Elevated cannabinoid 1 receptor mRNA is linked to eating disorder related behavior and attitudes in females with eating disorders

Epigenetic alterations in patients with anorexia nervosa-a systematic review

Anorexia nervosa (AN) is a complex metabolic and psychological disorder that is influenced by both heritable genetic components and environmental factors. Exposure to various environmental influences can lead to epigenetically induced changes in gene expression. Epigenetic research in AN is still in its infancy, and studies to date are limited in determining clear, valid links to disease onset and progression are limited. Therefore, the aim of this systematic review was to compile and critically evaluate the available results of epigenetic studies specifically in AN and to provide recommendations for future studies. In accordance with the PRISMA guidelines, a systematic literature search was performed in three different databases (PubMed, Embase, and Web of Science) through May 2023. Twenty-three original papers or conference abstracts on epigenetic studies in AN were collected. Epigenome-wide association studies (EWASs), which analyze DNA methylation across the genome in patients with AN and identify potential disease-relevant changes in promoter/regulatory regions of genes, are the most promising for future research. To date, five EWASs on AN have been published, suggesting a potential reversibility of malnutrition-induced epigenetic changes once patients recover. Hence, determining differential DNA methylation levels could serve as a biomarker for disease status or early diagnosis and might be involved in disease progression or chronification. For future research, EWASs with a larger sample size, longitudinal study design and uniform methods should be performed to contribute to the understanding of the pathophysiology of AN, the development of individual interventions and a better prognosis for affected patients.

Current perspectives on brain circuits involved in food addiction-like behaviors

There is an emerging view that the increased availability of energy-dense foods in our society is contributing to excessive food consumption which could lead to food addiction-like behavior. Particularly, compulsive eating patterns are predominant in people suffering from eating disorders (binge-eating disorder, bulimia and anorexia nervosa) and obesity. Phenotypically, the behavioral pattern exhibits a close resemblance to individuals suffering from other forms of addiction (drug, sex, gambling). Growing body of evidence in neuroscience research is showing that excessive consumption of energy-dense foods alters the brain circuits implicated in reward, decision-making, control, habit formation, and emotions that are central to drug addiction. Here, we review the current understanding of the circuits of food addiction-like behaviors and highlight the future possibility of exploring those circuits to combat obesity and eating disorders.

Exploring the influence of circulating endocannabinoids and nucleus accumbens functional connectivity on anorexia nervosa severity

Anorexia nervosa (AN) is a severe psychiatric disorder characterized by a harmful persistence of self-imposed starvation resulting in significant weight loss. Research suggests that alterations in the nucleus accumbens (NAcc) and circulating endocannabinoids (eCBs), such as anandamide (AEA) and 2-arachidonoylglycerol (2-AG), may contribute to increased severity and maladaptive behaviors in AN, warranting an examination of the interplay between central reward circuitry and eCBs. For this purpose, we assessed NAcc functional connectivity and circulating AEA and 2-AG concentrations in 18 individuals with AN and 18 healthy controls (HC) to test associations between circulating eCBs, NAcc functional connectivity, and AN severity, as defined by body mass index (BMI). Decreased connectivity was observed between the NAcc and the right insula (NAcc-insula; pFWE < 0.001) and the left supplementary motor area (NAcc-SMA; pFWE < 0.001) in the AN group compared to HC. Reduced NAcc-insula functional connectivity mediated the association between AEA concentrations and BMI in the AN group. However, in HC, NAcc-SMA functional connectivity had a mediating role between AEA concentrations and BMI. Although no significant differences in eCBs concentrations were observed between the groups, our findings provide insights into how the interaction between eCBs and NAcc functional connectivity influences AN severity. Altered NAcc-insula and NAcc-SMA connectivity in AN may impair the integration of interoceptive, somatosensory, and motor planning information related to reward stimuli. Furthermore, the distinct associations between eCBs concentrations and NAcc functional connectivity in AN and HC could have clinical implications for weight maintenance, with eCBs being a potential target for AN treatment.

CBD enhances the cognitive score of adolescent rats prenatally exposed to THC and fine-tunes relevant effectors of hippocampal plasticity

Introduction: An altered neurodevelopmental trajectory associated with prenatal exposure to ∆-9-tetrahydrocannabinol (THC) leads to aberrant cognitive processing through a perturbation in the effectors of hippocampal plasticity in the juvenile offspring. As adolescence presents a unique window of opportunity for "brain reprogramming", we aimed at assessing the role of the non-psychoactive phytocannabinoid cannabidiol (CBD) as a rescue strategy to temper prenatal THC-induced harm. Methods: To this aim, Wistar rats prenatally exposed to THC (2 mg/kg s.c.) or vehicle (gestational days 5-20) were tested for specific indexes of spatial and configural memory in the reinforcement-motivated Can test and in the aversion-driven Barnes maze test during adolescence. Markers of hippocampal excitatory plasticity and endocannabinoid signaling-NMDAR subunits NR1 and 2A-, mGluR5-, and their respective scaffold proteins PSD95- and Homer 1-; CB1R- and the neuromodulatory protein HINT1 mRNA levels were evaluated. CBD (40 mg/kg i.p.) was administered to the adolescent offspring before the cognitive tasks. Results: The present results show that prenatal THC impairs hippocampal memory functions and the underlying synaptic plasticity; CBD is able to mitigate cognitive impairment in both reinforcement- and aversion-related tasks and the neuroadaptation of hippocampal excitatory synapses and CB1R-related signaling. Discussion: While this research shows CBD potential in dampening prenatal THC-induced consequences, we point out the urgency to curb cannabis use during pregnancy in order to avoid detrimental bio-behavioral outcomes in the offspring.

The Use of Cannabidiol in Metabolic Syndrome-An Opportunity to Improve the Patient's Health or Much Ado about Nothing?

Cannabis-derived therapies are gaining popularity in the medical world. More and more perfect forms of cannabinoids are sought, which could be used in the treatment of many common diseases, including metabolic syndrome, whose occurrence is also increasing. The purpose of this review was to investigate the usefulness of cannabinoids, mainly cannabidiol (CBD), in individuals with obesity, impaired glucose and lipid metabolism, high blood pressure, and non-alcoholic fatty liver disease (NAFLD). We summarised the most recent research on the broad topic of cannabis-derived influence on metabolic syndrome components. Since there is a lot of work on the effects of Δ9-THC (Δ9-tetrahydrocannabinol) on metabolism and far less on cannabidiol, we felt it needed to be sorted out and summarised in this review. The research results on the use of cannabidiol in obesity are contraindicatory. When it comes to glucose homeostasis, it appears that CBD maintains it, sensitises adipose tissue to insulin, and reduces fasting glucose levels, so it seems to be a potential target in this kind of metabolic disorder, but some research results are inconclusive. CBD shows some promising results in the treatment of various lipid disorders. Some studies have proven its positive effect by decreasing LDL and increasing HDL as well. Despite their probable efficacy, CBD and its derivatives will likely remain an adjunctive treatment rather than a mainstay of therapy. Studies have also shown that CBD in patients with hypertension has positive effects, even though the hypotensive properties of cannabidiol are small. However, CBD can be used to prevent blood pressure surges, stabilise them, and have a protective effect on blood vessels. Results from preclinical studies have shown that the effect of cannabidiol on NAFLD may be potentially beneficial in the treatment of the metabolic syndrome and its components. Nevertheless, there is limited data on CBD and NAFLD in human studies. Because of the numerous confounding factors, the conclusions are unclear, and more research in this field is required.

The emerging role of the endocannabinoidome-gut microbiome axis in eating disorders

Among the sources of chemical signals regulating food intake, energy metabolism and body weight, few have attracted recently as much attention as the expanded endocannabinoid system, or endocannabinoidome (eCBome), and the gut microbiome, the two systems on which this review article is focussed. Therefore, it is legitimate to expect that these two systems also play a major role in the etiopathology of eating disorders (EDs), in particular of anorexia nervosa, bulimia nervosa and binge-eating disorder. The major mechanisms through which, also via interactions with other endogenous signaling systems, the eCBome, with its several lipid mediators and receptors, and the gut microbiome, via its variety of microbial kingdoms, phyla and species, and armamentarium of metabolites, intervene in these disorders, are described here, based on several published studies in either experimental models or patients. Additionally, in view of the emerging multi-faceted cross-talk mechanisms between these two complex systems, we discuss the possibility that the eCBome-gut microbiome axis is also involved in EDs.

Potential Role of Cannabinoid Type 2 Receptors in Neuropsychiatric and Neurodegenerative Disorders

The endocannabinoid system (ECS) is composed of the two canonical receptor subtypes; type-1 cannabinoid (CB1R) and type 2 receptor (CB2R), endocannabinoids (eCBs) and enzymes responsible for the synthesis and degradation of eCBs. Recently, with the identification of additional lipid mediators, enzymes and receptors, the expanded ECS called the endocannabinoidome (eCBome) has been identified and recognized. Activation of CB1R is associated with a plethora of physiological effects and some central nervous system (CNS) side effects, whereas, CB2R activation is devoid of such effects and hence CB2Rs might be utilized as potential new targets for the treatment of different disorders including neuropsychiatric disorders. Previous studies suggested that CB2Rs were absent in the brain and they were considered as peripheral receptors, however, recent studies confirmed the presence of CB2Rs in different brain regions. Several studies have now focused on the characterization of its physiological and pathological roles. Studies done on the role of CB2Rs as a therapeutic target for treating different disorders revealed important putative role of CB2R in neuropsychiatric disorders that requires further clinical validation. Here we provide current insights and knowledge on the potential role of targeting CB2Rs in neuropsychiatric and neurodegenerative disorders. Its non-psychoactive effect makes the CB2R a potential target for treating CNS disorders; however, a better understanding of the fundamental pharmacology of CB2R activation is essential for the design of novel therapeutic strategies.

Molecular Alterations of the Endocannabinoid System in Psychiatric Disorders

The therapeutic benefits of the current medications for patients with psychiatric disorders contrast with a great variety of adverse effects. The endocannabinoid system (ECS) components have gained high interest as potential new targets for treating psychiatry diseases because of their neuromodulator role, which is essential to understanding the regulation of many brain functions. This article reviewed the molecular alterations in ECS occurring in different psychiatric conditions. The methods used to identify alterations in the ECS were also described. We used a translational approach. The animal models reproducing some behavioral and/or neurochemical aspects of psychiatric disorders and the molecular alterations in clinical studies in post-mortem brain tissue or peripheral tissues were analyzed. This article reviewed the most relevant ECS changes in prevalent psychiatric diseases such as mood disorders, schizophrenia, autism, attentional deficit, eating disorders (ED), and addiction. The review concludes that clinical research studies are urgently needed for two different purposes: (1) To identify alterations of the ECS components potentially useful as new biomarkers relating to a specific disease or condition, and (2) to design new therapeutic targets based on the specific alterations found to improve the pharmacological treatment in psychiatry.

New Insights and Potential Therapeutic Targeting of CB2 Cannabinoid Receptors in CNS Disorders

The endocannabinoid system (ECS) is ubiquitous in most human tissues, and involved in the regulation of mental health. Consequently, its dysregulation is associated with neuropsychiatric and neurodegenerative disorders. Together, the ECS and the expanded endocannabinoidome (eCBome) are composed of genes coding for CB1 and CB2 cannabinoid receptors (CB1R, CB2R), endocannabinoids (eCBs), and the metabolic enzyme machinery for their synthesis and catabolism. The activation of CB1R is associated with adverse effects on the central nervous system (CNS), which has limited the therapeutic use of drugs that bind this receptor. The discovery of the functional neuronal CB2R raised new possibilities for the potential and safe targeting of the ECS for the treatment of CNS disorders. Previous studies were not able to detect CB2R mRNA transcripts in brain tissue and suggested that CB2Rs were absent in the brain and were considered peripheral receptors. Studies done on the role of CB2Rs as a potential therapeutic target for treating different disorders revealed the important putative role of CB2Rs in certain CNS disorders, which requires further clinical validation. This review addresses recent advances on the role of CB2Rs in neuropsychiatric and neurodegenerative disorders, including, but not limited to, anxiety, depression, schizophrenia, Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD) and addiction.

The Endocannabinoid System: A Potential Target for the Treatment of Various Diseases

The Endocannabinoid System (ECS) is primarily responsible for maintaining homeostasis, a balance in internal environment (temperature, mood, and immune system) and energy input and output in living, biological systems. In addition to regulating physiological processes, the ECS directly influences anxiety, feeding behaviour/appetite, emotional behaviour, depression, nervous functions, neurogenesis, neuroprotection, reward, cognition, learning, memory, pain sensation, fertility, pregnancy, and pre-and post-natal development. The ECS is also involved in several pathophysiological diseases such as cancer, cardiovascular diseases, and neurodegenerative diseases. In recent years, genetic and pharmacological manipulation of the ECS has gained significant interest in medicine, research, and drug discovery and development. The distribution of the components of the ECS system throughout the body, and the physiological/pathophysiological role of the ECS-signalling pathways in many diseases, all offer promising opportunities for the development of novel cannabinergic, cannabimimetic, and cannabinoid-based therapeutic drugs that genetically or pharmacologically modulate the ECS via inhibition of metabolic pathways and/or agonism or antagonism of the receptors of the ECS. This modulation results in the differential expression/activity of the components of the ECS that may be beneficial in the treatment of a number of diseases. This manuscript in-depth review will investigate the potential of the ECS in the treatment of various diseases, and to put forth the suggestion that many of these secondary metabolites of Cannabis sativa L. (hereafter referred to as "C. sativa L." or "medical cannabis"), may also have potential as lead compounds in the development of cannabinoid-based pharmaceuticals for a variety of diseases.

Binge sucrose-induced neuroadaptations: A focus on the endocannabinoid system

Binge eating, the defining feature of binge eating disorder (BED), is associated with a number of adverse health outcomes as well as a reduced quality of life. Animals, like humans, selectively binge on highly palatable food suggesting that the behaviour is driven by hedonic, rather than metabolic, signals. Given the links to both reward processing and food intake, this study examined the contribution of the endocannabinoid system (ECS) to binge-like eating in rats. Separate groups were given intermittent (12 h) or continuous (24 h) access to 10% sucrose and food over 28 days, with only the 12 h access group displaying excessive sucrose intake within a discrete period of time (i.e., binge eating). Importantly, this group also exhibited alterations in ECS transcripts and endocannabinoid levels in brain reward regions, including an increase in cannabinoid receptor 1 (CB1R) mRNA in the nucleus accumbens as well as changes in endocannabinoid levels in the prefrontal cortex and hippocampus. We then tested whether different doses (1 and 3 mg/kg) of a CB1R antagonist, Rimonabant, modify binge-like intake or the development of a conditioned place preference (CPP) to sucrose. CB1R blockade reduced binge-like intake of sucrose and blocked a sucrose CPP, but only in rats that had undergone 28 days of sucrose consumption. These findings indicate that sucrose bingeing alters the ECS in reward-related areas, modifications that exacerbate the effect of CB1R blockade on sucrose reward. Overall, our results broaden the understanding of neural alterations associated with bingeing eating and demonstrate an important role for CB1R mechanisms in reward processing. In addition, these findings have implications for understanding substance abuse, which is also characterized by excessive and maladaptive intake, pointing towards addictive-like properties of palatable food.

Late effects of early weaning on food preference and the dopaminergic and endocannabinoid systems in male and female rats

Early weaning (EW) is associated with obesity later in life. Here, using an EW model in rats, we investigated changes in feeding behavior and the dopaminergic and endocannabinoid systems (ECS) in the adult offspring. Lactating Wistar rats were divided into two groups: EW, dams were wrapped with a bandage to interrupt suckling during the last 3 days of breastfeeding; CONT; dams fed the pups throughout the period without hindrances. EW animals were compared with CONT animals of the same sex. At PN175, male and female offspring of both groups could freely self-select between high-fat and high-sugar diets (food challenge test). EW males preferred the high-fat diet at 30 min and more of the high-sugar diet after 12 h compared to CONT males. EW females did not show differences in their preference for the palatable diets compared to CONT females. Total intake of standard diet from PN30-PN180 was higher in both male and female EW animals, indicating hyperphagia. At PN180, EW males showed lower type 2 dopamine receptor (D2r) in the nucleus accumbens (NAc) and dorsal striatum, while EW females had lower tyrosine hydroxylase in the ventral tegmental area and NAc, D1r in the NAc, and D2r in the prefrontal cortex. In the lateral hypothalamus, EW males had lower fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase, whereas EW females showed lower N-arachidonoyl-phosphatidylethanolamine phospholipase-D and increased FAAH. Early weaning altered both the dopaminergic and ECS parameters at adulthood, contributing to the eating behavior changes of the progeny in a sex-dependent manner.

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.

DNA methylation of ghrelin and leptin receptors in underweight and recovered patients with anorexia nervosa

Epigenetic mechanisms, which modulate gene expression, are becoming increasingly important in the research on anorexia nervosa (AN). Patients with AN have difficulties with the perception of hunger even though hormones like high ghrelin and low leptin signal the need for energy intake. Given the prominent role of the growth hormone secretagogue receptor (GHS-R1a) and the leptin receptor (LEPR) in appetite regulation, a dysregulation of the receptors' expression levels, possibly resulting from altered DNA promoter methylation, may contribute to the pathophysiology of AN. Such alterations could be secondary effects of undernutrition (state markers) or biological processes that may play an antecedent, possibly causal, role in the pathophysiology (trait markers). Therefore, the objective of this study was to examine DNA promoter methylation of the GHS-R1a and LEPR gene promoter regions and investigate whether methylation levels are associated with AN symptoms. We studied medication-free underweight patients with acute AN as well as weight-recovered patients and normal-weight, healthy female control subjects. While DNA methylation of the LEPR gene was similar across groups, GHS-R1a promoter methylation was increased in underweight AN compared to healthy controls - a finding which can be interpreted within the framework of the "ghrelin-resistance" hypothesis in AN. The results of the current study suggest for the first time a potential epigenetic mechanism underlying altered GHS-R1a sensitivity or altered ghrelin signaling in acutely underweight AN. If a ghrelin-centered model of AN can be verified, a next step could be the search for a dietary or psychopharmacological modulation at the ghrelin receptor, potentially via epigenetic mechanisms.

Peripheral changes of endocannabinoid system components in episodic and chronic migraine patients: A pilot study

BACKGROUND

Preclinical and clinical evidence suggests a role for the dysregulation of the endocannabinoid system in migraine pain, particularly in subjects with chronic migraine.

METHODS

The gene expression of endocannabinoid system components was assayed in peripheral blood mononuclear cells of 25 subjects with episodic migraine, 26 subjects with chronic migraine with medication overuse (CM-MO) and 24 age-matched healthy controls. We also evaluated the protein expression of cannabinoid receptors 1 and 2 as well as DNA methylation changes in genes involved in endocannabinoid system components.

RESULTS

Both episodic migraine and CM-MO subjects showed higher cannabinoid receptor 1 and cannabinoid receptor 2 gene and protein expression compared to controls. Fatty acid amide hydrolase gene expression, involved in anandamide degradation, was lower in migraine groups compared to healthy control subjects. N-arachidonoyl phosphatidylethanolamine phospholipase D gene expression was significantly higher in all migraineurs, as were monoacylglycerol lipase and diacylglycerol lipase gene expressions. The above markers significantly correlated with the number of migraine days and with the days of acute drug intake.

CONCLUSION

The findings point to transcriptional changes in endocannabinoid system components occurring in migraineurs. These changes were detected peripherally, which make them amenable for a wider adoption to further investigate their role and applicability in the clinical field.clinicaltrials.gov NTC04324710.

Intuitive eating is associated with elevated levels of circulating omega-3-polyunsaturated fatty acid-derived endocannabinoidome mediators

The regulation of food intake and eating behaviours involves interactions between different systems. The endocannabinoidome, comprising several fatty acid-derived mediators, plays a central role in the regulation of food intake. Alterations of this system have been suggested to intervene in the aetiology of eating disorders. This study aimed to examine the associations between non-pathological eating behaviours and circulating endocannabinoidome mediators in a heterogeneous human population. Plasma 2-monoacyl-glycerol and N-acyl-ethanolamine congeners were measured by LC-MS/MS in a sample of 190 men and women. Eating behaviours were assessed using the Three-Factor Eating Questionnaire (TFEQ) and the Intuitive Eating Scale-2 (IES-2). Following adjustment for body mass index and age, plasma levels of omega-3 polyunsaturated fatty acid-derived 2-monoacyl-glycerols, 2-eicosapentaenoyl-glycerol (2-EPG) and 2-docosapentaenoyl-glycerol (2-DPG), were associated with higher intuitive eating scores (0.15 ≤ rho ≤ 0.20; p < 0.05). These associations were independent of the dietary intake of the fatty acid precursors of these 2-monoacyl-glycerols. However, almost no association was found between plasma levels of N-acyl-ethanolamine congeners and the TFEQ or the IES-2 scores. The results of the present study suggest the association of 2-monoacyl-glycerols, especially 2-EPG and 2-DPG, in the regulation of intuitive eating and the potential implication therein of bioactive lipids.

Impaired brain endocannabinoid tone in the activity-based model of anorexia nervosa

OBJECTIVE

Despite the growing knowledge on the functional relationship between an altered endocannabinoid (eCB) system and development of anorexia nervosa (AN), to date no studies have investigated the central eCB tone in the activity-based anorexia (ABA) model that reproduces key aspects of human AN.

METHOD

We measured levels of two major eCBs, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), those of two eCB-related lipids, oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), and the cannabinoid type-1 receptor (CB1R) density in the brain of female ABA rats, focusing on areas involved in homeostatic and rewarding-related regulation of feeding behavior (i.e., prefrontal cortex, nucleus accumbens, caudato putamen, amygdala, hippocampus and hypothalamus). Analysis was carried out also at the end of recovery from the ABA condition.

RESULTS

At the end of the ABA induction phase, 2-AG was significantly decreased in ABA rats in different brain areas but not in the caudato putamen. No changes were detected in AEA levels in any region, whereas the levels of OEA and PEA were decreased exclusively in the hippocampus and hypothalamus. Furthermore, CB1R density was decreased in the dentate gyrus of hippocampus and in the lateral hypothalamus. After recovery, both 2-AG levels and CB1R density were partially normalized in some areas. In contrast, AEA levels became markedly reduced in all the analyzed areas.

DISCUSSION

These data demonstrate an altered brain eCB tone in ABA rats, further supporting the involvement of an impaired eCB system in AN pathophysiology that may contribute to the maintenance of some symptomatic aspects of the disease.

Cigarette smoke during lactation in rat female progeny: Late effects on endocannabinoid and dopaminergic systems

AIMS

Maternal smoking is considered a risk factor for childhood obesity. In a rat model of tobacco exposure during breastfeeding, we previously reported hyperphagia, overweight, increased visceral fat and hyperleptinemia in adult female offspring. Obesity and eating disorders are associated with impairment in the endocannabinoid (EC) and dopaminergic (DA) systems. Considering that women are prone to eating disorders, we hypothesize that adult female Wistar rats that were exposed to cigarette smoke (CS) during the suckling period would develop EC and DA systems deregulation, possibly explaining the eating disorder in this model.

MATERIAL AND METHODS

To mimic maternal smoking, from postnatal day 3 to 21, dams and offspring were exposed to a smoking machine, 4×/day/1 h (CS group). Control animals were exposed to ambient air. Offspring were evaluated at 26 weeks of age.

KEY FINDINGS

Concerning the EC system, the CS group had increased expression of diacylglycerol lipase (DAGL) in the lateral hypothalamus (LH) and decreased in the liver. In the visceral adipose tissue, the EC receptor (CB1r) was decreased. Regarding the DA system, the CS group showed higher dopamine transporter (DAT) protein expression in the prefrontal cortex (PFC) and lower DA receptor (D2r) in the arcuate nucleus (ARC). We also assessed the hypothalamic leptin signaling, which was shown to be unchanged. CS offspring showed decreased plasma 17β-estradiol.

SIGNIFICANCE

Neonatal CS exposure induces changes in some biomarkers of the EC and DA systems, which can partially explain the hyperphagia observed in female rats.

Epigenetics in eating disorders: a systematic review

Eating disorders are complex heritable conditions influenced by both genetic and environmental factors. Given the progress of genomic discovery in anorexia nervosa, with the identification of the first genome-wide significant locus, as well as animated discussion of epigenetic mechanisms in linking environmental factors with disease onset, our goal was to conduct a systematic review of the current body of evidence on epigenetic factors in eating disorders to inform future directions in this area. Following PRISMA guidelines, two independent authors conducted a search within PubMed and Web of Science and identified 18 journal articles and conference abstracts addressing anorexia nervosa (n = 13), bulimia nervosa (n = 6), and binge-eating disorder (n = 1), published between January 2003 and October 2017. We reviewed all articles and included a critical discussion of field-specific methodological considerations. The majority of epigenetic analyses of eating disorders investigated methylation at candidate genes (n = 13), focusing on anorexia and bulimia nervosa in very small samples with considerable sample overlap across published studies. Three studies used microarray-based technologies to examine DNA methylation across the genome of anorexia nervosa and binge-eating disorder patients. Overall, results were inconclusive and were primarily exploratory in nature. The field of epigenetics in eating disorders remains in its infancy. We encourage the scientific community to apply methodologically sound approaches using genome-wide designs including epigenome-wide association studies (EWAS), to increase sample sizes, and to broaden the focus to include all eating disorder types.

Genetic risk factors for eating disorders: an update and insights into pathophysiology

Genome-wide-association studies (GWASs), epigenetic, gene-expression and gene-gene interaction projects, nutritional genomics and investigations of the gut microbiota have increased our knowledge of the pathophysiology of eating disorders (EDs). However, compared with anorexia nervosa, genetic studies in patients with bulimia nervosa and binge-eating disorder are relatively scarce, with the exception of a few formal genetic and small-sized candidate-gene-association studies. In this article, we review important findings derived from formal and molecular genetics in order to outline a genetics-based pathophysiological model of EDs. This model takes into account environmental and nutritional factors, genetic factors related to the microbiome, the metabolic and endocrine system, the immune system, and the brain, in addition to phenotypical traits of EDs. Shortcomings and advantages of genetic research in EDs are discussed against the historical background, but also in light of potential future treatment options for patients with EDs.

Association of Leptin Gene DNA Methylation With Diagnosis and Treatment Outcome of Anorexia Nervosa

Epigenetic alterations are increasingly implicated in the pathophysiology of anorexia nervosa (AN) but are as yet poorly understood. We investigated possible associations between the leptin gene (LEP) and the leptin receptor gene (LEPR) DNA promoter methylation and (1) a diagnosis of AN and (2) outcome after a 10 months psychotherapeutic outpatient treatment. 129 (LEPR: n = 135) patients with AN were investigated during the large scale psychotherapeutic Anorexia Nervosa Treatment Outpatient Study (ANTOP) trial, compared to 117 (LEPR: n = 119) age and height matched, normal-weight healthy controls. Blood samples were taken at baseline, the end of therapy (40 weeks) and the 12-months follow-up and compared to controls. Methylation was measured in whole blood via bisulfite sequencing. Within the promoter region 32 (LEP) and 39 CpG sites (LEPR) were analyzed. Two key findings were observed. First, LEP and LEPR methylation at baseline were lower in patients compared to controls (LEP: [%] AN: 30.94 ± 13.2 vs. controls: 34.53 ± 14.6); LEPR ([%] AN: 3.73 ± 5.4 vs. controls: 5.22 ± 8.3, mixed linear models: both P < 0.001). Second, lower DNA methylation of the LEP promoter, with a dynamic upregulation during treatment, was associated with a full recovery in AN patients (% change from baseline to follow-up in full recovery patients: +35.13% (SD: 47.56); mixed linear model: P < 0.0001). To test for potential predictive properties of mean LEP DNA methylation a LEP DNA methylation cut-off (31.25% DNA methylation) was calculated, which significantly discriminated full recovery vs. full syndrome AN patients. This cut-off was then tested in a group of previously unclassified patients (missing follow-up data of the Structured Interview for Anorexic and Bulimic disorders; n = 33). Patients below the cut-off (31.25% LEP DNA methylation) showed an increase in BMI over time, while those above the cut-off had a decrease in BMI (ANOVA at the 12-months follow-up: P = 0.0142). To our knowledge, this is the first study investigating epigenetic alterations in AN over time. Our findings indicate that LEP DNA methylation might be involved in the disease course of AN.

Cannabinoid CB1 /CB2 receptor agonists attenuate hyperactivity and body weight loss in a rat model of activity-based anorexia

BACKGROUND AND PURPOSE

Anorexia nervosa (AN) is a serious psychiatric condition characterized by excessive body weight loss and disturbed perceptions of body shape and size, often associated with excessive physical activity. There is currently no effective drug-related therapy of this disease and this leads to high relapse rate. Clinical data suggest that a promising therapy to treat and reduce reoccurrence of AN may be based on the use of drugs that target the endocannabinoid (EC) system, which appears dysregulated in AN patients.

EXPERIMENTAL APPROACH

The activity-based anorexia (ABA) rodent model mimics the severe body weight loss and increased physical activity, as well as the neuroendocrine disturbances (i.e. hypoleptinaemia and hypercortisolaemia) in AN. This study investigated whether cannabinoid agonists can effectively modify anorexic-like behaviours and neuroendocrine changes in rats subjected to a repeated ABA regime that mimics the human condition in which patients repeatedly undergo a recovery and illness cycle.

KEY RESULTS

Our data show that subchronic treatment with both the natural CB₁ /CB₂ receptor agonist Δ⁹ -tetrahydrocannabinol and the synthetic CB₁ /CB₂ receptor agonist CP-55,940 significantly reduced body weight loss and running wheel activity in ABA rats. These behavioural effects were accompanied by an increase in leptin signalling and a decrease in plasma levels of corticosterone.

CONCLUSION AND IMPLICATIONS

Taken together, our results further demonstrate the involvement of the EC system in AN pathophysiology and that strategies which modulate EC signalling are useful to treat this disorder, specifically in patients where physical hyperactivity plays a central role in its progression and maintenance.

Eating Disorders and Epigenetics

Eating disorders (EDs) are characterized by intense preoccupation with shape and weight and maladaptive eating practices. The complex of symptoms that characterize EDs often arise through the activation of latent genetic potentials by environmental exposures, and epigenetic mechanisms are believed to link environmental exposures to gene expression. This chapter provides an overview of genetic factors acting in the etiology of EDs. It then provides a background to the hypothesis that epigenetic mechanisms link stresses such as obstetric complications and childhood abuse as well as effects of malnutrition to eating disorders (EDs). The chapter then summarizes the emerging body of literature on epigenetics and EDs-mainly studies on DNA methylation in samples of anorexia and bulimia. The available evidence base suggests that an epigenetically informed perspective contributes in valuable ways to the understanding of why people develop EDs.

Contemporary views on the genetics of anorexia nervosa

Anorexia nervosa (AN) is a serious mental illness characterized by severe dietary restriction that leads to high rates of morbidity, chronicity, and mortality. Unfortunately, effective treatment is lacking and few options are available. High rates of familial aggregation and significant heritability suggested that the complex etiology of AN is affected by both genetic and environmental factors. In this paper, we review studies that reported common and rare genetic variation that influence susceptibility of AN through candidate gene studies, genome-wide association studies, and sequencing-based studies. We also discuss gene expression, methylation, imaging genetics, and pharmacogenetics to demonstrate that these studies have collectively advanced our knowledge of how genetic variation contributes to AN susceptibility and clinical course. Lastly, we highlight the importance of gene by environment interactions (G×E) and share our enthusiasm for the use of nutritional genomic approaches to elucidate the interaction among nutrients, metabolic intermediates, and genetic variation in AN. A deeper understanding of how nutrition alters genome stability, how genetic variation influences uptake and metabolism of nutrients, and how response to food components affects disordered eating, will lead to personalized dietary interventions and effective nutraceutical and pharmacological treatments for AN.

Endocannabinoid signalling in reward and addiction

Brain endocannabinoid (eCB) signalling influences the motivation for natural rewards (such as palatable food, sexual activity and social interaction) and modulates the rewarding effects of addictive drugs. Pathological forms of natural and drug-induced reward are associated with dysregulated eCB signalling that may derive from pre-existing genetic factors or from prolonged drug exposure. Impaired eCB signalling contributes to dysregulated synaptic plasticity, increased stress responsivity, negative emotional states and cravings that propel addiction. Understanding the contributions of eCB disruptions to behavioural and physiological traits provides insight into the eCB influence on addiction vulnerability.

Genetics and Epigenetics of Eating Disorders

Eating disorders (EDs) are serious psychiatric conditions influenced by biological, psychological, and sociocultural factors. A better understanding of the genetics of these complex traits and the development of more sophisticated molecular biology tools have advanced our understanding of the etiology of EDs. The aim of this review is to critically evaluate the literature on the genetic research conducted on three major EDs: anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). We will first review the diagnostic criteria, clinical features, prevalence, and prognosis of AN, BN, and BED, followed by a review of family, twin, and adoption studies. We then review the history of genetic studies of EDs covering linkage analysis, candidate gene association studies, genome-wide association studies, and the study of rare variants in EDs. Our review also incorporates a translational perspective by covering animal models of ED-related phenotypes. Finally, we review the nascent field of epigenetics of EDs and a look forward to future directions for ED genetic research.

Differential modulation of endogenous cannabinoid CB1 and CB2 receptors in spontaneous and splice variants of ghrelin-induced food intake in conscious rats

OBJECTIVE

Dysregulation of the endocannabinoid system can lead to the development of obesity and metabolic disorders. Endogenous endocannabinoids act on two cannabinoid receptor subtypes, type 1 (CB1) and type 2 (CB2), to exert their biological actions. The aim of this study was to determine whether CB1 and CB2 receptors modulate feeding behavior.

METHODS

We investigated the different roles of CB1 and CB2 receptors in spontaneous and centrally administered splice variants of ghrelin, O-n-octanoylated ghrelin and des-Gln(14)-ghrelin, stimulation of food intake in conscious rats.

RESULTS

Intraperitoneal (IP) injection of different doses of selective CB2 receptor antagonist AM-630 (0.3, 1, and 3 mg/kg) enhanced cumulative food intake during the first 12 h with a dome-shaped dose-response relationship in freely fed rats, with the most effective dose being 1 mg/kg. In comparison, the selective CB1 receptor antagonist AM-251 (0.3, 1, and 3 mg/kg, IP) dose-dependently suppressed the cumulative food intake in 16-h food-deprived rats. Centrally administered O-n-octanoylated ghrelin and des-Gln(14)-ghrelin-induced hyperphagic effects were counteracted dose-dependently by IP AM-251, but not AM-630.

CONCLUSIONS

We demonstrated that the endogenous CB2 receptor plays a role in inhibiting food intake in the satiated state, whereas the CB1 receptor promotes food intake in the fasted condition. The induction of feeding by central acyl ghrelin is a CB1 receptor-dependent mechanism. Differentially nibbling CB1 and CB2 receptor subtypes may provide a new avenue to treating eating and metabolic disorders.

Association of the c.385C>A (p.Pro129Thr) polymorphism of the fatty acid amide hydrolase gene with anorexia nervosa in the Japanese population

The functional c.385C>A single-nucleotide polymorphism (SNP) in the fatty acid amide hydrolase (FAAH) gene, one of the major degrading enzymes of endocannabinoids, is reportedly associated with anorexia nervosa (AN). We genotyped the c.385C>A SNP (rs324420) in 762 lifetime AN and 605 control participants in Japan. There were significant differences in the genotype and allele frequencies of c.385C>A between the AN and control groups. The minor 385A allele was less frequent in the AN participants than in the controls (allele-wise, odds ratio = 0.799, 95% confidence interval [CI] 0.653–0.976, P = 0.028). When the cases were subdivided into lifetime restricting subtype AN and AN with a history of binge eating or purging, only the restricting AN group exhibited a significant association (allele-wise, odds ratio = 0.717, 95% CI 0.557–0.922, P = 0.0094). Our results suggest that having the minor 385A allele of the FAAH gene may be protective against AN, especially restricting AN. This finding supports the possible role of the endocannabinoid system in susceptibility to AN.

Dysfunctions of leptin, ghrelin, BDNF and endocannabinoids in eating disorders: beyond the homeostatic control of food intake

A large body of literature documents the occurrence of alterations in the physiology of both central and peripheral modulators of appetite in acute patients with anorexia nervosa (AN) and bulimia nervosa (BN). Until more recently the role of most of the appetite modulators in the control of eating behavior was conceptualized solely in terms of their influence on homeostatic control of energy balance. However, it is becoming more and more evident that appetite modulators also affect the non-homeostatic cognitive, emotional and rewarding component of food intake as well as non food-related reward, and, recently, AN and BN have been pathophysiologically linked to dysfunctions of reward mechanisms. Therefore, the possibility exists that observed changes in appetite modulators in acute AN and BN may represent not only homeostatic adaptations to malnutrition, but also contribute to the development and/or the maintenance of aberrant non-homeostatic behaviors, such as self-starvation and binge eating. In the present review, the evidences supporting a role of leptin, ghrelin, brain-derived neurotrophic factor and endocannabinoids in the homeostatic and non-homeostatic dysregulations of patients with AN and BN will be presented. The reviewed literature is highly suggestive that changes in the physiology of these modulators may play a pivotal role in the pathophysiology of eating disorders by providing a possible link between motivated behaviors, reward processes, cognitive functions and energy balance.

Epigenetic mechanisms and endocannabinoid signalling

The endocannabinoid system, composed of endogenous lipids, their target receptors and metabolic enzymes, has been implicated in multiple biological functions in health and disease, both in the central nervous system and in peripheral organs. Despite the exponential growth of experimental evidence on the key role of endocannabinoid signalling in basic cellular processes, and on its potential exploitation for therapeutic interventions, much remains to be clarified about the respective regulatory mechanisms. Epigenetics refers to a set of post-translational modifications that regulate gene expression without causing variation in DNA sequence, endowed with a major impact on signal transduction pathways. The epigenetic machinery includes DNA methylation, histone modifications, nucleosome positioning and non-coding RNAs. Due to the reversibility of epigenetic changes, an emerging field of interest is the possibility of an 'epigenetic therapy' that could possibly be applied also to endocannabinoids. Here, we review current knowledge of epigenetic regulation of endocannabinoid system components under both physiological and pathological conditions, as well as the epigenetic changes induced by endocannabinoid signalling.

CB1 and CB2 receptor expression and promoter methylation in patients with cannabis dependence

CB1 and CB2 receptors are influenced via exogenous and endogenous cannabinoids. To date, little is known regarding changes in receptor expression and methylation in THC (tetrahydrocannabinol) dependence. Therefore, the CB1 and CB2 receptor mRNA expression levels and promoter methylation status in the peripheral blood cells of 77 subjects (36 with THC dependence, 21 cigarette smokers and 20 nonsmokers) were assessed by quantitative real-time PCR and methylation-specific PCR. There was a significant difference in CB1 receptor expression levels between the three groups (ANOVA, p < 0.001, d.f. = 2, F = 71.3). The mean promoter methylation (%) was significantly negatively correlated with CB1 receptor mRNA expression levels (Spearman's rho: r = -0.37; p = 0.002). Using a mixed general linear model, it was demonstrated that the CB1 mRNA expression (as the dependent variable) was associated with the satisfaction with life scale (SWLS) (r = 0.101; T = 2.8; p = 0.007), craving (as measured with the VAS; r = -0.023; T = -2.3; p = 0.023) and the WHO-Assist Subscale for Cannabis consumption (r = -0.068; T = -2.4; p = 0.02). CB1 receptor expression levels and methylation status appear to be altered in subjects with THC dependence.

Lower levels of cannabinoid 1 receptor mRNA in female eating disorder patients: association with wrist cutting as impulsive self-injurious behavior

The cannabinoid 1 (CB 1) receptor as the primary mediator of the endocannabinoid (EC) system was found to play a role in eating disorders (EDs), depression, anxiety, and suicidal behavior. The CB 1 receptor is assumed to play a crucial role in the central reward circuitry with impact on body weight and personality traits like novelty-seeking behavior. In a previous study we found higher levels of CB 1 receptor mRNA in patients with anorexia nervosa (AN) and bulimia nervosa (BN) compared to healthy control women (HCW). The aim of the present study was to investigate the possible influence of the EC and the CB 1 receptor system on wrist cutting as self-injurious behavior (SIB) in women with EDs (n=43; AN: n=20; BN: n=23). Nine ED patients with repetitive wrist cutting (AN, n=4; BN, n=5) were compared to 34 ED patients without wrist cutting and 26 HCW. Levels of CB 1 receptor mRNA were determined in peripheral blood samples using quantitative real-time PCR. ED patients with self-injurious wrist cutting exhibited significantly lower CB 1 receptor mRNA levels compared with ED patients without wrist cutting and HCW. No significant differences were found between ED patients without a history of wrist cutting and HCW. Furthermore, a negative association was detected between CB 1 receptor mRNA levels and Beck Depression Inventory (BDI) scores. To our knowledge, this is the first study reporting a down-regulation of CB 1 receptor mRNA in patients with EDs and wrist cutting as SIB. Due to the small sample size, our results should be regarded as preliminary and further studies are warranted to reveal the underlying mechanisms.

Smoking, but not malnutrition, influences promoter-specific DNA methylation of the proopiomelanocortin gene in patients with and without anorexia nervosa

OBJECTIVE

Our pilot study evaluates the impact of environmental factors, such as nutrition and smoking status, on epigenetic patterns in a disease-associated gene.

METHOD

We measured the effects of malnutrition and cigarette smoking on proopiomelanocortin (POMC) promoter-specific DNA methylation in female patients with and without anorexia nervosa (AN). POMC and its derived peptides (alpha melanocyte stimulating hormone and adrenocorticotropic hormone) are implicated in stress and feeding response. Promoter-specific DNA methylation of the POMC gene was determined in peripheral blood mononuclear cells of 54 healthy female control subjects, 40 underweight patients with AN, and 21 weight-restored patients with AN using bisulfite sequencing. Malnutrition was characterized by plasma leptin.

RESULTS

POMC promoter-specific DNA methylation was not affected by diagnosis or nutritional status but significantly negatively associated with cigarette smoking.

CONCLUSIONS

Although malnutrition may be expected to reduce DNA methylation through its effects on one-carbon metabolism, our negative results are in line with several in vitro and clinical studies that did not show a direct relation between gene-specific DNA methylation and folate levels. In contrast, smoking has been repeatedly reported to alter DNA methylation of specific genes and should be controlled for in future epigenetic studies.

Neurogenetics and Epigenetics in Impulsive Behaviour: Impact on Reward Circuitry

Adverse, unfavourable life conditions, particularly during early life stages and infancy, can lead to epigenetic regulation of genes involved in stress-response, behavioral disinhibition, and cognitive-emotional systems. Over time, the ultimate final outcome can be expressed through behaviors bedeviled by problems with impulse control, such as eating disorders, alcoholism, and indiscriminate social behavior. While many reward gene polymorphisms are involved in impulsive behaviors, a polymorphism by itself may not translate to the development of a particular behavioral disorder unless it is impacted by epigenetic effects. Brain-derived neurotrophic factor (BDNF) affects the development and integrity of the noradrenergic, dopaminergic, serotonergic, glutamatergic, and cholinergic neurotransmitter systems, and plasma levels of the neurotrophin are associated with both cognitive and aggressive impulsiveness. Epigenetic mechanisms associated with a multitude of environmental factors, including premature birth, low birth weight, prenatal tobacco exposure, non-intact family, young maternal age at birth of the target child, paternal history of antisocial behavior, and maternal depression, alter the developmental trajectories for several neuropsychiatric disorders. These mechanisms affect brain development and integrity at several levels that determine structure and function in resolving the final behavioral expressions.

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.

Endocannabinoid system and psychiatry: in search of a neurobiological basis for detrimental and potential therapeutic effects

Public concern on mental health has noticeably increased given the high prevalence of neuropsychiatric disorders. Cognition and emotionality are the most affected functions in neuropsychiatric disorders, i.e., anxiety disorders, depression, and schizophrenia. In this review, most relevant literature on the role of the endocannabinoid (eCB) system in neuropsychiatric disorders will be presented. Evidence from clinical and animal studies is provided for the participation of CB1 and CB2 receptors (CB1R and CB2R) in the above mentioned neuropsychiatric disorders. CBRs are crucial in some of the emotional and cognitive impairments reported, although more research is required to understand the specific role of the eCB system in neuropsychiatric disorders. Cannabidiol (CBD), the main non-psychotropic component of the Cannabis sativa plant, has shown therapeutic potential in several neuropsychiatric disorders. Although further studies are needed, recent studies indicate that CBD therapeutic effects may partially depend on facilitation of eCB-mediated neurotransmission. Last but not least, this review includes recent findings on the role of the eCB system in eating disorders. A deregulation of the eCB system has been proposed to be in the bases of several neuropsychiatric disorders, including eating disorders. Cannabis consumption has been related to the appearance of psychotic symptoms and schizophrenia. In contrast, the pharmacological manipulation of this eCB system has been proposed as a potential strategy for the treatment of anxiety disorders, depression, and anorexia nervosa. In conclusion, the eCB system plays a critical role in psychiatry; however, detrimental consequences of manipulating this endogenous system cannot be underestimated over the potential and promising perspectives of its therapeutic manipulation.

The Endocannabinoid System as Pharmacological Target Derived from Its CNS Role in Energy Homeostasis and Reward. Applications in Eating Disorders and Addiction

The endocannabinoid system (ECS) has been implicated in many physiological functions, including the regulation of appetite, food intake and energy balance, a crucial involvement in brain reward systems and a role in psychophysiological homeostasis (anxiety and stress responses). We first introduce this important regulatory system and chronicle what is known concerning the signal transduction pathways activated upon the binding of endogenous cannabinoid ligands to the G_i/0-coupled CB1 cannabinoid receptor, as well as its interactions with other hormones and neuromodulators which can modify endocannabinoid signaling in the brain. Anorexia nervosa (AN) and bulimia nervosa (BN) are severe and disabling psychiatric disorders, characterized by profound eating and weight alterations and body image disturbances. Since endocannabinoids modulate eating behavior, it is plausible that endocannabinoid genes may contribute to the biological vulnerability to these diseases. We present and discuss data suggesting an impaired endocannabinoid signaling in these eating disorders, including association of endocannabinoid components gene polymorphisms and altered CB1-receptor expression in AN and BN. Then we discuss recent findings that may provide new avenues for the identification of therapeutic strategies based on the endocannabinod system. In relation with its implications as a reward-related system, the endocannabinoid system is not only a target for cannabis but it also shows interactions with other drugs of abuse. On the other hand, there may be also a possibility to point to the ECS as a potential target for treatment of drug-abuse and addiction. Within this framework we will focus on enzymatic machinery involved in endocannabinoid inactivation (notably fatty acid amide hydrolase or FAAH) as a particularly interesting potential target. Since a deregulated endocannabinoid system may be also related to depression, anxiety and pain symptomatology accompanying drug-withdrawal states, this is an area of relevance to also explore adjuvant treatments for improving these adverse emotional reactions.

The cannabinoid receptor agonist THC attenuates weight loss in a rodent model of activity-based anorexia

Anorexia nervosa (AN) is characterized by anhedonia whereby patients experience little pleasure or reward in many aspects of their lives. Reward pathways and the endocannabionid system have been implicated in the mediation of food intake. The potential to exploit these systems to reverse weight loss is investigated in a rodent model of activity-based anorexia (ABA). The effect of subchronic (6 days) Δ(9)-tetrahydrocannabinol (THC) treatment (0.1, 0.5, or 2.0 mg/kg/day) was assessed on chow and high-fat diet (HFD) intake, body weight, running wheel activity (RWA) as well as thermogenesis in brown adipose tissue (BAT) and lipid metabolism in white adipose tissue (WAT). Limited time availability of food and continuous access to running wheels led to anorexia and significantly reduced body weight. THC treatment (0.5 and 2.0 mg/kg/day) transiently stimulated chow intake with a moderate effect on RWA. THC (2.0 mg/kg/day) significantly reduced body weight loss and shifted markers of thermogenesis in BAT and lipid metabolism in WAT in directions consistent with reduced energy expenditure and lipolysis. THC (2.0 mg/kg/day) combined with HFD, produced a transient increase in food intake, reduction in RWA, attenuation of body weight loss, and changes in markers of thermogensis in BAT and lipolysis in the WAT. These changes were significantly greater than those seen in vehicle (HFD), vehicle (chow), and THC (chow)-treated animals. These data show for the first time the effectiveness of the endocannabinoid system in attenuating the weight loss associated with the development of ABA via a mechanism involving reduced energy expenditure.

Promoter specific DNA methylation and gene expression of POMC in acutely underweight and recovered patients with anorexia nervosa

Proopiomelanocortin (POMC) and its derived peptides, in particular alpha-MSH, have been shown to play a crucial role in the regulation of hunger, satiety and energy homeostasis. Studies in patients with anorexia nervosa (AN) suggest an abnormal expression of appetite-regulating hormones. Hormone expression levels may be modulated by epigenetic mechanisms, which were recently shown to be implicated in the pathophysiology of eating disorders. We hypothesised that POMC promoter specific DNA methylation and gene expression will be affected by malnutrition and therefore differ in AN patients at distinct stages of the disorder. Promoter specific DNA methylation of the POMC gene and expression of POMC mRNA variants were determined in peripheral blood mononuclear cells (PBMC) of 30 healthy control women (HCW), 31 underweight (acAN) and 30 weight-recovered patients with AN (recAN). Malnutrition was characterized by plasma leptin. Expression of the functionally relevant long POMC mRNA transcript was significantly correlated with leptin levels and higher in acAN compared to recAN and HCW. Expression of the truncated form and mean promoter DNA methylation was similar in all three subgroups. Methylation of single CpG residues in the E2F binding site was inversely related to POMC expression. Our preliminary data on pattern of POMC regulation suggests an association with the underweight state rather than with persisting trait markers of AN. In contrast to POMC expression in the central nervous system, peripheral POMC mRNA expression decreased with malnutrition and hypoleptinemia. This may represent a counterregulatory mechanism as part of the crosstalk between the immune and neuroendocrine systems.

Activity-based anorexia in C57/BL6 mice: effects of the phytocannabinoid, Delta9-tetrahydrocannabinol (THC) and the anandamide analogue, OMDM-2

The activity-based anorexia (ABA) paradigm is one of the few animal models of human anorexia nervosa. We present here the translation of this approach to C57/BL6 mice, a common background for genetically modified mice, and investigate the effects of the cannabinoid agonist, Delta(9)-tetrahydrocannabinol (THC) and the endocannabinoid uptake inhibitor, OMDM-2 in this model. The ABA paradigm was optimised so that food-restricted wheel-running mice displayed anorexia, reduced body weight and disrupted activity and circadian cycles. These conditions produced a murine ABA model with a defined stage and stability to allow for pharmacological intervention. Daily Delta(9)-THC (0.5 mg/kg) decreased survival in the ABA animals but increased feeding in the survivors, OMDM-2 (3 mg/kg) increased food intake, but not sufficiently to reverse weight loss. The effects of this model on endocannabinoid tone in the brain remain to be determined. Since the endocannabinoid system may be implicated in anorexia nervosa and in view of the positive modulation by cannabinoids of some aspects of ABA in this study, further investigation of the effects of cannabinoids in ABA is warranted.

Smoking behaviour is associated with expression and phosphorylation of CREB in human buffy coat

Nicotine induces various acute und chronic pharmacological effects which can be long lasting and might lead to nicotine dependence. Nicotinic acetylcholine receptors (nAChRs) are involved in nicotine-induced phosphorylation of CREB (cyclic AMP response element-binding protein) in PC12h cells. Several studies, mainly done in animal models, report that CREB plays a role in anxiety, memory and substance abuse as well as in affective disorders. Information regarding nicotine effects on gene expression in humans in vivo is rare. The aim of our study was to determine whether or not there are differences between smokers and non-smoking controls in terms of CREB expression and phosphorylation in human buffy coat. Comparing 32 smokers with 76 non-smoking controls we found significantly elevated relative (p=0.043) and absolute (p=0.040) CREB phosphorylation in the blood of smokers who had smoked two cigarettes in the past 6 h. In contrast, the score of the State and Trait Anxiety Inventory, total-CREB and mRNA-CREB were not significantly different. Multiple regression analysis revealed a significant relation between the number of cigarettes smoked daily (R2=0.143, p=0.023), the Fagerström Test for Nicotine Dependence score (R2=0.145, p=0.022) and the expression of CREB. Moreover, in accord with previously published data our analysis suggests gender and age as factors that significantly influence expression and phosphorylation of CREB. It appears that human buffy coat is suitable for studying pharmacological effects of substances such as nicotine on selected signal transduction pathways in humans in vivo. This kind of study may be helpful for translating findings from animal models and cell cultures.

A nonsynonymous polymorphism in cannabinoid CB2 receptor gene is associated with eating disorders in humans and food intake is modified in mice by its ligands

Marijuana use activates cannabinoid receptors (CB-Rs) producing several behavioral effects related to addiction, mood, and appetite. We investigated the association between CNR2 gene, which encodes cannabinoid CB2 receptor (CB2-R) and eating disorders in 204 subjects with eating disorders and 1876 healthy volunteers in Japanese population. The effect of treatment with CB2-R ligands on mouse food consumption was also determined. The CB2-R ligands used suppressed food intake in a time- and strain-dependent manner when food was available ad libitum and during the 12-h fast except, AM 630-the CB2-R antagonist that stimulated food consumption in food-deprived mice. There is an association between the R63Q polymorphism of the CNR2 gene and eating disorders (P = 0.04; Odds ratio 1.24, 95% CI, (1.01-1.53). These results suggest that cannabinoid CB2-R is involved in the endocannabinoid signaling mechanisms associated with the regulation of food intake and in eating disorders.