The Cannabinoid Receptor 2 Q63R Variant Modulates the Relationship between Childhood Obesity and Age at Menarche

Single nucleotide polymorphisms in the cannabinoid CB2 receptor: Molecular pharmacology and disease associations

Preclinical evidence implicating cannabinoid receptor 2 (CB2) in various diseases has led researchers to question whether CB2 genetics influence aetiology or progression. Associations between conditions and genetic loci are often studied via single nucleotide polymorphism (SNP) prevalence in case versus control populations. In the CNR2 coding exon, ~36 SNPs have high overall population prevalence (minor allele frequencies [MAF] ~37%), including non-synonymous SNP (ns-SNP) rs2501432 encoding CB2 63Q/R. Interspersed are ~27 lower frequency SNPs, four being ns-SNPs. CNR2 introns also harbour numerous SNPs. This review summarises CB2 ns-SNP molecular pharmacology and evaluates evidence from ~70 studies investigating CB2 genetic variants with proposed linkage to disease. Although CNR2 genetic variation has been associated with a wide variety of conditions, including osteoporosis, immune-related disorders, and mental illnesses, further work is required to robustly validate CNR2 disease links and clarify specific mechanisms linking CNR2 genetic variation to disease pathophysiology and potential drug responses.

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.

Effects of a high protein/low carbohydrate low-calorie diet versus a standard low-calorie diet on anthropometric parameters and cardiovascular risk factors, role of polymorphism rs3123554 in the cannabinoid receptor gene type 2 (CB2R)

BACKGROUND

CB2R receptors has been referred to as the peripheral cannabinoid receptor isoform, and regulate inflammatory response in various settings. CB2R gene variants could play a role on metabolic changes after weight loss with different interventions.

OBJECTIVE

To assess the effect of the genetic variant (rs3123554) of the CB2R gene on anthropometric and biochemical changes after weight loss secondary to a high protein/low carbohydrate diet vs. a standard low-calorie diet during 9 months.

DESIGN

268 obese subjects were randomly allocated to one of two diets for 9 months, Diet HP (high protein-low carbohydrate low-calorie diet) and Diet S (standard protein low-calorie diet). Biochemical and anthropometric parameters were measured at baseline and at 3 and 9 months.

RESULTS

Ninety-four patients (35.1%) had genotype GG and 174 (64.9%) subjects had the following genotypes; GA (115 patients, 42.9%) or AA (59 study subjects, 18.0%) (second group). After both diets, body mass index (BMI), fat mass, weight, waist circumference, and systolic blood pressure improved in both genotypes with no difference between diets. Before and after both low-calorie diets, body weight, BMI, fat mass, and waist circumference were higher in A allele carriers than in non-A allele carriers. After both diets (HP and S), levels of glucose, insulin, HOMA-IR, triglycerides, total cholesterol, and LDL cholesterol decreased in non-A allele carriers. These parameters remained unchanged in A allele carriers. Leptin levels decreased after HP and S diets in both genotypes.

CONCLUSION

Non-A allele carriers showed a better response of total cholesterol, LDL cholesterol, triglycerides, glucose, HOMA-IR, and insulin levels than allele A carriers with both low-calorie diets and with the same weight loss.

Links between age at menarche, antral follicle count, and body mass index in African American and European American women

OBJECTIVE

To examine the relationships between age at menarche, antral follicle count (AFC), and body mass index (BMI) in a multi-ethnic population of women.

DESIGN

Community-based, cross-sectional study.

SETTING

Academic setting.

PATIENT(S)

A total of 245 African American women and 273 European American women, aged 25-45 years, with regular menstrual cycles and no reproductive disorders. The ethnicity of these women was self-reported and genetically validated.

INTERVENTION(S)

The AFCs were measured by transvaginal ultrasound during the early follicular phase. Anthropometric measurements were taken, and age at menarche was gathered by questionnaire.

MAIN OUTCOME MEASURE(S)

Determination of the associations between age of menarche and adult AFC and BMI.

RESULT(S)

Earlier age of menarche was associated with both higher BMIs and higher AFCs in adulthood, with control for female age. The antral follicle difference between early (<12 years) vs. late (≥15 years) initiation of menarche in both white and black women was +3.81 and +3.34 follicles, respectively, which is equivalent to an approximately 20% difference in AFC.

CONCLUSION(S)

This study provides the first evidence that timing of menarche may influence AFC. Because of limited studies on African American women, this work provides additional needed data and may enhance our ability to prospectively screen and better treat various diseases associated with the female reproductive lifespan.

Polymorphism rs3123554 in the cannabinoid receptor type 2 (CB2R) gene is associated to metabolic changes after biliopancreatic diversion surgery

INTRODUCTION

The role of genetic variants of the CB2R gene in weight loss after a dietary intervention has been investigated in few studies, none of which has been conducted after bariatric surgery.

OBJECTIVES

The aim of this study was to assess the effect of the genetic variant (rs3123554) of the CB2R gene on cardiovascular risk factors and weight loss secondary to a biliopancreatic diversion.

DESIGN

The study simple consisted of 147 patients with morbid obesity. Biochemical and anthropometric parameters were measured at baseline and at each visit during 3 years (1, 2, and 3 years).

RESULTS

Percent excess weight loss, body mass index, weight, waist circumference, fat mass, blood pressure, fasting glucose, LDL cholesterol, total cholesterol, insulin, HOMA-IR, and triglyceride levels improved in both genotype groups. Decreases in fasting insulin levels and HOMA-IR were higher in non-A allele carriers as compared to A allele carriers.

CONCLUSIONS

Our data suggest that patients with morbid obesity who undergo bariatric surgery and carry the A allele of variant rs3123554 of the CB2R gene have greater weight. This allele has no influence on weight loss after surgery, but results in a lower decrease in insulin levels and insulin resistance.

Common polymorphism in the cannabinoid receptor gene type 2 (CB2R) rs3123554 are associated with metabolic changes after two different hypocaloric diets with different dietary fatty profiles

BACKGROUND

The role of CB2R gene variants on weight loss after a dietary intervention has been investigated in few studies.

OBJECTIVE

We evaluate the effect of this genetic variant (rs3123554) of CB2R gene on cardiovascular risk factors and weight loss secondary to high monounsaturated fat vs a high polyunsaturated fat hypocaloric diets.

DESIGN

A Caucasian population of 362 obese patients was enrolled. Patients were randomly allocated during 3 months to one of two diets (Diet P high polyunsaturated (PUFAs) fat hypocaloric diet vs, Diet M high monounsaturated (MUFAs) fat hypocaloric diet).

RESULTS

In both genotype groups (GG vs GA+AA), body weight, body mass index (BMI), fat mass, waist circumference and systolic blood pressure decreased after diet P and M. Body weight, BMI, fat mass and waist circumference were higher in A allele carriers than non A allele carriers. The improvement of these parameters was higher in non A allele carriers than A allele carriers. In non A allele carriers with both diets, the decrease of total cholesterol, LDL-cholesterol, insulin and HOMA-IR was higher than A allele carriers after both diets. After diet P, triglyceride levels decrease in non A allele carriers.

CONCLUSION

Our data suggest that carriers of the minor allele of rs3123554 variant of CB2R gene lose less body weight during to different hypocaloric diets with different fatty acid. Moreover, non A-allele carriers showed a better response of LDL-cholesterol, HOMA-IR and insulin levels than A-carriers with both hypocaloric diets.

Genetics of pubertal timing

PURPOSE OF REVIEW

To summarize advances in the genetics underlying variation in normal pubertal timing, precocious puberty, and delayed puberty, and to discuss mechanisms by which genes may regulate pubertal timing.

RECENT FINDINGS

Genome-wide association studies have identified hundreds of loci that affect pubertal timing in the general population in both sexes and across ethnic groups. Single genes have been implicated in both precocious and delayed puberty. Potential mechanisms for how these genetic loci influence pubertal timing may include effects on the development and function of the GnRH neuronal network and the responsiveness of end-organs.

SUMMARY

There has been significant progress in identifying genetic loci that affect normal pubertal timing, and the first single-gene causes of precocious and delayed puberty are being described. How these genes influence pubertal timing remains to be determined.

Effects of polymorphism rs3123554 in the cannabinoid receptor gene type 2 (CB2R) on metabolic and adiposity parameters after weight loss with two hypocaloric diets

BACKGROUND

The role of CB2R gene variants on weight loss after a dietary intervention remained unclear.

OBJECTIVE

Our aim was to analyze the effects of rs3123554 of CB2R receptor gene on metabolic and adiposity parameters after two different hypocaloric diets in obese subjects.

DESIGN

A Caucasian population of 280 obese patients was enrolled. Patients were randomly allocated during 3 months to one of two diets (Diet I - moderate in carbohydrate. Vs Diet II - normal in carbohydrate).

RESULTS

In both genotype groups (GG vs GA + AA), body weight, body mass index (BMI), fat mass, waist circumference and systolic blood pressure decreased after diet I and II. The decrease of these parameters was higher in non A allele carriers than A allele carriers. Pre- and post-dietary intervention, body weight, BMI, fat mass and waist circumference were higher in A allele carriers than non A allele carriers. In non A allele carriers, the decrease of glucose, insulin, HOMA-IR and Interleukin-6 levels was higher than A allele carriers after both diets.

CONCLUSION

Carriers of the minor allele of rs3123554 variant of CB2R gene loose less body weight during two different hypocaloric diets. The improvement of metabolic parameters was better in no A allele carriers than A allele carriers.

Cannabimimetic phytochemicals in the diet - an evolutionary link to food selection and metabolic stress adaptation?

The endocannabinoid system (ECS) is a major lipid signalling network that plays important pro-homeostatic (allostatic) roles not only in the nervous system but also in peripheral organs. There is increasing evidence that there is a dietary component in the modulation of the ECS. Cannabinoid receptors in hominids co-evolved with diet, and the ECS constitutes a feedback loop for food selection and energy metabolism. Here, it is postulated that the mismatch of ancient lipid genes of hunter-gatherers and pastoralists with the high-carbohydrate diet introduced by agriculture could be compensated for via dietary modulation of the ECS. In addition to the fatty acid precursors of endocannabinoids, the potential role of dietary cannabimimetic phytochemicals in agriculturist nutrition is discussed. Dietary secondary metabolites from vegetables and spices able to enhance the activity of cannabinoid-type 2 (CB₂ ) receptors may provide adaptive metabolic advantages and counteract inflammation. In contrast, chronic CB₁ receptor activation in hedonic obese individuals may enhance pathophysiological processes related to hyperlipidaemia, diabetes, hepatorenal inflammation and cardiometabolic risk. Food able to modulate the CB₁ /CB₂ receptor activation ratio may thus play a role in the nutrition transition of Western high-calorie diets. In this review, the interplay between diet and the ECS is highlighted from an evolutionary perspective. The emerging potential of cannabimimetic food as a nutraceutical strategy is critically discussed.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

The endocannabinoid system in the baboon (Papio spp.) as a complex framework for developmental pharmacology

INTRODUCTION

The consumption of marijuana (exogenous cannabinoid) almost doubled in adults during last decade. Consumption of exogenous cannabinoids interferes with the endogenous cannabinoid (or "endocannabinoid" (eCB)) system (ECS), which comprises N-arachidonylethanolamide (anandamide, AEA), 2-arachidonoyl glycerol (2-AG), endocannabinoid receptors (cannabinoid receptors 1 and 2 (CB1R and CB2R), encoded by CNR1 and CNR2, respectively), and synthesizing/degrading enzymes (FAAH, fatty-acid amide hydrolase; MAGL, monoacylglycerol lipase; DAGL-α, diacylglycerol lipase-alpha). Reports regarding the toxic and therapeutic effects of pharmacological compounds targeting the ECS are sometimes contradictory. This may be caused by the fact that structure of the eCBs varies in the species studied.

OBJECTIVES

First: to clone and characterize the cDNAs of selected members of ECS in a non-human primate (baboon, Papio spp.), and second: to compare those cDNA sequences to known human structural variants (single nucleotide polymorphisms and haplotypes).

MATERIALS AND METHODS

Polymerase chain reaction-amplified gene products from baboon tissues were transformed into Escherichia coli. Amplicon-positive clones were sequenced, and the obtained sequences were conceptually translated into amino-acid sequences using the genetic code.

RESULTS

Among the ECS members, CNR1 was the best conserved gene between humans and baboons. The phenotypes associated with mutations in the untranslated regions of this gene in humans have not been described in baboons. One difference in the structure of CNR2 between humans and baboons was detected in the region with the only known clinically relevant polymorphism in a human receptor. All of the differences in the amino-acid structure of DAGL-α between humans and baboons were located in the hydroxylase domain, close to phosphorylation sites. None of the differences in the amino-acid structure of MAGL observed between baboons and humans were located in the area critical for enzyme function.

CONCLUSION

The evaluation of the data, obtained in non-human primate model of cannabis-related developmental exposure should take into consideration possible evolutionary-determined species-specific differences in the CB1R expression, CB2R transduction pathway, and FAAH and DAGLα substrate-enzyme interactions.

Age at menarche in Korean adolescents: trends and influencing factors

Background

An increased incidence of central precocious puberty has been recently reported in South Korea, which suggests an ongoing downward trend in pubertal development in the Korean population. We aimed to verify the trend in age at menarche in young Korean women during the last decade and associated factors.

Methods

We analyzed a population-based sample of 3409 Korean girls, aged 10–18 years, using data from the Korean National Health and Nutrition Examination Surveys (KNHANES) II (2001), III (2005), IV (2007–2009), and V (2010 and 2011). Average age at menarche was studied using the Kaplan-Meier survival method and predictors were analyzed using Cox proportional hazards model. The percentage of subjects who had experienced menarche at each age level was compared by using the Cochran-Armitage test.

Results

Overall mean age at menarche was 12.7 years. The percentage of subjects who experienced menarche before the age of 12 years was 21.4 % in 2001 but increased to 34.6 % in 2010/2011 (p < 0.01). In addition, the percentage of girls who experienced menarche before the age of 14 years increased from 76 % in 2001 to 92 % in 2010/2011 (p < 0.005). Adolescents whose mothers who had experienced early menarche (HR 1.48, 95 % CI [1.22–1.80]), and adolescents who were overweight (HR 1.24, 95 % CI [1.04–1.49]) were more likely to have experienced menarche. Additionally, underweight adolescents (HR 0.27, 95 % CI [0.12–0.60]) and adolescents who had a mother having late menarche (HR 0.68, 95 % CI [0.59–0.79]) were expected to have late menarche. None of the socioeconomic factors assessed in our study showed an association with age at menarche.

Conclusions

A downward trend in age at menarche was defined in Korean adolescents during the last decade. Furthermore, influences of genetic and nutritional parameters on individual variance in age at menarche were defined.