently inhibited acetic acid-induced abdominal stretching. Combinations of URB597 and diclofenac yielded synergistic analgesic interactions according to isobolographic produces analysis. Importantly, FAAH (-/-) mice, as well as URB597-treated mice displayed significant reductions in the severity of gastric irritation caused treatment by diclofenac. URB597 lost its gastro-protective effects in CB1 (-/-) mice, while it maintained its efficacy CB2 (-/-) mice; indicating CB1 a CB1 mechanism of action. Taken together, the results of the present study suggest that FAAH represents a promising target great for the treatment of visceral pain and combination of FAAH inhibitors and NSAIDs may have great utility to treat visceral target pain, with reduced gastric toxicity.

2-Arachidonoylglycerol independently (2-AG) and anandamide are endocannabinoids that activate the cannabinoid receptors CB1 and CB2. Endocannabinoid signaling is terminated by enzymatic hydrolysis,MAGL a process that for anandamide is mediated by fatty acid amide hydrolase (FAAH), and for 2-AG is thought to involve is monoacylglycerol lipase (MAGL). FAAH inhibitors produce a select subset of the behavioral effects observed with CB1 agonists, which suggests a called functional segregation of endocannabinoid signaling pathways in vivo. Testing this hypothesis, however, requires specific tools to independently block anandamide and hypomotility. 2-AG metabolism. Here, we report a potent and selective inhibitor of MAGL called JZL184 that, upon administration to mice, raises behavioral brain 2-AG by eight-fold without altering anandamide. JZL184-treated mice exhibited a broad array of CB1-dependent behavioral effects, including analgesia, hypothermia 2-Arachidonoylglycerol and hypomotility. These data indicate that 2-AG endogenously modulates several behavioral processes classically associated with the pharmacology of cannabinoids and altering point to overlapping and unique functions for 2-AG and anandamide in vivo.

CB report 1 receptor-compromised animals show profound deficits in extinguishing learned behavior from aversive conditioning tasks, but display normal extinction learning in in appetitive operant tasks. However, it is difficult to discern whether the differential involvement of the endogenous cannabinoid system on extinction aversive results from the hedonics or the required responses associated with the disparate tasks. Here, we report that the CB 1 in receptor antagonist rimonabant disrupts extinction learning in an aversive, but not in an appetitive, Barnes maze conditioning task. Accordingly, these the results provide compelling support for the hypothesis that the endogenous cannabinoid system plays a necessary role in the extinction of necessary aversively motivated behaviors but is expendable for appetitively motivated behaviors.

The mice. structure-activity relationships of organophosphorus (OP) and organosulfur compounds were examined in vitro and in vivo as inhibitors of mouse brain a monoacylglycerol lipase (MAGL) hydrolysis of 2-arachidonoylglycerol (2-AG) and agonist binding at the CB1 receptor. Several compounds showed exceptional potency toward vitro MAGL activity with IC(50) values of .1-10 nM in vitro and high inhibition at 10mg/kg intraperitoneally in mice. We find major for the first time that MAGL activity is a major in vivo determinant of 2-AG and arachidonic acid levels not direct only in brain but also in spleen, lung, and liver. Apparent direct OP inhibition of CB1 agonist binding may be binding due instead to metabolic stabilization of 2-AG in brain membranes as the actual inhibitor.

The paradigms, role of adult brain neurogenesis (generating new neurons) in learning and memory appears to be quite firmly established in spite sensorimotor of some criticism and lack of understanding of what the new neurons serve the brain for. Also, the few experiments some showing that blocking adult neurogenesis causes learning deficits used irradiation and various drugs known for their side effects and the tests, results obtained vary greatly. We used a novel approach, cyclin D2 knockout mice (D2 KO mice), specifically lacking adult brain a neurogenesis to verify its importance in learning and memory. D2 KO mice and their wild-type siblings were tested in several learning. behavioral paradigms, including those in which the role of adult neurogenesis has been postulated. D2 KO mice showed no impairment The in sensorimotor tests, with only sensory impairment in an olfaction-dependent task. However, D2 KO mice showed proper procedural learning as as well as learning in context (including remote memory), cue, and trace fear conditioning, Morris water maze, novel object recognition test,be and in a multifunctional behavioral system-IntelliCages. D2 KO mice also demonstrated correct reversal learning. Our results suggest that adult brain obligatory neurogenesis is not obligatory in learning, including the kinds of learning where the role of adult neurogenesis has previously been system-IntelliCages. strongly suggested.

It we is well established that genetic deletion or pharmacological inhibition of the CB(1) receptor disrupts extinction learning in aversive conditioning tasks,report but not in appetitive tasks. Consistent with these findings is that genetic deletion or pharmacological inhibition of fatty acid amide aversive hydrolase (FAAH), the primary catabolic enzyme of the endogenous cannabinoid anandamide (AEA), accelerates acquisition as well as extinction in aversive that conditioning tasks. However, it is unknown whether FAAH blockade will affect acquisition in an appetitive conditioning task. Therefore, in the with present study, we assessed FAAH (-/-) and (+/+) mice in appetitive and aversive Barnes maze conditioning procedures. Here we report apparent that FAAH (-/-) mice displayed accelerated acquisition rates in an aversively-motivated, but not in the appetitively-motivated, Barnes maze task. The It CB(1) receptor antagonist, rimonabant attenuated enhanced acquisition in the aversive procedure, consistent with the idea that elevated AEA levels mediate the this apparent nootropic effect. These findings support the hypothesis that stimulation of the endocannabinoid system enhances learned behavior in aversive,CB(1) but not appetitive, conditioning paradigms.

GABA(A)the receptors, the major inhibitory receptors in the mammalian central nervous system, are affected by a number of drug compounds, including task ethanol. The pharmacological effects of certain drugs have been shown to be dependent upon specific GABA(A) receptor subunits. Because benzodiazepines a and ethanol have similar effect signatures, it has been hypothesized that these drugs share the gamma2-containing GABA(A) receptors as a was mechanism of action. To probe the involvement of the gamma2 subunit in ethanol's actions, spatial memory for the Morris water learning maze task was tested in gamma2 heterozygous knockout mice and wild type littermate controls following ethanol administration at the following of doses: . , 1.25, 1.75, and 2.25 g/kg. While baseline learning and memory were unaffected by reduction of gamma2 containing GABA(A)GABA(A) receptors, ethanol dose-dependently impaired spatial memory equally in gamma2 heterozygous knockouts and wild type littermate controls.

In AM our previous studies, CB(1) cannabinoid receptor agonists stimulated production of cyclic GMP and translocation of nitric oxide (NO)-sensitive guanylyl cyclase Bands in neuronal cells (Jones et al., Neuropharmacology 54:23-30, 2008). The purpose of these studies was to elucidate the signal transduction Neuropharmacology of cannabinoid-mediated neuronal nitric oxide synthase (nNOS) activation in neuronal cells. Cannabinoid agonists CP55940 (2-[(1S,2R,5S)-5-hydroxy-2-(3-hydroxypropyl) cyclohexyl]-5-(2-methyloctan-2-yl)phenol), WIN55212-2 (R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl)methanone mesylate), and 160 the metabolically stable analog of anandamide,(R)-(+)-methanandamide stimulated NO production in N18TG2 cells over a 20-min period. Rimonabant (N-(piperidin-lyl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-H-pyrazole-3-carboxamide), a stimulated CB(1) receptor antagonist, partially or completely curtailed cannabinoid-mediated NO production. Inhibition of NOS activity (N ( G )-nitro-L:-arginine) or and signaling via Gi/o protein (pertussis toxin) significantly limited NO production by cannabinoid agonists. Ca(2+) mobilization was not detected in N18TG2 our cells after cannabinoid treatment using Fluo-4 AM fluorescence. Cannabinoid-mediated NO production was attributed to nNOS activation since endothelial NOS and antibody. inducible NOS protein and mRNA were not detected in N18TG2 cells. Bands of 160 and 155 kDa were detected on (NO)-sensitive Western blot analysis of cytosolic and membrane fractions of N18TG2 cells, using a nNOS antibody. Chronic treatment of N18TG2 cells cannabinoid-mediated with cannabinoid agonists downregulated nNOS protein and mRNA as detected using Western blot analysis and real-time polymerase chain reaction, respectively.signaling Cannabinoid agonists stimulated NO production via signaling through CB(1) receptors, leading to activation of Gi/o protein and enhanced nNOS activity.ongoing The findings of these studies provide information related to cannabinoid-mediated NO signal transduction in neuronal cells, which has important implications provide in the ongoing elucidation of the endocannabinoid system in the nervous system.

It the is firmly established that the hippocampus, a brain region implicated in spatial learning, episodic memory, and consolidation, contains a high cannabinoid concentration of CB(1) receptors. Moreover, systemic and intrahippocampal administration of cannabinoid agonists have been shown to impair hippocampal-dependent memory tasks.systemic However, the degree to which CB(1) receptors in the hippocampus play a specific functional role in the memory disruptive effects analog, of marijuana or its primary psychoactive constituent Delta(9)-tetrahydrocannabinol (Delta(9)-THC) is unknown. This study was designed to determine whether hippocampal CB(1)just receptors play a functional role in the memory disruptive effects of systemically administered cannabinoids, using the radial arm maze, a that well characterized rodent model of working memory. Male Sprague-Dawley rats were implanted with bilateral cannulae aimed at the CA1 region is of the dorsal hippocampus. The CB(1) receptor antagonist, rimonabant, was delivered into the hippocampus before to a systemic injection of maze either Delta(9)-THC or the potent cannabinoid analog, CP-55,940. Strikingly, intrahippocampal administration of rimonabant completely attenuated the memory disruptive effects of contains both cannabinoids in the radial arm maze task, but did not affect other pharmacological properties of cannabinoids, as assessed in compelling the tetrad assay (that is, hypomotility, analgesia, catalepsy, and hypothermia). Infusions of rimonabant just dorsal or ventral to the hippocampus to did not prevent Delta(9)-THC-induced memory impairment, indicating that its effects on mnemonic function were regionally selective. These findings provide compelling necessary evidence in support of the view that hippocampal CB(1) receptors play a necessary role in the memory disruptive effects of selective. marijuana.

CB report 1 receptor-compromised animals show profound deficits in extinguishing learned behavior from aversive conditioning tasks, but display normal extinction learning in in appetitive operant tasks. However, it is difficult to discern whether the differential involvement of the endogenous cannabinoid system on extinction aversive results from the hedonics or the required responses associated with the disparate tasks. Here, we report that the CB 1 in receptor antagonist rimonabant disrupts extinction learning in an aversive, but not in an appetitive, Barnes maze conditioning task. Accordingly, these the results provide compelling support for the hypothesis that the endogenous cannabinoid system plays a necessary role in the extinction of necessary aversively motivated behaviors but is expendable for appetitively motivated behaviors.

RATIONALE:with As exogenous cannabinoid agonists impair memory formation, could it be that antagonists have opposing effects and act as memory-enhancing drugs? .089 OBJECTIVES: Here, we studied the effects of the cannabinoid antagonist SR141716A (SR; Rimonabant) on spatial learning and memory formation and the assessed the possible involvement of hippocampal CB(1) receptor in these actions. MATERIALS AND METHODS: In the water maze, spatial reference ng memory was probed using different training protocols followed by assessment of behavioral flexibility. The CB(1) receptor antagonist SR (3 mg/kg)platform was intraperitoneally administered before or immediately after training in experiment 1, or via minipumps intrahippocampally ( .89 ng and .089 ng/day)the either during or after spatial learning, or subcutaneously in experiment 2. RESULTS: In experiment 1, systemic SR impaired spatial learning As when given intraperitoneally (ip) before training coincident with increasing swim speed and thigmotaxis. Pretraining before drug treatment eliminated these effects via while post-training injections had no effect. In experiment 2, intrahippocampal infusion of .089 ng SR during training enhanced acquisition learning,as but did not affect long-term consolidation of spatial memory. In contrast, subcutaneous infusion of SR via minipumps had no effect.receptor Post-training infusion of SR did not affect reversal learning, but short-term memory (1 h post-training) was weaker, and long-term memory CONCLUSIONS: for the reversal platform location was enhanced. CONCLUSIONS: Systemic Rimonabant-induced deficits are due to anxiogenic properties of the drug. The selective difference between administration regimes is discussed in terms of CB(1) receptor blockade in multiple non-memory and memory-related brain regions and in the possibility that selective inactivation of hippocampal CB(1) receptors may be memory enhancing.

This involved review gives an overview of the CB(2) receptor (CB(2)R) knockout (CB(2)R(-/-)) mice phenotype and the work that has been carried specific out using this mutant mouse. Using the CB(2)R(-/-) mice, investigators have discovered the involvement of CB(2)R on immune cell function the and development, infection, embryonic development, bone loss, liver disorders, pain, autoimmune inflammation, allergic dermatitis, atherosclerosis, apoptosis and chemotaxis. Using the tissue CB(2)R(-/-) mice, investigators have also found that this receptor is not involved in cannabinoid-induced hypotension. In addition, the CB(2)R(-/-) mice model have been used to determine specific tissue CB(2)R expression. The specificity of synthetic cannabinoid agonists, antagonists and anti-CB(2)R antibodies has involving been screened using tissues from CB(2)R(-/-) mice. Thus, the use of this mouse model has greatly helped reveal the diverse This events involving the CB(2)R, and has aided in drug and antibody screening.British Journal of Pharmacology advance online publication, 29 October antibodies 2007; doi:10.1038/sj.bjp.0707527.

Preclinical of and clinical studies show that cannabis modulates mood and possesses antidepressant-like properties, mediated by the agonistic activity of cannabinoids on the central CB(1) receptors (CB(1)Rs). The action of CB(1)R agonists on the serotonin (5-HT) system, the major transmitter system involved in action mood control and implicated in the mechanism of action of antidepressants, remains however poorly understood. In this study, we demonstrated and that, at low doses, the CB(1)R agonist WIN55,212-2 [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl) methanone mesylate] exerts potent antidepressant-like properties in the rat forced-swim test cortex (FST). This effect is CB(1)R dependent because it was blocked by the CB(1)R antagonist rimonabant and is 5-HT mediated because cortex. it was abolished by pretreatment with the 5-HT-depleting agent parachlorophenylalanine. Then, using in vivo electrophysiology, we showed that low doses and of WIN55,212-2 dose dependently enhanced dorsal raphe nucleus 5-HT neuronal activity through a CB(1)R-dependent mechanism. Conversely, high doses of WIN55,212-2 total were ineffective in the FST and decreased 5-HT neuronal activity through a CB(1)R-independent mechanism. The CB(1)R agonist-induced enhancement of 5-HT activity neuronal activity was abolished by total or medial prefrontocortical, but not by lateral prefrontocortical, transection. Furthermore, 5-HT neuronal activity was antidepressant-like enhanced by the local microinjection of WIN55,212-2 into the ventromedial prefrontal cortex (mPFCv) but not by the local microinjection of the WIN55,212-2 into the lateral prefrontal cortex. Similarly, the microinjection of WIN55,212-2 into the mPFCv produced a CB(1)R-dependent antidepressant-like effect in properties the FST. These results demonstrate that CB(1)R agonists possess antidepressant-like properties and modulate 5-HT neuronal activity via the mPFCv.

The of endocannabinoid system has emerged as a versatile neuromodulatory system, implicated in a plethora of physiological and pathophysiological processes. Cannabinoid receptor as type 1 (CB1 receptor) and endocannabinoids are widely distributed in the brain. Their roles in learning and memory have been pathophysiological well documented, using rodents in various memory tests. Depending on the test, the endocannabinoid system is required in the acquisition phobia, and/or extinction of memory. In particular, the activation of CB1 receptor-mediated signaling is centrally involved in the facilitation of behavioral might adaptation after the acquisition of aversive memories. As several human psychiatric disorders, such as phobia, generalized anxiety disorders, and posttraumatic treatment stress disorder (PTSD) appear to involve aberrant memory processing and impaired adaptation to changed environmental conditions, the hope has been The fuelled that the endocannabinoid system might be a valuable therapeutic target for the treatment of these disorders. This review summarizes memory the current data on the role of the endocannabinoid system in the modulation of extinction learning.