Genetic variation in cannabinoid receptor 1 (CNR1) is associated with derangements in lipid homeostasis, independent of body mass index

Loss of thyroid gland circadian PER2 rhythmicity in aged mice and its potential association with thyroid cancer development

Molecular clocks operate in peripheral tissues, including endocrine glands, and play important regulatory roles in this context. However, potential age-related changes in the expression rhythmicity of clock genes and the effects of these changes on the thyroid gland remain unknown. In the present study, we evaluated the expression rhythmicity of peripheral thyroid clock genes in aged mice using RNA-seq transcriptomic analysis in young (3.5-month) versus aged (20-month) mice. In addition, we determined the cellular effects of silencing of PER2, a major clock gene regulator, in human thyroid cell lines. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that differentially expressed genes (DEGs) in the thyroid glands of aged mice were involved in mitogen-activated protein kinase (MAPK) signaling, chemokine signaling, circadian entrainment, PI3K/AKT signaling, and Apelin signaling. The expression of circadian clock genes Arntl/Bmal1 was significantly downregulated in thyroid glands of aged mice, whereas the expression of genes involved in regulation of cell proliferation, migration, and tumorigenesis was upregulated. Peripheral thyroid clock genes, particularly Per mRNA and PER2 protein, were downregulated in the thyroid glands of aged mice, and circadian oscillation of these genes was declined. Knockdown of the circadian clock gene PER2 in human thyroid follicular cells induced AP-1 activity via JNK MAPK signaling activation, which increased cell proliferation. Furthermore, the aging-related loss of PER2 circadian oscillation activated the AP-1 transcription factor via the JNK MAPK pathway, which could contribute to thyroid hyperplasia, a common age-related condition.

Changes in High-Density Lipoprotein (HDL), Low-Density Lipoprotein (LDL) and Cholesterol Concentration in Heavy Cannabis Users: A Single-Centre Study in Cusco, Peru

Background: The effect of cannabis on cholesterol and lipid balance has been reported for decades. However, there are conflicting reports on the reduction of low-density lipoprotein (LDL-C) and total cholesterol. The purpose of this study was to determine the immediate changes of Cannabis spp. consumption by pyrolytic route in heavy users. Methods: A cross-sectional study on 20 Peruvian heavy cannabis users (mean age: 31 ± 9.5 years). The inclusion criteria were males with an average weight of 50–70 kg, normal BMI, and having used cannabis, without association with other drugs, for at least one year with a high frequency per week (use: 4–7 days/week). High-density lipoprotein (HDL-C), LDL-C, and total cholesterol were evaluated 30 and 120 min after the administration of Cannabis spp. (~0.2 g by inhalation). Results: Of the total 12 (60%), 10 (50%), and 11 (55%) had desirable total cholesterol, fairly good HDL-C (40–60 mg/dL) and fairly good LDL-C (100–129 mg/dL) values, respectively. The mean basal concentration of total cholesterol, HDL-cholesterol, and LDL-cholesterol was 193.37 ± 20.18 mg/dL, 60.05 ± 6.36 mg/dL, and 129.65 ± 14.50 mg/dL, respectively. HDL-cholesterol showed progressive increases in participants with desirable HDL-C > 60 mg/dL at 30 min (10 vs. 14 participants, p < 0.001) and at 120 min (10 vs. 16 participants, p < 0.001), while LDL-C peaked in participants with concentrations < 100 mg/dL at 30 min (desirable cholesterol: 0 vs. 2, p = 0.001). HDL-C concentration showed differences after cannabis consumption, showing increases at 30 (63.25 ± 7.68 mg/dL) and 120 min (69.15 ± 18.67 mg/dL) and total cholesterol concentration changed to 180.95 ± 19.3 mg/dL (95%CI 172.5 to 189.4) at 120 min (p = 0.007). Conclusions: HDL-C cholesterol increased 30 and 120 min after Cannabis spp. ingestion, while LDL-C and total cholesterol showed partial reductions in heavy-users from Cusco, Peru.

The Endocannabinoid System and Cannabidiol: Past, Present, and Prospective for Cardiovascular Diseases

In the past, cannabis was commonly associated with mysticism and illegality. Fortunately, in recent years perspectives and discourses have changed. More prominence has been given to the rigorous scientific effort that led to the discovery of cannabis' many physiological actions and endogenous signalling mechanisms. The endocannabinoid system is a complex and heterogeneous pro-homeostatic network comprising different receptors with several endogenous ligands, numerous metabolic enzymes and regulatory proteins. Therefore, it is not surprising that alterations and dysfunctions of the endocannabinoid system are observed in almost every category of disease. Such high degree of pathophysiological involvement suggests the endocannabinoid system is a promising therapeutic target and prompted the translation of resurgent scientific findings into clinical therapies. Shifting attitudes toward cannabis also raised other matters such as increased patient awareness, prescription requests, self-medication, recreational use, recognition of new knowledge gaps, renewed scientific activity, and seemingly exponential growth of the cannabis industry. This review, following a general overview of cannabis and the endocannabinoid system, assiduously describes its role within the context of cardiovascular diseases, paying particular attention to the Janus influence that endocannabinoid system modulators can have on the cardiovascular system.

High genes: Genetic underpinnings of cannabis use phenotypes

Cannabis is one of the most widely used substances across the globe and its use has a substantial heritable component. However, the heritability of cannabis use varies according to substance use phenotype, suggesting that a unique profile of gene variants may contribute to the different stages of use, such as age of use onset, lifetime use, cannabis use disorder, and withdrawal and craving during abstinence. Herein, we review a subset of genes identified by candidate gene, family-based linkage, and genome-wide association studies related to these cannabis use phenotypes. We also describe their relationships with other substances, and their functions at the neurobiological, cognitive, and behavioral levels to hypothesize the role of these genes in cannabis use risk. Delineating genetic risk factors in the various stages of cannabis use will provide insight into the biological mechanisms related to cannabis use and highlight points of intervention prior to and following the development of dependence, as well as identify targets to aid drug development for treating problematic cannabis use.

What Role Does the Endocannabinoid System Play in the Pathogenesis of Obesity?

The endocannabinoid system (ECS) is an endogenous signaling system formed by specific receptors (cannabinoid type 1 and type 2 (CB₁ and CB₂)), their endogenous ligands (endocannabinoids), and enzymes involved in their synthesis and degradation. The ECS, centrally and peripherally, is involved in various physiological processes, including regulation of energy balance, promotion of metabolic process, food intake, weight gain, promotion of fat accumulation in adipocytes, and regulation of body homeostasis; thus, its overactivity may be related to obesity. In this review, we try to explain the role of the ECS and the impact of genetic factors on endocannabinoid system modulation in the pathogenesis of obesity, which is a global and civilizational problem affecting the entire world population regardless of age. We also emphasize that the search for potential new targets for health assessment, treatment, and the development of possible therapies in obesity is of great importance.

On the Role of Central Type-1 Cannabinoid Receptor Gene Regulation in Food Intake and Eating Behaviors

Different neuromodulatory systems are involved in long-term energy balance and body weight and, among these, evidence shows that the endocannabinoid system, in particular the activation of type-1 cannabinoid receptor, plays a key role. We here review current literature focusing on the role of the gene encoding type-1 cannabinoid receptors in the CNS and on the modulation of its expression by food intake and specific eating behaviors. We point out the importance to further investigate how environmental cues might have a role in the development of obesity as well as eating disorders through the transcriptional regulation of this gene in order to prevent or to treat these pathologies.

Association Between Cannabinoid Receptor-1 Gene Polymorphism and the Risk of Diabetic Nephropathy Among Patients with Type 2 Diabetes Mellitus

Background

The cannabinoid receptor 1 (CNR1) gene polymorphism is reportedly associated with components of metabolic syndrome and coronary artery diseases in patients with type 2 diabetes mellitus (T2DM). We investigated whether the common variant rs10493353 polymorphism is associated with diabetic nephropathy (DN) in T2DM patients.

Patients and Methods

T2DM patients with DN were enrolled as a case group, and patients with only T2DM as a control group. Demographic data and biochemical parameters were collected. The polymerase chain reaction-based restriction fragment length polymorphism technique was used for genotyping. The odds ratio and 90% confidence interval were calculated to assess the association between genotypes and the risk of DN.

Results

In total, 320 T2DM patients and 320 DN patients were enrolled. Compared with T2DM patients, the DN patients have a significantly larger body mass index (BMI), longer duration of disease, and higher proportions of smokers, drinkers, and hypertension. The risk of DN was significantly decreased by genotypes AA (OR=0.39, 95% CI=0.23–0.67) and GA (OR=0.53, 95% CI=0.37–0.75) vs GG (codominant model), GA/AA vs GG (OR=0.49, 95% CI=0.35–0.67; dominant model), AA vs GG/GA (OR=0.47, 95% CI=0.28–0.80; recessive model), and the A allele (OR=0.52, 95% CI=0.40–0.68; allele model). Multiple logistic regressions still show significant levels. Negative interactions were found between gene and clinical parameters, including drinking, smoking, BMI, and hypertension.

Conclusion

The A allele of CNR1 gene rs10493353 may be a protective factor for DN in T2DM patients. The risk factors of DN can affect the protective role of A allele in the progression of DN.

Association study of candidate genes with obesity and metabolic traits in antipsychotic-treated patients with first-episode psychosis over a 2-year period

AIMS

Patients with a first episode of psychosis (FEP) often display different metabolic disturbances even independently of drug therapy. However, antipsychotic (AP) treatment, especially with second-generation APs, is strongly linked to weight gain, which increases patients' risk of developing obesity and other metabolic diseases. There is an important genetic risk component that can contribute to the appearance of these disturbances. The aim of the present study was to evaluate the effect of polymorphisms in selected candidate genes on obesity and other anthropometric and metabolic traits in 320 AP-treated FEP patients over the course of a 2-year follow-up.

METHODS

These patients were recruited in the multicentre PEPs study (Phenotype-genotype and environmental interaction; Application of a predictive model in first psychotic episodes). A total of 127 validated single nucleotide polymorphisms (SNPs) in 18 candidate genes were included in the genetic analysis.

RESULTS

After Bonferroni correction, SNPs in ADRA2A, FTO, CNR1, DRD2, DRD3, LEPR and BDNF were associated with obesity, abdominal circumference, triglycerides, HDL cholesterol, and/or percentage of glycated haemoglobin.

CONCLUSIONS

Although our results should be interpreted as exploratory, they support previous evidence of the impact of these candidate genes on obesity and metabolic status. Further research is required to gain a better knowledge of the genetic variants that can be considered relevant metabolic risk factors. The ability to identify FEP patients at higher risk for these metabolic disturbances would enable clinicians to better select and control their AP treatment.

Anti-obesity therapy with peripheral CB1 blockers: from promise to safe(?) practice

Pharmacological blockers of the cannabinoid receptor type-1 (CB1) have been considered for a long time as the holy grail of obesity pharmacotherapy. These agents were hastily released in the clinical setting, due to their clear-cut therapeutic efficacy. However, the first generation of these drugs, which were able to target both the brain and peripheral tissues, had serious neuropsychiatric effects, leading authorities to ban their clinical use. New peripherally restricted CB1 blockers, characterized by low brain penetrance, have been developed over the past 10 years. In preclinical studies, these molecules seem to overcome the neuropsychiatric negative effects previously observed with brain-penetrant CB1 inhibitors, while retaining or even outperforming their efficacy. The mechanisms of action of these peripherally restricted compounds are only beginning to emerge, and a balanced discussion of the risk/benefits ratio associated to their possible clinical use is urgently needed, in order to avoid repeating past mistakes. Here, we will critically discuss the advantages and the possible hidden threats associated with the use of peripheral CB1 blockers for the pharmacotherapy of obesity and its associated metabolic complications. We will address whether this novel pharmacological approach might 'compete' with current pharmacotherapies for obesity and diabetes, while also conceptualizing future CB1-based pharmacological trends that may significantly lower the risk/benefits ratio associated with the use of these drugs.

G1359A Polymorphism of the Cannabinoid Receptor 1 Is Not Associated with Overweight and Dyslipidemia in Young Northeastern Mexicans

There is extensive evidence to believe that the endocannabinoid system plays an important role in energy homeostasis through a variety of mechanisms. This study aimed to analyze the association between polymorphism rs12720071 of the cannabinoid type 1 receptor (CNR1) gene with dyslipidemia and overweight in young, healthy Mexicans. The association was analyzed with a logistic regression model and expressed as odds ratio (OR). A total of 148 individuals agreed to participate. Overall, the serum concentrations of lipids were found to be in the normal range. However, females presented higher levels of cholesterol and low-density lipoprotein (LDL) than males [probability value (p) = <0.05]. In addition, females presented higher risk of being overweight (BMI: >25) [OR = 3.57; 95% confidence interval (CI): 1.05-12.20; p = 0.04], than males. Our results suggest that this polymorphism could influence BMI in young females.

Multiple endocannabinoid-mediated mechanisms in the regulation of energy homeostasis in brain and peripheral tissues

The endocannabinoid (eCB) system is widely expressed in many central and peripheral tissues, and is involved in a plethora of physiological processes. Among these, activity of the eCB system promotes energy intake and storage, which, however, under pathophysiological conditions, can favour the development of obesity and obesity-related disorders. It is proposed that eCB signalling is evolutionary beneficial for survival under periods of scarce food resources. Remarkably, eCB signalling is increased both in hunger and in overnutrition conditions, such as obesity and type-2 diabetes. This apparent paradox suggests a role of the eCB system both at initiation and at clinical endpoint of obesity. This review will focus on recent findings about the role of the eCB system controlling whole-body metabolism in mice that are genetically modified selectively in different cell types. The current data in fact support the notion that eCB signalling is not only engaged in the development but also in the maintenance of obesity, whereby specific cell types in central and peripheral tissues are key sites in regulating the entire body's energy homeostasis.

Genetic polymorphisms of the endocannabinoid system in obesity and diabetes

The endocannabinoid system (ECS) is involved in many physiological processes including fertility, pain and energy regulation. The aim of this systematic review was to examine the contribution of single nucleotide polymorphisms (SNPs) of the ECS to adiposity and glucose metabolism. Database searches identified 734 articles, of which 65 were included; these covered 70 SNPs in genes coding for cannabinoid receptors 1 and 2 (CB₁ , CB₂ ), fatty acid amide hydrolase (FAAH) and N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD). No studies included SNPs relating to monoacylglycerol lipase or diacylglycerol lipase. The CB₁ receptor SNP rs1049353 showed 17 associations with lower body mass index (BMI) and fat mass (five studies). It also showed three associations with lower insulin levels (one study). Conversely, the CB₁ receptor SNP rs806368 was associated with increased BMI and waist circumference (two studies). The FAAH SNP rs324420 was associated with increased obesity (three studies). A haplotype of NAPE-PLD was associated with decreased BMI (one study). A total of 60 SNPs showed no association with any measured outcome. This review suggests a complex but important role of ECS SNPs in energy and glucose metabolism.

The Endocannabinoid System and Heart Disease: The Role of Cannabinoid Receptor Type 2

Decades of research has provided evidence for the role of the endocannabinoid system in human health and disease. This versatile system, consisting of two receptors (CB1 and CB2), their endogenous ligands (endocannabinoids), and metabolic enzymes has been implicated in a wide variety of disease states, ranging from neurological disorders to cancer. CB2 has gained much interest for its beneficial immunomodulatory role that can be obtained without eliciting psychotropic effects through CB1. Recent studies have shed light on a protective role of CB2 in cardiovascular disease, an ailment which currently takes more lives each year in Western countries than any other disease or injury. By use of CB2 knockout mice and CB2-selective ligands, knowledge of how CB2 signaling affects atherosclerosis and ischemia has been acquired, providing a major stepping stone between basic science and translational clinical research. Here, we summarize the current understanding of the endocannabinoid system in human pathologies and provide a review of the results from preclinical studies examining its function in cardiovascular disease, with a particular emphasis on possible CB2-targeted therapeutic interventions to alleviate atherosclerosis.

Association between gene polymorphisms and obesity and physical fitness in Korean children

Obesity is affected by genetic factors and environmental influences. This research was undertaken to identify single nucleotide polymorphisms (SNPs) related to obesity and physical fitness and then to analyse and compare interactions between physical fitness and obesity-associated genotypes. To investigate relationships between physical fitness and major SNPs previously reported to be related to obesity, 68 SNPs in 32 genes were genotyped in 71 Korean children. Tests were conducted to evaluate five elements of physical fitness (speed, aerobic endurance, muscular endurance, muscular strength, and flexibility). The results obtained showed significant (P<0.02) differences in physical fitness scores for the following genotypes: CNR1 (rs1049353; GG), LEP (rs7799039; AA+AG), HHEX (rs1111875; TT), GC (rs16847015; TG+GG), LRP5 (rs4988300; GG+GT), NPY2R (rs2880415; CT+CC), PPY (rs231472; GG), UCP2 (rs660339; CT+TT), CDKN2B (rs10811661; AA+AG), and ADIPOQ (rs266729; CG+GG). Ten physical fitness-related genotypes were newly identified during the present study. This study suggests that classification of genotypes by physical fitness level could be used as an index for predicting the risk of obesity and for selecting individuals for intervention programmes. Furthermore, the study shows that even children participating in the same physical fitness improvement programme can exhibit different genotype dependencies.

MECHANISMS IN ENDOCRINOLOGY: Endocannabinoids and metabolism: past, present and future

The endocannabinoid system (ECS), including cannabinoid type 1 and type 2 receptors (CB₁R and CB₂R), endogenous ligands called endocannabinoids and their related enzymatic machinery, is known to have a role in the regulation of energy balance. Past information generated on the ECS, mainly focused on the involvement of this system in the central nervous system regulation of food intake, while at the same time clinical studies pointed out the therapeutic efficacy of brain penetrant CB₁R antagonists like rimonabant for obesity and metabolic disorders. Rimonabant was removed from the market in 2009 and its obituary written due to its psychiatric side effects. However, in the meanwhile a number of investigations had started to highlight the roles of the peripheral ECS in the regulation of metabolism, bringing up new hope that the ECS might still represent target for treatment. Accordingly, peripherally restricted CB₁R antagonists or inverse agonists have shown to effectively reduce body weight, adiposity, insulin resistance and dyslipidemia in obese animal models. Very recent investigations have further expanded the possible toolbox for the modulation of the ECS, by demonstrating the existence of endogenous allosteric inhibitors of CB₁R, the characterization of the structure of the human CB₁R, and the likely involvement of CB₂R in metabolic disorders. Here we give an overview of these findings, discussing what the future may hold in the context of strategies targeting the ECS in metabolic disease.

The Endocannabinoid System: Pivotal Orchestrator of Obesity and Metabolic Disease

The endocannabinoid system (ECS) functions to adjust behavior and metabolism according to environmental changes in food availability. Its actions range from the regulation of sensory responses to the development of preference for the consumption of calorically-rich food and control of its metabolic handling. ECS activity is beneficial when access to food is scarce or unpredictable. However, when food is plentiful, the ECS favors obesity and metabolic disease. We review recent advances in understanding the roles of the ECS in energy balance, and discuss newly identified mechanisms of action that, after the withdrawal of first generation cannabinoid type 1 (CB1) receptor antagonists for the treatment of obesity, have made the ECS once again an attractive target for therapy.

Polymorphism G1359A of the cannabinoid receptor gene (CNR1): allelic frequencies and influence on cardiovascular risk factors in a multicentre study of Castilla-Leon

BACKGROUND

A polymorphism (1359 G/A) of the CNR1 gene was reported as a common polymorphism in Caucasian populations and was related to cardiovascular risk factors. The present study aimed to investigate the allelic distribution of polymorphism (G1359A) of the CB1 receptor gene in a geographical area of Spain (Community of Castilla y Leon) and to evaluate the influence of this polymorphism on obesity anthropometric parameters and cardiovascular risk factors in the fasted state in obese patients.

METHODS

A population of 341 obese subjects was analysed. Tetrapolar electrical bioimpedance measurement, blood pressure measurement, a serial assessment of nutritional intake with 3 days of written food records and a biochemical analysis were all performed.

RESULTS

One hundred and seventy-seven patients (51.9%) had the genotype G1359G (wild-type group) and 164 (48.1%) patients were A carriers: G1359A (136 patients; 39.9%) or A1359A (28 patients; 8.2%) (mutant type group). The Health Area of Palencia had a lower frequency of wild-type genotype and G allelic frequency than all the other Health Areas. Segovia and Burgos Areas had a higher frequency of wild-type genotype and G allelic frequency than the other Health Areas. High-density lipoprotein (HDL) cholesterol was higher in the mutant type group and blood tryglicerides were lower in the same group.

CONCLUSIONS

In conclusion, the novel finding of the present study is the association of the mutant type group G1359A and A1359A with a better lipid profile (triglycerides and HDL cholesterol) than the wild-type group. The frequencies of this polymorphism are different among Health Areas of Castilla y Leon (Spain).

Association of G1359A polymorphism of the cannabinoid receptor gene (CNR1) with macronutrient intakes in obese females

BACKGROUND

The endogenous cannabinoid system plays a role in metabolic aspects of body weight and feeding behaviour. A polymorphism (1359 G/A) (rs1049353) of the CB1 gene was reported as a common polymorphism in the Caucasian population. The present study aimed to investigate the association of the polymorphism (G1359A) of the CB1 receptor gene on macronutrient intake in females with obesity.

METHODS

A sample of 896 females was analysed. A bioimpedance measurement, a blood pressure measurement, a serial assessment of nutritional intake with 3 days of written food records, and a biochemical analysis were all performed. The genotype of the CNR1 receptor gene polymorphism (rs1049353) was studied.

RESULTS

Five hundred and sixteen patients (57.6%) had the genotype G1359G (non-A carriers) and 380 (42.4%) patients had G1359A (328 patients, 36.6%) or A1359A (52 patients, 5.8%) (A carriers). Triglycerides and high-density lipoprotein (HDL) cholesterol levels were higher in A non-A allele carriers than non-A allele carriers. The intakes of dietary cholesterol and saturated fat for the upper tertile (T3) compared to the baseline tertile were inversely associated with the CB1-R 1359 G/A polymorphism [odds ratio (OR) = 0.59; 95% confidence interval (CI) = 0.30-0.92 and OR = 0.66; 95% CI = 0.39-0.91, respectively]. These data were observed in the second tertile (T2) (OR = 0.61; 95% CI = 0.29-0.94 and OR = 0.58; 95% CI = 0.31-0.90, respectively).

CONCLUSIONS

The present study reports an association of the A allele with a better lipid profile (triglycerides and HDL cholesterol) than non-A allele carriers. In addition, this polymorphism is associated with a specific macronutrient intake, as well as with low cholesterol and fat saturated intakes.

A common functional promoter variant links CNR1 gene expression to HDL cholesterol level

CB₁ receptor blockers increase HDL-C levels. Although genetic variation in the CB₁ receptor – encoded by the CNR1 gene – is known to influence HDL-C level as well, human studies conducted to date have been limited to genetic markers such as haplotype tagging SNPs. Here we identify rs806371 in the CNR1 promoter as the causal variant. We resequenced the CNR1 gene and genotype all variants in a DNA biobank linked to comprehensive electronic medical records. By testing each variant for association with HDL-C level in a clinical practice-based setting, we localize a putative functional allele to a 100bp window in the 5′-flanking region. Assessment of variants in this window for functional impact on electrophoretic mobility shift assay identified rs806371 as a novel regulatory binding element. Reporter gene assays confirm that rs806371 reduces HDL-C gene expression, thereby linking CNR1 gene variation to HDL-C level in humans.

CNR1 gene and risk of the metabolic syndrome in patients with schizophrenia

Metabolic disturbances are more prevalent in patients with schizophrenia (SCZ) than in the general population. The endocannabinoid system plays an important role in the regulation of dopamine transmission and several metabolic pathways, and the endocannabinoid receptor type 1 gene (CNR1) is considered a candidate gene for both SCZ and metabolic disorders. We examined whether genetic variation in CNR1 was associated with metabolic syndrome (MetS) in a naturalistic cohort of 407 patients with SCZ. The minor alleles of rs6928499, rs1535255, and rs2023239 were nominally associated with a lower risk of MetS [odds ratio (OR), 0.56; 95% confidence interval (CI), 0.37-0.84; P = 0.006; OR, 0.56; 95% CI, 0.37-0.84; P = 0.006; and OR, 0.44; 95% CI, 0.27-0.72; P = 0.001, respectively, adjusted for age, sex, duration of illness, clozapine or olanzapine treatment). These differences were mainly due to differences in high-density lipoprotein cholesterol and fasting glucose but not in body mass index or waist circumference. No significant association of the other polymorphisms (rs806377, rs1049353, rs6454674, and rs806379) with MetS was found. These results provide evidence that the prevalence of MetS is associated with the CNR1 gene in patients with SCZ during long-term treatment with antipsychotic treatment. Further studies are needed to uncover the exact molecular basis for this association, which could provide novel treatment targets for the MetS.

Endocannabinoids and endovanilloids: a possible balance in the regulation of the testicular GnRH signalling

Reproductive functions are regulated both at central (brain) and gonadal levels. In this respect, the endocannabinoid system (eCS) has a very influential role. Interestingly, the characterization of eCS has taken many advantages from the usage of animal models different from mammals. Therefore, this review is oriented to summarize the main pieces of evidence regarding eCS coming from the anuran amphibian Rana esculenta, with particular interest to the morphofunctional relationship between eCS and gonadotropin releasing hormone (GnRH). Furthermore, a novel role for endovanilloids in the regulation of a testicular GnRH system will be also discussed.

CNR1 genotype influences HDL-cholesterol response to change in dietary fat intake

BACKGROUND

Success in further reducing the burden of cardiovascular disease (CVD) is threatened by the increasing prevalence of obesity-related atherogenic dyslipidemia. HDL-cholesterol (HDL-C) level is inversely correlated with CVD risk; each 1 mg/dl decrease in HDL-C is associated with a 6% reduction in risk. We previously showed that a common CNR1 haplotype, H3 (frequency 20%), is protective against the reduction in HDL-C that typically accompanies weight gain. In the present study, we extend that observation by reporting the effect of CNR1 haplotype on HDL-C response to modification of dietary fat intake in weight maintenance and weight loss.

METHODS

Six haplotype tagging SNPs that cover the CNR1 gene locus were genotyped in 590 adults of varying body mass index (cohort 1 is 411 males with BMI 18.5-30.0 kg/m(2); cohort 2 is 71 females with BMI18.5-30.0 kg/m(2); and cohort 3 is 108 females with BMI 30-39.9 kg/m(2)). Dietary intakes were modified so that fat intake in the "high fat" condition was 15-20% greater than in the "low fat" condition, and lipid profiles were compared between carriers versus noncarriers for each of the five commonly observed CNR1 haplotypes (H1-H5).

RESULTS

In normal to overweight subjects on eucaloric diets, the H3 haplotype was significantly associated with short-term high fat diet induced changes in HDL-C level in females (carriers 5.9 mg/dl>noncarriers, p = 0.007). The H3 haplotype was also significantly associated with HDL-C level after 16 weeks on high fat calorie restricted diet in obese females (carriers 6.8 mg/dl>noncarriers, p = 0.009).

CONCLUSION

Variability within the CNR1 gene locus contributes to gender-related differences in the HDL-cholesterol response to change in dietary fat intake. Functional characterization of this relationship in vitro may offer insights that potentially yield therapeutic guidance targeting dietary macronutrient composition, a direction much needed in the current epidemic of obesity.

The role of the endocannabinoid system in the neuroendocrine regulation of energy balance

Animal and human studies carried out so far have established a role for the endocannabinoid system (ECS) in the regulation of energy balance. Here we critically discuss the role of the endocannabinoid signalling in brain structures, such as the hypothalamus and reward-related areas, and its interaction with neurotransmitter and neuropeptide systems involved in the regulation of food intake and body weight. The ECS has been found to interact with peripheral signals, like leptin, insulin, ghrelin and satiety hormones and the resulting effects on both central and peripheral mechanisms affecting energy balance and adiposity will be described. Furthermore, ECS dysregulation has been associated with the development of dyslipidemia, glucose intolerance and obesity; phenomena that are often accompanied by a plethora of neuroendocrine alterations which might play a causal role in determining ECS dysregulation. Despite the withdrawal of the first generation of cannabinoid type 1 receptor (CB1) antagonists from the pharmaceutical market due to the occurrence of psychiatric adverse events, new evidence suggests that peripherally restricted CB1 antagonists might be efficacious for the treatment of obesity and its associated metabolic disorders. Thus, a perspective on new promising strategies to selectively target the ECS in the context of energy balance regulation is given.

Endocannabinoid type 1 receptor gene (CNR1) polymorphisms (rs806381, rs10485170, rs6454674, rs2023239) and cardiovascular risk factors in postmenopausal women

INTRODUCTION

The risk of cardiovascular diseases (CVD) in women increases with menopausal stage. Obesity with metabolic disorders is the most important risk factor for CVD. The incidence of this phenotype of obesity increases in postmenopausal women. The endocannabinoid system plays an important role in regulation of several metabolic pathways. The aim of this work was to investigate whether genetic variations in the cannabinoid receptor gene (CNR1) can affect cardiovascular risk factors (e.g. fat distribution, obesity, fasting glucose, lipid profile, blood pressure, and free androgen and estrogen indexes) in postmenopausal women.

METHODS

The rs806381, rs10485170, rs6454674, and rs2023239 polymorphisms of the CNR1 gene were genotyped in 384 randomly selected postmenopausal Polish women (aged 50-60) using the minisequencing technique.

RESULTS

The rs806381, rs10485170, rs6454674, and rs2023239 polymorphisms were not significantly associated with anthropometric measures (waist circumference, carbohydrate and lipid metabolism, body mass index [BMI], total fat, glucose, insulin, fasting insulin resistance index [FIRI]). However, the rs2023239 polymorphism was associated with the free androgen index (p = 0.03).

DISCUSSION

It seems that further genotyping of the endocannabinoid receptor gene cannot be used as a significant marker of predisposition to CVD in postmenopausal women, but it would be interesting to study this interrelation on a larger population of postmenopausal women.

Contributions of endocannabinoid signaling to psychiatric disorders in humans: genetic and biochemical evidence

The endocannabinoid signaling system is a widespread, neuromodulatory system in brain and is also widely utilized in the periphery to modulate metabolic functions and the immune system. Preclinical data demonstrate that endocannabinoid signaling is an important stress buffer and modulates emotional and cognitive functions. These data suggest the hypothesis that endocannabinoid signaling could be dysfunctional in a number of mental disorders. Genetic polymorphisms in the human genes for two important proteins of the endocannabinoid signaling system, the CB1 cannabinoid receptor (CB1R) and fatty acid amide hydrolase (FAAH), have been explored in the context of normal and pathological conditions. In the case of the gene for FAAH, the mechanistic relationships among the common genetic polymorphism, the expression of the FAAH protein, and its likely impact on endocannabinoid signaling are understood. However, multiple polymorphisms in the gene for the CB1R occur and are associated with human phenotypic differences without an understanding of the functional relationships among the gene, mRNA, protein, and protein function. The endocannabinoid ligands are found in the circulation, and several studies have identified changes in their concentrations under various conditions. These data are reviewed for the purpose of generating hypotheses and to encourage further studies in this very interesting and important area.

Variants at the endocannabinoid receptor CB1 gene (CNR1) and insulin sensitivity, type 2 diabetes, and coronary heart disease

Inhibition of the endocannabinoid receptor CB1 improves insulin sensitivity, lowers glycemia, and slows atherosclerosis. We analyzed whether common variants in the gene encoding CB1, CNR1, are associated with insulin resistance, risk of type 2 diabetes (T2D) or coronary heart disease (CHD). We studied 2,411 participants of the Framingham Offspring Study (mean age 60 years, 52% women) for quantitative traits and CHD, and the Framingham SHARe database for T2D risk. We genotyped 19 single-nucleotide polymorphisms (SNPs) that tagged 85% (at r(2) = 0.8) of common (>5%) CNR1 SNPs. Fasting blood glucose and insulin at the 7th (1999-2001) exam were collected. We used age-, sex-, BMI-adjusted models to test additive associations of genotype with homeostasis model assessment of insulin resistance (HOMA(IR)) (linear mixed-effect models), T2D, or CHD. To account for multiple tests of SNPs, we generated empirical P values. The C allele at SNP rs806365 (frequency, 57.4%), ~4.1 kb 3' from CNR1, was associated with increased HOMA(IR) (n = 2,261, β = 0.05 per C, empirical P = 0.01), risk of T2D (674 cases, odds ratio = 1.19 per C, nominal P = 0.01) and CHD (237 cases, hazard ratio = 1.23 per C, nominal P = 0.04). The association of rs806365 with HOMA(IR) was replicated in a meta-analysis of two independent cohorts (National Health and Nutrition Examination Survey III genetic cohort (NHANES-III) plus Partners Case-Control Diabetes Study; 2,540 white individuals, β = 0.037, nominal P = 0.007), but not in the large Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) Consortium (n = 29,248, nominal P = 0.74). The association of rs806365 was not replicated either with T2D in Diabetes Genetics Replication and Meta-analysis (DIAGRAM) (n = 10,128, nominal P = 0.31), or with CHD in PROCARDIS (n = 13,614, nominal P = 0.37). Although supported by initial results, we found no reproducible statistical association of common variation at CNR1 with insulin resistance, T2D, or CHD.

Relation of G1359A polymorphism of the cannabinoid receptor (CB1) gene with metabolic syndrome by ATP III classification

BACKGROUND

A polymorphism (1359 G/A) of the cannabinoid type-1 receptor gene was reported as a common polymorphism in Caucasian populations. Some metabolic disorders are related to this polymorphism.

OBJECTIVE

The aim of our study was to investigate the association between metabolic syndrome and this polymorphism.

DESIGN

A population of 917 obese patients was analysed in a cross-sectional survey. Bioimpedance, blood pressure, an assessment of nutritional intake and biochemical analysis were recorded.

RESULTS

Five hundred and twelve patients (55.8%) had the genotype G1359G (wild-type group), whereas 344 (37.5%) had genotype G1359A and 61 (6.7%) patients had A1359A. (G1359A and A1359A were included in the mutant-type group; 44.2% total). In wild type patients, metabolic syndrome prevalence was higher (54.9% versus 45.1%; p < 0.05) than no metabolic syndrome prevalence. In patients with mutant genotypes, metabolic syndrome prevalence was lower (43.7% versus 56.3%; p < 0.05). Glucose, insulin and homeostasis model assessment levels were higher in patients with the wild genotype than in those with the mutant type. Adiponectin levels were lower in patients with the wild genotype than in those with the mutant type.

CONCLUSION

The novel finding of this study is the association of the G1359A and A1359A cannabinoid type-1 genotypes with a lower prevalence of metabolic syndrome than the G1359G genotype.

Influence of G1359A polymorphism of the cannabinoid receptor gene on anthropometric parameters and insulin resistance in women with obesity

A silent polymorphism (1359 G/A) of the cannabinoid receptor gene was reported as a common polymorphism in white populations. The aim of our study was to investigate the influence of this polymorphism (G1359A) of cannabinoid receptor gene on obesity, insulin resistance, and adipocytokines in women with obesity. A population of 290 women was analyzed. Indirect calorimetry, tetrapolar electrical bioimpedance, blood pressure measurement, serial assessment of nutritional intake with 3-day written food records, and biochemical analysis were performed. One hundred fifty-nine patients (54.8%) had the genotype G1359G (wild-type group), and 131 (45.2%) patients had G1359A (116 patients, 40.0%) or A1359A (15 patients, 5.2%) (mutant-type group). Triglycerides (122.3 ± 65.9 vs 107.2 ± 44.8 mg/dL, P < .05), insulin (15.8 ± 9.4 vs 13.6 ± 6.9 mUI/L, P < .05), and homeostasis model assessment values (3.85 ± 2.2 vs 3.33 ± 1.9, P < .05) were higher in the wild-type group than the mutant-type group. High-density lipoprotein cholesterol levels (56.8 ± 24.1 vs 58.3 ± 13.9 mg/dL, P < .05) were higher in the mutant-type group than the wild-type group. The novel finding of this study is the association of the mutant-type group G1359A and A1359A with a better cardiovascular profile (triglyceride, high-density lipoprotein cholesterol, insulin, and homeostasis model assessment levels) than the wild-type group.

G1359A polymorphism in the cannabinoid receptor-1 gene is associated with metabolic syndrome in the Chinese Han population

BACKGROUND AND AIMS

Recent studies suggest that endocannabinoids modulate food intake and lipogenesis through cannabinoid receptor-1 (CNR1). This study aims to determine the association between G1359A polymorphism of CNR1 and metabolic syndrome (MetS) in the Chinese Han population.

METHODS

A total of 382 subjects at risk for MetS and 136 healthy subjects from Tianjin, China were genotyped for the G1359A polymorphism of CNR1 using TaqMan assay. Anthropometric measurements and serum analyses were done for body mass index (BMI), waist circumference, blood pressure, serum triglycerides (TG), serum total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting plasma glucose, and plasma insulin levels.

RESULTS

GG genotype of CNR1 has a higher incidence in MetS subjects than in control subjects. Logistic regression analysis shows that the GG genotype was significantly associated with the increased risk of developing MetS (OR 2.204, 95% CI 1.277-3.803, p = 0.005). Compared with CNR1 GG genotype in MetS subjects, CNR1 GA and AA genotypes in subjects with MetS had relatively lower levels of BMI, waist circumference, homeostasis model assessment of insulin resistance (HOMA-IR) and TG.

CONCLUSIONS

Results suggest that the G1359A polymorphism of the CNR1 gene may contribute to MetS susceptibility in the Chinese Han population.

A common CNR1 (cannabinoid receptor 1) haplotype attenuates the decrease in HDL cholesterol that typically accompanies weight gain

We have previously shown that genetic variability in CNR1 is associated with low HDL dyslipidemia in a multigenerational obesity study cohort of Northern European descent (209 families, median  = 10 individuals per pedigree). In order to assess the impact of CNR1 variability on the development of dyslipidemia in the community, we genotyped this locus in all subjects with class III obesity (body mass index >40 kg/m(2)) participating in a population-based biobank of similar ancestry. Twenty-two haplotype tagging SNPs, capturing the entire CNR1 gene locus plus 15 kb upstream and 5 kb downstream, were genotyped and tested for association with clinical lipid data. This biobank contains data from 645 morbidly obese study subjects. In these subjects, a common CNR1 haplotype (H3, frequency 21.1%) is associated with fasting TG and HDL cholesterol levels (p = 0.031 for logTG; p = 0.038 for HDL-C; p = 0.00376 for log[TG/HDL-C]). The strength of this relationship increases when the data are adjusted for age, gender, body mass index, diet and physical activity. Mean TG levels were 160±70, 155±70, and 120±60 mg/dL for subjects with 0, 1, and 2 copies of the H3 haplotype. Mean HDL-C levels were 45±10, 47±10, and 48±9 mg/dL, respectively. The H3 CNR1 haplotype appears to exert a protective effect against development of obesity-related dyslipidemia.

High-density lipoprotein (HDL) cholesterol: leveraging practice-based biobank cohorts to characterize clinical and genetic predictors of treatment outcome

Over the past decade, large multicenter trials have unequivocally demonstrated that decreasing low-density lipoprotein (LDL) cholesterol can reduce both primary and secondary cardiovascular events in patients at risk. However, even in the context of maximal LDL lowering, there remains considerable residual cardiovascular risk. Some of this risk can be attributed to variability in high-density lipoprotein (HDL) cholesterol. As such, there is tremendous interest in defining determinants of HDL homeostasis. Risk prediction models are being constructed based upon (1) clinical contributors, (2) known molecular determinants and (3) the genetic architecture underlying HDL cholesterol levels. To date, however, no single resource has combined these factors within the context of a practice-based data set. Recently, a number of academic medical centers have begun constructing DNA biobanks linked to secure encrypted versions of their respective electronic medical record. As these biobanks combine resources, the clinical community is in a position to characterize lipid-related treatment outcome on an unprecedented scale.

Role of genetic variation in the cannabinoid type 1 receptor gene (CNR1) in the pathophysiology of human obesity

AIMS

The endocannabinoid system may contribute to the association of visceral fat accumulation with metabolic diseases. Here we investigated the effects of genetic variation in the cannabinoid type 1 receptor gene (CNR1) on its mRNA expression in adipose tissue from visceral and subcutaneous depots and on the development of obesity.

MATERIALS & METHODS

CNR1 was sequenced in 48 nonrelated German Caucasians to detect genetic variation. Five representative variants including HapMap tagging SNPs (rs12720071, rs806368, rs806370, rs1049353 and rs806369) were genotyped for subsequent association studies in two independent cohorts (total n = 2774) with detailed metabolic testing: subjects from the Leipzig Study (n = 1857) and a self-contained population of Sorbs from Germany (n = 917).

RESULTS

In a case-control study of lean (BMI <25 kg/m(2)) versus obese (BMI >30 kg/m(2)) subjects, rs806368 was found to be nominally associated with obesity in the Sorbian cohort (adjusted p < 0.05), but not in the Leipzig cohort. Also, several SNPs (rs806368, rs806370 and rs12720071) were nominally associated with serum leptin levels (p < 0.05 after adjusting for age, sex and BMI). However, none of these associations remained significant after accounting for multiple testing. Furthermore, none of the SNPs were related to CNR1 mRNA expression in visceral and subcutaneous fat.

CONCLUSION

The data suggest that common genetic variation in the CNR1 gene does not influence mRNA expression in adipose tissue nor does it play a significant role in the pathophysiology of obesity in German and Sorbian populations.

Quantification of the clinical modifiers impacting high-density lipoprotein cholesterol in the community: Personalized Medicine Research Project

High-density lipoprotein (HDL) cholesterol levels are inversely correlated with the development of cardiovascular disease. To date, genetic association studies have explained only a small proportion of the overall variance in HDL cholesterol. Further studies are needed, within practice-based cohorts, to place genetic findings into context alongside important clinical variables (eg, age, sex, body mass index, medication use, and clinical comorbidity). The Marshfield Clinic Personalized Medicine Research Project database was designed for large-scale studies of genetic epidemiology in a clinical practice-based setting. Because of its size and its unique practice-based design, this resource will provide adequate statistical power for the assessment of genetic findings related to HDL cholesterol level within the context of covariates known to modify lipid homeostasis. The authors report construction and validation of novel electronic phenotyping algorithms that can be used to model individual baseline HDL cholesterol levels within this practice-based resource. Because these algorithms were developed in a setting that reflects routine clinical care, future genetic studies using these algorithms within practice-based DNA biobanks should facilitate the identification of markers with optimal effect size after adjustment for known clinical factors contributing to the overall variance in HDL cholesterol level within the community.

Obesity-related dyslipidemia associated with FAAH, independent of insulin response, in multigenerational families of Northern European descent

A more thorough understanding of the genetic architecture underlying obesity-related lipid disorders could someday facilitate cardiometabolic risk reduction through early clinical intervention based upon improved characterization of individual risk. In recent years, there has been tremendous interest in understanding the endocannabinoid system as a novel therapeutic target for the treatment of obesity-related dyslipidemia.

AIMS

N-arachidonylethanolamine activates G-protein-coupled receptors within the endocannabinoid system. Fatty acid amide hydrolase (FAAH) is a primary catabolic regulator of N-acylethanolamines, including arachidonylethanolamine. Genetic variants in FAAH have inconsistently been associated with obesity. It is conceivable that genetic variability in FAAH directly influences lipid homeostasis. The current study characterizes the relationship between FAAH and obesity-related dyslipidemia, in one of the most rigorously-phenotyped obesity study cohorts in the USA.

MATERIALS & METHODS

Members of 261 extended families (pedigrees ranging from 4 to 14 individuals) were genotyped using haplotype tagging SNPs obtained for the FAAH locus, including 5 kb upstream and 5 kb downstream. Each SNP was tested for basic obesity-related phenotypes (BMI, waist and hip circumference, waist:hip ratio, fasting glucose, fasting insulin and fasting lipid levels) in 1644 individuals within these 261 families. Each SNP was also tested for association with insulin responsiveness using data obtained from a frequently sampled intravenous glucose tolerance test in 399 individuals (32 extended families).

RESULTS

A well characterized coding SNP in FAAH (rs324420) was associated with increased BMI, increased triglycerides, and reduced levels of high-density lipoprotein cholesterol. Mean (standard deviation) high-density lipoprotein cholesterol level was 40.5 (14.7) mg/dl for major allele homozygotes, 39.1 (10.4) mg/dl for heterozygotes, and 34.8 (8.1) mg/dl for minor allele homozygotes (p < 0.01, Family-Based Association Test). This SNP was not associated with insulin sensitivity, acute insulin response to intravenous glucose, glucose effectiveness or glucose disposition index.

CONCLUSION

Genetic variability in FAAH is associated with dyslipidemia, independent of insulin response.

A common polymorphism in the cannabinoid receptor 1 (CNR1) gene is associated with antipsychotic-induced weight gain in Schizophrenia

Antipsychotic-induced weight gain has emerged as a serious complication in the treatment of patients with atypical antipsychotic drugs. The cannabinoid receptor 1 (CNR1) is expressed centrally in the hypothalamic region and associated with appetite and satiety, as well as peripherally. An antagonist of CNR1 (rimonabant) has been effective in causing weight loss in obese patients indicating that CNR1 might be important in antipsychotic-induced weight gain. Twenty tag SNPs were analyzed in 183 patients who underwent treatment (with either clozapine, olanzapine, haloperidol, or risperidone) for chronic schizophrenia were evaluated for antipsychotic-induced weight gain for up to 14 weeks. The polymorphism rs806378 was nominally associated with weight gain in patients of European ancestry treated with clozapine or olanzapine. 'T' allele carriers (CT+TT) gained more weight (5.96%), than the CC carriers (2.76%, p=0.008, FDR q-value=0.12). This translated into approximately 2.2 kg more weight gain in patients carrying the T allele than the patients homozygous for the CC genotype (CC vs CT+TT, 2.21+/-4.51 vs 4.33+/-3.89 kg; p=0.022). This was reflected in the allelic analysis (C vs T allele, 3.84 vs 5.83%, p=0.035). We conducted electrophoretic mobility shift assays which showed that the presence of the T allele created a binding site for arylhydrocarbon receptor translocator (ARNT), a member of the basic helix-loop-helix/Per-Arnt-Sim protein family. In this study, we provide evidence that the CNR1 gene may be associated with antipsychotic-induced weight gain in chronic schizophrenia patients. However, these observations were made in a relatively small patient population; therefore these results need to be replicated in larger sample sets.