Julia Wilhelm

Epigenetic dysregulation of dopaminergic genes in eating disorders

OBJECTIVE The pathophysiology of eating disorders such as anorexia nervosa (AN) and bulimia nervosa (BN) has been linked to an impaired dopaminergic neurotransmission, still the origin of this disturbance remains unknown. The aim of the present study was, therefore, to evaluate whether the expression of dopaminergic genes is altered in the blood of patients suffering from eating disorders and if these alterations can be explained by changes in the promoter specific DNA methylation of the genes. METHOD We used quantitative real-time PCR to measure both the expression and the promoter specific DNA methylation of the dopamine transporter (DAT), and the D2 (DRD2) and D4 receptor (DRD4) gene in the blood of 46 patients (22 AN, 24 BN) and 30 healthy controls. RESULTS Patients showed an elevated expression of DAT mRNA when compared with the controls and a downregulation of the DRD₂ expression. The upregulation of the DAT gene was accompanied by a hypermethylation of the genes promoter in the AN and BN group while a significant hypermethylation of the DRD₂ promoter was only present in the AN group. No differences in expression or methylation were found for the other dopamine receptors investigated. DISCUSSION Our study shows a disturbed expression of dopaminergic genes that is accompanied by a dysregulation of the epigenetic DNA methylation. Further studies are necessary to provide more insight into the epigenetic dysregulation of the dopaminergic neurotransmission in the pathophysiology of eating disorders.

Hyperhomocysteinemia as a new risk factor for brain shrinkage in patients with alcoholism.

Chronic alcohol consumption can induce brain atrophy, whereby the exact mechanism of brain damage in alcoholics remains unknown. There is evidence that chronic alcoholism is associated with hyperhomocysteinemia. Homocysteine is an excitatory amino acid which markedly enhances the vulnerability of neuronal cells to excitotoxic and oxidative injury in vitro and in vivo. The present volumetric magnetic resonance imaging study included 52 chronic alcoholics and 30 non-drinking healthy controls. Patients were active drinkers and had an established diagnosis of alcohol dependence. We investigated the influence of different variables on the hippocampal volume of patients suffering from chronic alcoholism. We observed that pathological raised levels of plasma homocysteine showed the most significant correlation to hippocampal volume reduction (P<0.001, multiple regression analysis). Raised plasma levels of homocysteine are associated with hippocampal (brain) atrophy in alcoholism.

Promoter specific methylation of the dopamine transporter gene is altered in alcohol dependence and associated with craving

Dopaminergic neurotransmission plays a crucial role in the genesis and maintenance of alcohol dependence. Epigenetic regulation via promoter specific DNA methylation of the dopamine transporter gene (DAT) may influence altered dopaminergic neurotransmission in alcoholism. Aim of the present study was to investigate DNA promoter methylation of DAT in early alcohol withdrawal and in relation to alcohol craving. We analyzed blood samples of 76 patients admitted for detoxification treatment and compared them to 35 healthy controls. Methylation specific quantitative real-time PCR was used to measure the promoter specific DNA methylation of the dopamine transporter. We assessed the extent of alcohol craving using the obsessive compulsive drinking scale (OCDS). Compared to healthy controls we found a significant hypermethylation of the DAT-promoter (Mann-Whitney U-test: p=0.001). Ln-transformed methylation of the DAT-promoter was negatively associated with the OCDS (linear regression: Beta=-0.275, p=0.016), particularly with the obsessive subscale (Beta=-0.300, p=0.008). Findings of the present study show that the epigenetic regulation of the DAT-promoter is altered in patients undergoing alcohol withdrawal. Furthermore, hypermethylation of the DAT-promoter may play an important role in dopaminergic neurotransmission and is associated with decreased alcohol craving.

Global DNA hypomethylation and DNA hypermethylation of the alpha synuclein promoter in females with anorexia nervosa

Global DNA hypomethylation and DNA hypermethylation of the alpha synuclein promoter in females with anorexia nervosa

Epigenetic down regulation of nerve growth factor during alcohol withdrawal

We investigated the Cytosin‐phosphatidyl‐Guanin (CpG) island promoter methylation (mean and methylation of individual CpG‐sites) of the nerve growth factor (NGF) gene in the blood of alcohol‐dependent patients (57 male patients) during withdrawal (days 1, 7 and 14). Methylation and NGF serum levels did not change significantly from days 1–7. From days 7–14, mean methylation increased (F = 30.55, P < 0.001), whereas the NGF serum levels decreased significantly (days 7–14: F = 17.95, P < 0.001). The NGF serum levels were significantly associated with the mean methylation of the investigated CpG‐sites (F = 1.55, P < 0.001). These results imply an epigenetic regulation of the NGF gene during alcohol withdrawal.

Epigenetic Downregulation of Atrial Natriuretic Peptide but not Vasopressin mRNA Expression in Females with Eating Disorders is Related to Impulsivity

Disturbances of volume-regulating mechanisms have already been implicated in the pathophysiology of eating disorders like anorexia or bulimia nervosa with the peptide hormones vasopressin and atrial natriuretic peptide (ANP) being of special interest. Aim of the present study was to investigate, whether the expression of the corresponding genes was altered and if so, if these changes could be explained by epigenetic mechanisms such as DNA methylation. We analyzed blood samples of 46 women suffering from anorexia (n=22) or bulimia nervosa (n=24) as well as of 30 healthy controls. Peripheral mRNA expression and DNA methylation of the vasopressin and the ANP precursor genes were assessed using real-time PCR. We found significantly lower levels of ANP mRNA in patients with eating disorders. This downregulation was accompanied by a hypermethylation of the ANP gene promoter in the bulimic subgroup. We did not find differences regarding expression or methylation of the vasopressin gene. ANP mRNA expression was inversely associated with impaired impulse regulation. We conclude that epigenetic mechanisms may contribute to the known alterations of ANP homeostasis in women with eating disorders.

BDNF and GDNF serum levels in alcohol-dependent patients during withdrawal.

Preclinical study results suggest that brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) modulate addictive behaviour. Therefore we investigated alterations in BDNF (81 male patients) and GDNF serum levels (52 male patients) in alcohol-dependent patients during alcohol withdrawal (day 1, 7 and 14) in comparison to healthy controls (41 male controls). BDNF serum levels were not significantly altered in alcohol-dependent patients compared to healthy controls (p=0.685). GDNF serum levels were significantly reduced in the alcohol-dependent patients (p<0.001). BDNF (p=0.265) and GDNF (p=0.255) serum levels did not change significantly during alcohol withdrawal. BDNF serum levels were significantly negatively associated with alcohol withdrawal severity on day 1 (CIWA-Ar score, p=0.004). GDNF serum levels were significantly negatively associated with individual estimation of alcohol tolerance (SESA-XT score, p=0.028). There was no further association with psychometric dimensions of alcohol withdrawal. In conclusion we found that GDNF serum levels are significantly reduced in alcohol-dependent patients. GDNF serum levels were negatively associated with alcohol tolerance. Moreover BDNF serum levels were found to be associated with withdrawal severity.

Epigenetic regulation and gene expression of vasopressin and atrial natriuretic peptide in alcohol withdrawal

Disturbances of volume regulating peptides like vasopressin and atrial natriuretic peptide (ANP) have been described in early abstinent patients. Aim of the present study was to evaluate possible alterations of the promoter-related DNA methylation of the ANP and vasopressin precursor genes and the related mRNA-expression of these genes in early alcohol withdrawal. We analyzed blood samples of 57 healthy controls and of 111 patients suffering from alcohol dependence that were admitted for detoxification treatment. Promoter-related DNA methylation and mRNA-expression of vasopressin and ANP genes were assessed using real-time PCR. Vasopressin mRNA-expression was not statistically different between patients and controls. However, we found a significantly elevated promoter-related DNA methylation of the vasopressin gene in patients with alcohol dependence (Mann-Whitney U-test: Z=-2.178, p=0.029). ANP mRNA-expression was significantly elevated in alcoholic patients (Z=-6.240, p<0.001) while promoter-related DNA methylation of ANP was significantly decreased (Z=-2.282, p=0.023). Furthermore, promoter-related DNA methylation of ANP was significantly correlated to the extent of craving measured with the OCDS (r=-0.197, p=0.040). The findings of the present study show significant alterations of the mRNA-expression and promoter-related DNA methylation of vasopressin and especially ANP precursor genes in patients with alcohol dependence. Further studies focusing on longitudinal changes of epigenetic regulation and gene expression of both peptides are needed to clarify the pathophysiological role of these findings.

Short-term cognition deficits during early alcohol withdrawal are associated with elevated plasma homocysteine levels in patients with alcoholism

Summary.Higher plasma homocysteine levels have been found in actively drinking alcoholics as well as in early abstinent patients. Furthermore, elevated homocysteine levels are associated with cognitive decline in dementia and in healthy elderly people. The aim of this prospective study was to investigate a possible association between homocysteine serum levels and clinically well known cognitive deficits during alcohol withdrawal. We examined 89 patients (67 men, 22 women) during early withdrawal treatment. Cognitive function was assessed using the c.I.-Test. Patients with cognitive deficits showed significantly higher homocysteine serum levels (Mann-Whitney-U, p = 0.004) than patients without cognitive deficits, while the difference in blood alcohol concentration was not significant. Using logistic regression analysis, cognitive deficits were best predicted by high homocysteine serum levels (Wald χ2 = 4.071, OR = 1.043, 95% CI 1.001–1.086, p<0.05), which was confirmed by Receiver Operating Curves (AUC = 0.68, 95% CI = 0.57–0.79, p = 0.004). The present results show first evidence of an association between elevated plasma homocysteine levels in alcoholics and cognition deficits in patients undergoing alcohol withdrawal.

Increased levels of adiponectin and resistin in alcohol dependence—possible link to craving

Recent studies suggested a role of appetite regulating peptides like leptin and ghrelin in alcohol dependence and particularly in the neurobiology of alcohol craving. Aim of the present study was to investigate alterations of the adipocytokines adiponectin and resistin in alcohol-dependent patients. We analyzed a sample of 88 patients at admission for alcohol detoxification and after 1 week of withdrawal treatment in comparison to 89 healthy controls. Adiponectin and resistin serum levels were measured using commercial ELISA kits. The extent of alcohol craving was obtained using the Obsessive Compulsive Drinking Scale (OCDS). Adiponectin and resistin serum levels were significantly elevated in patients with alcohol dependence at both dates (admission and after 1 week of treatment) compared to healthy controls. Adiponectin decreased significantly during the course of withdrawal (T=3.44, p=0.001) while resistin serum levels showed a slight increase (T=-1.83, p=0.071). In a multivariate approach the extent of alcohol craving was significantly associated with adiponectin but not with resistin serum levels in male patients (Beta=-0.255, p=0.025). Results for female patients were not significant. Our findings provide first evidence for an alteration of the adipocytokines adiponectin and resistin during alcohol withdrawal. Furthermore, adiponectin may be involved in the neurobiology of alcohol craving, possibly via its effects on the hypothalamic circuits.