Fatty Acid Amide Hydrolase and Cannabinoid Receptor Type 1 Genes Regulation is Modulated by Social Isolation in Rats.

Social isolation is a state of lack of social connections, involving the modulation of different molecular signalling cascades and associated with high risk of mental health issues. To investigate if and how gene expression is modulated by social experience at the central level, we analyzed the effects of 5 weeks of social isolation in rats focusing on endocannabinoid system genes transcription in key brain regions involved in emotional control. We observed selective reduction in mRNA levels for fatty acid amide hydrolase (Faah) and cannabinoid receptor type 1 (Cnr1) genes in the amygdala complex and of Cnr1 in the prefrontal cortex of socially isolated rats when compared to controls, and these changes appear to be partially driven by trimethylation of Lysine 27 and acetylation of Lysine 9 at Histone 3. The alterations of Cnr1 transcriptional regulation result also directly correlated with those of oxytocin receptor gene. We here suggest that to counteract the effects of SI, it is of relevance to restore the endocannabinoid system homeostasis via the use of environmental triggers able to revert those epigenetic mechanisms accounting for the alterations observed.

DNA methylation at cannabinoid type 1 and dopamine D2 receptor genes in saliva samples of psychotic subjects: Is there an effect of Cannabis use?

Psychosis is a characterizing feature of many mental disorders that dramatically affects human thoughts and perceptions, influencing the ability to distinguish between what is real and what is not. Both genetic and environmental factors, such as stressful events or drug use, play a pivotal role in the development of symptomatology and therefore changes in the epigenome may be of relevance in modeling a psychotic phenotype. According to the well-documented dysregulation of endocannabinoid and dopaminergic system genes in schizophrenia, we investigated DNA methylation cannabinoid type 1 receptor (CNR1) and dopamine D2 receptor (DRD2) genes in saliva samples from psychotic subjects using pyrosequencing. The epigenetic mark was significantly higher and directly correlated for both genes in psychotic subjects compared to healthy controls. We also showed that these DNA methylation levels were lower in psychotic subjects reporting current delta-9-tetrahydrocannabinol (THC) consumption, a well-known risk factor for developing psychosis throughout the lifespan, resembling those of controls at least for the DRD2 gene. Overall, our data confirm the key role of CNR1 and DRD2 gene regulation in psychosis and suggest DNA methylation levels at specific CpG sites as potential biomarkers, but just in those psychotic subjects not consuming THC.

Repeated binge-like eating episodes in female rats alter adenosine A2A and dopamine D2 receptor genes regulation in the brain reward system.

OBJECTIVE: Binge-eating disorder is an eating disorder characterized by recurrent binge-eating episodes, during which individuals consume excessive amounts of highly palatable food (HPF) in a short time. This study investigates the intricate relationship between repeated binge-eating episode and the transcriptional regulation of two key genes, adenosine A2A receptor (A2AAR) and dopamine D2 receptor (D2R), in selected brain regions of rats. METHOD: Binge-like eating behavior on HPF was induced through the combination of food restrictions and frustration stress (15 min exposure to HPF without access to it) in female rats, compared to control rats subjected to only restriction or only stress or none of these two conditions. After chronic binge-eating episodes, nucleic acids were extracted from different brain regions, and gene expression levels were assessed through real-time quantitative PCR. The methylation pattern on genes' promoters was investigated using pyrosequencing. RESULTS: The analysis revealed A2AAR upregulation in the amygdala and in the ventral tegmental area (VTA), and D2R downregulation in the nucleus accumbens in binge-eating rats. Concurrently, site-specific DNA methylation alterations at gene promoters were identified in the VTA for A2AAR and in the amygdala and caudate putamen for D2R. DISCUSSION: The alterations on A2AAR and D2R genes regulation highlight the significance of epigenetic mechanisms in the etiology of binge-eating behavior, and underscore the potential for targeted therapeutic interventions, to prevent the development of this maladaptive feeding behavior. These findings provide valuable insights for future research in the field of eating disorders. PUBLIC SIGNIFICANCE: Using an animal model with face, construct, and predictive validity, in which cycles of food restriction and frustration stress evoke binge-eating behavior, we highlight the significance of epigenetic mechanisms on adenosine A2A receptor (A2AAR) and dopamine D2 receptor (D2R) genes regulation. They could represent new potential targets for the pharmacological management of eating disorders characterized by this maladaptive feeding behavior.

Peripheral control of psychiatric disorders: Focus on OCD. Are we there yet?

"We are all in this together" - we often hear this phrase when we want to flag up a problem that is not for a single individual but concerns us all. A similar reflection has been recently made in the field of mental disorders where brain-centric scientists have started to zoom out their brain-focused graphical representations of the mechanisms regulating psychiatric diseases to include other organs or mediators that did not belong historically to the world of neuroscience. The brain itself - that has long been seen as a master in command secluded in its fortress (the blood brain barrier), has now become a collection of Airbnb(s) where all sorts of cells come in and out and sometimes even rearrange the furniture! Under this new framework of reference, mental disorders have become multisystem pathologies where different biological systems - not just the CNS -contribute 'all together' to the development and severity of the disease. In this narrative review article, we will focus on one of the most popular biological systems that has been shown to influence the functioning of the CNS: the immune system. We will specifically highlight the two main features of the immune system and the CNS that we think are important in the context of mental disorders: plasticity and memory.

Neurobehavioral alterations induced by third-trimester gestation-equivalent ethanol exposure are inhibited by folate administration.

Prenatal ethanol exposure (PEE) causes several neurobehavioral impairments in the fetus. Postnatal days (PDs) 4-9 in rodents are considered equivalent to the third trimester of gestation in humans. This period is characterized by high rates of synaptogenesis and myelination and the maturation of key structures and transmitter systems. Nutritional supplements, such as folate, have gained attention as putative treatments to mitigate detrimental effects of PEE. Folate is crucial for DNA synthesis and amino acid metabolism and heightens antioxidant defenses. The present study examined neurobehavioral effects of the concurrent administration of folate (20 mg/kg/day) and ethanol (5 g/kg/day) during PDs 4-9 in male and female Wistar rats. During PDs 16-18, the rat pups were tested for anxiety-like and exploratory activity in the light-dark box (LDB), open field (OF), and concentric square field (CSF) tests. After weaning, they were tested for sucrose preference and ethanol intake. Neonatal ethanol exposure reduced body weight in infancy but did not enhance ethanol self-administration or significantly affect performance in the OF or LDB. Neonatal ethanol exposure also reduced sucrose intake in the preference test and increased shelter-seeking in the CSF, and folate significantly inhibited these effects. The present findings suggest that folate, a treatment that is devoid of serious side effects, can ameliorate some neurobehavioral effects of PEE.

Folate administration ameliorates neurobehavioral effects of prenatal ethanol exposure.

Background: Prenatal ethanol exposure (PEE) induces heightened ethanol intake at adolescence in preclinical studies. Ethanol intake alters the absorption of folate, a methyl-group donor critical for numerous cellular functions. The prenatal administration of folate is, therefore, a promising approach to reduce the effects of PEE.Objectives: Experiment 1 determined if prenatal folate modulated the effects of PEE on ethanol intake, anxiety-like response, and exploratory behaviors (Experiment 1) in Wistar rats. Experiment 2 assessed, in rats not given PEE, if postnatal folate reversed effects of ethanol exposure at postnatal days 28-42. Experiment 3 assessed if folate altered blood ethanol levels (BELs).Methods: Experiment 1 involved 242 (125 male) adolescent Wistar rats derived from dams given folate (20 mg/kg, gestational days - GD- 13-20) + ethanol (2.0 g/kg, GD 17-20), ethanol, or vehicle only at pregnancy. Experiment 2 involved 29 male adolescents administered vehicle or ethanol doses co-administered or not with folate. In Experiment 3 twelve adult females were tested for BELs after folate administration. These tests were applied: intake tests, light dark box (LDB), elevated plus maze, open field and concentric square field.Results: PEE heightened ethanol intake (η2 ps = 0.06-07) and induced hyperactivity and a reduced latency to exit the white area of the LDB (η2 ps = 0.12-17). These effects were partially inhibited by folate (p > .05). Rats exposed to ethanol exposure at adolescence exhibited reduced motor activity (η2 p = .17), regardless of folate treatment. Folate did not affect BELs.Conclusion: Folate administration should be considered as a preventive or acute treatment to attenuate the neurobehavioral effects of PEE.

The Effects of Peripubertal THC Exposure in Neurodevelopmental Rat Models of Psychopathology.

Adolescent exposure to cannabinoids as a postnatal environmental insult may increase the risk of psychosis in subjects exposed to perinatal insult, as suggested by the two-hit hypothesis of schizophrenia. Here, we hypothesized that peripubertal Δ9-tetrahydrocannabinol (aTHC) may affect the impact of prenatal methylazoxymethanol acetate (MAM) or perinatal THC (pTHC) exposure in adult rats. We found that MAM and pTHC-exposed rats, when compared to the control group (CNT), were characterized by adult phenotype relevant to schizophrenia, including social withdrawal and cognitive impairment, as revealed by social interaction test and novel object recognition test, respectively. At the molecular level, we observed an increase in cannabinoid CB1 receptor (Cnr1) and/or dopamine D2/D3 receptor (Drd2, Drd3) gene expression in the prefrontal cortex of adult MAM or pTHC-exposed rats, which we attributed to changes in DNA methylation at key regulatory gene regions. Interestingly, aTHC treatment significantly impaired social behavior, but not cognitive performance in CNT groups. In pTHC rats, aTHC did not exacerbate the altered phenotype nor dopaminergic signaling, while it reversed cognitive deficit in MAM rats by modulating Drd2 and Drd3 gene expression. In conclusion, our results suggest that the effects of peripubertal THC exposure may depend on individual differences related to dopaminergic neurotransmission.

Methyl-CpG binding protein 2 dysfunction provides stress vulnerability with sex- and zygosity-dependent outcomes.

Stress vulnerability is a critical factor for the development of trauma-related disorders; however, its biological underpinnings are not clear. We demonstrated that dysfunctions in the X-linked epigenetic factor methyl-CpG binding protein 2 (MeCP2) provide trauma vulnerability in male mice. Given the prominent role of sex in stress outcomes, we explored the effects of MeCP2 hypofunctionality in females. Female mice carrying truncated MeCP2 (heterozygous and homozygous) and wild type controls (wt) were tested for fear memory. Stress-induced corticosterone release and brain expression of hypothalamic-pituitary-adrenal (HPA) axis regulatory genes were also evaluated in wt and mutant mice of both sexes. Although heterozygous females displayed a normal stress-related behavioural profile, homozygous mice showed enhanced memory recall for the threatening context compared to wt, thus recapitulating the phenotype previously evidenced in hemizygous males. Interestingly, MeCP2 truncation abolished the sex differences in stress-induced corticosterone release, which was found increased in mutant males, whereas blunted in mutant females in a zygosity-independent manner. Although heterozygous mice did not differ from controls, homozygous females and hemizygous males showed increased hypotalamic Crh and Avp mRNAs and a differentially altered expression of Fkbp5 in cortical areas. Present results demonstrate that in female mice carrying truncated MeCP2, altered stress responsivity is driven by homozygosity, whereas heterozygosity does not lead to maladaptive stress outcomes. MeCP2 dysfunctions thus provide stress vulnerability in mice with sex- and zygosity-dependent outcomes.

Dopamine-transporter heterozygous rats carrying maternal wild-type allele are more vulnerable to the development of compulsive behavior.

Compulsivity is defined as an unstoppable tendency toward repetitive and habitual actions, which are reiterated despite negative consequences. Polydipsia is induced preclinically by intermittent reward, leading rodents to ingest large amounts of fluids. We focused on the role of dopamine transporter (DAT) and inheritance factors in compulsive behavior. Our sample consisted of DAT heterozygous (HET) rats with different genetic inheritance (MAT-HET, born from WT-dams × KO-fathers; MIX-HET, born from HET-dams × KO-fathers). As controls, we used both wild-type (WT) rats and their socially-isolated (WTi) siblings. We ran the schedule-induced polydipsia (SIP) protocol, to induce compulsive behavior; then the Y-maze and marble-burying tests, to verify its actual development. Only MAT-HET (who inherited the functional DAT allele from the WT mother) is vulnerable to developing compulsive behavior. MAT-HET rats drank increasingly more water during SIP; they showed significant perseverance in the Y-maze test and exhibited compulsive actions in the marble-burying test. Interestingly, compulsive behaviors of MAT-HET rats correlated with expression ex vivo of different genes in different areas. Regarding the prefrontal cortex (PFC), D2R correlated with Y-maze "perseverance" in addition to BDNF; considering the amygdala (AMY), both D3R and OXTR correlated with SIP "licks." Indeed, compulsivity may be linked to D2R and BDNF in PFC, while extreme anxiety in MAT-HET rats may be associated with D3R and OXTR in the AMY. These results confirm some similarities between MAT-HET and DAT-KO subjects, and link the epigenetic context of the DAT gene to the development of compulsive behavior.

Cannabis use and related clinical variables in patients with obsessive-compulsive disorder.

OBJECTIVE: Limited studies have investigated cannabis use in patients with obsessive-compulsive disorder (OCD), despite its widespread use by patients with psychiatric illnesses. The aim of this study was to assess the frequency, correlates, and clinical impact of cannabis use in an Italian sample of patients with OCD. METHODS: Seventy consecutive outpatients with OCD were recruited from a tertiary specialized clinic. To assess cannabis-related variables, patients completed a questionnaire developed for the purpose of this study, investigating cannabis use-related habits and the influence of cannabis use on OCD symptoms and treatments. A set of clinician and self-reported questionnaires was administered to measure disease severity. The sample was then divided into three subgroups according to the pattern of cannabis use: "current users" (CUs), "past-users" (PUs), and "non-users" (NUs). RESULTS: Approximately 42.8% of patients reported lifetime cannabis use and 14.3% reported current use. Approximately 10% of cannabis users reported an improvement in OCD symptoms secondary to cannabis use, while 23.3% reported an exacerbation of anxiety symptoms. CUs showed specific unfavorable clinical variables compared to PUs and NUs: a significant higher rate of lifetime use of tobacco, alcohol, and other substances, and a higher rate of pre-OCD onset comorbidities. Conversely, the three subgroups showed a similar severity of illness. CONCLUSION: A considerable subgroup of patients with OCD showed a predisposition towards cannabis use and was associated with some specific clinical characteristics, suggesting the need for targeted consideration and interventions in this population.

Endocannabinoid System Regulation in Female Rats with Recurrent Episodes of Binge Eating.

Recurrent Binge Eating (BE) episodes characterize several eating disorders. Here, we attempted to reassemble a condition closer to BE disorder, and we analyzed whether recurrent episodes might evoke molecular alterations in the hypothalamus of rats. The hypothalamus is a brain region which is sensitive to stress and relevant in motivated behaviors, such as food intake. A well-characterized animal model of BE, in which a history of intermittent food restriction and stress induce binge-like palatable food consumption, was used to analyze the transcriptional regulation of the endocannabinoid system (ECS). We detected, in rats showing the BE behavior, an up-regulated gene expression of cannabinoid type-1 receptor (CB1), sn-1-specific diacylglycerol lipase, as well as fatty acid amide hydrolase (Faah) and monoacylglycerol lipase. A selective reduction in DNA methylation was also observed at the promoter of Faah, which is consistent with the changes in the gene expression. Moreover, BE behavior in rats was associated with an increase in anandamide (AEA) levels. Our findings support the relevant role of the ECS in the regulation of food intake in rats subjected to repeated BE episodes, and, in particular, on AEA signaling, acting via CB1 and FAAH modulation. Notably, the epigenetic regulation of the Faah gene might suggest this enzyme as a possible target for developing new therapeutical approaches.

Crosstalk between the transcriptional regulation of dopamine D2 and cannabinoid CB1 receptors in schizophrenia: Analyses in patients and in perinatal Δ9-tetrahydrocannabinol-exposed rats.

Perinatal exposure to Δ9-tetrahydrocannabinol (THC) affects brain development and might increase the incidence of psychopathology later in life, which seems to be related to a dysregulation of endocannabinoid and/or dopaminergic systems. We here evaluated the transcriptional regulation of the genes encoding for the cannabinoid CB1 receptor (Cnr1) and the dopamine D2 receptor (Drd2) in perinatal THC-(pTHC) exposed male rats, focusing on the role of DNA methylation analyzed by pyrosequencing. Simultaneously, the molecular and behavioral abnormalities at two different time points (i.e., neonatal age and adulthood) and the potential preventive effect of peripubertal treatment with cannabidiol, a non-euphoric component of Cannabis, were assessed. The DRD2 methylation was also evaluated in a cohort of subjects with schizophrenia. We observed an increase in both Cnr1 and Drd2 mRNA levels selectively in the prefrontal cortex of adult pTHC-exposed rats with a consistent reduction in DNA methylation at the Drd2 regulatory region, paralleled by social withdrawal and cognitive impairment which were reversed by cannabidiol treatment. These adult abnormalities were preceded at neonatal age by delayed appearance of neonatal reflexes, higher Drd2 mRNA and lower 2-arachidonoylglycerol (2-AG) brain levels, which persisted till adulthood. Alterations of the epigenetic mark for DRD2 were also found in subjects with schizophrenia. Overall, reported data add further evidence to the dopamine-cannabinoid interaction in terms of DRD2 and CNR1 dysregulation which could be implicated in the pathogenesis of schizophrenia spectrum disorders, suggesting that cannabidiol treatment may normalize pTHC-induced psychopathology by modulating the altered dopaminergic activity.

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.

Immuno-moodulin: A new anxiogenic factor produced by Annexin-A1 transgenic autoimmune-prone T cells.

Patients suffering from autoimmune diseases are more susceptible to mental disorders yet, the existence of specific cellular and molecular mechanisms behind the co-morbidity of these pathologies is far from being fully elucidated. By generating transgenic mice overexpressing Annexin-A1 exclusively in T cells to study its impact in models of autoimmune diseases, we made the unpredicted observation of an increased level of anxiety. Gene microarray of Annexin-A1 CD4+ T cells identified a novel anxiogenic factor, a small protein of approximately 21 kDa encoded by the gene 2610019F03Rik which we named Immuno-moodulin. Neutralizing antibodies against Immuno-moodulin reverted the behavioral phenotype of Annexin-A1 transgenic mice and lowered the basal levels of anxiety in wild type mice; moreover, we also found that patients suffering from obsessive compulsive disorders show high levels of Imood in their peripheral mononuclear cells. We thus identify this protein as a novel peripheral determinant that modulates anxiety behavior. Therapies targeting Immuno-moodulin may lead to a new type of treatment for mental disorders through regulation of the functions of the immune system, rather than directly acting on the nervous system.

DNA methylation of the 5'-UTR DAT 1 gene in Parkinson's disease patients.

OBJECTIVES: The involvement of epigenetics mechanisms in the transcriptional regulation of key genes has been investigated in the initiation and progression of neurodegenerative disorders, including Parkinson's disease (PD). Among others, we, here, focused the attention on the dopamine transporter (DAT) gene playing a critical role in maintaining the integrity of dopaminergic neurons. MATERIALS AND METHODS: We performed bisulfite pyrosequencing to examine DNA methylation levels of six CpG sites in the 5'-UTR of DAT1 gene in human peripheral blood mononuclear cells (PBMCs) obtained from 101 sporadic PD patients and 59 healthy controls. RESULTS: We selectively report for CpG5 an increase in DNA methylation levels in PD subjects respect to controls, that almost reaches statistical significance (30.06 ± 12.4 vs 26.58 ± 7.6, P = .052). Of interest, a significantly higher methylation at specific CpG sites (ANOVA: P = .029) was observed in PD subjects with advanced stage of illness. Namely, a multivariate regression analysis showed that a higher methylation level at specific CpG sites in the group of PD patients was associated with increased methylation at CpG2, CpG3, and with H&Y stage but not with age and gender. This regression model explains the 38% of the variance of methylation at CpG5. CONCLUSION: Our results do seem to suggest that the methylation level of CpG5 is different between PD patients and controls. Moreover, this methylation level for CpG5 may be associated also with the stage of disease.

Epigenetic regulation of the cannabinoid receptor CB1 in an activity-based rat model of anorexia nervosa.

OBJECTIVE: Both environmental and genetic factors are known to contribute to the development of anorexia nervosa (AN), but the exact etiology remains poorly understood. Herein, we studied the transcriptional regulation of the endocannabinoid system, an interesting target for body weight maintenance and the control of food intake and energy balance. METHOD: We used two well-characterized animal models of AN: (a) the activity-based anorexia (ABA) model in which rats, housed with running wheels and subjected to daily food restriction, show reductions in body weight and increase in physical activity; (b) the genetic anx/anx mouse displaying the core features of AN: low food intake and emaciation. RESULTS: Among the evaluated endocannabinoid system components, we observed a selective and significant down-regulation of the gene encoding for the type 1 cannabinoid receptor (Cnr1) in ABA rats' hypothalamus and nucleus accumbens and, in the latter area, a consistent, significant and correlated increase in DNA methylation at the gene promoter. No changes were evident in the anx/anx mice except for a down-regulation of Cnr1, in the prefrontal cortex. DISCUSSION: Our findings support a possible role for Cnr1 in the ABA animal model of AN. In particular, its regulation in the nucleus accumbens appears to be triggered by environmental cues due to the consistent epigenetic modulation of the promoter. These data warrant further studies on Cnr1 regulation as a possible target for treatment of AN.

Transcriptional regulation of the endocannabinoid system in a rat model of binge-eating behavior reveals a selective modulation of the hypothalamic fatty acid amide hydrolase gene.

OBJECTIVE: Binge-eating episodes are recurrent and are defining features of several eating disorders. Thus binge-eating episodes might influence eating disorder development of which exact underlying mechanisms are still largely unknown. METHODS: Here we focused on the transcriptional regulation of the endocannabinoid system, a potent regulator of feeding behavior, in relevant rat brain regions, using a rat model in which a history of intermittent food restriction and a frustration stress induce binge-like palatable food consumption. RESULTS: We observed a selective down-regulation of fatty acid amide hydrolase (faah) gene expression in the hypothalamus of rats showing the binge-eating behavior with a consistent reduction in histone 3 acetylation at lysine 4 of the gene promoter. No relevant changes were detected for any other endocannabinoid system components in any brain regions under study, as well as for the other epigenetic mechanisms investigated (DNA methylation and histone 3 lysine 27 methylation) at the faah gene promoter. DISCUSSION: Our findings suggest that faah transcriptional regulation is a potential biomarker of binge-eating episodes, with a relevant role in the homeostatic regulation of food intake.

Potential for diagnosis versus therapy monitoring of attention deficit hyperactivity disorder: a new epigenetic biomarker interacting with both genotype and auto-immunity.

In view of the need for easily accessible biomarkers, we evaluated in ADHD children the epigenetic status of the 5'-untranslated region (UTR) in the SLC6A3 gene, coding for human dopamine transporter (DAT). We analysed buccal swabs and sera from 30 children who met DSM-IV-TR criteria for ADHD, assigned to treatment according to severity. Methylation levels at six-selected CpG sites (among which, a CGGCGGCGG and a CGCG motif), alone or in combination with serum titers in auto-antibodies against dopamine transporter (DAT aAbs), were analysed for correlation with CGAS scores (by clinicians) and Conners' scales (by parents), collected at recruitment and after 6 weeks. In addition, we characterized the DAT genotype, i.e., the variable number tandem repeat (VNTR) polymorphisms at the 3'-UTR of the gene. DAT methylation levels were greatly reduced in ADHD patients compared to control, healthy children. Within patients carrying at least one DAT 9 allele (DAT 9/x), methylation at positions CpG2 and/or CpG6 correlated with recovery, as evident from delta-CGAS scores as well as delta Conners' scales ('inattentive' and 'hyperactive' subscales). Moreover, hypermethylation at CpG1 position denoted severity, specifically for those patients carrying a DAT 10/10 genotype. Intriguingly, high serum DAT-aAbs titers appeared to corroborate indications from high CpG1 versus high CpG2/CpG6 levels, likewise denoting severity versus recovery in DAT 10/10 versus 9/x patients, respectively. These profiles suggest that DAT 5'UTR epigenetics plus serum aAbs can serve as suitable biomarkers, to confirm ADHD diagnosis and/or to predict the efficacy of treatment.

Epigenetic regulation of nociceptin/orphanin FQ and corticotropin-releasing factor system genes in frustration stress-induced binge-like palatable food consumption.

Evidence suggests that binge eating may be caused by a unique interaction between dieting and stress. We developed a binge-eating model in which female rats with a history of intermittent food restriction show binge-like palatable food consumption after a 15-minute exposure to the sight of the palatable food (frustration stress). The aim of the present study was to investigate the regulation of the stress neurohormone corticotropin-releasing factor (CRF) system and of the nociceptin/orphanin FQ (N/OFQ) system genes in selective rat brain regions, using our animal model. Food restriction by itself seems to be responsible in the hypothalamus for the downregulation on messenger RNA levels of CRF-1 receptor, N/OFQ and its receptor (NOP). For the latter, this alteration might be due to selective histone modification changes. Instead, CRF gene appears to be upregulated in the hypothalamus as well as in the ventral tegmental area only when rats are food restricted and exposed to frustration stress, and, of relevance, these changes appear to be due to a reduction in DNA methylation at gene promoters. Moreover, also CRF-1 receptor gene resulted to be differentially regulated in these two brain regions. Epigenetic changes may be viewed as adaptive mechanisms to environmental perturbations concurring to facilitate food consumption in adverse conditions, that is, in this study, under food restriction and stressful conditions. Our data on N/OFQ and CRF signaling provide insight on the use of this binge-eating model for the study of epigenetic modifications in controlled genetic and environmental backgrounds.

Global changes in DNA methylation in Alzheimer's disease peripheral blood mononuclear cells.

Changes in epigenetic marks may help explain the late onset of Alzheimer's disease (AD). In this study we measured genome-wide DNA methylation by luminometric methylation assay, a quantitative measurement of genome-wide DNA methylation, on DNA isolated from peripheral blood mononuclear cells of 37 subjects with late-onset AD (LOAD) and 44 healthy controls (CT). We found an increase in global DNA methylation in LOAD subjects compared to CT (p=0.0122), associated with worse cognitive performances (p=0.0002). DNA hypermethylation in LOAD group was paralleled by higher DNA methyltransferase 1 (DNMT1) gene expression and protein levels. When data were stratified on the basis of the APOE polymorphisms, higher DNA methylation levels were associated with the presence of APOE ε4 allele (p=0.0043) in the global population. Among the APOE ε3 carriers, a significant increase of DNA methylation was still observed in LOAD patients compared to healthy controls (p=0.05). Our data suggest global DNA methylation in peripheral samples as a useful marker for screening individuals at risk of developing AD.