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

Homocysteine Thiolactone Detoxifying Enzymes and Alzheimer's Disease

Elevated levels of homocysteine (Hcy) and related metabolites are associated with Alzheimer's disease (AD). Severe hyperhomocysteinemia causes neurological deficits and worsens behavioral and biochemical traits associated with AD. Although Hcy is precluded from entering the Genetic Code by proofreading mechanisms of aminoacyl-tRNA synthetases, and thus is a non-protein amino acid, it can be attached to proteins via an N-homocysteinylation reaction mediated by Hcy-thiolactone. Because N-homocysteinylation is detrimental to a protein's function and biological integrity, Hcy-thiolactone-detoxifying enzymes-PON1, BLMH, BPHL-have evolved. This narrative review provides an account of the biological function of these enzymes and of the consequences of their impairments, leading to the phenotype characteristic of AD. Overall, accumulating evidence discussed in this review supports a hypothesis that Hcy-thiolactone contributes to neurodegeneration associated with a dysregulated Hcy metabolism.

Homocysteine metabolites inhibit autophagy, elevate amyloid beta, and induce neuropathy by impairing Phf8/H4K20me1-dependent epigenetic regulation of mTOR in cystathionine β-synthase-deficient mice

The loss of cystathionine β-synthase (CBS), an important homocysteine (Hcy)-metabolizing enzyme or the loss of PHF8, an important histone demethylase participating in epigenetic regulation, causes severe intellectual disability in humans. Similar neuropathies were also observed in Cbs-/- and Phf8-/- mice. How CBS or PHF8 depletion can cause neuropathy was unknown. To answer this question, we examined a possible interaction between PHF8 and CBS using Cbs-/- mouse and neuroblastoma cell models. We quantified gene expression by RT-qPCR and western blotting, mTOR-bound H4K20me1 by chromatin immunoprecipitation (CHIP) assay, and amyloid β (Aβ) by confocal fluorescence microscopy using anti-Aβ antibody. We found significantly reduced expression of Phf8, increased H4K20me1, increased mTOR expression and phosphorylation, and increased App, both on protein and mRNA levels in brains of Cbs-/- mice versus Cbs+/- sibling controls. Autophagy-related Becn1, Atg5, and Atg7 were downregulated while p62, Nfl, and Gfap were upregulated on protein and mRNA levels, suggesting reduced autophagy and increased neurodegeneration in Cbs-/- brains. In mouse neuroblastoma N2a or N2a-APPswe cells, treatments with Hcy-thiolactone, N-Hcy-protein or Hcy, or Cbs gene silencing by RNA interference significantly reduced Phf8 expression and increased total H4K20me1 as well as mTOR promoter-bound H4K20me1. This led to transcriptional mTOR upregulation, autophagy downregulation, and significantly increased APP and Aβ levels. The Phf8 gene silencing increased Aβ, but not APP, levels. Taken together, our findings identify Phf8 as a regulator of Aβ synthesis and suggest that neuropathy of Cbs deficiency is mediated by Hcy metabolites, which transcriptionally dysregulate the Phf8 → H4K20me1 → mTOR → autophagy pathway thereby increasing Aβ accumulation.

Advances in DNA, histone, and RNA methylation mechanisms in the pathophysiology of alcohol use disorder

Alcohol use disorder (AUD) has a complex, multifactorial etiology involving dysregulation across several brain regions and peripheral organs. Acute and chronic alcohol consumption cause epigenetic modifications in these systems, which underlie changes in gene expression and subsequently, the emergence of pathophysiological phenotypes associated with AUD. One such epigenetic mechanism is methylation, which can occur on DNA, histones, and RNA. Methylation relies on one carbon metabolism to generate methyl groups, which can then be transferred to acceptor substrates. While DNA methylation of particular genes generally represses transcription, methylation of histones and RNA can have bidirectional effects on gene expression. This review summarizes one carbon metabolism and the mechanisms behind methylation of DNA, histones, and RNA. We discuss the field's findings regarding alcohol's global and gene-specific effects on methylation in the brain and liver and the resulting phenotypes characteristic of AUD.

The Status of Oxidative Stress in Patients with Alcohol Dependence: A Meta-Analysis

Alcohol-induced oxidative stress (OS) plays a pivotal role in the pathophysiology of alcohol dependence (AD). This meta-analysis was aimed at investigating the changes in the levels of OS biomarkers in AD patients. We included relevant literature published before 1 April 2022, from the PubMed, Web of Science, and EBSCO databases following PRISMA guidelines. Finally, 15 eligible articles were enrolled in this meta-analysis, including 860 patients and 849 controls. Compared with healthy controls, AD patients had lower activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzymes, and lower levels of albumin, while levels of malondialdehyde (MDA), vitamin B12, homocysteine, and bilirubin were significantly increased in serum/plasma samples of AD subjects (all p < 0.05). In male patients, the activities of SOD and GPx were increased in serum/plasma but decreased in erythrocytes (all p < 0.05). The opposite trends in the level of SOD and GPx activities in serum/plasma and erythrocytes of male patients could be used as the biomarker of alcohol-induced OS injury, and the synergistic changes of MDA, vitamin B12, albumin, bilirubin, and homocysteine levels should also be considered.

Alcohol use disorders and the brain

A diagnosis of alcohol use disorder is associated with a higher risk of dementia, but a dose-response relationship between alcohol intake consumption and cognitive impairment remains unclear. Alcohol is associated with a range of effects on the central nervous system at different doses and acts on a number of receptors. Acute disorders include Wernicke's encephalopathy (WE), traumatic brain injury, blackouts, seizures, stroke and hepatic encephalopathy. The most common manifestations of chronic alcohol consumption are Korsakoff's syndrome (KS) and alcohol-related dementia (ARD). There is limited evidence for benefit from memantine in the treatment of ARD, but stronger evidence for the use of high-dose parenteral thiamine in the progression of neuropsychiatric symptoms for WE. Accumulating evidence exists for pharmacological treatment in the prevention of hepatic encephalopathy. Rehabilitation of people with ARD may take several years, and requires an approach that addresses physical and psychosocial factors.

Grey matter structural differences in alcohol-dependent individuals with and without comorbid depression/anxiety-an MRI study

Although depression and anxiety disorders are common comorbid conditions in alcohol dependence, few structural brain imaging studies have compared alcohol-dependent subjects with and without such comorbidity. In the current study, brain scans of 35 alcohol-dependent with and 40 individuals without diagnosis of a comorbid ICD-10 depressive or anxiety disorder receiving detoxification inpatient treatment were evaluated. Thickness and volumes of automatically segmented neuroanatomical structures were measured in FreeSurfer. Furthermore, associations of brain structure with biological markers and clinical severity markers of alcohol dependence were assessed. Despite comparable addiction severity, the non-comorbid group had evidence of higher cytotoxic effects of alcohol use on hepatic and haematological markers, and showed significantly smaller volumes of total cerebral, and cerebellar grey matter. Similarly, they showed unexpected smaller hippocampal and nucleus accumbens volumes, and thinner frontal, temporal and occipital cortices. Smaller brain volumes correlated with increased markers of hepatic and haematological dysfunction, and with longer duration of alcohol dependence in the non-comorbid group. Evidence of higher biomarkers of alcohol use may be indicative of more severe alcohol dependence or higher vulnerability to ethanol toxicity in this group. Furthermore, psychopathology-related drug treatment, which occurred in 53% of the comorbid group over the recent years, or tissue inflammation may have a moderate effect on the grade of cerebral atrophy in alcohol-dependent patients. Longitudinal studies are needed to investigate this issue more fully.

CerefolinNAC Therapy of Hyperhomocysteinemia Delays Cortical and White Matter Atrophy in Alzheimer's Disease and Cerebrovascular Disease

We examined whether using a medical food therapy for hyperhomocysteinemia (HHcy) in patients with Alzheimer's disease (AD) or cognitive impairment due to cerebrovascular disease (CVD) with Cerefolin®/CerefolinNAC® (CFLN: L-methylfolate, methylcobalamin, and N-acetyl-cysteine) slowed regional brain atrophy. Thirty HHcy patients with AD and related disorders (ADRD) received CFLN (HHcy+CFLN: duration [μ ±  σ] = 18.6±16.1 months); a sub-sample of this group did not receive CFLN for varying periods of time (HHcy+NoCFLN: duration [μ ±  σ] = 12.6±5.6 months). Thirty-seven NoHHcy patients with ADRD did not receive CFLN (NoHHcy+NoCFLN: duration [μ ±  σ] = 13.3±17.7 months). No participant took supplemental B vitamins. Regional brain volumes were measured at baseline and end of study, and covariate-adjusted rates of hippocampal, cortical, and forebrain parenchymal (includes white matter) atrophy were predicted. The HHcy+CFLN group's hippocampal and cortical atrophy adjusted rates were 4.25 and 11.2 times slower than those of the NoHHcy+NoCFLN group (p < 0.024). The HHcy+CFLN group's forebrain parenchyma atrophy rate was significantly slower only for CVD; the rate of slowing was proportional to the degree of homocysteine lowering (p < 0.0001). CFLN was associated with significantly slowed hippocampal and cortical atrophy rates in ADRD patients with HHcy, and forebrain parenchymal atrophy rates in CVD patients with HHcy. The present results should be further validated.

The Protective Effect of Hydroalcoholic Extract of Zingiber officinale Roscoe (Ginger) on Ethanol-Induced Reproductive Toxicity in Male Rats

This study was conducted to evaluate the prophylactic effect of ginger extract on ethanol-induced reproductive toxicity in male rats. Twenty-eight adult male Sprague-Dawley rats were randomly divided into 4 groups and treated daily for 28 days as follows: control, control-ginger (1 g/kg of body weight [BW]/day by gavage), ethanol group (ethanol 4 g/kg of BW/day by gavage), and ginger-ethanol group. At the end of the experiment, all the rats were sacrificed and their testes were removed and used for measurement of the total homocysteine (tHcy), trace elements, antioxidant enzymes activity, and malondialdehyde (MDA). The results in the ethanol group indicate that ethanol decreased antioxidant enzymes activity and increased MDA and tHcy compared with the control groups ( P < .05). In ginger-ethanol group, ginger improved antioxidant enzymes activity and reduced tHcy and MDA compared to ethanol group ( P < .05). It can be concluded that ginger protects the ethanol-induced testicular damage and improves the hormonal levels, trace elements, antioxidant enzymes activity, and decreases tHcy and MDA.

Homocysteine, Liver Function Derangement and Brain Atrophy in Alcoholics

AIMS

Hyperhomocysteinemia may be involved in the development of brain atrophy in alcoholics. Its pathogenesis is multifactorial. In the present study, we analyse the relationship between homocysteine levels and brain atrophy, and the relative weight of co-existing factors such as liver function impairment, the amount of ethanol consumed, serum vitamin B12, B6, and folic acid levels on homocysteine levels and brain alterations in alcoholic patients.

METHODS

We included 59 patients admitted to this hospital for major withdrawal symptoms and 24 controls. The mini-mental state examination test and a brain computed tomography (CT) scan were performed and several indices were calculated. Serum levels of homocysteine, folic acid, vitamin B6 and vitamin B12 were determined. Liver function was assessed by Child-Pugh score. The daily consumption of ethanol in grams per day and years of addiction were recorded.

RESULTS

A total of 83.6% and 80% of the patients showed cerebellar or frontal atrophy, respectively. Patients showed altered values of brain indices, higher levels of homocysteine and vitamin B12, but lower levels of folic acid, compared with controls. Homocysteine, B12 and liver function variables showed significant correlations with brain CT indices. Multivariate analyses disclosed that Pugh's score, albumin and bilirubin were independently related to cerebellar atrophy, frontal atrophy, cella index or ventricular index. Serum vitamin B12 was the only factor independently related to Evans index. It was also related to cella index, but after bilirubin. Homocysteine levels were independently related to ventricular index, but after bilirubin.

CONCLUSION

Vitamin B12 and homocysteine levels are higher among alcoholics. Liver function derangement, vitamin B12 and homocysteine are all independently related to brain atrophy, although not to cognitive alterations.

SHORT SUMMARY

Hyperhomocysteinemia has been described in alcoholics and may be related to brain atrophy, a reversible condition with an obscure pathogenesis. We studied 59 patients and found that liver function derangement, vitamin B12 and homocysteine levels are all independently related to brain atrophy assessed by computed tomography, although we found no association between these parameters and cognitive alterations.

Apolipoprotein E genotype modulates effects of vitamin B12 and homocysteine on grey matter volume in Alzheimer's disease

AIMS

The aim of the present study was to investigate whether the effects of vitamin B12 and homocysteine on brain volume are influenced by apolipoprotein E (APOE) genotype. We examined the effects in each subgroup (APOE ε4 carriers and non-carriers) of Alzheimer's disease (AD) patients and healthy normal controls.

METHODS

Forty participants with AD and 20 healthy normal controls were recruited from memory impairment clinics at Pusan National University Hospital in Korea. All participants were APOE genotyped and underwent magnetic resonance imaging, including 3-D volumetric images for grey matter (GM) volume. A multiple regression model integrated into statistical parametric mapping was used to see if there was any correlation between vitamin B12 or homocysteine and GM volume in each subgroup (APOE ε4 carriers and non-carriers) of AD patients and healthy normal controls.

RESULTS

There was a significant positive correlation between serum concentrations of vitamin B12 and regional GM volume in APOE ε4 carriers with AD but not in non-carriers. We also found that there was a significant negative correlation between serum concentrations of homocysteine and regional GM volume in APOE ε4 non-carriers with AD but not in carriers (P < 0.001, uncorrected for multiple comparisons; extent threshold = 100 voxel).

CONCLUSION

The present findings suggest that the effects of vitamin B12 and homocysteine on GM volume might be influenced by APOE genotype.

Correlations between homocysteine and grey matter volume in patients with Alzheimer's disease

BACKGROUND

Previous studies have reported that elevated total homocysteine levels are associated with cognitive dysfunction. However, few studies have examined the radiological markers of associated neuropathology in Alzheimer's disease (AD). We hypothesized that elevated levels of homocysteine are associated with cerebral grey matter volume loss. We compared the grey matter in a high homocysteine group and a normal homocysteine group using an optimized voxel-based morphometry.

METHODS

The study included 79 patients with AD who were divided into two groups: a high homocysteine group and a normal homocysteine group. The participants underwent brain magnetic resonance imaging using a standardized protocol and neurocognitive evaluation. Homocysteine tests and other routine laboratory examinations for dementia assessment were carried out in all patients.

RESULTS

There was no significant difference in grey matter volume between the patients with high homocysteine levels and those with normal homocysteine levels. A multiple regression analysis also revealed that the levels of homocysteine were not associated with the grey matter volume in patients with AD. Homocysteine levels were not correlated significantly with Mini-Mental State Examination, Global Deterioration Scale, or Clinical Dementia Rating.

CONCLUSION

Our results showed that elevated homocysteine levels are not associated with reduced cerebral grey matter volume in AD. Larger samples will be needed to assess potential correlations between homocysteine and neuroanatomical pathology in the future.

Dendritic remodeling of hippocampal neurons is associated with altered NMDA receptor expression in alcohol dependent rats

Prolonged alcohol exposure has been previously shown to impair the structure and function of the hippocampus, although the underlying structural and biochemical alterations contributing to these deleterious effects are unclear. Also unclear is whether these changes persist into prolonged periods of abstinence. Previous work from our lab utilizing a clinically relevant rodent model of alcohol consumption demonstrated that alcohol dependence (induced by chronic intermittent ethanol vapor exposure or CIE) decreases proliferation and survival of neural stem cells in the hippocampal subgranular zone and hippocampal neurogenesis in the dentate gyrus, implicating this region of the cortex as particularly sensitive to the toxic effects of prolonged ethanol exposure. For this study, we investigated seven weeks of CIE-induced morphological changes (dendritic complexity and dendritic spine density) of dentate gyrus (DG) granule cell neurons, CA3, and CA1 pyramidal neurons and the associated alterations in biochemical markers of synaptic plasticity and toxicity (NMDA receptors and PSD-95) in the hippocampus in ethanol-experienced Wistar rats 3h (CIE) and 21days (protracted abstinence) after the last ethanol vapor exposure. CIE reduced dendritic arborization of DG neurons and this effect persisted into protracted abstinence. CIE enhanced dendritic arborization of pyramidal neurons and this effect did not persist into protracted abstinence. The architectural changes in dendrites did not correlate with alterations in dendritic spine density, however, they were associated with increases in the expression of pNR2B, total NR2B, and total NR2A immediately following CIE with expression levels returning to control levels in prolonged abstinence. Overall, these data provide the evidence that CIE produces profound changes in hippocampal structural plasticity and in molecular tools that maintain hippocampal structural plasticity, and these alterations may underlie cognitive dysfunction associated with alcohol dependence. In addition, the compensatory state concurrent with reduced plasticity during protracted abstinence could leave the hippocampus vulnerable to subsequent insult following chronic ethanol exposure.

Chronic alcohol consumption and its effect on nodes of frontocerebellar and limbic circuitry: comparison of effects in France and the United States

Alcohol use disorders present a significant public health problem in France and the United States (U.S.), but whether the untoward effect of alcohol on the brain results in similar damage in both countries remains unknown. Accordingly, we conducted a retrospective collaborative investigation between two French sites (Caen and Orsay) and a U.S. laboratory (SRI/Stanford University) with T1-weighted, structural MRI data collected on a common imaging platform (1.5T, General Electric) on 288 normal controls (NC), 165 uncomplicated alcoholics (ALC), and 26 patients with alcoholic Korsakoff's syndrome (KS) diagnosed at all sites with a common interview instrument. Data from the two countries were pooled, then preprocessed and analyzed together at the U.S. site using atlas-based parcellation. National differences indicated that thalamic volumes were smaller in ALC in France than the U.S. despite similar alcohol consumption levels in both countries. By contrast, volumes of the hippocampus, amygdala, and cerebellar vermis were smaller in KS in the U.S. than France. Estimated amount of alcohol consumed over a lifetime, duration of alcoholism, and length of sobriety were significant predictors of selective regional brain volumes in France and in the U.S. The common analysis of MRI data enabled identification of discrepancies in brain volume deficits in France and the U.S. that may reflect fundamental differences in the consequences of alcoholism on brain structure between the two countries, possibly related to genetic or environmental differences.

Cold-inducible RNA-binding protein is an important mediator of alcohol-induced brain inflammation

Binge drinking has been associated with cerebral dysfunction. Ethanol induced microglial activation initiates an inflammatory process that causes upregulation of proinflammatory cytokines which in turn creates neuronal inflammation and damage. However, the molecular mechanism is not fully understood. We postulate that cold-inducible RNA-binding protein (CIRP), a novel proinflammatory molecule, can contribute to alcohol-induced neuroinflammation. To test this theory male wild-type (WT) mice were exposed to alcohol at concentrations consistent to binge drinking and blood and brain tissues were collected. At 5 h after alcohol, a significant increase of 53% in the brain of CIRP mRNA was observed and its expression remained elevated at 10 h and 15 h. Brain CIRP protein levels were increased by 184% at 10 h and remained high at 15 h. We then exposed male WT and CIRP knockout (CIRP^−/−) mice to alcohol, and blood and brain tissues were collected at 15 h post-alcohol infusion. Serum levels of tissue injury markers (AST, ALT and LDH) were significantly elevated in alcohol-exposed WT mice while they were less increased in the CIRP^−/− mice. Brain TNF-α mRNA and protein expressions along with IL-1β protein levels were significantly increased in WT mice, which was not seen in the CIRP^−/− mice. In cultured BV2 cells (mouse microglia), ethanol at 100 mM showed an increase of CIRP mRNA by 274% and 408% at 24 h and 48 h respectively. Corresponding increases in TNF-α and IL-1β were also observed. CIRP protein levels were markedly increased in the medium, suggesting that CIRP was secreted by the BV2 cells. From this we conclude that alcohol exposure activates microglia to produce and secrete CIRP and possibly induce pro-inflammatory response and thereby causing neuroinflammation. CIRP could be a novel mediator of alcohol-induced brain inflammation.

Sex differences in neuroadaptation to alcohol and withdrawal neurotoxicity

Recent work suggests that sex differences exist with regard to both the nature of neuroadaptation to alcohol during the development of dependence, and possibly, the neurodegenerative consequences of alcohol dependence. Volumetric studies in human samples show that females may demonstrate increased volumetric brain loss with equal or lesser dependence histories than males. Furthermore, animal studies demonstrate sex differences in glutamatergic, GABAergic, and adenosinergic receptor signaling and endocrine responses following prolonged alcohol exposure. These differences may influence the development of dependence, neuronal function, and viability, particularly during alcohol withdrawal. The present review discusses the current state of knowledge in this regard. It is concluded that there exists a clear need for a more extensive examination of potential sex differences in neurodegenerative consequences of alcohol dependence in men and women, particularly with regard to the role that alterations in amino acid signaling and hypothalamic-pituitary-adrenal axis function may play. Furthermore, we note the need for expanded examination of the unique role that alcohol withdrawal-associated neuronal activity may have in the development of dependence-associated neurotoxicity.

Alzheimer's disease, β-amyloid, glutamate, NMDA receptors and memantine--searching for the connections

β-amyloid (Aβ) is widely accepted to be one of the major pathomechanisms underlying Alzheimer's disease (AD), although there is presently lively debate regarding the relative roles of particular species/forms of this peptide. Most recent evidence indicates that soluble oligomers rather than plaques are the major cause of synaptic dysfunction and ultimately neurodegeneration. Soluble oligomeric Aβ has been shown to interact with several proteins, for example glutamatergic receptors of the NMDA type and proteins responsible for maintaining glutamate homeostasis such as uptake and release. As NMDA receptors are critically involved in neuronal plasticity including learning and memory, we felt that it would be valuable to provide an up to date review of the evidence connecting Aβ to these receptors and related neuronal plasticity. Strong support for the clinical relevance of such interactions is provided by the NMDA receptor antagonist memantine. This substance is the only NMDA receptor antagonist used clinically in the treatment of AD and therefore offers an excellent tool to facilitate translational extrapolations from in vitro studies through in vivo animal experiments to its ultimate clinical utility.

Alcohol and cognition in the elderly: a review

Consumption of large amounts of alcohol is known to have negative effects, but consumption in smaller amounts may be protective. The effect of alcohol may be greater in the elderly than in younger adults, particularly with regard to cognition. However, the drinking pattern that will provide optimal protection against dementia and cognitive decline in the elderly has not been systematically investigated. The present paper is a critical review of research on the effect of alcohol on cognitive function and dementia in the elderly. Studies published from 1971 to 2011 related to alcohol and cognition in the elderly were reviewed using a PubMed search. Alcohol may have both a neurotoxic and neuroprotective effect. Longitudinal and brain imaging studies in the elderly show that excessive alcohol consumption may increase the risk of cognitive dysfunction and dementia, but low to moderate alcohol intake may protect against cognitive decline and dementia and provide cardiovascular benefits. Evidence suggesting that low to moderate alcohol consumption in the elderly protects against cognitive decline and dementia exists; however, because of varying methodology and a lack of standardized definitions, these findings should be interpreted with caution. It is important to conduct more, well-designed studies to identify the alcohol drinking pattern that will optimally protect the elderly against cognitive decline and dementia.

S100B and homocysteine in the acute alcohol withdrawal syndrome

Elevations of serum homocysteine levels are a consistent finding in alcohol addiction. Serum S100B levels are altered in different neuropsychiatric disorders but not well investigated in alcohol withdrawal syndromes. Because of the close connection of S100B to ACTH and glutamate secretion that both are involved in neurodegeneration and symptoms of alcoholism the relationship of S100B and homocysteine to acute withdrawal variables has been examined. A total of 22 male and 9 female inpatients (mean age 46.9 ± 9.7 years) with an ICD-10 diagnosis of alcohol addiction without relevant affective comorbidity were examined on admission and after 24, 48, and 120 h during withdrawal. S100B and homocysteine levels in serum were collected, and severity of withdrawal symptoms (AWS-scale), applied withdrawal medication, initial serum ethanol levels and duration of addiction were recorded. Serum S100B and homocysteine levels declined significantly (P < .05) over time. Both levels declined with withdrawal syndrome severity. Females showed a trend to a more intense decline in serum S100B levels compared to males at day 5 (P = .06). Homocysteine levels displayed a negative relationship to applied amount of clomethiazole (P < .05) and correlated with age of onset of addiction. No withdrawal seizures were recorded during the trial. As it is known for homocysteine, S100B revealed to decline rapidly over withdrawal treatment in alcoholism. This effect is more pronounced in female patients. S100B could be of relevance in the neurobiology of alcohol withdrawal syndromes. It may be indirectly related to the level of stress level or glutamatergic activity during alcohol withdrawal.

Reduced de novo synthesis of 5-methyltetrahydrofolate and reduced taurine levels in ethanol-treated chick brains

In previous studies, exogenous ethanol (3 mmol EtOH/kg egg) caused a 1.6-fold increase in chick brain homocysteine (HoCys) levels at 11 days of development and the mixture of 3 mmol EtOH/kg egg and 34 micromol folic acid/kg egg attenuated EtOH-induced increases in chick brain HoCys levels. Because HoCys is converted to methionine utilizing the methyl donor, 5-methyltetrahydrofolate (5-methyl THF), we studied whether exogenous ethanol (3 mmol EtOH/kg egg) or the mixture of 3 mmol EtOH/kg egg and 34 micromol 5-methyl THF/kg egg inhibited chick brain 10-formyltetrahydrofolate dehydrogenase (10-FTHF DH; EC 1.5.1.6) activities and brain N5, N10-methylenetetrahydrofolate reductase (MTHFR; EC 1.5.1.20) activities at 11 days of development. Three daily dosages of 3 mmol EtOH/kg egg (E0-2) caused approximately a 7-fold reduction in brain 10-FTHF DH activities and approximately a 1.9-fold reduction in brain MTHFR activities as compared to controls at 11 days of development (p<or=0.05). Because HoCys is also removed by the transsulfuration pathway, which synthesizes taurine, we studied whether exogenous ethanol (3 mmol EtOH/kg egg) or the mixture of 3 mmol EtOH/kg egg and 34 micromol 5-methyl THF/kg egg influenced chick brain taurine levels. In EtOH-treated and EtOH and 5-methyl THF-treated embryos, brain taurine levels decreased by approximately 5.5-fold and 6.2-fold as compared to controls, respectively (p<or=0.05). Exogenous 5-methyl THF failed to attenuate EtOH-induced decreased brain taurine levels at 11 days of development.

Ethanol and cognition: indirect effects, neurotoxicity and neuroprotection: a review

Ethanol affects cognition in a number of ways. Indirect effects include intoxication, withdrawal, brain trauma, central nervous system infection, hypoglycemia, hepatic failure, and Marchiafava-Bignami disease. Nutritional deficiency can cause pellagra and Wernicke-Korsakoff disorder. Additionally, ethanol is a direct neurotoxin and in sufficient dosage can cause lasting dementia. However, ethanol also has neuroprotectant properties and in low-to-moderate dosage reduces the risk of dementia, including Alzheimer type. In fetuses ethanol is teratogenic, and whether there exists a safe dose during pregnancy is uncertain and controversial.

Exogenous folate ameliorates ethanol-induced brain hyperhomocysteinemia and exogenous ethanol reduces taurine levels in chick embryos

The effects of exogenous ethanol and/or folic acid on endogenous homocysteine (HoCys) and SAM (S-adenosylmethionine)/SAH (S-adenosylhomocysteine) levels in chick brains were studied at 11 days of development. Embryonic EtOH (3.0 mmol/kg egg) exposure caused a 1.6-fold increase in brain HoCys levels and a 9-fold decrease in brain SAM/SAH levels as compared to controls (p<or=0.05). Brain HoCys and SAM/SAH levels returned to control values when injected with a mixture of EtOH and folic acid (3.0 mmol EtOH/kg egg and 34 mumol folic acid/kg egg). The effects of exogenous EtOH on the remethylation pathway, as measured by 10-formyltetrahydrofolate dehydrogenase (10-FTHF DH) activities, and the transsulfuration pathway, as measured by taurine levels, were studied at 18 days of development. A single dosage of EtOH (3.0 mmol/kg egg; E(0)) and two daily dosages of EtOH (E(0-1)) failed to influence brain and hepatic 10-FTHF DH activities when compared to controls. However, three daily dosages of EtOH (E(0-2)) caused approximately a two-fold increase in brain 10-FTHF DH activities and a three-fold increase in hepatic 10-FTHF DH activities as compared to controls (p<or=0.05). Three daily EtOH dosages (E(0-2)) caused reduced taurine levels in both brain and hepatic tissues (p<or=0.05). Meanwhile, a single EtOH dosage (E(0)), two daily EtOH dosages (E(0-1)), and three daily EtOH dosages (E(0-2)), caused reduced hepatic taurine levels as compared to controls (p<or=0.05).

Protective effect of vitamin E against ethanol-induced hyperhomocysteinemia, DNA damage, and atrophy in the developing male rat brain

BACKGROUND

Chronic alcoholism leads to elevated plasma and brain homocysteine (Hcy) levels, as demonstrated by clinical investigations and animal experiments. It has been posited that elevated levels of Hcy mediate DNA damage, brain atrophy, and excitotoxicity. The current study sought to elucidate the effect of vitamin E on ethanol-induced hyperhomocysteinemia, DNA damage, and atrophy in the developing hippocampus and cerebellum of rats.

METHODS

Pregnant Wistar rats received ethanol with or without vitamin E from gestation day 7 throughout lactation. Weight changes in the brain, hippocampus and cerebellum, DNA damage, and Hcy levels in the plasma, hippocampus, and cerebellum of male offspring were measured at the end of lactation.

RESULTS

The results revealed that along with a significant decrease in brain, cerebellum, and hippocampus weights in animals that received alcohol, the levels of DNA damage and Hcy significantly increased. Significant amelioration of brain atrophy and DNA damage as well as restoration of the elevated level of Hcy to that of controls were found in vitamin E-treated rats.

CONCLUSIONS

These findings strongly support the idea that ethanol intake by dams during pregnancy and lactation induces Hcy-mediated oxidative stress in the developing hippocampus and cerebellum of offspring rats, and that these effects can be alleviated by vitamin E as an antioxidant.

Herp mRNA expression in patients classified according to Lesch's typology

Chronic alcoholism is associated with hyperhomocysteinemia. Herp (homocysteine-induced endoplasmic reticulum [ER] protein) levels are elevated as a response to ER stress prior to mitochondrial dysfunction and cell death. The Lesch classification system has been applied in many studies and has been found useful. This study was undertaken to assess Herp mRNA expression in actively drinking patients with alcoholism who were classified according to Lesch's typology. Herp mRNA expression levels were measured by quantitative PCR in the blood of 76 male alcoholic patients. Patients were classified according to Lesch's typology (type I-IV). With respect to Lesch's typology, a significant difference in Herp mRNA expression regarding the four subtypes could be shown (F[3,72]=2.83, P=.044). In a logistic regression model (dependent variable Herp dichotomized by a median-split; adjusted for age and homocysteine levels) the subtype II differed statistically significant from the others (odds ratio, 5.75; 95% confidence interval, 2.07-15.98; P=.001). Type II alcoholic patients had a statistically significant higher expression of Herp mRNA due to upregulation of the expression of this neuroprotective cell non-chaperone by toxic effects of ethanol. These findings might explain why type II patients do not express severe withdrawal symptomatology (i.e., withdrawal seizures). These findings may be useful in the understanding and treatment considerations of different subtypes of alcohol dependence.

Breath alcohol level and plasma amino acids: a comparison between older and younger chronic alcohol-dependent patients

AIM

The aim of the present study is to examine the distribution of plasma excitatory and inhibitory amino acids, according to the age and current breath alcohol levels (BrAl+/-), of alcohol-dependent patients.

PARTICIPANTS AND METHODS

78 alcohol-dependent patients (mean age=46.2+/-11 years, men/women=54/24) were clinically tested, including the determination of the major excitatory as well as inhibitory amino acids. The independent variables were gender, age and current alcohol consumption measured with the breath alcohol level (BrAl+/-status).

RESULTS

In comparison to BrAl negatives, BrAl positives had higher plasma levels of glutamic acid (P=0.01) and proline (P=0.026), and lower levels of aminobutyric acid (P=0.002), serine (P=0.031) and urea (P=0.01). In the BrAl positives, no age effect was found related to the plasma amino acids. In contrast, the BrAl negatives displayed age-related differences. The older (>or=50 years) BrAl negative patients had higher plasma levels of cystine, tyrosine, citrulline and urea, and lower histidine levels, compared to the younger group (<50 years). In general, differences in plasma levels of certain amino acids were dependent on gender, BrAl status, age and biochemical markers (GGT, MCV) of alcohol abuse.

CONCLUSIONS

Abstaining patients (BrAl-/) display age-related differences in AAs' distribution, while active drinking (BrAl+/) seems to even out those differences, underpinning the hypothesis that drinking mimics changes seen with advanced age.

Hippocampal volumes and depression subtypes

Studies of depression and hippocampal volume have yielded inconsistent results. This inconsistency could stem from the heterogeneity of depressive disorders. We conducted cross-sectional and longitudinal analyses of hippocampal volumes in atypical depressive, melancholic depressive, and control subjects. We found no effect of depression subtype on hippocampal volume or memory performance.

Protective effect against alcohol dependence of the thermolabile variant of MTHFR

BACKGROUND

Hyperhomocysteinemia is frequently observed in alcohol-dependent subjects, in particularly in those with marked withdrawal symptoms. The common C677T transition on the methylenetetrahydrofolate reductase (MTHFR) gene influences homocysteinemia. Our objective was to study the prevalence of the MTHFR C677T polymorphism in alcohol-dependent subjects and the influence of this polymorphism on symptoms associated with alcoholism.

METHODS

MTHFR C677T polymorphism was determined in 93 control subjects and 242 alcohol-dependent subjects. Serum homocysteine, folate and vitamin B12 levels together with hepatic biological parameters were determined in the control and alcohol-dependent subjects.

RESULTS

Hyperhomocysteinemia is frequently observed in alcohol-dependent subjects, particularly in those with marked withdrawal symptoms. Alcohol-dependent subjects showed a significant decrease in MTHFR 677TT prevalence (9%, 21/242) compared to controls (18%, 17/93) (p<0.02). The relative risk estimated as an odds ratio for alcoholism in subjects with the TT genotype is 0.42 (odd ratio 95% confidence interval, 0.21-0.83). Moreover, drinkers with TT genotype presented lower values for markers of alcohol misuse (p<0.05), better liver function tests, a lower frequency of relapses and no marked withdrawal symptoms as assessed by the Lesch typology.

CONCLUSION

MTHFR 677TT genotype could play a protective role against alcohol dependence. Moreover, when subjects with MTHFR 677TT genotype become dependent to alcohol, they seem to constitute a subgroup of alcoholic patients with a decreased risk for developing neurotoxic withdrawal symptoms and hepatic toxicity.

Homocysteine activates calcium-mediated cell signaling mechanisms targeting the cytoskeleton in rat hippocampus

Homocysteine is considered to be neurotoxic and a risk factor for neurodegenerative diseases. Despite the increasing evidences of excitotoxic mechanisms of homocysteine (Hcy), little is known about the action of Hcy on the cytoskeleton. In this context, the aim of the present work was to investigate the signaling pathways involved in the mechanism of action of Hcy on cytoskeletal phosphorylation in cerebral cortex and hippocampus of rats during development. Results showed that 100 microM Hcy increased the intermediate filament (IF) phosphorylation only in 17-day-old rat hippocampal slices without affecting the cerebral cortex from 9- to 29-day-old animals. Stimulation of (45)Ca(2+) uptake supported the involvement of NMDA receptors and voltage-dependent channels in extracellular Ca(2+) flux, as well as Ca(2+) release from intracellular stores through inositol-3-phosphate and ryanodine receptors. Moreover, the mechanisms underlying the Hcy effect on hippocampus cytoskeleton involved the participation of phospholipase C, protein kinase C, mitogen-activated protein kinase, phosphoinositol-3 kinase and calcium/calmodulin-dependent protein kinase II. The Hcy-induced IF hyperphosphorylation was also related to G(i) protein and inhibition of cAMP levels. These findings demonstrate that Hcy at a concentration described to induce neurotoxicity activates the IF-associated phosphorylating system during development in hippocampal slices of rats through different cell signaling mechanisms. These results probably suggest that hippocampal rather than cortical cytoskeleton is susceptible to neurotoxical concentrations of Hcy during development and this could be involved in the neural damage characteristic of mild homocystinuric patients.

Greater intake of vitamins B6 and B12 spares gray matter in healthy elderly: a voxel-based morphometry study

Previous studies have reported that high concentrations of homocysteine and lower concentrations of vitamins B6, B12, and folate increase the risk for cognitive decline and pathology in aging populations. In this cross-sectional study, high resolution magnetic resonance imaging (MRI) scans and a 3-day food diary were collected on 32 community-dwelling adults between the ages of 59 and 79. We examined the relation between vitamins B6, B12, and folate intake on cortical volume using an optimized voxel-based morphometry (VBM) method and global gray and white matter volume after correcting for age, sex, body mass index, calorie intake, and education. All participants met or surpassed the recommended daily intake for these vitamins. In the VBM analysis, we found that adults with greater vitamin B6 intake had greater gray matter volume along the medial wall, anterior cingulate cortex, medial parietal cortex, middle temporal gyrus, and superior frontal gyrus, whereas people with greater B12 intake had greater volume in the left and right superior parietal sulcus. These effects were driven by vitamin supplementation and were negated when only examining vitamin intake from diet. Folate had no effect on brain volume. Furthermore, there was no relationship between vitamins B6, B12, or folate intake on global brain volume measures, indicating that VBM methods are more sensitive for detecting localized differences in gray matter volume than global measures. These results are discussed in relation to a growing literature on vitamin intake on age-related neurocognitive deterioration.

Ethanol-induced increased endogenous homocysteine levels and decreased ratios of SAM/SAH are only partially attenuated by exogenous glycine in developing chick brains

The effects of exogenous ethanol (EtOH) and/or glycine on chick (Gallus gallus) embryo viability, brain apoptosis (caspase-3 activities), and the endogenous levels of brain homocysteine (HoCys), S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), and SAM/SAH were studied. Embryonic EtOH exposure caused decreased embryo viability as measured by EtOH-induced reductions in % living embryos at theoretical stage 37, EtOH-induced reductions in embryo masses, and EtOH-induced reductions in brain caspase-3 (Casp-3) activities. Exogenous glycine failed to attenuate EtOH-induced decreased embryo viability and EtOH-induced increased brain Casp-3 activities. Embryonic EtOH exposure caused elevated levels of endogenous HoCys, decreased levels of SAM, increased levels of SAH, and decreased SAM/SAH ratios in embryonic chick brains. While exogenous glycine failed to attenuate EtOH-induced increased HoCys levels, exogenous glycine attenuated EtOH-induced decreased levels of SAM, increased levels of SAH, and decreased SAM/SAH levels in embryonic chick brains.

Smooth muscle-associated protein 8: distribution and biological activity in the rat brain

With the use of an antiserum directed against the human smooth muscle-associated protein 8 (SMAP8) fragment SMAP8(98-138), Western blot and immunohistochemical studies revealed SMAP8 expression in the rat brain. A band with a molecular size of about 45 kDa was detected in tissues from the rat hypothalamus and a weaker band from the cortex. SMAP8 immunoreactivity (irSMAP8) was detected in neurons of the hypothalamic paraventricular, supraoptic, and supraoptic retrochiasmatic nuclei; a few irSMAP8 cells were scattered in the zona incerta as well as the cerebral cortex. Immunoreactive cell processes were detected mostly in the internal layer of the median eminence. Double labeling the hypothalamic sections with SMAP8 and vasopressin (VP) or oxytocin (OT) antiserum revealed that a population of VP- and OT-immunoreactive neurons expressed irSMAP8. The biological activity of SMAP8 in rat central neurons was assessed by the calcium microfluorimetric Fura-2 method. SMAP8 (100 nM) elevated cytosolic calcium concentrations [Ca2+]i in a population of dissociated and cultured rat hypothalamic neurons; the response was eliminated in Ca2+-free saline. This is the first evidence of irSMAP8 in a population of VP/OT-containing hypothalamic neurons in the rat, and the peptide is biologically active in hypothalamic neurons, as evidenced by mobilization of extracellular Ca2+.

Apolipoprotein E polymorphism, homocysteine serum levels and hippocampal volume in patients with alcoholism: an investigation of a gene-environment interaction

There is growing evidence that disadvantageous influences of the apolipoprotein E4 allele in the central nervous system are modified by environmental and dietary conditions. The present study investigated the gene-environment interaction of apolipoprotein E4 with homocysteine serum levels in patients with alcohol dependence with regard to alcohol-related hippocampal volume loss using volumetric high-resolution magnetic resonance imaging. We included 52 patients with alcohol-dependence. ApoE genotypes, homocysteine serum levels and hippocampal volumes were determined. We found a significant impact of homocysteine (F=13.2; df=1; P<0.001; 1-beta=0.95), not for ApoE4 genotype (F=0.482; df=1; P=0.49; 1-beta=0.05) on hippocampal volume. There was a significant interaction between both factors (ApoE4 x Hcy; F=8.8; df=1; P=0.005; 1-beta=0.80). The ApoE4 allele constitutes a risk factor for hippocampal volume loss in patients with alcohol dependence under the conditions of hyperhomocysteinemia. We suggest that the disadvantageous effects of apolipoprotein E4 on alcohol-related brain volume loss are based on certain gene-environment interactions.

Hippocampus volume loss due to chronic heavy drinking

OBJECTIVE

No clear consensus exists regarding the effect of sustained, heavy drinking on hippocampal volume. Our prior work hypothesized significantly lowered total hippocampus volumes in heavy chronically drinking alcohol-dependent (AD) subjects compared with light-drinking nondependent control subjects matched for age and gender.

METHOD

Using a series of applicable exclusion criteria culled from previous published studies, we measured hippocampal volumes from MRI scan data acquired on a 3T scanner and subjected those data to automated volume analysis blind to the drinking history.

RESULTS

Comparison with AD test (n=8) and non-AD control (n=8) subjects found significant lessening in total (p=0.020) and left (p=0.010) hippocampal volumes with a near-significant difference on the right (p=0.051). Linear regression demonstrated that neither total brain volume nor intracranial volume affected the hippocampus measures.

CONCLUSIONS

These data support the view that heavy drinking exerts a unique and selectively injurious effect on the hippocampus. Further study in larger samples must verify this in a search for possible mechanisms of injury.

Binding of copper is a mechanism of homocysteine toxicity leading to COX deficiency and apoptosis in primary neurons, PC12 and SHSY-5Y cells

Children with hereditary severe hyperhomocysteinemia present with a variety of neurological impairment, and mild hyperhomocysteinemia has been associated with neurodegeneration in the elderly. The link of hyperhomocysteinemia to neurological dysfunction is unknown. We investigated mitochondrial mechanisms of homocysteine (HCys) neurotoxicity in rat dopaminergic pheochromocytoma cells, human neuroblastoma cells and primary rat cerebellar granule neurons. HCys dose dependently impaired cytochrome c oxidase (COX) activity as well as stability and induced reactive oxygen species and apoptotic cell death. We found that HCys binds the COX cofactor Cu(2+), and Cu(2+) supplementation prior to HCys treatment preserved COX activity and prevented cell death. The Cu(2+) chelating action of HCys and impairement of COX activity represent novel mechanisms of HCys neurotoxicity, which might be preventable by supplementation of Cu(2+).

Differential aging of the brain: patterns, cognitive correlates and modifiers

Deciphering the secret of successful aging depends on understanding the patterns and biological underpinnings of cognitive and behavioral changes throughout adulthood. That task is inseparable from comprehending the workings of the brain, the physical substrate of behavior. In this review, we summarize the extant literature on age-related differences and changes in brain structure, including postmortem and noninvasive magnetic resonance imaging (MRI) studies. Among the latter, we survey the evidence from volumetry, diffusion-tensor imaging, and evaluations of white matter hyperintensities (WMH). Further, we review the attempts to elucidate the mechanisms of age-related structural changes by measuring metabolic markers of aging through magnetic resonance spectroscopy (MRS). We discuss the putative links between the pattern of brain aging and the pattern of cognitive decline and stability. We then present examples of activities and conditions (hypertension, hormone deficiency, aerobic fitness) that may influence the course of normal aging in a positive or negative fashion. Lastly, we speculate on several proposed mechanisms of differential brain aging, including neurotransmitter systems, stress and corticosteroids, microvascular changes, calcium homeostasis, and demyelination.

ER stress: can the liver cope?

Hepatocytes contain abundant endoplasmic reticulum (ER) which is essential for protein metabolism and stress signaling. Hepatic viral infections, metabolic disorders, mutations of genes encoding ER-resident proteins, and abuse of alcohol or drugs can induce ER stress. Liver cells cope with ER stress by an adaptive protective response termed unfolded protein response (UPR), which includes enhancing protein folding and degradation in the ER and down-regulating overall protein synthesis. When the UPR adaptation to ER stress is insufficient, the ER stress response unleashes pathological consequences including hepatic fat accumulation, inflammation and cell death which can lead to liver disease or worsen underlying causes of liver injury, such as viral or diabetes-obesity-related liver disease.

An assessment of the potential value of elevated homocysteine in predicting alcohol-withdrawal seizures

PURPOSE

Higher homocysteine levels were found in actively drinking patients with alcohol dependence. Recent studies have shown that high homocysteine levels are associated with alcohol-withdrawal seizures. The aim of the present study was to calculate the best predictive cutoff value of plasma homocysteine levels in actively drinking alcoholics (n = 88) with first-onset alcohol-withdrawal seizures.

METHODS

The present study included 88 alcohol-dependent patients of whom 18 patients had a first-onset withdrawal seizure. All patients were active drinkers and had an established diagnosis of alcohol dependence, according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Sensitivity and specificity were calculated by using every homocysteine plasma level found in the study population as cut-off value. A Bayes theorem was used to calculate positive (PPV) and negative (NPV) predictive values for all cutoff values used.

RESULTS

The highest combined sensitivity and specificity was reached at a homocysteine plasma cutoff value of 23.9 microM. Positive predictive values ranged from 0.23 to 0.745; the maximum was reached at a homocysteine plasma level of 41.7 microM. Negative predictive values ranged from 0.50 to 0.935, with a maximum at a homocysteine plasma level of 15.8 microM.

CONCLUSIONS

Homocysteine levels above this cutoff value on admission are a useful screening tool to identify actively drinking patients at higher risk of alcohol-withdrawal seizures. This pilot study gives further hints that biologic markers may be helpful to predict patients at risk for first-onset alcohol-withdrawal seizures.

Epigenetic DNA hypermethylation of the HERP gene promoter induces down-regulation of its mRNA expression in patients with alcohol dependence

BACKGROUND

Elevated plasma homocysteine concentrations can influence genomic and gene-specific DNA methylation in peripheral blood cells. The aim of this study was to investigate in patients with alcohol dependence, who show chronically elevated homocysteine levels, whether DNA methylation pattern within the HERP (homocysteine-induced endoplasmic reticulum protein) promoter region and expression of HERP mRNA is altered.

METHODS

The HERP mRNA expression level was measured by quantitative PCR in the blood of 66 male alcoholic patients and 55 nondrinking healthy controls. Epigenetic genomic DNA methylation status and HERP promoter methylation were measured with a nonradioactive elongation assay.

RESULTS

We observed a significant increase (7.6%) in the HERP promoter DNA methylation in patients with alcohol dependence (t test, t = -2.45, p < 0.02) when compared with healthy controls (80.4%, SD 14.5), which was significantly associated with their elevated homocysteine levels (multiple linear regression, p < 0.007). Furthermore, we found a significantly lower HERP mRNA expression in patients with alcohol dependence (t test, -7.61 DeltaCT; SD 1.87, p < 0.001) when compared with healthy controls (-6.04 DeltaCT; SD 2.41). The lowered HERP mRNA expression in alcoholic patients was best explained by the hypermethylation of the regulatory HERP gene promoter (regression analysis, p = 0.004).

CONCLUSIONS

To our knowledge, this is the first study evaluating HERP mRNA expression and its specific gene promoter methylation in alcoholic patients. As hypermethylation of DNA is an important epigenetic factor in the down-regulation of gene expression, and as HERP has been considered to play an essential role within the intracellular defense system, these findings may be useful in the understanding and treatment of different disease conditions associated with alcohol dependence.

DIFFERENT ALLELE-DISTRIBUTION OF MTHFR 677 C → T AND MTHFR −393 C → A IN PATIENTS CLASSIFIED ACCORDING TO SUBTYPES OF LESCH'S TYPOLOGY

AIMS

The typology by Lesch distinguishes between four subtypes: type 1 (model of allergy), type 2 (model of anxiety or conflict), type 3 (alcohol as an antidepressant), and type 4 (alcohol as adaptation). Taking into account that alcohol dependence is associated with elevated homocysteine levels, this study was undertaken to investigate different MTHFR (methylenetetrahydrofolate reductase) genotypes related to homocysteine metabolism in patients with alcohol dependence who were classified according to Lesch's typology (LT).

SUBJECTS AND METHODS

134 non-abstinent chronic alcoholics (112 males, 22 females; mean age 44.2 (SD 8.9) years) were classified according to LT and divided into four groups: LT 1 (n = 26), LT 2 (n = 65), LT 3 (n = 58), and LT 4 (n = 18). Total plasma homocysteine levels and MTHFR genotypes -393, 677, and 1,793 were determined.

RESULTS

We observed a significantly higher frequency of the thermolabile MTHFR 677 C-->T variant (TT) in patients classified as subtype LT4 when compared with subtypes LT2 and LT3 (P = 0.005). Furthermore, for the MTHFR -393 C --> A-polymorphism, significantly more AC/AA variants were found in subtype LT4 (P = 0.034). No differences in allele-distribution were detected for MTHFR 1793.

CONCLUSION

To our knowledge, this is the first study evaluating MTHFR genotypes in patients who were classified according to LT. Significantly different distributions of MTHFR 677 and -393 variants within Lesch Type 4 as compared with Types 2 and 3 hint at genetic determination of Lesch subtypes.

High homocysteine serum levels in young male schizophrenia and bipolar patients and in an animal model

Elevated plasma homocysteine has been found to be a risk factor for Alzheimer's disease as well as cerebral vascular disease, suggesting that some risk factors can accelerate or increase the severity of several CNS disease processes. We screened plasma total homocysteine levels of 193 schizophrenic patients vs. 762 controls for plasma homocysteine levels. The effect of schizophrenia was marked (p<0.0001) and mean homocysteine level was 16.3+/-12 (S.D.) microM in schizophrenic patients vs. 10.6+/-3.6 (S.D.) microM in healthy controls. The increase was almost entirely in young male schizophrenic patients. It seemed important to determine if this finding is already present in newly admitted schizophrenic patients. Serum homocysteine levels were studied in 184 consecutively admitted schizophrenic patients and 305 control subjects. Homocysteine levels were markedly increased in this population of newly admitted schizophrenic patients, especially in young males. However, no difference was found for CSF homocysteine levels between schizophrenia patients and controls. We also examined homocysteine levels in 41 euthymic outpatients with bipolar disorder. Functional deterioration in patients was rated as 'present' or 'absent' by consensus of two treating clinicians. Young male bipolar patients were found to have higher homocysteine levels than controls. Among the male subjects, bipolar patients showing deterioration had homocysteine levels which were significantly higher than other patients. We attempted to develop a model of homocysteine neurotoxicity in mice. Mice were fed homocysteine in water at a dose of 200 mg/kg per mouse per day. Independent samples of animals were studied at 2 to 6 months with behavioral tests including apomorphine-induced stereotypy and spatial learning and memory in the Morris Water Maze. Homocysteine levels were elevated up to 800% at months 5 and 6 by this procedure. No homocysteine-induced defects were found in any behavioral test until month 5 when mild but statistically significant abnormalities in the Morris Water Maze were detected.

Long-term homocysteine exposure induces alterations in spatial learning, hippocampal signalling and synaptic plasticity

Abnormally high levels of homocysteine (HCY) have been linked to neurodegenerative diseases, but it remains unclear whether this is the cause or effect of degenerative processes. Here, we investigated the effects of prolonged HCY exposure on cognitive abilities and physiological parameters by injecting rats daily with either 20 or 200 mg/kg HCY over a period of up to 14 weeks. Notwithstanding a significant weight reduction in the 200 mg HCY group, HCY-exposed animals did not show a behavioural deficit when tested repeatedly (in weeks 1, 3, 5, 7 and 13) in a reference memory version of the water maze. Unexpectedly, some improvement in repeated reversal learning was observed in HCY exposed animals compared to controls. Pre-treatment with HCY for 3 weeks before water maze training did not uncover any cognitive alterations. Increased plasma concentrations of HCY were revealed only for the 200 mg HCY group after 14 weeks of injections, but no evidence for DNA damage was obtained. Immunocytochemically, HCY was detected in the brain after 14 weeks of treatment (both 20 and 200 mg/kg), but not after 5 weeks. Bidirectional changes in basic synaptic transmission and long-term potentiation of hippocampal CA1 pyramidal cells were observed at 5, 7 and 14 weeks in both HCY groups, indicative of complex, multifactorial time- and concentration-dependent changes. Overall, it is concluded that healthy adult rats are able to cope with continuous exposure to HCY. While HCY affects growth and neuronal excitability, this does not precipitate into an immediate impairment of cognitive function.

Activation of catechol-O-methyltransferase in astrocytes stimulates homocysteine synthesis and export to neurons

Elevation of the total homocysteine (tHcy) concentration in plasma has been implicated in neurodegeneration in patients with stroke, dementia, Alzheimer disease, and Parkinson disease. Because the mechanisms controlling brain tHcy are unknown, the present study investigated its synthesis and transport in primary rat brain cell cultures. We found that the catechol-O-methyltransferase (COMT) substrate 3,4-dihydroxybenzoic acid (DHB) increased export of tHcy in astrocytes, but not in neurons. The export mechanism was selective for tHcy over cyst(e)ine, total glutathione (tGSH) or cysteinylglycine (Cys-Gly). tHcy export from astrocytes was also induced by the COMT substrates levodopa (L-DOPA), dopamine and quercetin, and it was blocked by the COMT inhibitors tropolone and entacapone. This export was associated with increased synthesis of tHcy because both intracellular and extracellular tHcy concentrations rose during COMT activation. Incubation in cyst(e)ine-deficient medium inhibited the tHcy export response to COMT activation. Exogenous tHcy (100 muM) was accumulated into neurons, but not into astrocytes. We conclude that activation of COMT causes sustained synthesis of Hcy in astrocytes and transport of this amino acid to neurons.

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

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 chi2=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.