Folic acid supplementation can reduce the endothelial damage in rat brain microvasculature due to hyperhomocysteinemia

The protective effects of butorphanol tartrate against homocysteine-induced blood-brain barrier dysfunction

A high concentration of homocysteine (Hcy) has been recently reported to be closely associated with the development of stroke, which is related to the Hcy-induced blood-brain barrier (BBB) dysfunction. Butorphanol tartrate is a promising analgesic agent that targets the opiate receptor and shows promising protective effects on ischemia/reperfusion injury. The present research proposes to investigate the protective effect of butorphanol tartrate on Hcy-induced BBB disruption to explore the potential application of butorphanol tartrate in treating Hcy-induced stroke. Hcy was utilized to establish both an in vivo animal model and in vitro human brain vascular endothelial cells (HBVECs) injury model. We found that the increased diffusion of sodium fluorescein and Evan’s blue, declined expression of Claudin-5, and increased production of interleukin- 6 (IL-6) and tumor necrosis factor-α (TNF-α) were observed in Hcy-treated mice, which were all significantly reversed by butorphanol tartrate. In Hcy-stimulated HBVECs, increased endothelial permeability and reduced expression levels of Claudin-5 and Krüppel-like factor 5 (KLF5) were observed, all of which were dramatically rescued by 2 and 5 µM butorphanol tartrate. Lastly, the protective function of butorphanol tartrate in Hcy-stimulated HBVECs was dramatically abolished by the knockdown of KLF5. Collectively, butorphanol tartrate showed protective effects on Hcy-induced BBB disruption by upregulating the KLF5/Claudin-5 axis.

The potential use of folate and its derivatives in treating psychiatric disorders: A systematic review

OBJECTIVES

To examine the strengths and limitations of existing data to provide guidance for the use of folate supplements as treatment, with or without other psychotropic medications, in various psychiatric disorders. To identify area for further research in terms of the biosynthesis of mechanism of folate and genetic variants in metabolic pathway in human.

METHODS

A systematic review of published literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, to assess whether folate supplements are beneficial in certain psychiatric disorders (depression, bipolar disorder, schizophrenia, autism spectrum disorder, and attention deficit hyperactivity disorder). Methodology of this review is registered with Prospero (Registration number CRD 42021266605).

DATA SOURCES

Eligible studies were identified using a systematic search of four electronic databases: Embase, Pubmed, PsycINFO, and Cochrane. The search strategy covered the time period from 1974 to August 16th, 2021. Therefore, this review examines randomized control trials or open-label trials completed during this period.

RESULTS

We identified 23 studies of folate supplements in various psychiatric disorders for critical review. Of these, 9 studies investigated the efficacy of folate supplements in major depressive disorders, 5 studies in schizophrenia, 6 studies in autism spectrum disorder, 2 studies in bipolar affective disorder and 1 study in attention deficit hyperactive disorder. The most consistent finding association of oral levomefolic acid or 5-methylfolate with improvement in clinical outcomes in mental health conditions as mentioned above, especially in major depressive disorder (including postpartum and post-menopausal depression), schizophrenia, autism spectrum disorder, attention deficit hyperactivity disorder and bipolar affective disorder. Folate supplements were well tolerated.

LIMITATION

Our results are not representative of all types of studies such as case reports or case series studies, nor are they representative of the studies conducted in languages that are not in English or not translated in English.

CONCLUSION

Increasing evidence from clinical trials consistently demonstrate folate supplements, especially levomefolic acid or 5-methylfolate, may improve clinical outcomes for certain psychiatric diseases, especially as an adjunct pharmacotherapy with minimal side effects.

Effects of Inadequate Folate Intake on the Onset and Progression of Hypertensive Vascular Injury

We investigated the effects of inadequate folate intake on the onset and progression of hypertensive organ injury. In the present study, 5-wk-old male stroke-prone spontaneously hypertensive rats (SHRSP) were fed with a normal-folate (control; 160-170 μg of folate/100 g diet) or low-folate (8-10 μg of folate/100 g diet) diet until they reached 25 wk of age. After the animals reached 10 wk of age, the bodyweight of the rats in the low-folate group was lower than that of the rats in the control group. Regarding blood pressure, both groups had severe hypertension of ≥230 mmHg at 12 wk of age that was not significantly different between the groups. At 16 wk of age, the low-folate group had a low number of blood cell types. The folate levels in the serum, liver, and kidneys of these rats were significantly lower (p<0.01) and the serum homocysteine level in the low-folate group was significantly higher than in the controls. The low-folate group had a significantly lower testicular weight than the control group (p<0.05) and arterial hypertrophy, spermatogenesis arrest, and interstitial connective tissue hyperplasia were observed. However, there was no clear difference in lesions in other organs. These results indicated that under low folate status, SHRSP causes hematopoietic disorders and exacerbates hypertensive vascular injury at various degrees by organ type.

Preliminary analysis of immunoregulatory mechanism of hyperhomocysteinemia-induced brain injury in Wistar-Kyoto rats

Hyperhomocysteinemia (HHcy) can be used as an independent risk factor for predicting cardiovascular disease, stroke and vitamin B12 deficiency. Patients with HHcy have elevated plasma homocysteine (Hcy) concentrations. Enhancing cerebrovascular permeability of substances such as Hcy and brain damage will synergistically increase the symptoms of hypertension, but the specific immune regulation mechanism is still not clear. The purpose of the present study was to preliminarily explore the immunomodulatory mechanism of brain damage caused by HHcy in Wistar-Kyoto (WKY) rats. A total of 60 WKYs were randomly divided into three groups: WKY control group (WKY-C group), WKY methionine group (WKY-M group) and WKY treatment group (WKY-T group; vitamin B6, B12 and folic acid were used as treatment), with 20 rats in each group. Physical examination of body weight, systolic blood pressure (SBP) and plasma Hcy content was performed routinely. The concentration of cytokines, including IL-6, IL-10, IL-17A and TGF-β, associated with T helper cell 17 (Th17) and regulatory T (Treg) cells and key regulator genes, including retinoic acid-related orphan receptor γ t (RORγt) and forkhead box P3 (FoxP3), were detected by ELISA, reverse transcription-quantitative PCR and western blotting. Th17/Treg lymphocytes were determined by flow cytometry. MRI scan was preliminarily used to detect the changes characteristic of the ischemic stroke. The results revealed that high methionine diets might have a significant effect on the body weight and SBP. The inflammatory response effect of Treg cells was significantly inhibited in the WKY-M group, and that of Th17 cells was upregulated when compared to the WKY-T group. Compared with the WKY-T group, the expression levels of IL-17A and RORγt in the WKY-M group were significantly upregulated, while the mRNA levels of FoxP3 in the WKY-M group were significantly downregulated. The diet intervention (including vitamins B6 and B12 and folic acid) could reduce the level of Hcy in the blood, but also reduce the inflammatory response and rectify the Treg/Th17 immune imbalance to ameliorate the brain tissue damage. In conclusion, the present study indicated that HHcy can promote inflammation by triggering Treg/Th17 immune imbalance to ameliorate the brain tissue damage.

Scutellarin-treated exosomes increase claudin 5, occludin and ZO1 expression in rat brain microvascular endothelial cells

Homocysteine has been reported to be an independent risk factor for stroke. Scutellarin (Scu) dilates cerebral blood vessels and promotes anti-platelet aggregation; however, the mechanism by which Scu and Scu-treated exosomes protect against cerebrovascular disease is unclear. The aim of the present study was to investigate the mechanisms underlying the effects of Scu and Scu-treated exosomes on tight junction proteins in the blood-brain barrier. Rat brain microvascular endothelial cells (RBMVECs) were cultured and divided into five groups: Control, model, Scu, exosomes derived from RBMVECs and exosomes derived from RBMVECs after Scu administration. MTT, lactate dehydrogenase (LDH) and nitric oxide (NO) assays were performed to assess cell viability and injury. Reactive oxygen species (ROS) levels were detected using spectrophotometry and immunofluorescence. Western blotting and immunofluorescence were performed to measure cluster of differentiation (CD) 63, claudin 5, occludin and tight junction protein 1 (ZO1) expression. The results revealed that treatment with Scu and Scu-treated exosomes enhanced cell viability, reduced cell injury, increased NO levels, upregulated CD63, claudin 5, occludin and ZO1, and decreased LDH and ROS levels. These data suggest that Scu and Scu-treated exosomes protect homocysteine-induced RBMVECs via increased claudin 5, occludin and ZO1 expression.

The immunomodulatory mechanism of brain injury induced by hyperhomocysteinemia in spontaneously hypertensive rats

BACKGROUND

Elevated plasma homocysteine (Hcy) concentration is considered as the diagnostic criteria of Hyperhomocysteinemia (HHcy), which is associated with the inflammatory response and blood-brain barrier disruption. Previous studies have proposed that HHcy with hypertension was associated with the brain injury by enhancing the cerebrovascular permeability, however, the immune mechanism remains obscure. The purpose of the study is to explore the immunomodulatory mechanism of brain injury in spontaneously hypertensive rats (SHRs) induced by HHcy.

MATERIALS AND METHODS

Sixty SHRs were randomly assigned to three groups: SHR-C (control group), SHR-M (methionine group) and SHR-T (treatment group). Physical examination of body weight, systolic blood pressure (SBP) and plasma Hcy content was measured every 4 weeks. Besides, T-helper cell 17 and regulatory T cells (Treg)-related inflammatory cytokines (interleukin [IL]-6, IL-17, IL-10, and transforming growth factor beta [TGF-β]) and genes (RORγt and FoxP3) were detected by enzyme-linked immunosorbent assay, quantitative polymerase chain reaction , Western blot, and immunohistochemistry.

RESULTS

High methionine diet could cause weight loss, SBP rising, and plasma Hcy content significantly elevated. IL-16 and IL-17A levels in peripheral blood and in brain tissue both lifted, while IL-10 and TGF-β levels dropped; RORγt expression raised in brain, nevertheless, FoxP3 levels were the opposite. After the intervention with vitamin B6, B12, and folic acid in SHR-T group, these trends would be eased or completely changed. Furthermore, brain tissue slices showed that IL-17-positive cells tended to decrease, and IL-10-positive cells increased in SHR-T group, which was reversed in SHR-M group.

CONCLUSIONS

HHcy may promote inflammation that can lead to brain lesions and down-regulate immune response to protect the brain.

Hyperhomocysteinemia induced by excessive methionine intake promotes rupture of cerebral aneurysms in ovariectomized rats

Background

Hyperhomocysteinemia (HHcy) is associated with inflammation and a rise in the expression of matrix metalloproteinase-9 (MMP-9) in the vascular wall. However, the role of HHcy in the growth and rupture of cerebral aneurysms remains unclear.

Methods

Thirteen-week-old female Sprague-Dawley rats were subject to bilateral ovariectomy and ligation of the right common carotid artery and fed an 8 % high-salt diet to induce cerebral aneurysms. Two weeks later, they underwent ligation of the bilateral posterior renal arteries. They were divided into two groups and methionine (MET) was or was not added to their drinking water. In another set of experiments, the role of folic acid (FA) against cerebral aneurysms was assessed.

Results

During a 12-week observation period, subarachnoid hemorrhage due to aneurysm rupture was observed at the anterior communicating artery (AcomA) or the posterior half of the circle of Willis. HHcy induced by excessive MET intake significantly increased the incidence of ruptured aneurysms at 6–8 weeks. At the AcomA of rats treated with MET, we observed the promotion of aneurysmal growth and infiltration by M1 macrophages. Furthermore, the mRNA level of MMP-9, the ratio of MMP-9 to the tissue inhibitor of metalloproteinase-2, and the level of interleukin-6 were higher in these rats. Treatment with FA abolished the effect of MET, suggesting that the inflammatory response and vascular degradation at the AcomA is attributable to HHcy due to excessive MET intake.

Conclusions

We first demonstrate that in hypertensive ovariectomized rats, HHcy induced by excessive MET intake may be associated with the propensity of the aneurysm wall to rupture.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0634-3) contains supplementary material, which is available to authorized users.

Homocysteine, hyperhomocysteinemia and vascular contributions to cognitive impairment and dementia (VCID)

Homocysteine is produced physiologically in all cells, and is present in plasma of healthy individuals (plasma [HCy]: 3-10μM). While rare genetic mutations (CBS, MTHFR) cause severe hyperhomocysteinemia ([HCy]: 100-200μM), mild-moderate hyperhomocysteinemia ([HCy]: 10-100μM) is common in older people, and is an independent risk factor for stroke and cognitive impairment. As B-vitamin supplementation (B6, B12 and folate) has well-validated homocysteine-lowering efficacy, this may be a readily-modifiable risk factor in vascular contributions to cognitive impairment and dementia (VCID). Here we review the biochemical and cellular actions of HCy related to VCID. Neuronal actions of HCy were at concentrations above the clinically-relevant range. Effects of HCy <100μM were primarily vascular, including myocyte proliferation, vessel wall fibrosis, impaired nitric oxide signalling, superoxide generation and pro-coagulant actions. HCy-lowering clinical trials relevant to VCID are discussed. Extensive clinical and preclinical data support HCy as a mediator for VCID. In our view further trials of combined B-vitamin supplementation are called for, incorporating lessons from previous trials and from recent experimental work. To maximise likelihood of treatment effect, a future trial should: supply a high-dose, combination supplement (B6, B12 and folate); target the at-risk age range; and target cohorts with low baseline B-vitamin status. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.

Therapeutic potential of folic acid supplementation for cardiovascular disease prevention through homocysteine lowering and blockade in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a chronic inflammatory disease that preferentially affects joints, and characterized by an approximately two-fold increased risk of cardiovascular diseases compared with the general population. Beyond classical cardiovascular risk factors, systemic inflammatory markers are primarily involved. Hence, anti-inflammatory strategies such as homocysteine-lowering interventions are warranted. Indeed, hyperhomocysteinemia is commonly found in RA patients as a result of both genetic and non-genetic factors including older age, male gender, disease-specific features and disease-modifying antirheumatic drugs. Most importantly in the pathophysiology of hyperhomocysteinemia and its related cardiovascular diseases in RA, there is a bi-directional link between immuno-inflammatory activation and hyperhomocysteinemia. As such, chronic immune activation causes B vitamins (including folic acid) depletion and subsequent hyperhomocysteinemia. In turn, hyperhomocysteinemia may perpetrate immuno-inflammatory stimulation via nuclear factor ƙappa B enhancement. This chronic immune activation is a key determinant of hyperhomocysteinemia-related cardiovascular diseases in RA patients. Folate, a homocysteine-lowering therapy could prove valuable for cardiovascular disease prevention in RA patients in the near future with respect to homocysteine reduction along with blockade of subsequent oxidative stress, lipid peroxidation, and endothelial dysfunction. Thus, large scale and long term homocysteine-lowering clinical trials would be helpful to clarify the association between hyperhomocysteinemia and cardiovascular diseases in RA patients and to definitely state conditions surrounding folic acid supplementation. This article reviews direct and indirect evidence for cardiovascular disease prevention with folic acid supplementation in RA patients.

Iron-induced damage in corpus striatal cells of neonatal rats: attenuation by folic acid

BACKGROUND

Iron supplementation is recommended during pregnancy to meet the needs of the rapidly growing fetus. However, its intake is associated with the generation of destructive free radicals, i.e., oxidative damage to the fetal brain. Folic acid supplementation is needed during pregnancy to reduce the risk of neural tube defects.

HYPOTHESIS

Intake of folic acid can ameliorate the morphological features of cell damage in the striatal tissue (brain of neonatal rats) associated with the intake of iron.

OBJECTIVES AND METHODS

To test this hypothesis, an animal model (pregnant Albino rats) was established. The animals were divided into three groups: group A, control animals treated with saline only; group B, animals treated with iron gluconate; and group C, animals treated concomitantly with iron gluconate and folic acid. The striatal brain tissues of the neonates were examined for features of cellular damage, using immunohistological and ultrastructural methods.

RESULTS

The authors found significant variations among the three groups. The intake of iron (group B) and its deposition in the striatal tissue (neurons and glial cells) was associated with changes indicative of both cellular injury and regeneration. The former includes neuronal apoptosis and necrosis, and destruction of the organelles, including the mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosomes of the neurons and glial cells. The latter includes microgliosis, astrogliosis, upregulation of glial fibrillary acidic protein, and inducible nitric oxide synthase. These changes were absent in the striatal tissue of the control group (group A) and in animals treated concomitantly with both iron gluconate and folic acid (group C).

CONCLUSION

Intake of folic acid can protect the neonatal striatal tissue against iron-induced oxidative stress damage.

Mild hyperhomocysteinemia alters extracellular adenine metabolism in rat brain

Since homocysteine (Hcy) is considered a risk factor to cerebral diseases and adenine nucleotides are important molecules to brain normal function, in the present study we investigated the effect of chronic mild hyperhomocysteinemia on ectonucleotidase activities and expression in rat cerebral cortex. The levels of ATP, ADP, AMP and adenosine (Ado) in cerebrospinal fluid (CSF) of adult rats also were evaluated by high-performance liquid chromatography. For the chronic chemically induced mild hyperhomocysteinemia, Hcy (0.03 μmol/g of body weight) was administered subcutaneously from the 30th to the 60th day of life. Control rats received saline solution in the same volumes. Results showed that Hcy significantly decreased nucleotide hydrolysis in the synaptosomal fraction and increased E-NTPDase1 and ecto-5'-nucleotidase transcripts in rat cerebral cortex. ATP levels were significantly increased, while Ado decreased in CSF of Hcy-treated rats. These findings suggest that the unbalance in ATP and Ado levels may be, at last in part, involved in the cerebral toxicity of mild hyperhomocysteinemia.

Differential effects of short- and long-term hyperhomocysteinaemia on cholinergic neurons, spatial memory and microbleedings in vivo in rats

Hyperhomocysteinaemia (HHcy) has been identified as a cardiovascular risk factor for neurodegenerative brain diseases. The aim of the present study was to investigate the effects of short (5 months) or long (15 months) HHcy in Sprague–Dawley rats in vivo. Short- and long-term HHcy differentially affected spatial memory as tested in a partially baited eight-arm radial maze. HHcy significantly reduced the number of choline acetyltransferase (ChAT)-positive neurons in the basal nucleus of Meynert and ChAT-positive axons in the cortex only after short-term but not long-term treatment, while acetylcholine levels in the cortex were decreased at both time points. Nerve growth factor (NGF) was significantly enhanced in the cortex only after 15 months of HHcy. HHcy did not affect cortical levels of amyloid precursor protein, beta-amyloid(1-42), tau and phospho-tau181 and several inflammatory markers, as well as vascular RECA-1 and laminin density. However, HHcy induced cortical microbleedings, as illustrated by intensive anti-rat IgG-positive spots in the cortex. In order to study the regulation of the key enzyme ChAT, organotypic rat brain slices were incubated with homocysteine, which induced a decline of ChAT that was counteracted by NGF treatment. In conclusion, our data demonstrate that chronic short- and long-term HHcy differentially caused memory impairment, cholinergic dysfunction, NGF expression and vascular microbleedings.

Experimental models of vascular dementia and vascular cognitive impairment: a systematic review

Vascular cognitive impairment (VCI) encompasses vascular dementia and is the second most common cause of dementing illness after Alzheimer's disease. The main causes of VCI are: cerebral small vessel disease; multi-infarct dementia; strategic infarct (i.e. located in a functionally-critical brain area); haemorrhage/microbleed; angiopathy (including cerebral amyloid angiopathy); severe hypoperfusion (e.g. cardiac arrhythmia); and hereditary vasculopathy (e.g. cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, CADASIL). In this systematic analysis, we aimed to relate cognitive and neuropathological features of experimental models to clinical VCI. We extracted data from 107 studies covering 16 models. These included: brief global ischaemic insults (in rats, mice or gerbils); chronic global hypoperfusion (rats, mice, gerbils); chronic hypertension (in primates or stroke-prone, spontaneously-hypertensive rats); multiple ischaemic lesions because of intra-vascular emboli (in rodents, rabbits or primates); strategic ischaemic lesions (in rats or mini-pigs); generalised vasculopathies, because of mutant Notch3, hyperhomocysteinaemia, experimental diabetes mellitus or lack of cerebral vasodilator M(5) receptors (rats or mice). Most cognitive testing showed deficits in working and reference memory. The lesions observed were microinfarcts, diffuse white matter lesions, hippocampal neuronal death, focal ischaemic lesions and micro-haemorrhages. The most-used model was bilateral carotid artery occlusion in rats, leading to chronic hypoperfusion and white matter injury.

Tratamento dietético da hiper-homocisteinemia na doença arterial periférica

A homocisteína está envolvida na gênese da aterosclerose e, assim, é considerada um importante e prevalente fator de risco na doença arterial periférica. O estado nutricional vitamínico deficiente, em especial do folato, é a principal causa de hiper-homocisteinemia nesses casos. Embora ainda não haja consenso sobre a dose exata e a forma de utilização do folato em suplementos e sobre adequação alimentar ou fortificação de cereais para o tratamento da hiper-homocisteinemia, diversos estudos realizados em pacientes com doença vascular periférica mostraram que o folato, isoladamente, pode reduzir as concentrações de homocisteína, bem como a concentração de alguns marcadores biológicos do processo de aterosclerose. No entanto, estudos recentes não comprovaram esse benefício sobre o processo inflamatório associado à hiper-homocisteinemia. Desta forma, embora a utilização isolada do folato seja uma terapêutica custo-efetiva no controle da hiper-homocisteinemia, seu impacto na evolução das doenças arteriais ainda persiste inconclusivo. Esta revisão abordará os efeitos obtidos com as diversas formas de utilização do folato no tratamento da hiper-homocisteinemia.

Effect of folate deficiency on placental DNA methylation in hyperhomocysteinemic rats

We report that the maternal folate status can influence folate-mediated one-carbon metabolism and DNA methylation in the placenta. Thirty-six female Sprague-Dawley rats were divided into the following three dietary groups: folate-supplemented (FS; 8 mg/kg folic acid, n=12), homocystine- and folate-supplemented (HFS; 0.3% homocystine and 8 mg/kg folic acid, n=12) and homocystine-supplemented and folate-deficient (HFD; 0.3% homocystine and no folic acid, n=12). The animals were fed their experimental diets from 4 weeks prior to mating until Day 20 of pregnancy (n=7-9 per group). The HFS diet increased the plasma homocysteine and placental DNA methylation but did not affect plasma folate, vitamin B-12, S-adenosyl methionine (SAM) or S-adenosyl homocysteine (SAH) levels, or the SAM/SAH ratio in the liver and placenta compared with the FS diet. The HFD diet induced severely low plasma folate concentrations, with plasma homocysteine levels increasing up to 100 micromol/L, and increased hepatic SAH and decreased placental SAM levels and SAM/SAH ratio in both tissues, with a concomitant decrease in placental DNA methylation. Placental DNA methylation was significantly correlated with placental (gamma=0.819), hepatic (gamma=0.7) and plasma (gamma=0.752) folate levels; plasma homocysteine level (gamma=-0.688); hepatic SAH level (gamma=-0.662) and hepatic SAM/SAH ratio (gamma=0.494). These results suggest that the maternal folate status in hyperhomocysteinemic rats influences the homeostasis of folate-mediated one-carbon metabolism and the methyl pool, which would, in turn, affect placental DNA methylation by altering the methylation potential of the liver.

The molecular basis of homocysteine thiolactone-mediated vascular disease

Accumulating evidence suggests that a metabolite of homocysteine (Hcy), the thioester Hcy-thiolactone, plays an important role in atherogenesis and thrombosis. Hcy-thiolactone levels are elevated in hyperhomocysteinemic humans and mice. The thioester chemistry of Hcy-thiolactone underlies its ability to form isopeptide bonds with protein lysine residues, which impairs or alters the protein's function. Protein targets for the modification by Hcy-thiolactone in human blood include fibrinogen, low-density lipoprotein, and high-density lipoprotein. Protein N-homocysteinylation leads to pathophysiological responses, including increased susceptibility to thrombogenesis caused by N-Hcy-fibrinogen, and an autoimmune response elicited by N-Hcy-proteins. Chronic activation of these responses in hyperhomocysteinemia over many years could lead to vascular disease. This article reviews recent evidence supporting the hypothesis that Hcy-thiolactone contributes to pathophysiological effects of Hcy on the vascular system.

The potential role of nutritional components in the management of Alzheimer's Disease

Epidemiological evidence linking nutrition to the incidence and risk of Alzheimer Disease is rapidly increasing. The specific nutritional deficiencies in Alzheimer patients may suggest a relative shortage of specific macro- and micronutrients. These include omega-3 fatty acids, several B-vitamins and antioxidants such as vitamins E and C. Recent mechanistic studies in cell systems and animal models also support the idea that nutritional components are able to counteract specific aspects of the neurodegenerative and pathological processes in the brain. In addition, it has been shown that several nutritional components can also effectively stimulate membrane formation and synapse formation as well as improve behavior and cerebrovascular health. The suggested synergy between nutritional components to improve neuronal plasticity and function is supported by epidemiological studies as well as experimental studies in animal models. The ability of nutritional compositions to stimulate synapse formation and effectively reduce Alzheimer Disease neuropathology in these preclinical models provides a solid basis to predict potential to modify the disease process, especially during the early phases of Alzheimer Disease.

Mechanisms of homocysteine neurotoxicity in neurodegenerative diseases with special reference to dementia

Mild to moderate hyperhomocysteinemia is a risk factor for neurodegenerative diseases. Human studies suggest that homocysteine (Hcy) plays a role in brain damage, cognitive and memory decline. Numerous studies in recent years investigated the role of Hcy as a cause of brain damage. Hcy itself or folate and vitamin B12 deficiency can cause disturbed methylation and/or redox potentials, thus promoting calcium influx, amyloid and tau protein accumulation, apoptosis, and neuronal death. The Hcy effect may also be mediated by activating the N-methyl-D-aspartate receptor subtype. Numerous neurotoxic effects of Hcy can be blocked by folate, glutamate receptor antagonists, or various antioxidants. This review describes the most important mechanisms of Hcy neurotoxicity and pharmacological agents known to reverse Hcy effects.