5-methyltetrahydrofolate and Alcoholism

Topics: Alcoholism; Anemia, Hemolytic; Anticonvulsants; Bone Marrow Cells; Bone Marrow Diseases; Cells; Deoxyuridine; Erythrocytes, Abnormal; Female; Fluorouracil; Folic Acid; Folic Acid Deficiency; Formyltetrahydrofolates; Homocysteine; Humans; Hypothyroidism; Lymphocyte Activation; Methionine; Pregnancy; Pregnancy Complications; Statistics as Topic; Tetrahydrofolates; Vitamin B 12; Vitamin B 12 Deficiency

Folates, an essential component (important B vitamin) in the human diet, are involved in many metabolic pathways, mainly in carbon transfer reactions such as purine and pyrimidine biosynthesis and amino acid interconversions. Deficiency of this micronutrient leads to the disruption of folate-dependent metabolic pathways that lead to the development of clinical abnormalities ranging from anaemia to growth retardation. Folate deficiency due to alcohol ingestion is quite common, primarily due to malabsorption. The present study dealt with the mechanistic insights of folate malabsorption in colonic basolateral membrane (BLM). Wistar rats (n 12) were fed 1 g/kg body weight per d ethanol (20 %) solution orally for 3 months and folate transport was studied in the isolated colonic BLM. The folate exit across colon BLM shows characteristics of carrier-mediated process with the major involvement of reduced folate carrier (RFC). The chronic ethanol ingestion decreased the uptake by decreasing the affinity by 46 % (P < 0·01) and the number of transport molecules by 43 % (P < 0·001) at the colon BLM. The decreased uptake was associated with down-regulation of proton-coupled folate transporter (PCFT) and RFC expression at mRNA and protein levels. The extent of decrease was 44 % (P < 0·01) and 24 % (P < 0·05) for PCFT and 23 % (P < 0·01) and 57 % (P < 0·01) for RFC at mRNA and protein levels, respectively. Moreover, folate transporters were associated with lipid rafts (LR) of colon BLM, and chronic alcoholism decreased the association of these transporters with LR.

Topics: Alcoholism; Animals; Cell Membrane; Colon; Down-Regulation; Folic Acid; Folic Acid Deficiency; Intestinal Absorption; Intestinal Mucosa; Kinetics; Malabsorption Syndromes; Male; Membrane Microdomains; Membrane Transport Proteins; Minor Histocompatibility Antigens; Proton-Coupled Folate Transporter; Random Allocation; Rats; Rats, Wistar; Reduced Folate Carrier Protein; RNA, Messenger; Tetrahydrofolates

We studied the effect of chronic ethanol ingestion on folate transport across the colonic apical membranes (CAM) in rats. Male Wistar rats were fed 1 g/kg body weight/day ethanol (20%) solution orally for 3 months and folate transport was studied in the isolated colon apical membrane vesicles. The folate transport was found to be carrier mediated, saturable, with pH optima at 5.0. Chronic ethanol ingestion reduced the folate transport across the CAM by decreasing the affinity of transporters (high Km) for the substrate and by decreasing the number of transporter molecules (low Vmax) on the colon luminal surface. The decreased transport activity at the CAM was associated with down-regulation of the proton-coupled folate transporter (PCFT) and the reduced folate carrier (RFC) which resulted in decreased PCFT and RFC protein levels in the colon of rats fed alcohol chronically. Moreover, the PCFT and the RFC were found to be distributed in detergent insoluble fraction of the CAM in rats. Floatation experiments on Optiprep density gradients demonstrated the association of the PCFT and the RFC protein with lipid rafts (LR). Chronic alcoholism decreased the PCFT and the RFC protein levels in the CAM LR in accordance with the decreased synthesis. Hence, we propose that downregulation in the expression of the PCFT and the RFC in colon results in reduced levels of these transporters in colon apical membrane LR as a mechanism of folate malabsorption during chronic alcoholism.

Topics: Alcoholism; Animals; Biological Transport; Blotting, Western; Cell Polarity; Chronic Disease; Colon; Gene Expression Regulation; Malabsorption Syndromes; Male; Membrane Microdomains; Proton-Coupled Folate Transporter; Rats; Rats, Wistar; Reduced Folate Carrier Protein; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tetrahydrofolates; Time Factors

This study sought to determine the intestinal in vivo absorption of folic acid and methyltetrahydrofolate (MTHF) by jejunum surface at different times, after 20 weeks of 30% ethanol ingestion. The absorption results were compared with the data of control rats. In general after ethanol treatment jejunal folic acid absorption was higher than in control rats. When the folic acid concentrations in the perfusion medium were 0.5 microM an increase at later times in ethanol-fed rats was found. At 1 microM the folic acid absorption values were significantly higher at the earlier time. When the concentration assayed was 2.5 microM, significant modifications were only seen at 30 min. Results of MTHF absorption by jejunum of ethanol-fed rats were similar to absorption values of control rats. No significant differences between both groups were found. The results obtained in the present work suggested a different absorptive behavior of both substrates and a different effect of ethanol on folic acid and MTHF absorption in the jejunum.

Topics: Alcoholism; Animals; Carbon Radioisotopes; Ethanol; Folic Acid; Intestinal Absorption; Jejunum; Male; Rats; Rats, Wistar; Tetrahydrofolates

This study was designed to determine the intestinal in vivo absorption of folic acid and methyltetrahydrofolate (MTHF) by the caecum surface at different times after 20 weeks of 30% ethanol ingestion. The absorption results were compared to the data of control rats. Chow and fluid consumption and body weight were significantly lower in ethanol-fed rats. The absorption of folic acid and MTHF by the caecum surface (pmol/cm2) was generally decreased in ethanol-fed rats at all concentrations assayed with respect to control animals (except for absorption of 0.5 and 2.5 microM folic acid at 15-min intervals). The results obtained in the present work also suggest a different absorptive behaviour of folic acid and MTHF in the caecum under the influence of chronic alcohol ingestion.

Topics: Alcoholism; Animals; Cecum; Ethanol; Folic Acid; Intestinal Absorption; Male; Rats; Rats, Wistar; Tetrahydrofolates

Acute ethanol treatment enhances the urinary excretion of endogenous folate. This effect has been implicated in the development of folate deficiency associated with chronic alcoholism. Previous studies have shown that urinary excretion of total [3H]-label after administration of [3H]folic acid is slightly higher in ethanol-treated rats because of conversion of the tracer to forms whose excretion is not affected by ethanol. Since [3H]folic acid is not the physiological substrate for the kidney, studies were performed using a high specific activity 5-methyltetrahydrofolic acid ([3H]5-CH3-H4 folic acid). Male Sprague-Dawley rats were given four consecutive hourly doses of ethanol at 1 g/kg, followed by infusion of [3H]5-CH3-H4 folic acid at 5 h. Urine samples were collected to 6 h, when rats were killed, and plasma, liver and kidney samples were collected. Endogenous urinary folate excretion and the fractional urinary excretion of both endogenous and [3H]5-CH3-H4 folic acid at the 5-6 h time period were significantly higher in ethanol-treated rats. The kidney had a tenfold greater specific incorporation of [3H]-label than did the liver. High performance liquid chromatography (HPLC) analysis of the plasma obtained at 6 h showed that 68% of the label was [3H]5-CH3-H4 folic acid, and HPLC analysis of the urine obtained from 5-6 h showed that only 10% of the label was [3H]5-CH3-H4 folic acid. The data indicate that [3H]5-CH3-H4 folic acid was rapidly taken up by the kidney and metabolized to other folate and nonfolate forms, which were then secreted into the renal tubule for excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Alcoholism; Animals; Chromatography, High Pressure Liquid; Ethanol; Folic Acid; Folic Acid Deficiency; Kidney; Liver; Male; Plasma; Rats; Rats, Inbred Strains; Tetrahydrofolates

Chronic alcoholics (greater than 150 g/day) showing minor serum and histological changes have been studied, compared to healthy non alcoholic subjects, and the following parameters have been considered: S. (Serum)cholesterol (CH), S.phospholipids (PH), S.folate level, and mean corpuscular volume (MCV). Erythrocyte ghosts have been studied for CH and PH content and membrane fluidity using diphenylhexatriene as a probe. All alcoholics showed decreased fluidity of red cell membrane with increased CH/PH ratio, even in patients showing normal MCV or minimal alterations of functional tests, suggesting that changes in red cell membrane fluidity represent an early sign of ethanol abuse. These likely reflect the diffuse interaction of ethanol with biological membranes. The administration of N5-Methyltetrahydrofolate produced an increase of membrane fluidity over the 3 weeks considered, associated with modest changes of MCV. The latter were delayed with respect to changes in fluidity. If changes of red cell membrane fluidity are a sensitive index of alcohol abuse, they could be a useful marker for detection and follow-up of chronic alcoholism.

Topics: Adult; Aged; Alcoholism; Erythrocyte Membrane; Female; Fluorescence Polarization; Humans; Liver Function Tests; Male; Membrane Fluidity; Middle Aged; Tetrahydrofolates

The effect of long-term ethanol supplementation on folate metabolism was studied in McCollum rats receiving approximately 30% of their caloric intake as ethanol. Ethanol did not significantly affect hepatic or plasma total folate levels. The net hepatic uptake and metabolism of a labeled folate dose to polyglutamate forms were unimpaired by ethanol administration. In fact, the ethanol-fed animals metabolized hepatic pteroylmonoglutamates to polyglutamate forms, predominantly the pentaglutamate, at a slightly faster rate than the control animals, and the net hepatic uptake of the labeled dose was higher than in the controls. Tetrahydrofolate derivatives were the predominant one-carbon form of folate in the livers of ethanol-fed and control animals, although the proportion of folate in the 5-methyltetrahydrofolate form was slightly increased after ethanol supplementation. Although hepatic metabolism of folate appears to be unimpaired in the ethanol-fed rat, an increased rate of pteroylpolyglutamate synthesis, with a resulting increase in the tissue storage of folate, might be a contributing factor to the low serum folate levels reported in alcoholics.

Topics: Alcoholism; Animals; Body Weight; Female; Folic Acid; Humans; Liver; Male; Organ Size; Pregnancy; Pteroylpolyglutamic Acids; Rats; Tetrahydrofolates