Folate-deficient Rats Research Articles

Effect of N,N-Dimethylglycine on Homocysteine Metabolism in Rats Fed Folate-Sufficient and Folate-Deficient Diets

ObjectiveThis study aimed to investigate the effects of N,N-dimethylglycine (DMG) on the concentration and metabolism of plasma homocysteine (pHcy) in folate-sufficient and folate-deficient rats. MethodsIn this study, 0.1% DMG was supplemented in 20% casein diets that were either folate-sufficient (20C) or folate-deficient (20CFD). Blood and liver of rats were subjected to assays of Hcy and its metabolites. Hcy and its related metabolite concentrations were determined using a liquid chromatographic system. ResultsFolate deprivation significantly increased pHcy concentration in rats fed 20C diet (from 14.19 ± 0.39 µmol/L to 28.49 ± 0.50 µmol/L; P < 0.05). When supplemented with DMG, pHcy concentration was significantly decreased (12.23 ± 0.18 µmol/L) in rats fed 20C diet but significantly increased (31.56 ± 0.59 µmol/L) in rats fed 20CFD. The hepatic methionine synthase activity in the 20CFD group was significantly lower than that in the 20C group; enzyme activity was unaffected by DMG supplementation regardless of folate sufficiency. The activity of hepatic cystathionine β-synthase (CBS) in the 20CFD group was decreased but not in the 20C group; DMG supplementation enhanced hepatic CBS activity in both groups, in which the effect was significant in the 20C group but not in the other group. ConclusionDMG supplementation exhibited hypohomocysteinemic effects under folate-sufficient conditions. By contrast, the combination of folate deficiency and DMG supplementation has deleterious effect on pHcy concentration.

Screening of folate-producing lactic acid bacteria and modulatory effects of folate-biofortified yogurt on gut dysbacteriosis of folate-deficient rats.

Folate deficiency is accompanied by gut dysbacteriosis. To understand dietary intervention in folate deficiency, a folate-deficient rat model was used to evaluate the modulatory effects of folate-producing lactic acid bacteria (LAB) and biofortified yogurt on gut dysbacteriosis. The high folate-producing strain was screened from 12 LABs, and its variant, namely Lactobacillus plantarum GSLP-7 V, with folate productivity in yogurt at 3.72 μg mL-1, was obtained by stressing with 5.0 mg L-1 methotrexate and 100.00 mg L-1 Ca2+. To our knowledge, this is the highest folate productivity in yogurt by LAB strains ever reported. To further examine the folate supplement effect in vivo, a folate-deficient rat model was established and fed a folate-free diet for 8 weeks. Also, the effects of L. plantrum GSLP-7 V, yogurt fermented with L. plantrum GSLP-7 V, plain yogurt, and chemical folic acid on folate deficiency and gut dysbacteriosis were examined. Analysis of the change in gut microbiota showed that the gut dysbacteriosis was significantly correlated with folate deficiency. Administration of L. plantrum GSLP-7 V and its fermented yogurt for 10 days restored the disrupted gut microbiota and recovered the serum folate and homocysteine to normal levels, while chemical folic acid worsened the gut dysbacteriosis. Chemical folic acid only enriched Akkermansia, while L. plantrum GSLP-7 V and its fermented yogurt modulated the gut microbiota comprehensively through 7 and 10 key genera, respectively. This study confirmed the effectiveness of dietary intervention with folate-biofortified yogurt through modulating gut microbiota, suggesting the potential of the folate-producing LAB as an agent for the treatment of folate-deficiency related diseases.

Stable Liposome in Cosmetic Platforms for Transdermal Folic acid delivery for fortification and treatment of micronutrient deficiencies

Oral folate fortification has been successful in many developed nations, however, developing countries still face low compliance and high incidence of folate deficiency associated with low birth weight infants and preterm deliveries. We report safe and efficient approach for transdermal systemic folate delivery using fluidising liposomes (120 ± 4 nm) stabilised within 3D matrix of naturally occurring cosmetic bases: Fuller’s earth and henna with room temperature stability. The proof of stratum corneum fluidisation was established ex-vivo by Langmuir-Blodgett film, FTIR and confocal imaging in rat skin. In-vivo topical application in rats showed 11-fold increase in plasma folate within 2 hr, confirming systemic delivery through skin. Efficacy study in folate deficient rats over 4 weeks showed significantly higher plasma levels compared to oral delivery with significant skin depot. Sub-acute toxicity studies in rats at 750-fold higher doses showed safety after 4 weeks daily application. Primary irritation patch test on 25 healthy human volunteers proved non-irritant nature of the nutricosmetics. The technology is first demonstration of transdermal folate fortification with nanosized liposome incorporated in cosmetics, without synthetic surfactants/ethanol or need of external energy. The platform technology opens the possibility of delivering multiple nutrients systemically through skin and can be scaled for affordable community fortification.

Disruption of redox homeostasis in liver function and activation of apoptosis on consumption of aspartame in folate deficient rat model

This study assesses the effect of long-term intake of aspartame on liver function and apoptosis signaling pathway in the Wistar albino rats. Several reports have suggested that methanol is one of the major metabolites of Aspartame. Non-primate animals are usually resistant to methanol-induced metabolic acidosis due to high levels of hepatic folate content; hence a folate deficiency model was induced by treating animals with methotrexate (MTX) prior to aspartame exposure. The aspartame treated MTX animals exhibited a marked significant increase in hepatic alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and lactic acid dehydrogenase (LDH) activity compared to controls. Aspartame treated MTX animals additionally exhibited down-regulation of genes namely B-cell lymphoma 2 (Bcl2) expression and up-regulation of Bcl-2-associated X protein (Bax), Fas-associated protein with death domain (FADD) and Caspase 3, 9 genes and apoptotic protein expression, indicating the augmentation of hepatic apoptosis. Nuclear condensation, micro vacuole formation in the cytoplasm and necrosis were observed in the liver of the aspartame treated animals on histopathology evaluation. Additionally, Immunohistochemical analysis revealed a significant increase in positive cells expressing Fas, FADD, Bax and Caspase 9 protein, indicating an increase in apoptotic protein expression in the liver. Thus, Aspartame may act as a chemical stressor which alters the functional status of liver, leading to hepatotoxicity.

Neurobehavioral changes and activation of neurodegenerative apoptosis on long-term consumption of aspartame in the rat brain

Though several studies on toxic effect of aspartame metabolite have been studied, there are scanty data on whether aspartame exposure administration could release formate, a methanol metabolite thereby inducing oxidative stress and neurodegeneration in brain discrete region. To mimic the human methanol metabolism, the methotrexate (MTX) treated folate deficient rats were used. Aspartame was administered orally to the MTX treated animals and was studied along with controls and MTX treated controls. Oral intubations of FDA approved 40 mg/kg b.wt aspartame were given daily for 90 days. The loco–motor activity and emotionality behavior in the aspartame treated animals showed a marked increase in the immobilization, fecal bolus with a marked decrease in ambulation, rearing, grooming. The anxiety behavior in the aspartame treated animals showed a marked decrease in percentage of open arm entry, percentage of time spent in open arm and number of head dips. It is appropriate to point out, formaldehyde and formate could have led to an increased formation of free radical in the aspartame treated animals resulting in altered neurobehavioral changes owing to neuronal oxidative damage. Aspartame induced ROS may be also linked to increased neuronal apoptosis. In this study the aspartame treated animals showed an up regulation in the apoptotic gene expression along with protein expression in the respective brain region indicating the enhancement of neuronal cell death. This study intends to corroborate that chronic aspartame consumption can alter the behavior and neurodegeneration in brain discrete regions.

Maternal micronutrient deficiency leads to alteration in the kidney proteome in rat pups

Maternal nutritional deficiency significantly perturbs the offspring's physiology predisposing them to metabolic diseases during adulthood. Vitamin B12 and folate are two such micronutrients, whose deficiency leads to elevated homocysteine levels. We earlier generated B12 and/or folate deficient rat models and using high-throughput proteomic approach, showed that maternal vitamin B12 deficiency modulates carbohydrate and lipid metabolism in the liver of pups through regulation of PPAR signaling pathway. In this study, using similar approach, we identified 26 differentially expressed proteins in the kidney of pups born to mothers fed with vitamin B12 deficient diet while only four proteins were identified in the folate deficient group. Importantly, proteins like calreticulin, cofilin 1 and nucleoside diphosphate kinase B that are involved in the functioning of the kidney were upregulated in B12 deficient group. Our results hint towards a larger effect of vitamin B12 deficiency compared to that of folate presumably due to greater elevation of homocysteine in vitamin B12 deficient group. In view of widespread vitamin B12 and folate deficiency and its association with several diseases like anemia, cardiovascular and renal diseases, our results may have large implications for kidney diseases in populations deficient in vitamin B12 especially in vegetarians and the elderly people.This article is part of a Special Issue entitled: Proteomics in India.

In Vivo Kinetics of Formate Metabolism in Folate-deficient and Folate-replete Rats

It is now established that the mitochondrial production of formate is a major process in the endogenous generation of folate-linked one-carbon groups. We have developed an in vivo approach involving the constant infusion of [(13)C]formate until isotopic steady state is attained to measure the rate of endogenous formate production in rats fed on either a folate-replete or folate-deficient diet. Formate was produced at a rate of 76 μmol·h(-1)·100 g of body weight(-1) in the folate-replete rats, and this was decreased by 44% in folate-deficient rats. This decreased formate production was confirmed in isolated rat liver mitochondria where formate production from serine, the principal precursor of one-carbon groups, was decreased by 85%, although formate production from sarcosine and dimethylglycine (choline metabolites) was significantly increased. We attribute this unexpected result to the demonstrated production of formaldehyde by sarcosine dehydrogenase and dimethylglycine dehydrogenase from their respective substrates in the absence of tetrahydrofolate and subsequent formation of formate by formaldehyde dehydrogenase. Comparison of formate production with the ingestion of dietary formate precursors (serine, glycine, tryptophan, histidine, methionine, and choline) showed that ∼75% of these precursors were converted to formate, indicating that formate is a significant, although underappreciated end product of choline and amino acid oxidation. Ingestion of a high protein diet did not result in increased production of formate, suggesting a regulation of the conversion of these precursors at the mitochondrial level to formate.

Effect of long intake of aspartame on ionic imbalance in immune organs of immunized wistar albino rats

Aspartame was approved by the U.S. Food and Drug Administration (FDA) in 1981 for dry food in 1983 for soft drinks and in 1996 for all foods. In 2006, it was approved for use throughout the European Union [EFSA] on safety dose (40mg/kg b.w). The artificial dipeptide sweetener aspartame [APM; L- aspartyl-L- phenylalanine methyl ester] is present in many products especially unsweetened and sugar products. These products are frequently utilized by people trying to lose weight or patients with diabetes. Concern relating to the possible adverse effect has been raised due to aspartame metabolic components. Aspartame is rapidly and completely metabolized in humans and experimental animals to aspartic acid (40%), phenylalanine (50%) and methanol (10%). Methanol, a toxic metabolite is primarily metabolized by oxidation to formaldehyde and then to formate these processes are accompanied by the formation of superoxide anion and hydrogen peroxide. This study focus is to understand whether the oral administration of aspartame (40mg/kg b.w.) for 90days, have any effect on membrane bound ATPase's, which may cause ionic disproportion and imbalance the homeostasis of immune organs in wistar albino rats. To mimic human methanol metabolism, folate deficient rats were used. After 90days of aspartame administration, showed a significant alteration in membrane bound ATPase's and serum ions. Excess free radical generation is confirmed by increase in lipid peroxidation and nitric oxide level. This study concludes that oral administration of aspartame (40mg/kg b.w.) for longer duration altered the homeostasis of immune organs, may cause oxidative stress in immune organs of wistar albino rats.

English

Aspartame (L- aspartyl- L-phenylalanine methyl ester) is one of the most widely artificial sweeteners consumed in so many products worldwide in various countries which added to a large variety of food, most commonly found in low calorie beverages. On metabolism in humans and experimental animals, aspartame is rapidly and completely metabolized to aspartic acid (40%), phenylalanine (50%) and methanol (10%). Methanol, a toxic metabolite is primarily metabolized by oxidation to formaldehyde and then to formate; these processes are accompanied by the formation of superoxide anion and hydrogen peroxide. This study focus is to understand whether the oral administration of aspartame (40 mg/kg b.w) for 15, 30 and 90 days have any effect on the antioxidant status (enzymatic and non-enzymatic) in immune organs such as the spleen, thymus, lymph nodes and bone marrow of rats. To mimic human methanol metabolism, folate deficient rats were used. After 15 days of aspartame administration, animals showed a significant increase in free radical production as indicated by the increase in both enzymatic (superoxide dismutase, catalase, glutathione peroxidase) and non-enzymatic (reduced glutathione and vitamin C) antioxidant level along with the marked increase in lipid peroxidation and nitric oxide level. However, after repeated long term administration (30 and 90 days), the generation of reactive free radicals overwhelmed the antioxidant defense as indicated by an increase in lipid peroxidation with the decrease in antioxidants level. This study concludes that administration of aspartame even at the Food and Drug Administration permitted level its repeated exposure causes oxidative stress by altering the oxidant/antioxidant balance in immune organs of the rats and its effects also reflected in the histology of the spleen and lymph nodes Key words: Aspartame, folate- deficient, immune organs, oxidative stress.

Effect of aspartame in spinal cord and its motor behavior in Wistar albino rats.

More than 90 countries have given the artificial sweetener aspartame the green light to be used in thousands of food and beverage products. Two hundred times sweeter than sugar, aspartame allows food manufacturers to produce sweet foods they can market as “low calorie,” “diet,” or sugar-free,” appealing to hundreds of millions of consumers looking to cut sugar from their diets. Concern relating to the possible adverse effect has been raised due to aspartames metabolic components. Aspartame is rapidly and completely metabolized in humans and experimental animals to aspartic acid (40%), phenylalanine (50%) and methanol (10%). Methanol, a toxic metabolite is primarily metabolized by oxidation to formaldehyde and then to formate these processes are accompanied by the formation of superoxide anion and hydrogen peroxide. This study focus is to understand whether the oral administration of aspartame (40 mg/kg b.w) for 90 days, have any effect on membrane bound ATPase’s, and antioxidant status in spinal cord of rats. To mimic human methanol metabolism, folate deficient rats were used. After 90 days of aspartame administration, shows a significant change in membrane bound ATPase’s and antioxidant level. This study concludes that oral administration of aspartame (40mg/kg.bw) for longer duration may cause oxidative stress in spinal cord, which didn’t have any consequence on motor behavior, but may cause other neuronal complication because oxidative stress in spinal cord can’t be ignored.

Effect of long-term aspartame (artificial sweetener) on anxiety, locomotor activity and emotionality behavior in Wistar Albino rats

The focus of the study is to investigate whether the long-term (90days) oral administration of aspartame (75mg/kg) has an effect in the anxiety, locomotor activity and emotionality behavior of Wistar strain male Albino rats. Aspartame releases methanol as one of its metabolites during metabolism. To mimic the human methanol metabolism, the methotrexate (MTX)-treated folate-deficient rats were used. Aspartame was administered orally to the MTX-treated animals and was studied along with controls and MTX-treated controls. The locomotor activity and emotionality behavior in the MTX-treated animals did not differ from the controls. However, the aspartame-treated MTX animals showed a marked increase in the immobilization, fecal bolus with a marked decrease in ambulation (peripheral square and central square), rearing, grooming from the control as well the MTX-treated animals. The anxiety state behavior in the MTX-treated animals did not differ from the controls. However, the aspartame-treated MTX animals showed a marked decrease in the number of open arm entry, percentage of open arm entry, time spent in open arm, percentage of time spent in open arm and number of head dips from the control as well the MTX-treated animals. It is relevant to point out that methanol released by aspartame may add an effect in the brain and that could be the additional contributing factor for the observed changes in the locomotor and their anxiety levels. This study intends to substantiate that long-term aspartame consumption can alter the behavior.

Adaptive transport of folic acid across renal epithelia in folate-deficient rats

Folate (vitamin B(9)) is an essential vitamin for a wide spectrum of biochemical reactions; however, unlike bacteria and plants, mammals are devoid of folate biosynthesis and thus must obtain this cofactor from exogenous sources. The activities of folate transporters on the kidneys play an important role in conserving folate excretion and reabsorption across the apical membrane of the renal proximal tubules. The different transport system activities may become identifiable in response to external stimuli, such as folate availability and exposure to chemotherapeutic agents. We have explored the effect of folate deficiency on the activity and expression of folate transporters in rat kidneys. Wistar rats were fed a folate-containing diet (2 mg folic acid kg(-1) diet) or a folic acid-free diet over a 3-month period, and mechanisms of folate transport were studied in renal brush border membrane vesicles and basolateral membrane vesicles. The renal folate uptake process is saturable and pH dependent, and it involves the folate receptor and reduced folate carrier (RFC) systems and possibly the proton coupled folate transporter (PCFT) system. We found that folate deficiency increased the renal brush border membrane and basolateral folate uptake by increasing the number of transporter molecules. The observed up-regulation of mRNA expression was also associated with a significant increase in RFC and PCFT expression at the protein level.

Formate can differentiate between hyperhomocysteinemia due to impaired remethylation and impaired transsulfuration

Formate can differentiate between hyperhomocysteinemia due to impaired remethylation and impaired transsulfuration. Am J Physiol Endocrinol Metab 301: E000-E000, 2011. First published September 20, 2011; 10.1152/ajpendo.00345.2011.-We carried out a (1)H-NMR metabolomic analysis of sera from vitamin B(12)-deficient rats. In addition to the expected increases in methylmalonate and homocysteine (Hcy), we observed an approximately sevenfold increase in formate levels, from 64 μM in control rats to 402 μM in vitamin B(12)-deficient rats. Urinary formate was also elevated. This elevation of formate could be attributed to impaired one-carbon metabolism since formate is assimilated into the one-carbon pool by incorporation into 10-formyl-THF via the enzyme 10-formyl-THF synthase. Both plasma and urinary formate were also increased in folate-deficient rats. Hcy was elevated in both the vitamin B(12)- and folate-deficient rats. Although plasma Hcy was also elevated, plasma formate was unaffected in vitamin B(6)-deficient rats (impaired transsulfuration pathway). These results were in accord with a mathematical model of folate metabolism, which predicted that reduction in methionine synthase activity would cause increased formate levels, whereas reduced cystathionine β-synthase activity would not. Our data indicate that formate provides a novel window into cellular folate metabolism, that elevated formate can be a useful indicator of deranged one-carbon metabolism and can be used to discriminate between the hyperhomocysteinemia caused by defects in the remethylation and transsulfuration pathways.

Cerebral perfusion and oxygenation are impaired by folate deficiency in rat: Absolute measurements with noninvasive near-infrared spectroscopy

Brain microvascular pathology is a common finding in Alzheimer's disease and other dementias. However, the extent to which microvascular abnormalities cause or contribute to cognitive impairment is unclear. Noninvasive near-infrared spectroscopy (NIRS) can address this question, but its use for clarifying the role of microvascular dysfunction in dementia has been limited due to theoretical and practical considerations. We developed a new noninvasive NIRS method to obtain quantitative, dynamic measurements of absolute brain hemoglobin concentration and oxygen saturation and used it to show significant cerebrovascular impairments in a rat model of diet-induced vascular cognitive impairment. We fed young rats folate-deficient (FD) and control diets and measured absolute brain hemoglobin and hemodynamic parameters at rest and during transient mild hypoxia and hypercapnia. With respect to control animals, FD rats featured significantly lower brain hemoglobin concentration (72±4 μmol/L versus 95±6 μmol/L) and oxygen saturation (54%±3% versus 65%±2%). By contrast, resting arterial oxygen saturation was the same for both groups (96%±4%), indicating that decrements in brain hemoglobin oxygenation were independent of blood oxygen carrying capacity. Vasomotor reactivity in response to hypercapnia was also impaired in FD rats. Our results implicate microvascular abnormality and diminished oxygen delivery as a mechanism of cognitive impairment.

Short-term nutritional folate deficiency in rats has a greater effect on choline and acetylcholine metabolism in the peripheral nervous system than in the brain, and this effect escalates with age

The hypothesis of this study is that a folate-deficient diet (FD) has a greater effect on cholinergic system in the peripheral nervous system than in the brain, and that this effect escalates with age. It was tested by comparing choline and acetylcholine levels in male Sprague Dawley rats fed either control or folate-deficient diets for 10 weeks, starting at age 4 weeks (the young group) or 9 months (the adult group). Folate-deficient diet consumption resulted in depletion of plasma folate in both age groups. In young folate-deficient rats, liver and lung choline levels were significantly lower than those in the respective controls. No other significant effects of FD on choline and acetylcholine metabolism were found in young rats. In adult rats, FD consumption markedly decreased choline levels in the liver, kidneys, and heart; furthermore, choline levels in the cortex and striatum were moderately elevated, although hippocampal choline levels were not affected. Acetylcholine levels were higher in the heart, cortex, and striatum but lower in the hippocampus in adult folate-deficient rats, as compared to controls. Higher acetylcholine levels in the striatum in adult folate-deficient rats were also associated with higher dopamine release in the striatal slices. Thus, both age groups showed higher cholinergic metabolic sensitivity to FD in the peripheral nervous system than in the brain. However, compensatory abilities appeared to be better in the young group, implicating the adult group as a preferred model for further investigation of folate-choline-acetylcholine interactions and their role in brain plasticity and cognitive functions.

Genistein mediates perturbations in one‐carbon metabolism during diet‐induced folate deficiency

Populations consuming isoflavone‐rich diets exhibit lower prevalence of heart disease and estrogen‐responsive cancers. Genistein, a17β‐estradiol‐like isoflavone, has been shown to modify the fetal epigenome in utero in the agouti mouse model and modulate DNA methylation patterns in estrogen‐responsive tissues. Moreover, it also exhibits antiproliferative action in cancerous cells via suppression of S‐adenosylmethionine –dependent DNA methyltransferases, leading to site‐specific hypomethylation. However, it is not known if genistein modulates one‐carbon metabolism, a process that when disrupted leads to dysregulation of the epigenome. The objective of this study was to characterize the metabolic actions of genistein during moderate dietary folate deficiency. Male Sprague Dawley ratswere fed an ad lib control or folate‐deficient (FD) diet with or without genistein supplementation (300 mg/kg diet) for 8 wk. Plasma homocysteine (Hcy) concentrations in genistein‐supplemented, FD animals (16.7 μM) was lower (P = 0.02) than the Hcy concentration of FD animals not supplemented with genistein (27.9 μM). Hepatic enzyme analysis suggests the ability of genistein to attenuate hyperhomocysteinemia in FD rats is not linked to diminished Hcy production. Clearly, genistein has the ability to modulate Hcy and methyl‐group metabolism; however, the underlying mechanisms remain unknown.Grant Funding Source: AHA assn

Genistein reduces plasma homocysteine concentrations in a folate deficient rat model

Hyperhomocysteinemia is an independent risk factor for cardiovascular disease. Homocysteine (Hcy) is an intermediate in methyl group metabolism, as S‐adenosylmethionine (SAM), the methyl group donor for most biological methylations, results in the formation of S‐adenosylhomocysteine and ultimately Hcy. Genistein, a 17β‐estradiol‐like isoflavone, has been shown to maintain normal methyl group metabolism in the agouti mouse model fed a methyl‐deficient diet. Although dietary genistein does not provide a methyl group, it may modulate the one‐carbon pool and influence DNA methylation in estrogen‐responsive tissues. To date, it is not known to what extent genistein directly influences Hcy and methyl group metabolism. In the present study, the effects of genistein supplementation on elevated Hcy during moderate folate deficiency were examined. Male Sprague Dawley rats (n=24) were fed ad‐lib control and folate deficient (FD) diets for 14 d, followed by supplementation of each diet with 300mg/kg diet genistein for an additional 24 d. Hcy concentrations in the genistein supplemented FD animals (18.2 + 0.9μM) were reduced (24%; P = 0.01) relative to concentration in unsupplemented, FD rats (24.0 + 2.2μM). Analysis of other hepatic enzymes (i.e. GNMT, PEMT) indicate that the Hcy‐lowering effect of genistein does not reside in reduced production, but rather in increased metabolism.

Cognitive Impairment in Folate-Deficient Rats Corresponds to Depleted Brain Phosphatidylcholine and Is Prevented by Dietary Methionine without Lowering Plasma Homocysteine

Poor folate status is associated with cognitive decline and dementia in older adults. Although impaired brain methylation activity and homocysteine toxicity are widely thought to account for this association, how folate deficiency impairs cognition is uncertain. To better define the role of folate deficiency in cognitive dysfunction, we fed rats folate-deficient diets (0 mg FA/kg diet) with or without supplemental L-methionine for 10 wk, followed by cognitive testing and tissue collection for hematological and biochemical analysis. Folate deficiency with normal methionine impaired spatial memory and learning; however, this impairment was prevented when the folate-deficient diet was supplemented with methionine. Under conditions of folate deficiency, brain membrane content of the methylated phospholipid phosphatidylcholine was significantly depleted, which was reversed with supplemental methionine. In contrast, neither elevated plasma homocysteine nor brain S-adenosylmethionine and S-adenosylhomocysteine concentrations predicted cognitive impairment and its prevention by methionine. The correspondence of cognitive outcomes to changes in brain membrane phosphatidylcholine content suggests that altered phosphatidylcholine and possibly choline metabolism might contribute to the manifestation of folate deficiency-related cognitive dysfunction.

Efficacy of dl-α-lipoic acid on methanol induced free radical changes, protein oxidative damages and hsp70 expression in folate deficient rat nervous tissue

dl-α-Lipoic acid (LPA) was reported to be effective in reducing free radicals generated by oxidative stress. The protective of effect of LPA on methanol (MeOH) induced free radical changes and oxidative damages in discrete regions of rat brain have been reported in this study. Folate deficient rat (FDD) model was used. The five animal groups (saline control, FDD control, FDD + MeOH, FDD + LPA + MeOH, LPA control) were used. The FDD + MeOH and FDD + LPA + MeOH animals were injected intraperitoneally with methanol (3 gm/kg). After 24 h, the level of free radical scavengers such as, superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione was estimated in six discrete regions of brain, retina and optic nerve. Level of protein thiol, protein carbonyl and lipid peroxidation was also estimated. Expression of heat shock protein 70 mRNA ( hsp70) was studied in the cerebellum and hippocampus by reverse transcriptase PCR. All the samples showed elevation in the level of free radical scavenging enzymes and reduced level of glutathione in the FDD + MeOH group in relation to the other groups. hsp70 expression was more in FDD + MeOH group when compared to FDD + LPA + MeOH group. In conclusion, MeOH exposure leads to increased free radical generation and protein oxidative damages in the rat nervous tissue. Treatment with LPA prevents oxidative damage induced by MeOH exposure.

Folate status modulates the induction of hepatic glycineN-methyltransferase and homocysteine metabolism in diabetic rats

A diabetic state induces the activity and abundance of glycine N-methyltransferase (GNMT), a key protein in the regulation of folate, methyl group, and homocysteine metabolism. Because the folate-dependent one-carbon pool is a source of methyl groups and 5-methyltetrahydrofolate allosterically inhibits GNMT, the aim of this study was to determine whether folate status has an impact on the interaction between diabetes and methyl group metabolism. Rats were fed a diet containing deficient (0 ppm), adequate (2 ppm), or supplemental (8 ppm) folate for 30 days, after which diabetes was initiated in one-half of the rats by streptozotocin treatment. The activities of GNMT, phosphatidylethanolamine N-methyltransferase (PEMT), and betaine-homocysteine S-methyltransferase (BHMT) were increased about twofold in diabetic rat liver; folate deficiency resulted in the greatest elevation in GNMT activity. The abundance of GNMT protein and mRNA, as well as BHMT mRNA, was also elevated in diabetic rats. The marked hyperhomocysteinemia in folate-deficient rats was attenuated by streptozotocin, likely due in part to increased BHMT expression. These results indicate that a diabetic state profoundly modulates methyl group, choline, and homocysteine metabolism, and folate status may play a role in the extent of these alterations. Moreover, the upregulation of BHMT and PEMT may indicate an increased choline requirement in the diabetic rat.