Cannabis and endogenous cannabinoid systems

A systematic review of novel cannabinoids and their targets: Insights into the significance of structure in activity

To provide a comprehensive framework of the current information on the potency and efficacy of interaction between phyto- and synthetic cannabinoids and their respective receptors, an electronic search of the PubMed, Scopus, and EMBASE literature was performed. Experimental studies included reports of mechanistic data providing affinity, efficacy, and half-maximal effective concentration (EC50). Among the 108 included studies, 174 structures, and 16 targets were extracted. The most frequent ligands belonged to the miscellaneous category with 40.2% followed by phytocannabinoid-similar, indole-similar, and pyrrole-similar structures with an abundance of 17.8%, 16.6%, and 12% respectively. 64.8% of structures acted as agonists, 17.1 % appeared as inverse agonists, 10.8% as antagonists, and 7.2% of structures were reported with antagonist/inverse agonist properties. Our outcomes identify the affinity, EC50, and efficacy of the interactions between cannabinoids and their corresponding receptors and the subsequent response, evaluated in the available evidence. Considering structures' significance and very important effects of on the activities, the obtained results also provide clues to drug repurposing.

Effects of Δ9-Tetrahydrocannabinol and the Aminoalkylindole K2/Spice Constituent JWH-073 on Cardiac Tissue and Mesenteric Vascular Reactivity

Background: Although use of Cannabis sativa is not associated with serious adverse effects, recreational use of aminoalkylindole (AAI) cannabinoid receptor agonists found in K2/Spice herbal blends has been reported to cause adverse cardiovascular events, including angina, arrhythmia, changes in blood pressure, ischemic stroke, and myocardial infarction. Δ9-Tetrahydrocannabinol (Δ9-THC) is the primary CB1 agonist found in cannabis and JWH-073 is one of the AAI CB1 agonists found in K2/Spice brands sold to the public. Methods: This study used in vitro, in vivo, and ex vivo approaches to investigate potential differences on cardiac tissue and vascular effects betweenJWH-073 and Δ9-THC. Male C57BL/6 mice were treated with JWH-073 or Δ9-THC and cardiac injury was assessed by histology. Effects of JWH-073 and Δ9-THC on H9C2 cell viability and ex vivo mesenteric vascular reactivity were also determined. Results: JWH-073 or Δ9-THC induced typical cannabinoid effects of antinociception and hypothermia but did not promote death of cardiac myocytes. No differences in cell viability were observed in cultured H9C2 cardiac myocytes after 24 h of treatment. In isolated mesenteric arteries from drug-naive animals, JWH-073 produced significantly greater maximal relaxation (96%±2% vs. 73%±5%, p<0.05) and significantly greater inhibition of phenylephrine-mediated maximal contraction (Control 174%±11%KMAX) compared with Δ9-THC (50%±17% vs. 119%±16%KMAX, p<0.05). Discussion: These findings suggest that neither cannabinoid at the concentrations/dose studied caused cardiac cell death, but JWH-073 has the potential for greater vascular adverse events than Δ9-THC through an increased vasodilatory effect.

Rhodium-Catalyzed Asymmetric Addition to 4- or 5-Carbonyl-cycloenones through Dynamic Kinetic Resolution: Enantioselective Synthesis of (-)-Cannabidiol

The reaction of 4/5-carbonyl-cycloalkenone 1 or its achiral isomer 1' with organoboronic acid 2 in the presence of a chiral diene (S,S)-Fc-tfb-rhodium catalyst gave disubstituted trans-cycloalkanone 3 with high diastereo- and enantioselectivity. This highly efficient dynamic kinetic resolution is achieved by fast racemization of 1 through the formation of a dienolate followed by kinetic resolution with the chiral catalyst. The utility is demonstrated by the synthesis of key intermediates en route to (-)-cannabidiol.

Effects of Delta-9 Tetrahydrocannabinol (THC) on Oocyte Competence and Early Embryonic Development

Recent changes in legal status and public perception of cannabis have contributed to an increase use amongst women of reproductive age. Concurrently, there is inadequate evidence-based knowledge to guide clinical practice regarding cannabis and its effects on fertility and early embryonic development. This study aimed to evaluate the effects of the primary psychoactive component of cannabis, delta-9 tetrahydrocannabinol (THC), during oocyte maturation, and its impact on the developing embryo. Bovine oocytes were matured in vitro for 24 h under clinically relevant doses of THC mimicking plasma levels achieved after therapeutic (0.032 μM) and recreational (0.32 and 3.2 μM) cannabis use. THC-treated oocytes were assessed for development and quality parameters at both the oocyte and embryo level. Characteristics of oocytes treated with cannabinoid receptor antagonists were also assessed. Oocytes treated with 0.32 and 3.2 μM THC, were significantly less likely to reach metaphase II (p < 0.01) and consequently had lower cleavage rates at day 2 post-fertilization (p < 0.0001). Treatment with cannabinoid receptor antagonists restored this effect (p < 0.05). Oocytes that did reach MII showed no differences in spindle morphology. Oocytes treated with 0.032 μM THC had significantly lower connexin mRNA (p < 0.05) (correlated with decreased quality), but this was not confirmed at the protein level. At the blastocyst stage there were no significant differences in developmental rates or the proportion of trophectoderm to inner cell mass cells between the control and treatment groups. These blastocysts, however, displayed an increased level of apoptosis in the 0.32 and 3.2 μM groups (p < 0.0001). Our findings suggest a possible disruptive effect of cannabis on oocyte maturation and early embryonic development.

Cannabinoids in Breast Cancer: Differential Susceptibility According to Subtype

Although cannabinoids have been used for centuries for diverse pathological conditions, recently, their clinical interest and application have emerged due to their diverse pharmacological properties. Indeed, it is well established that cannabinoids exert important actions on multiple sclerosis, epilepsy and pain relief. Regarding cancer, cannabinoids were first introduced to manage chemotherapy-related side effects, though several studies demonstrated that they could modulate the proliferation and death of different cancer cells, as well as angiogenesis, making them attractive agents for cancer treatment. In relation to breast cancer, it has been suggested that estrogen receptor-negative (ER-) cells are more sensitive to cannabinoids than estrogen receptor-positive (ER+) cells. In fact, most of the studies regarding their effects on breast tumors have been conducted on triple-negative breast cancer (TNBC). Nonetheless, the number of studies on human epidermal growth factor receptor 2-positive (HER2+) and ER+ breast tumors has been rising in recent years. However, besides the optimistic results obtained thus far, there is still a long way to go to fully understand the role of these molecules. This review intends to help clarify the clinical potential of cannabinoids for each breast cancer subtype.

Associations of CB1 cannabinoid receptor (CNR1) gene polymorphisms with risk for alcohol dependence: Evidence from meta-analyses of genetic and genome-wide association studies

OBJECTIVES

Reported associations of the cannabinoid receptor 1 (CNR1) single nucleotide polymorphisms (SNPs) with alcohol dependence (AD) have been inconsistent, prompting a meta-analysis to obtain more precise estimates.

METHODS

A Boolean search of 4 databases (PubMed, Scopus, Google Scholar, and Mednar) sought articles that evaluated the association between CNR1 polymorphisms and risk of AD. We selected the articles with sufficient genotype frequency data to enable calculation of odds ratios (ORs) and 95% confidence intervals (CIs). Using the Population Intervention Comparators Outcome elements, AD patients (P) were compared by genotype data between AD-participants (I) and non-AD-participants (C) in order to determine the risk of AD (O) attributed to the CNR1 SNPs. Analyzing 4 SNPs (rs1049353, rs1535255, rs2023239, and rs806379) using standard genetic models, we examined associations where multiple comparisons were Holm-Bonferroni corrected. The pooled ORs were assessed for aggregate statistical power and robustness (sensitivity analysis). Subgroups were Caucasians and African-Americans.

RESULTS

From 32 comparisons, 14 were significant indicating increased risk, from which 5 outcomes (P-value for association [Pa] = .003 to <.001) survived the Holm-Bonferroni-correction, which were deemed robust. In the rs1535255 outcomes, the codominant effect (OR = 1.43, 95% CIs = 1.24-1.65, Pa < .001) had greater statistical power than the dominant effect (OR = 1.30, 95% CI = 1.08-1.57, Pa = .006). In contrast, the rs2023239 codominant outcome was underpowered. Significance of both rs806379 Caucasian outcomes (ORs = 1.20-1.43, 95% CIs = 1.07-1.57, Pa = .003) contrasted with the null effects in African-Americans (ORs = 0.98-1.08, 95% CIs = 0.70-1.53).

CONCLUSIONS

Three CNR1 SNPs (rs1535255, rs2023239, and rs806379) were implicated in their associations with development of AD: based on aggregate statistical power, rs1535255 presented greater evidence for associations than rs2023239; rs806379 implicated the Caucasian subgroup. Multiple statistical and meta-analytical features (consistency, robustness, and high significance) underpinned the strengths of these outcomes. Our findings could render the CNR1 polymorphisms useful in the clinical genetics of AD.

The Molecular Basis of Alcohol Use Disorder (AUD). Genetics, Epigenetics, and Nutrition in AUD: An Amazing Triangle

Alcohol use disorder (AUD) is a very common and complex disease, as alcohol is the most widely used addictive drug in the world. This disorder has an enormous impact on public health and social and private life, and it generates a huge number of social costs. Alcohol use stimulates hypothalamic-pituitary-adrenal (HPA) axis responses and is the cause of many physical and social problems (especially liver disease and cancer), accidental injury, and risky sexual behavior. For years, researchers have been trying to identify the genetic basis of alcohol use disorder, the molecular mechanisms responsible for its development, and an effective form of therapy. Genetic and environmental factors are known to contribute to the development of AUD, and the expression of genes is a complicated process that depends on epigenetic modulations. Dietary nutrients, such as vitamins, may serve as one these modulators, as they have a direct impact on epigenomes. In this review, we connect gathered knowledge from three emerging fields-genetics, epigenetics, and nutrition-to form an amazing triangle relating to alcohol use disorder.

Distribution of the Cannabinoid Receptor Type 1 in the Brain of the Genetically Audiogenic Seizure-Prone Hamster GASH/Sal

The endocannabinoid system modulates epileptic seizures by regulating neuronal excitability. It has become clear that agonist activation of central type I cannabinoid receptors (CB1R) reduces epileptogenesis in pre-clinical animal models of epilepsy. The audiogenic seizure-prone hamster GASH/Sal is a reliable experimental model of generalized tonic-clonic seizures in response to intense sound stimulation. However, no studies hitherto had investigated CB1R in the GASH/Sal. Although the distribution of CB1R has been extensively studied in mammalian brains, their distribution in the Syrian golden hamster brain also remains unknown. The objective of this research is to determine by immunohistochemistry the differential distribution of CB1R in the brains of GASH/Sal animals under seizure-free conditions, by comparing the results with wild-type Syrian hamsters as controls. CB1R in the GASH/Sal showed a wide distribution in many nuclei of the central nervous system. These patterns of CB1R-immunolabeling are practically identical between the GASH/Sal model and control animals, varying in the intensity of immunostaining in certain regions, being slightly weaker in the GASH/Sal than in the control, mainly in brain regions associated with epileptic networks. The RT-qPCR analysis confirms these results. In summary, our study provides an anatomical basis for further investigating CB1R in acute and kindling audiogenic seizure protocols in the GASH/Sal model as well as exploring CB1R activation via exogenously administered cannabinoid compounds.

The Impact of Controlled Ovarian Stimulation Hormones on the Metabolic State and Endocannabinoid System of Human Cumulus Cells

Different Follicle Stimulating Hormone (FSH) formulation and Luteinizing Hormone (LH) are used in Assisted Reproductive Technology (ART) to induce follicles development and oocytes maturation, but it is still under debate which protocol is to be preferred. In the present study, the different effects on cumulus cells (CCs) of three controlled ovarian stimulation (COS) protocols, based on urinary FSH, recombinant FSH, or human Menopausal Gonadotropin (hMG) administration, were assessed. CCs were obtained from 42 normal-responders women undergoing COS, randomly divided into three groups according to the used gonadotropin formulation. Differences were found in the expression of genes belonging to the endocannabinoid system (the receptors CNR1, CNR2 and TRPV1, and the enzymes involved in the metabolisms of anandamide, NAPE-PLD and FAAH, and 2-acylglycerol, DAGL and MAGL); consistently, changes in lipid (PPARα, and FASN) and carbohydrate (GLUT1 and GLUT9) metabolisms, in CCs’ macromolecules composition (highlighted by Fourier Transform Infrared Microspectroscopy, FTIRM), and in the number of retrieved oocytes were found. For the first time, statistically significant evidence on the differences related to each COS protocol on the endocannabinoid system, metabolism and macromolecular composition of CCs was found, representing a proof of concept to be further confirmed in a larger cohort of patients.

Role of the Endocannabinoidome in Human and Mouse Atherosclerosis

The Endocannabinoid (eCB) system and its role in many physiological and pathological conditions is well described and accepted, and includes cardiovascular disorders. However, the eCB system has been expanded to an "-ome"; the endocannabinoidome (eCBome) that includes endocannabinoid-related mediators, their protein targets and metabolic enzymes, many of which significantly impact upon cardiometabolic health. These recent discoveries are here summarized with a special focus on their potential involvement in atherosclerosis. We described the role of classical components of the eCB system (eCBs, CB1 and CB2 receptors) and eCB-related lipids, their regulatory enzymes and molecular targets in atherosclerosis. Furthermore, since increasing evidence points to significant cross-talk between the eCBome and the gut microbiome and the gut microbiome and atherosclerosis, we explore the possibility that a gut microbiome - eCBome axis has potential implications in atherosclerosis.

Targeting the endocannabinoid system: a predictive, preventive, and personalized medicine-directed approach to the management of brain pathologies

Cannabis-inspired medical products are garnering increasing attention from the scientific community, general public, and health policy makers. A plethora of scientific literature demonstrates intricate engagement of the endocannabinoid system with human immunology, psychology, developmental processes, neuronal plasticity, signal transduction, and metabolic regulation. Despite the therapeutic potential, the adverse psychoactive effects and historical stigma, cannabinoids have limited widespread clinical application. Therefore, it is plausible to weigh carefully the beneficial effects of cannabinoids against the potential adverse impacts for every individual. This is where the concept of "personalized medicine" as a promising approach for disease prediction and prevention may take into the account. The goal of this review is to provide an outline of the endocannabinoid system, including endocannabinoid metabolizing pathways, and will progress to a more in-depth discussion of the therapeutic interventions by endocannabinoids in various neurological disorders.

Prediction and Experimental Confirmation of Novel Peripheral Cannabinoid-1 Receptor Antagonists

Small molecules targeting peripheral CB1 receptors have therapeutic potential in a variety of disorders including obesity-related, hormonal, and metabolic abnormalities, while avoiding the psychoactive effects in the central nervous system. We applied our in-house algorithm, iterative stochastic elimination, to produce a ligand-based model that distinguishes between CB1R antagonists and random molecules by physicochemical properties only. We screened ∼2 million commercially available molecules and found that about 500 of them are potential candidates to antagonize the CB1R. We applied a few criteria for peripheral activity and narrowed that set down to 30 molecules, out of which 15 could be purchased. Ten out of those 15 showed good affinity to the CB1R and two of them with nanomolar affinities (K_i of ∼400 nM). The eight molecules with top affinities were tested for activity: two compounds were pure antagonists, and five others were inverse agonists. These molecules are now being examined in vivo for their peripheral versus central distribution and subsequently will be tested for their effects on obesity in small animals.

Innovative Therapeutic Potential of Cannabinoid Receptors as Targets in Alzheimer’s Disease and Less Well-Known Diseases

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The discovery of cannabinoid receptors at the beginning of the 1990s, CB1 cloned in 1990 and CB2 cloned in 1993, and the availability of selective and potent cannabimimetics could only be justified by the existence of endogenous ligands that are capable of binding to them. Thus, the characterisation and cloning of the first cannabinoid receptor (CB1) led to the isolation and characterisation of the first endocannabinoid, arachidonoylethanolamide (AEA), two years later and the subsequent identification of a family of lipid transmitters known as the fatty acid ester 2-arachidonoylglycerol (2-AG).

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The endogenous cannabinoid system is a complex signalling system that comprises transmembrane endocannabinoid receptors, their endogenous ligands (the endocannabinoids), the specific uptake mechanisms and the enzymatic systems related to their biosynthesis and degradation.

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The endocannabinoid system has been implicated in a wide diversity of biological processes, in both the central and peripheral nervous systems, including memory, learning, neuronal development, stress and emotions, food intake, energy regulation, peripheral metabolism, and the regulation of hormonal balance through the endocrine system.

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In this context, this article will review the current knowledge of the therapeutic potential of cannabinoid receptor as a target in Alzheimer’s disease and other less well-known diseases that include, among others, multiple sclerosis, bone metabolism, and Fragile X syndrome.

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The therapeutic applications will be addressed through the study of cannabinoid agonists acting as single drugs and multi-target drugs highlighting the CB2 receptor agonist.

Sex, THC, and hormones: Effects on density and sensitivity of CB1 cannabinoid receptors in rats

BACKGROUND

The recent NIH mandate to consider sex as a biological variable in preclinical research has focused attention on delineation of sex differences in behavior. To investigate mechanisms underlying sex differences in Δ⁹-tetrahydrocannabinol (THC) effects, we examined the effects of sex and gonadal hormones on CB₁ receptors in cerebellum, hippocampus, prefrontal cortex, and striatum.

METHODS

Adult Sprague-Dawley rats underwent gonadectomy (GDX) or sham-GDX. Half of the GDX females and males received estradiol or testosterone replacement (GDX+H), respectively. All rats were injected with vehicle or 30 mg/kg THC twice daily for 1 week before brain collection. CP55,940-stimulated [³⁵S]GTPγS and [³H]SR141716A saturation binding assays were performed.

RESULTS

With exception of enhanced receptor activation in the hippocampi of female rats compared to males, vehicle-treated rats exhibited minimal sex differences in CB₁ receptor densities or G-protein coupling. Repeated treatment with THC resulted in pronounced CB₁ receptor desensitization and downregulation in both sexes in all brain regions with a greater magnitude of change in females.

CONCLUSIONS

These results suggest that sex differences in the density and G-protein coupling of brain CB₁ receptors may play a limited role in sex differences in acute THC effects not mediated by the hippocampus. In contrast, sex differences after repeated THC were common, with females (intact, GDX, and GDX+H) showing greater downregulation or desensitization in all four brain regions compared to the respective male groups. This result is consistent with a finding that women tend to progress to tolerance and dependence quicker than men after initiation of cannabis use.

Marijuana Use and Depressive Symptoms; Gender Differences in African American Adolescents

Introduction: This study aimed to examine gender differences in the bidirectional associations between marijuana use and depressive symptoms among African American adolescents. The study also tested gender differences in the effects of socioeconomic status, maternal support, and friends' drug use on adolescents' depressive symptoms and marijuana use. Methods: This is a secondary analysis of the Flint Adolescent Study (FAS). Six hundred and eighty one African American adolescents (335 males and 346 females) were followed for 3 years, from 1995 (mean age 16) to 1997 (mean age 19). Depressive symptoms (Brief Symptom Inventory) and marijuana use were measured annually during the follow up. We used multi-group latent growth curve modeling to explore the reciprocal associations between depressive symptoms and marijuana use over time based on gender. Results: Baseline marijuana use was predictive of an increase in depressive symptoms over time among male but not female African American adolescents. Baseline depressive symptoms were not predictive of an increase in marijuana use among male or female adolescents. Conclusion: Study findings suggest that male African American adolescents who use marijuana are at an increased risk of subsequent depressive symptoms. Interventions that combine screening and treatment for marijuana use and depression may be indicated for African American male adolescents.

Investigation of non-CB1, non-CB2 WIN55212-2-sensitive G-protein-coupled receptors in the brains of mammals, birds, and amphibians

PURPOSE

Previous studies have found non-CB₁ non-CB₂ G-protein-coupled receptors in rodents that are activated by the aminoalkylindole cannabinoid agonist WIN55212-2. This work obtained evidence for the presence or absence of similar receptors in the brains of other mammals, birds and amphibians.

MATERIALS AND METHODS

Antagonism of the stimulation of [³⁵S]GTPγS binding by WIN55212-2 and CP55940 was assessed in multiple CNS regions of rat and canine, and in whole brain membranes from shrew, pigeon, frog and newt. A bioinformatics approach searched for orthologs of GRP3, GPR6, and GPR12 (closely related to cannabinoid receptors) in the genomes of these or related species. Orthologs were examined for amino acid motifs known to impart functionality to receptors.

RESULTS

In mammals and pigeon, but not amphibians, a significant fraction of the stimulation of [³⁵S]GTPγS binding by WIN55212-2 was not blocked by the CB₁ antagonist SR141716A. BLAST searches found that GPR3 was restricted to mammals. GPR12 orthologs existed in all species, and they shared identical amino acid motifs. GPR6 orthologs existed all species, but with significant departures in the identity of some critical amino acids in bird, more so in amphibian.

CONCLUSIONS

The portion of WIN55212-2-stimulated [³⁵S]GTPγS binding that was antagonized by SR141716A was consistent with stimulation via CB₁ receptors, indicating that antagonist-insensitive activity was via a different G-protein coupled receptor. Pharmacological evidence of this receptor was found in the brains of mammals and pigeon, but not frog or newt. Bioinfomatics results implicate GPR6 as a possible candidate for the additional WIN55212-2-sensitive receptor.

Cannabidiol as a Therapeutic Alternative for Post-traumatic Stress Disorder: From Bench Research to Confirmation in Human Trials

Post-traumatic stress disorder (PTSD) is characterized by poor adaptation to a traumatic experience. This disorder affects approximately 10% of people at some point in life. Current pharmacological therapies for PTSD have been shown to be inefficient and produce considerable side effects. Since the discovery of the involvement of the endocannabinoid (eCB) system in emotional memory processing, pharmacological manipulation of eCB signaling has become a therapeutic possibility for the treatment of PTSD. Cannabidiol (CBD), a phytocannabinoid constituent of Cannabis sativa without the psychoactive effects of Δ⁹-tetrahydrocannabinol, has gained particular attention. Preclinical studies in different rodent behavioral models have shown that CBD can both facilitate the extinction of aversive memories and block their reconsolidation, possibly through potentialization of the eCB system. These results, combined with the currently available pharmacological treatments for PTSD being limited, necessitated testing CBD use with the same therapeutic purpose in humans as well. Indeed, as observed in rodents, recent studies have confirmed the ability of CBD to alter important aspects of aversive memories in humans and promote significant improvements in the symptomatology of PTSD. The goal of this review was to highlight the potential of CBD as a treatment for disorders related to inappropriate retention of aversive memories, by assessing evidence from preclinical to human experimental studies.

Genetic or pharmacological depletion of cannabinoid CB1 receptor protects against dopaminergic neurotoxicity induced by methamphetamine in mice

Accumulating evidence suggests that cannabinoid ligands play delicate roles in cell survival and apoptosis decisions, and that cannabinoid CB1 receptors (CB1R) modulate dopaminergic function. However, the role of CB1R in methamphetamine (MA)-induced dopaminergic neurotoxicity in vivo remains elusive. Multiple high doses of MA increased phospho-ERK and CB1R mRNA expressions in the striatum of CB1R (+/+) mice. These increases were attenuated by CB1R antagonists (i.e., AM251 and rimonabant), an ERK inhibitor (U0126), or dopamine D2R antagonist (sulpiride). In addition, treatment with MA resulted in dopaminergic impairments, which were attenuated by CB1R knockout or CB1R antagonists (i.e., AM251 and rimonabant). Consistently, MA-induced oxidative stresses (i.e., protein oxidation, lipid peroxidation and reactive oxygen species) and pro-apoptotic changes (i.e., increases in Bax, cleaved PKCδ- and cleaved caspase 3-expression and decrease in Bcl-2 expression) were observed in the striatum of CB1R (+/+) mice. These toxic effects were attenuated by CB1R knockout or CB1R antagonists. Consistently, treatment with four high doses of CB1R agonists (i.e., WIN 55,212-2 36mg/kg and ACEA 16mg/kg) also resulted in significant oxidative stresses, pro-apoptotic changes, and dopaminergic impairments. Since CB1R co-immunoprecipitates PKCδ in the presence of MA or CB1R agonists, we applied PKCδ knockout mice to clarify the role of PKCδ in the neurotoxicity elicited by CB1Rs. CB1R agonist-induced toxic effects were significantly attenuated by CB1R knockout, CB1R antagonists or PKCδ knockout. Therefore, our results suggest that interaction between D2R, ERK and CB1R is critical for MA-induced dopaminergic neurotoxicity and that PKCδ mediates dopaminergic damage induced by high-doses of CB1R agonist.

The association of cannabis use on inpatient psychiatric hospital outcomes

BACKGROUND

The associations between cannabis use and psychosis are well documented in numerous studies. There is a need to evaluate the impact of cannabis use on inpatient psychiatric utilization and outcomes.

OBJECTIVES

To evaluate the impact of cannabis use on psychiatric hospital outcomes.

METHODS

This study was conducted between April 20, 2015 and October 20, 2015. All patients (n = 120) admitted to Denver Health with psychotic symptoms were administered a urine toxicology screening testing for the presence of 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THC-COOH, the active metabolite of cannabis). Patients with positive tests were compared to those with negative tests on several measures, including length of stay, presence or lack of 30-day readmission, Brief Psychotic Rating Scale (BPRS) score, and use of antipsychotics and/or sedatives/anxiolytics.

RESULTS

There were 120 patients. Twenty nine were women and 91 were men. Patients testing positive for THC-COOH had a shorter length of stay compared to patients testing negative for THC-COOH, after adjusting for age, prior psychiatric admissions, history of a psychotic-spectrum disorder, and comorbid additional substance use (p = 0.02). There were no differences in 30-day readmissions, 30-day post-discharge presentation to the Denver Health psychiatric emergency department, BPRS scores, and medication administration.

CONCLUSION

Patients presenting with psychotic symptoms and cannabis use require shorter inpatient psychiatric hospitalizations. This study is the first to quantify this observation and highlights the need for future clinical decision-making tools that would ideally correlate cannabis use with the degree of potential need for expensive and scarce mental health resources, such as psychiatric hospitalization.

Cannabinoid Analgesia as a Potential New Therapeutic Option in the Treatment of Chronic Pain

Objective:

To review the literature concerning the physiology of the endocannabinoid system, current drug development of cannabinoid agonists, and current clinical research on the use of cannabinoid agonists for analgesia.

Data Sources:

Articles were identified through a search of MEDLINE (1966–August 2005) using the key words cannabis, cannabinoid, cannabi*, cannabidiol, nabilone, THC, pain, and analgesia. No search limits were included. Additional references were located through review of the bibliographies of the articles identified.

Study Selection and Data Extraction:

Studies of cannabinoid agonists for treatment of pain were selected and were not limited by pain type or etiology. Studies or reviews using animal models of pain were also included. Articles that related to the physiology and pharmacology of the endocannabinoid system were evaluated.

Data Synthesis:

The discovery of cannabinoid receptors and endogenous ligands for these receptors has led to increased drug development of cannabinoid agonists. New cannabimimetic agents have been associated with fewer systemic adverse effects than delta-9-tetrahydrocannabinol, including recent development of cannabis medicinal extracts for sublingual use (approved in Canada), and have had promising results for analgesia in initial human trials. Several synthetic cannabinoids have also been studied in humans, including 2 cannabinoid agonists available on the international market.

Conclusions:

Cannabinoids provide a potential approach to pain management with a novel therapeutic target and mechanism. Chronic pain often requires a polypharmaceutical approach to management, and cannabinoids are a potential addition to the arsenal of treatment options.

Cannabinoid Hyperemesis Syndrome: A Case Report of Cyclic Severe Hyperemesis and Abdominal Pain with Long-Term Cannabis Use

Introduction. Cannabinoid Hyperemesis Syndrome (CHS) is a rare condition that includes cyclic severe vomiting in subjects who have been consuming large doses of cannabis for several years. One of the major diagnostic criteria is the alleviation of symptoms by hot showers. The syndrome was first described in 2004 and is so far neither completely understood nor well known. The latter leads to continued morbidity in concerned subjects and unnecessary expenses for futile investigations. Standard treatments of vomiting as 5-HT3 or D2-receptor antagonists have been shown to be ineffective in alleviating the symptoms. The only long-term satisfying treatment option is the complete abstinence from cannabis consumption. Case Summary. In this case report we describe a 26-year-old male Caucasian long-term cannabis consumer who repeatedly presented in our emergency room with cyclic severe nausea and vomiting ceased by hot showers and resistant to all other treatments. The final diagnosis was not established until his third visit to the ER. Conclusion. CHS is an important differential diagnosis in patients who present with cyclic vomiting and abdominal pain with a history of long-term cannabis use. Recognition of this syndrome is important in order to avoid unnecessary clinical testing and to help the patients break the cycle of drug use.

Lifetime use of cannabis from longitudinal assessments, cannabinoid receptor (CNR1) variation, and reduced volume of the right anterior cingulate

Lifetime measures of cannabis use and co-occurring exposures were obtained from a longitudinal cohort followed an average of 13 years at the time they received a structural MRI scan. MRI scans were analyzed for 88 participants (mean age=25.9 years), 34 of whom were regular users of cannabis. Whole brain voxel based morphometry analyses (SPM8) were conducted using 50 voxel clusters at p=0.005. Controlling for age, familial risk, and gender, we found reduced volume in Regular Users compared to Non-Users, in the lingual gyrus, anterior cingulum (right and left), and the rolandic operculum (right). The right anterior cingulum reached family-wise error statistical significance at p=0.001, controlling for personal lifetime use of alcohol and cigarettes and any prenatal exposures. CNR1 haplotypes were formed from four CNR1 SNPs (rs806368, rs1049353, rs2023239, and rs6454674) and tested with level of cannabis exposure to assess their interactive effects on the lingual gyrus, cingulum (right and left) and rolandic operculum, regions showing cannabis exposure effects in the SPM8 analyses. These analyses used mixed model analyses (SPSS) to control for multiple potentially confounding variables. Level of cannabis exposure was associated with decreased volume of the right anterior cingulum and showed interaction effects with haplotype variation.

Augmentation of Evidence-Based Psychotherapy for PTSD With Cognitive Enhancers

Exposure-based therapy has proven to be useful to treat various anxiety disorders as well as post-traumatic stress disorder (PTSD). Despite its efficacy, a fair proportion of patients remain symptomatic after treatment. Different lines of research have put considerable efforts to investigate ways to enhance the efficacy of exposure-based therapy, which could ultimately lead to better clinical outcomes for patients. Given that this type of therapy relies on extinction learning principles, neuroscience research has tested different adjuncts that could be used as cognitive enhancers through their impact on extinction learning and its consolidation. The current review will summarize some of the latest compounds that have received attention and show some promise to be used in clinical settings to improve the efficacy of exposure-based therapy.

Stress: perspectives on its impact on cognition and pharmacological treatment

Stress in life is unavoidable, affecting everyone on a daily basis. Psychological stress in mammals triggers a rapidly organized response for survival, but it may also cause a variety of behavioral disorders and damage cognitive function. Stress is associated with biases in cognitive processing; some of the most enduring memories are formed by traumatic events. Our understanding of how cognition is shaped by stress is still relatively primitive; however, evidence is rapidly accumulating that the 'mature' brain has a great capacity for plasticity and that there are numerous ways through which pharmacological therapeutics could rescue cognitive function and regain cognitive balance. In this review, we discuss recent advances in our understanding of the interplay between stress and cognitive processes and potential therapeutic approaches to stress-related behavioral and cognitive disorders.

Effect of Acetaldehyde Intoxication and Withdrawal on NPY Expression: Focus on Endocannabinoidergic System Involvement

Acetaldehyde (ACD), the first alcohol metabolite, plays a pivotal role in the rewarding, motivational, and addictive properties of the parental compound. Many studies have investigated the role of ACD in mediating neurochemical and behavioral effects induced by alcohol administration, but very little is known about the modulation of neuropeptide systems following ACD intoxication and withdrawal. Indeed, the neuropeptide Y (NPY) system is altered during alcohol withdrawal in key regions for cerebrocortical excitability and neuroplasticity. The primary goal of this research was to investigate the effects of ACD intoxication and withdrawal by recording rat behavior and by measuring NPY immunoreactivity in hippocampus and NAcc, two brain regions mainly involved in processes which encompass neuroplasticity in alcohol dependence. Furthermore, on the basis of the involvement of endocannabinoidergic system in alcohol and ACD reinforcing effects, the role of the selective CB1 receptor antagonist AM281 in modulating NPY expression during withdrawal was assessed. Our results indicate that (i) ACD intoxication induced a reduction in NPY expression in hippocampus and NAcc; (ii) symptoms of physical dependence, similar to alcohol's, were scored at 12 h from the last administration of ACD; and (iii) NPY levels increased in early and prolonged acute withdrawal in both brain regions examined. The administration of AM281 was able to blunt signs of ACD-induced physical dependence, to modulate NPY levels, and to further increase NPY expression during ACD withdrawal both in hippocampus and NAcc. In conclusion, the present study shows that complex plastic changes take place in NPY system during ACD intoxication and subsequent withdrawal in rat hippocampal formation and NAcc. The pharmacological inhibition of CB1 signaling could counteract the neurochemical imbalance associated with ACD, and alcohol withdrawal, likely boosting the setting up of homeostatic functional recovery.

Single doses of THC and cocaine decrease proficiency of impulse control in heavy cannabis users

BACKGROUND AND PURPOSE

Cannabis is the most popular drug used in the European Union, closely followed by cocaine. Whereas cannabis impairs neurocognitive function in occasional cannabis users, such impairments appear less prominent in heavy users, possibly as a result of tolerance. The present study was designed to assess whether the impairing effects of Δ(9) -tetrahydrocannabinol (THC) in heavy cannabis users would present in a wide range of neuropsychological functions or selectively affect specific performance domains. We also assessed the acute effects of cocaine on neurocognitive functions of heavy cannabis users.

EXPERIMENTAL APPROACH

Heavy cannabis users, who had a history of cocaine use (n = 61), participated in a double-blind, placebo-controlled, three-way crossover study. Subjects received single doses of cocaine HCl (300 mg), cannabis (THC μg·kg(-1) ) and placebo, and completed a number of tests measuring impulse control and psychomotor function.

KEY RESULTS

Single doses of cannabis impaired psychomotor function and increased response errors during impulsivity tasks. Single doses of cocaine improved psychomotor function and decreased response time in impulsivity tasks, but increased errors.

CONCLUSIONS AND IMPLICATIONS

Heavy cannabis users display impairments in a broad range of neuropsychological domains during THC intoxication. Impairments observed in psychomotor tasks, but not in impulsivity tasks, appeared smaller in magnitude as compared with those previously reported in occasional cannabis users. Heavy cannabis users were sensitive to the stimulating and inhibitory effects of cocaine on psychomotor function and impulsivity respectively. The reduction in proficiency in impulse control may put drug users at increased risk of repeated drug use and addiction.

Compulsive showering and marijuana use - the cannabis hyperemisis syndrome

Patient: Male, 26

Final Diagnosis: Marihuana addiction

Symptoms: Compulsive showering • nausea • vomiting

Medication: —

Clinical Procedure: —

Specialty: Toxicology

Cannabinoids and glucocorticoids modulate emotional memory after stress

Bidirectional and functional relationships between glucocorticoids and the endocannabinoid system have been demonstrated. Here, I review the interaction between the endocannabinoid and glucocorticoid/stress systems. Specifically, stress is known to produce rapid changes in endocannabinoid signaling in stress-responsive brain regions. In turn, the endocannabinoid system plays an important role in the downregulation and habituation of hypothalamic-pituitary-adrenocortical (HPA) axis activity in response to stress. Glucocorticoids also recruit the endocannabinoid system to exert rapid negative feedback control of the HPA axis during stress. It became increasingly clear, however, that cannabinoid CB1 receptors are also abundantly expressed in the basolateral amygdala (BLA) and other limbic regions where they modulate emotional arousal effects on memory. Enhancing cannabinoids signaling using exogenous CB1 receptor agonists prevent the effects of acute stress on emotional memory. I propose a model suggesting that the ameliorating effects of exogenously administered cannabinoids on emotional learning after acute stress are mediated by the decrease in the activity of the HPA axis via GABAergic mechanisms in the amygdala.

Cannabinoid CB1 receptor is expressed in chromophobe renal cell carcinoma and renal oncocytoma

OBJECTIVE

To analyze the mRNA and protein expression of cannabinoid receptors CB1 and CB2 in chromophobe renal cell carcinoma (ChRCC) and renal oncocytoma (RO).

DESIGN AND METHODS

Fresh and formalin-fixed tissue samples of ChRCC and RO were analyzed by using real-time quantitative RT-PCR and immunohistochemical techniques (n=40).

RESULTS

Quantitative RT-PCR analysis showed that CB1 mRNA was underexpressed by 12-fold in ChRCC and had a variable expression in RO. CB1 protein showed intense positive immunostaining in both neoplasms. Both CB2 mRNA and protein were not expressed in tumor and non tumor renal tissue.

CONCLUSION

This distinct immunoprofile may eventually be used as an additional tool with practical interest in the differential diagnosis of renal tumors.

Neuropathological Alterations in Illicit Drug Abuse

A variety of neuropathological findings has been described in illicit drug abusers. The majority of these alterations result from the consequences of hypoxia-ischemia and from cerebrovascular diseases. Within the last few years, widespread morphological alterations of the cellular elements of the brain have been detected. These changes consist of neuronal loss, a numerical reduction of astrocytes, widespread axonal damage with concomitant microglial activation and reactive and degenerative changes of the cerebral microvessels. Based on various studies there is also concern that drug abusers develop neurodegeneration or Parkinsonism as they age. However, whether or to what extent neurodegeneration occurs in human drug abusers remains to be established. In the present paper a brief overview on the neuropathological changes in drug abuse is presented for the forensic pathologist/toxi-cologist with reference to the most pertinent literature.

A current overview of cannabinoids and glucocorticoids in facilitating extinction of aversive memories: potential extinction enhancers

Emotional learning is extremely important for the survival of an individual. However, once acquired, emotional associations are not always expressed. The regulation of emotional responses under different environmental conditions is essential for mental health. Indeed, pathologic feelings of fear and anxiety are defining features of many serious psychiatric illness, including post-traumatic stress disorder (PTSD) and specific phobias. The simplest form of regulation of emotional responses is extinction, in which the conditioned response to a stimulus decreases when reinforcement (stimulus) is omitted. In addition to modulating basal anxiety states, recent studies suggest an important role for the endocannabinoid (eCB) and glucocorticoid systems in the modulation of emotional states and extinction of aversive memories in animals. The purpose of this review is to briefly outline the animal models of fear extinction and to describe how these have been used to examine the potential of extinction enhancing agents which specifically alter the eCB and glucocorticoid systems. Pharmacological manipulations of these systems by agents such as cannabinoid or glucocorticoid agonists can enhance the extinction process and avoid the retention of memories which have the potential to trigger trauma. A better understanding of these findings through animal models highlights the possibilities of using combined extinction enhancing agents in exposure-based psychotherapies for anxiety disorders related to inappropriate retention of aversive memories. This article is part of a special issue entitled 'Cognitive Enhancers'.

Differential treatment regimen-related effects of HU210 on CB(1) and D(2)-like receptor functionality in the rat basal ganglia

BACKGROUND/AIMS

Functional linkages between the cannabinoid CB(1) and the dopaminergic systems have been reported although the observations and the mechanisms hypothesizing their interactions at the G protein-coupled receptor (GPCR) functionality level are conflicting.

METHODS

Administration of a potent cannabinoid agonist, HU210, at various doses (25-100 μg/kg) and treatment regimens (1- to 14-day treatment) in rats was carried out to investigate the effect of HU210 treatment on the CB(1) and D(2)-like agonist-mediated GPCR activation.

RESULTS

The desensitizations (reduced coupling) of both D(2) agonist- and CB(1) agonist-mediated GPCR activation was found to be treatment duration dependent and region specific, suggesting implication of receptor tolerance and adaptation due to the cannabinoid treatment. The effect of HU210 on the CB(1) agonist-mediated GPCR desensitization in all treatment groups was not dose dependent.

CONCLUSIONS

The desensitization of D(2)-like receptors found after a cannabinoid treatment in this study strengthens the evidence that the two neurotransmitter systems interact at the intercellular level; this interaction might occur via multiple mechanisms, which also vary according to region.

Cannabis sativa and the endogenous cannabinoid system: therapeutic potential for appetite regulation

The herb Cannabis sativa (C. sativa) has been used in China and on the Indian subcontinent for thousands of years as a medicine. However, since it was brought to the UK and then the rest of the western world in the late 19th century, its use has been a source of controversy. Indeed, its psychotropic side effects are well reported but only relatively recently has scientific endeavour begun to find valuable uses for either the whole plant or its individual components. Here, we discuss evidence describing the endocannabinoid system, its endogenous and exogenous ligands and their varied effects on feeding cycles and meal patterns. Furthermore we also critically consider the mounting evidence which suggests non-Δ(9) tetrahydrocannabinol phytocannabinoids play a vital role in C. sativa-induced feeding pattern changes. Indeed, given the wide range of phytocannabinoids present in C. sativa and their equally wide range of intra-, inter- and extra-cellular mechanisms of action, we demonstrate that non-Δ(9) tetrahydrocannabinol phytocannabinoids retain an important and, as yet, untapped clinical potential.

Contribution of limbic norepinephrine to cannabinoid-induced aversion

RATIONALE

The cannabinoid system has risen to the forefront in the development of novel treatments for a number of pathophysiological processes. However, significant side effects have been observed in clinical trials raising concerns regarding the potential clinical utility of cannabinoid-based agents. Understanding the neural circuits and neurochemical substrates impacted by cannabinoids will provide a better means of gaging their actions within the central nervous system that may contribute to the expression of unwanted side effects.

OBJECTIVES

In the present study, we investigated whether norepinephrine (NE) in the limbic forebrain is a critical determinant of cannabinoid receptor agonist-induced aversion and anxiety in rats.

METHODS

An immunotoxin lesion approach was combined with behavioral analysis using a place conditioning paradigm and the elevated zero maze.

RESULTS

Our results show that the non-selective CB1/CB2 receptor agonist, WIN 55,212-2, produced a significant place aversion in rats. Further, NE in the nucleus accumbens was critical for WIN 55,212-2-induced aversion but did not affect anxiety-like behaviors. Depletion of NE from the bed nucleus of the stria terminalis was ineffective in altering WIN 55,212-2-induced aversion and anxiety.

CONCLUSIONS

These results indicate that limbic, specifically accumbal, NE is required for cannabinoid-induced aversion but is not essential to cannabinoid-induced anxiety.

Abnormal cerebellar morphometry in abstinent adolescent marijuana users

Functional neuroimaging data from adults have, in general, revealed frontocerebellar dysfunction associated with acute and chronic marijuana (MJ) use. The goal of this study was to characterize cerebellar volume in adolescent chronic MJ users following 1 month of monitored abstinence. Participants were MJ users (n=16) and controls (n=16) aged 16-18 years. Extensive exclusionary criteria included history of psychiatric or neurologic disorders. Drug use history, neuropsychological data, and structural brain scans were collected after 28 days of monitored abstinence. Trained research staff defined cerebellar volumes (including three cerebellar vermis lobes and both cerebellar hemispheres) on high-resolution T1-weighted magnetic resonance images. Adolescent MJ users demonstrated significantly larger inferior posterior (lobules VIII-X) vermis volume than controls, above and beyond effects of lifetime alcohol and other drug use, gender, and intracranial volume. Larger vermis volumes were associated with poorer executive functioning. Following 1 month of abstinence, adolescent MJ users had significantly larger posterior cerebellar vermis volumes than non-using controls. These greater volumes are suggested to be pathological based on linkage to poorer executive functioning. Longitudinal studies are needed to examine typical cerebellar development during adolescence and the influence of marijuana use.

CB1 cannabinoid receptors increase neuronal precursor proliferation through AKT/glycogen synthase kinase-3beta/beta-catenin signaling

The endocannabinoid system is involved in the regulation of many physiological effects in the central and peripheral nervous system. Recent findings have demonstrated the presence of a functional endocannabinoid system within neuronal progenitors located in the hippocampus and ventricular/subventricular zone that participates in the regulation of cell proliferation. It is presently unknown whether the endocannabinoid system exerts a widespread effect on neuronal precursors from different neurogenic regions, and very little is known about the signaling by which it regulates neuronal precursor proliferation. Herein, we demonstrate the presence of cannabinoid CB(1) receptors in granule cell precursors (GCPs) during early cerebellar development. Activation of CB(1) receptors by HU-210 promoted GCP proliferation in vitro, an effect that was prevented by a selective CB(1) antagonist. Accordingly, in vivo experiments showed that GCP proliferation was increased by chronic HU-210 treatment and that in CB(1)-deficient mice cell proliferation was significantly lower than in wild-type littermates, indicating that the endocannabinoid system is physiologically involved in regulation of GCP proliferation. The pro-proliferative effect of cannabinoids in GCPs was mediated through the CB(1)/AKT/glycogen synthase kinase-3beta/beta-catenin pathway. Involvement of this pathway was also observed in cultures of neuronal precursors from the subventricular zone, suggesting that this pathway may be a general mechanism by which endocannabinoids regulate proliferation of neuronal precursors. These observations suggest that endocannabinoids constitute a new family of lipid signaling cues that may exert a widespread effect on neuronal precursor proliferation during brain development.

The association between cannabinoid receptor 1 gene (CNR1) and cannabis dependence symptoms in adolescents and young adults

OBJECTIVE

This study examined the genetic association between variation in the cannabinoid receptor 1 (CNR1) gene and cannabis dependence symptoms.

METHOD

Adolescent and young adult subjects were recruited from three settings: a treatment program for youth with substance use disorders, the criminal justice system, and the community. A case-control sample consisted of 224 cases who endorsed at least one dependence symptom and 108 controls who tried cannabis but endorsed no symptoms. A family-based sample of 219 families was also analyzed.

RESULTS

Case-control analysis identified a nominal association between SNP rs1049353 and having one or more cannabis dependence symptoms (p=.029), but the association did not hold up in a combined sample. Family-based analysis found a trend for the same SNP (p=.07). We did not replicate a previous report that SNP rs806380 was associated with the development of cannabis dependence.

CONCLUSION

These results provide inconclusive evidence of association between rs1049353/rs806380 and the development of cannabis dependence, and underscore the importance of replicating results of genetic association studies. Additional family-based studies are needed to clarify the role of the CNR1 gene, and its various SNPs, in the development of cannabis use disorders.

Cannabinoid hyperemesis syndrome: Clinical diagnosis of an underrecognised manifestation of chronic cannabis abuse

Cannabis is a common drug of abuse that is associated with various long-term and short-term adverse effects. The nature of its association with vomiting after chronic abuse is obscure and is underrecognised by clinicians. In some patients this vomiting can take on a pattern similar to cyclic vomiting syndrome with a peculiar compulsive hot bathing pattern, which relieves intense feelings of nausea and accompanying symptoms. In this case report, we describe a twenty-two year-old-male with a history of chronic cannabis abuse presenting with recurrent vomiting, intense nausea and abdominal pain. In addition, the patient reported that the hot baths improved his symptoms during these episodes. Abstinence from cannabis led to resolution of the vomiting symptoms and abdominal pain. We conclude that in the setting of chronic cannabis abuse, patients presenting with chronic severe nausea and vomiting that can sometimes be accompanied by abdominal pain and compulsive hot bathing behaviour, in the absence of other obvious causes, a diagnosis of cannabinoid hyperemesis syndrome should be considered.

Localisation and function of the endocannabinoid system in the human ovary

BACKGROUND

Although anandamide (AEA) had been measured in human follicular fluid and is suggested to play a role in ovarian follicle and oocyte maturity, its exact source and role in the human ovary remains unclear.

METHODS AND FINDINGS

Immunohistochemical examination of normal human ovaries indicated that the endocannabinoid system was present and widely expressed in the ovarian medulla and cortex with more intense cannabinoid receptor 2 (CB2) than CB1 immunoreactivity in the granulosa cells of primordial, primary, secondary, tertiary follicles, corpus luteum and corpus albicans. The enzymes, fatty acid amide hydrolase (FAAH) and N-acyclphosphatidylethanolamine-phospholipase D (NAPE-PLD), were only found in growing secondary and tertiary follicles and corpora lutea and albicantes. The follicular fluid (FF) AEA concentrations of 260 FF samples, taken from 37 infertile women undergoing controlled ovarian hyperstimulation for in vitro fertilisation and intracytoplasmic sperm injection with embryo transfer, were correlated with ovarian follicle size (P = 0.03). Significantly higher FF AEA concentrations were also observed in mature follicles (1.43+/-0.04 nM; mean+/-SEM) compared to immature follicles (1.26+/-0.06 nM), P = 0.0142 and from follicles containing morphologically assessed mature oocytes (1.56+/-0.11 nM) compared to that containing immature oocytes (0.99+/-0.09 nM), P = 0.0011. ROC analysis indicated that a FF AEA level of 1.09 nM could discriminate between mature and immature oocytes with 72.2% sensitivity and 77.14% specificity, whilst plasma AEA levels and FF AEA levels on oocyte retrieval day were not significantly different (P = 0.23).

CONCLUSIONS

These data suggest that AEA is produced in the ovary, is under hormonal control and plays a role in folliculogenesis, preovulatory follicle maturation, oocyte maturity and ovulation.

Sensitivity to delta9-tetrahydrocannabinol is selectively enhanced in beta-arrestin2 -/- mice

Little is known about the roles of beta-arrestins in the regulation of brain CB1 cannabinoid receptors. This study investigated the role of beta-arrestin2 in cannabinoid behavioral effects using beta-arrestin2 -/- mice and their wild-type counterparts. A variety of cannabinoid ligands from different chemical classes that exhibit a variety of efficacies for activation of CB1 receptors were investigated, including Delta-tetrahydrocannabinol, CP55940, methanandamide, JWH-073, and O-1812. Delta-tetrahydrocannabinol produced both greater antinociception and greater decreases in body temperature in beta-arrestin2 -/- compared with beta-arrestin2 +/+ mice. No significant differences were, however, present in either assay for the other CB1 agonists. Antagonist radioligand binding indicated no difference in the density of cannabinoid CB1 receptors in the cerebellum, cortex, or hippocampus of beta-arrestin2 +/+ and -/- mice. These data demonstrate that beta-arrestin2 may regulate cannabinoid CB1 receptor sensitivity in an agonist-specific manner.

Mechanisms for recycling and biosynthesis of endogenous cannabinoids anandamide and 2-arachidonylglycerol

The mechanisms of endogenous cannabinoid biosynthesis are not completely understood. We hypothesized that anandamide could be recycled by the cell to form new endocannabinoid molecules and released into the extracellular space. We determined that new endocannabinoids derived from exogenous anandamide or arachidonic acid were synthesized and released from RBL-2H3 cells in response to ionomycin. Treatment of RBL-2H3 cells with nystatin and progesterone, agents that disrupt organization of lipid raft/caveolae, resulted in the attenuation of anandamide and 2-arachidonyl glycerol synthesis and/or release in response to stimulation with ionomycin suggesting a role for these membrane microdomains in endocannabinoid biosynthesis. Furthermore, anandamide synthesis may be independent of N-acyl phosphatidylethanolamine phospholipase D as expression of the enzyme was not detected in RBL-2H3 cells. We also established that extracellular calcium is necessary for endocannabinoid biosynthesis because release of intracellular calcium stores alone does not promote endocannabinoid biosynthesis. Next, we examined the role of calcium as a 'switch' to activate the synthesis of anandamide and simultaneously reduce uptake. Indeed, [(3)H] anandamide uptake was reduced in the presence of calcium. Our findings suggest a mechanism indicative of calcium-modulated activation of anandamide synthesis and simultaneous termination of uptake.

Membrane microdomains and metabolic pathways that define anandamide and 2-arachidonyl glycerol biosynthesis and breakdown

Anandamide (AEA) and 2-arachidonyl glycerol (2-AG), endogenous ligands for the CB1 and CB2 cannabinoid receptors, are referred to as endocannabinoids because they mimic the actions of delta9-tetrahydrocannabinol (Delta9-THC), a plant-derived cannabinoid. The processes by which AEA and 2-AG are biosynthesized, released, taken up by cells and hydrolyzed have been of much interest as potential therapeutic targets. In this review we will discuss the progress that has been made to characterize the primary pathways for AEA and 2-AG formation and breakdown as well as the role that specialized membrane microdomains known as lipid rafts play in these processes. Furthermore we will review the recent advances made to track and detect AEA in biological matrices.

Central glucocorticoid receptors regulate the upregulation of spinal cannabinoid-1 receptors after peripheral nerve injury in rats

Previous studies have shown that peripheral nerve injury upregulated both glucocorticoid receptors (GR) and cannabinoid-1 receptors (CB1R) within the spinal cord dorsal horn in rats. However, the relationship between the expression of spinal GR and CB1R after nerve injury remains unclear. Here, we examined the hypothesis that the upregulation of spinal CB1R induced by chronic constriction nerve injury (CCI) in rats would be regulated by spinal GR. CCI induced the upregulation of spinal CB1R primarily within the ipsilateral spinal cord dorsal horn as revealed by Western blot and immunohistochemistry. The expression of CB1R in CCI rats was substantially attenuated by intrathecal treatment with either the GR antagonist RU38486 or a GR antisense oligonucleotide given twice daily for postoperative day 1-6, whereas the expression of spinal CB1R was enhanced following intrathecal administration of a GR sense oligonucleotide twice daily for postoperative day 1-6. Furthermore, the upregulation of spinal CB1R after nerve injury was prevented in adrenalectomized rats, which was at least partially restored with the intrathecal administration of an exogenous GR agonist dexamethasone, indicating that corticosteroids (endogenous GR agonists) were critical to spinal GR actions. Since the development of neuropathic pain behaviors in CCI rats was attenuated by either RU38486 or a GR antisense oligonucleotide, these results suggest that CB1R is a downstream target for spinal GR actions contributory to the mechanisms of neuropathic pain.

Neuropsychological functioning in adolescent marijuana users: subtle deficits detectable after a month of abstinence

In adults, studies examining the long-lasting cognitive effects of marijuana use demonstrate subtle deficits in attention, executive function, and memory. Because neuromaturation continues through adolescence, these results cannot necessarily generalize to adolescent marijuana users. The goal of this study was to examine neuropsychological functioning in abstinent marijuana using and demographically similar control adolescents. Data were collected from 65 adolescent marijuana users (n=31, 26% females) and controls (n=34, 26% females) 16-18 years of age. Extensive exclusionary criteria included independent psychiatric, medical, and neurologic disorders. Neuropsychological assessments were conducted after>23 days of monitored abstinence. After controlling for lifetime alcohol use and depressive symptoms, adolescent marijuana users demonstrated slower psychomotor speed (p<.05), and poorer complex attention (p<.04), story memory (p<.04), and planning and sequencing ability (p<.001) compared with controls. Post hoc analysis revealed that the number of lifetime marijuana use episodes was associated with poorer cognitive function, even after controlling for lifetime alcohol use. The general pattern of results suggested that, even after a month of monitored abstinence, adolescent marijuana users demonstrate subtle neuropsychological deficits compared with nonusers. It is possible that frequent marijuana use during adolescence may negatively influence neuromaturation and cognitive development.

Depressive symptoms in adolescents: associations with white matter volume and marijuana use

BACKGROUND

Depressed mood has been associated with decreased white matter and reduced hippocampal volumes. However, the relationship between brain structure and mood may be unique among adolescents who use marijuana heavily. The goal of this study was to examine the relationship between white matter and hippocampal volumes and depressive symptoms among adolescent marijuana users and controls.

METHODS

Data were collected from marijuana users (n = 16) and demographically similar controls (n = 16) aged 16-18. Extensive exclusionary criteria included psychiatric and neurologic disorders, including major depression. Substance use, mood, and anatomical measures were collected after 28 days of monitored abstinence.

RESULTS

Marijuana (MJ) users demonstrated more depressive symptoms than controls (p < .05). MJ use (beta = .42, p < .005) and smaller white matter volume (beta = -.34, p < .03) each predicted higher levels of depressive symptoms on the Hamilton Depression Rating Scale. MJ use interacted with white matter volume (beta = -.55, p < .03) in predicting depression scores on the Beck Depression Inventory: among MJ users, but not controls, white matter volume was negatively associated with depressive symptoms.

CONCLUSIONS

Marijuana use and white matter volume were additive and interactive in predicting depressive symptoms among adolescents. Subtle neurodevelopmental white matter abnormalities may disrupt the connections between areas involved in mood regulation.

Effects of alcohol and combined marijuana and alcohol use during adolescence on hippocampal volume and asymmetry

BACKGROUND

Converging lines of evidence suggest that the hippocampus may be particularly vulnerable to deleterious effects of alcohol and marijuana use, especially during adolescence. The goal of this study was to examine hippocampal volume and asymmetry in adolescent users of alcohol and marijuana.

METHODS

Participants were adolescent (aged 15-18) alcohol (ALC) users (n=16), marijuana and alcohol (MJ+ALC) users (n=26), and demographically similar controls (n=21). Extensive exclusionary criteria included prenatal toxic exposure, left handedness, and psychiatric and neurologic disorders. Substance use, cognitive, and anatomical measures were collected after at least 2 days of abstinence from all substances.

RESULTS

Adolescent ALC users demonstrated a significantly different pattern of hippocampal asymmetry (p<.05) and reduced left hippocampal volume (p<.05) compared to MJ+ALC users and non-using controls. Increased alcohol abuse/dependence severity was associated with increased right>left (R>L) asymmetry and smaller left hippocampal volumes while marijuana abuse/dependence was associated with increased L>R asymmetry and larger left hippocampal volumes. Although MJ+ALC users did not differ from controls in asymmetry, functional relationships with verbal learning were found only among controls, among whom greater right than left hippocampal volume was associated with superior performance (p<.05).

CONCLUSIONS

Aberrations in hippocampal asymmetry and left hippocampal volumes were found for adolescent heavy drinkers. Further, the functional relationship between hippocampal asymmetry and verbal learning was abnormal among adolescent substance users compared to healthy controls. These findings suggest differential effects of alcohol and combined marijuana and alcohol use on hippocampal morphometry and the relationship between hippocampal asymmetry and verbal learning performance among adolescents.

Cannabis receptor haplotype associated with fewer cannabis dependence symptoms in adolescents

Cannabis is a major substance of abuse, and the gene encoding for the central cannabinoid receptor (CNR1) is a logical candidate gene for vulnerability toward developing symptoms of cannabis dependence. We studied four single-nucleotide polymorphisms (SNPs) in the CNR1 gene for association with having one or more symptoms of cannabis dependence in 541 adolescent subjects who had all tried cannabis five or more times. Cases (327) were defined as those who had tried marijuana and developed one or more symptoms, and controls (214) as those who had tried marijuana but developed no dependence symptoms. Cannabis dependence symptoms were assessed in these youth when they were 17 or older with the Composite International Diagnostic Interview--Substance Abuse Module. Univariate (single-marker) association tests demonstrated that SNP rs806380, located in intron 2 of the CNR1 gene, was significantly associated with developing one or more cannabis dependence symptoms, with the G allele having a protective effect (P < 0.02). This was consistent with the results of the global haplotype test (P < 0.01). One of the common haplotypes examined (present in 21% of the subjects) was significantly associated with a lower rate of having one or more cannabis dependence symptoms. Our findings provide evidence suggesting that a common CNR1 haplotype is associated with developing fewer cannabis dependence symptoms among adolescents who have experimented with cannabis.