Effect Of Chronic Alcohol Feeding Research Articles

Effects of chronic alcohol feeding on learning and memory in mice carrying risk mutations for Alzheimer's disease

Effects of chronic alcohol feeding on learning and memory in mice carrying risk mutations for Alzheimer's disease

Effect of chronic alcohol feeding on physiological and molecular parameters of thiamin uptake by pancreatic acinar cells of transgenic reporter mice carrying the human SLC19A2 and SLC19A3 promoters

Thiamin is essential for metabolic functions of pancreatic acinar cells. These cells obtain the vitamin from their surrounding via a specific carrier‐mediated process that involves THTR‐1 and THTR‐2 (products of SLC19A2 and SLC19A3 genes, respectively). We have previously shown that chronic alcohol exposure inhibit thiamin uptake by these cells but little is known if the effect is mediated at the transcriptional level of the involved transporters. We addressed this issue using transgenic mice carrying the human SLC19A2 and SLC19A3 promoters and pancreatic acinar 266–6 cells expressing these human promoters. Chronic alcohol feeding (4 weeks) of transgenic mice led to a significant inhibition in carrier‐mediated thiamin uptake, a reduction in level of the expression of endogenous mouse THTR‐1 and THTR‐2 at the protein and mRNA levels, and a significant reduction in activity of SLC19A2 and SLC19A3 promoters. Similar findings were observed in alcohol exposed 266–6 cells. In the latter model, we were also able to determine the alcohol sensitive region within the SLC19A2 and SLC19A3 promoters using a series of truncated promoter constructs. These studies provide clear evidence that the effect of chronic alcohol exposure on pancreatic acinar thiamin uptake is mediated at the level of transcription of SLC19A2 and SLC19A3 genes. [Supported by DVA and NIH grants DK56061 and AA018071].

Thiamin uptake by pancreatic acinar cells: effect of chronic alcohol feeding/exposure

Thiamin is important for normal function of pancreatic acinar cells, but little is known about its mechanism of uptake and about the effect of chronic alcohol use on the process. We addressed these issues using freshly isolated rat primary and rat-derived cultured AR42J pancreatic acinar cells as models. Results showed thiamin uptake by both primary and cultured AR42J pancreatic acinar cells to be via a specific carrier-mediated mechanism and that both of the thiamin transporters 1 and 2 (THTR-1 and THTR-2) are expressed in these cells. Chronic alcohol feeding of rats was found to lead to a significant inhibition of carrier-mediated thiamin uptake by pancreatic acinar cells and was associated with a significant reduction in level of expression of THTR-1 and THTR-2 at the protein and mRNA levels. Chronic exposure (96 h) of AR42J cells to alcohol also led to a significant decreased carrier-mediated thiamin uptake, an effect that was associated with a significant decrease in the activity of the human SLC19A2 and SLC19A3 promoters expressed in these cells. We also examined the effect of chronic alcohol feeding of rats on level of expression of key thiamin metabolizing enzymes (thiamin phosphokinase and thiamin pyrophosphatase) as well as on level of expression of the mitochondrial thiamin pyrophosphate transporter of pancreatic acinar cells and observed a significant inhibition in all these parameters. These results demonstrate for the first time that thiamin uptake by pancreatic acinar cells is via a carrier-mediated process and that both the THTR-1 as well as THTR-2 are expressed in these cells. Also, chronic alcohol feeding/exposure inhibits thiamin uptake process and the inhibition is, at least in part, being exerted at the transcriptional level. Furthermore, chronic alcohol feeding also negatively impacts intracellular parameters of thiamin metabolism in pancreatic acinar cells.

Chronic alcohol exposure negatively impacts the physiological and molecular parameters of the renal biotin reabsorption process

Normal body homeostasis of biotin is critically dependent on its renal recovery by kidney proximal tubular epithelial cells, a process that is mediated by the sodium-dependent multivitamin transporter (SMVT; a product of the SLC5A6 gene). Chronic ethanol consumption interferes with the renal reabsorption process of a variety of nutrients, including water-soluble vitamins. To date, however, there is nothing known about the effect of chronic alcohol feeding on physiological and molecular parameters of the renal biotin reabsorption process. We addressed these issues using rats and transgenic mice carrying the human SLC5A6 (P1P2) 5'-regulatory region as an in vivo model systems of alcohol exposure, and cultured human renal proximal tubular epithelial HK-2 cells chronically exposed to alcohol as an in vitro model of alcohol exposure. The [(3)H]biotin uptake results showed that chronic ethanol feeding in rats leads to a significant inhibition in carrier-mediated biotin transport across both renal brush border and basolateral membrane domains. This inhibition was associated with a marked reduction in the level of expression of SMVT protein, mRNA, and heterogenous nuclear RNA (hnRNA). Furthermore, studies with transgenic mice carrying the SLC5A6 5'-regulatory region showed that chronic alcohol feeding leads to a significant decrease in promoter activity. Studies with HK-2 cells chronically exposed to alcohol again showed a marked reduction in carrier-mediated biotin uptake, which was associated with a significant reduction in promoter activity of the human SLC5A6 5'-regulatory region. These findings demonstrate for the first time that chronic ethanol feeding inhibits renal biotin transport and that this effect is, at least in part, being exerted at the transcriptional level.

Effect of chronic alcohol feeding on physiological and molecular parameters of renal thiamin transport

The renal thiamin reabsorption process plays an important role in regulating thiamin body homeostasis and involves both thiamin transporters-1 and -2 (THTR1 and THTR2). Chronic alcohol use is associated with thiamin deficiency. Although a variety of factors contribute to the development of this deficiency, effects of chronic alcohol use on renal thiamin transport have not been thoroughly examined. We addressed this issue by examining the effect of chronic alcohol feeding of rats with liquid diet on physiological and molecular parameters of renal thiamin transport. Chronic alcohol feeding caused a significant inhibition in carrier-mediated thiamin transport across the renal brush-border membrane and was evident as early as 2 wk after initiation of alcohol feeding. Similarly, thiamin transport across the renal basolateral membrane was significantly inhibited by chronic alcohol feeding. The inhibition in renal thiamin transport was associated with a marked decrease in the level of expression of THTR1 and -2 proteins, mRNAs, and heterogeneous nuclear RNAs. Chronic alcohol feeding also caused a significant reduction in the level of expression of thiamin pyrophosphokinase but not that of the mitochondrial thiamin pyrophosphate transporter. These studies show that chronic alcohol feeding inhibits the entry and exit of thiamin in the polarized renal epithelial cells and that the effect is, at least in part, mediated at the transcriptional level. These findings also suggest that chronic alcohol feeding interferes with the normal homeostasis of thiamin in renal epithelial cells.

Effect of chronic alcohol feeding on vitamin B1 (thiamine) transport in rat kidneys

Renal uptake of thiamine plays an important role in regulating the vitamin body homeostasis and is mediated by thiamine transporters1 and 2 (THTR1 and THTR2). Little is known about the effect of chronic alcohol consumption on renal thiamine transport. We addressed this issue in this investigation using purified renal brush border membrane vesicles (BBMV) and basolateral membrane vesicles (BLMV) isolated from rats fed alcohol liquid diet (36% calories) for 2, 4 and 6 weeks and compared the findings to those of pair‐fed controls (alcohol free liquid diet). Results showed that chronic ethanol feeding significantly inhibits carrier mediated thiamine uptake in renal BBMV and the effect was evident as early as 2 weeks after the start of alcohol feeding. Uptake of thiamine by renal BLMV was similarly inhibited. This decrease in thiamine transport was associated with parallel decrease in mRNA level of THTR1 and 2 (detected by real‐time PCR) as well as in level of transcription of their respective genes [established from level of expression of heterogeneous nuclear RNA (hnRNA)]. These studies show for the first time that chronic alcohol consumption leads to inhibition in renal thiamine uptake and the effect appears to be mediated (at least in part) via transcriptional mechanism(s). (Supported by grants from DVA and NIH).

Gender differences in the relative abundance of RGS2 mRNA in brain-stem, cortex, cerebellum and midbrain and the effects of chronic alcohol feeding

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Hepatic S-adenosylmethionine after maternal alcohol exposure on offspring rats

S-adenosylmethionine (SAM) is an universal methyl donor for biological systems in transmethylation reactions. Another metabolic pathway involving S-adenosylmethionine is initiated with the release of -CH3 from the molecule and the formation of S-adenosylhomocysteine and then homocysteine and cysteine, a precursor of the main cellular antioxidant glutathione. Chronic ethanol consumption could affect the bioavailability of amino acids such as methionine. Our purpose was to determine the effect of chronic alcohol feeding during gestation or lactation on hepatic S-adenosyl-methionine, S-adenosylhomocysteine, DNA methylation and homocysteine serum concentration at the end of the lactation period (21-day-old offspring). Wistar dam rats were fed with alcohol during periconceptional, gestation and lactation periods (alcohol-fed rats). This study was conducted with three groups of offspring with different periods of alcohol exposure: control offspring (C), no treatment; and gestation (G) and lactation (L) offspring, exposed to alcohol only during gestation or lactation, respectively. To obtain these last two groups of offspring, on parturition day control newborn rats were cross-fostered to alcohol-fed dams (L) and alcohol new-born rats were cross-fostered to control dams (G). In conclusion, these results indicate that exposure of rats to ethanol during the lactation period affects SAM values more severely than ethanol exposure only during gestation.

Effects of chronic alcohol treatment on the synthesis, sialylation, and disposition of nascent apolipoprotein E by peritoneal macrophages of rats

Plasma apolipoprotein (apo) E, a sialoprotein, plays an important role in reverse cholesterol transport. Previously, we showed that chronic alcohol consumption impairs glycosylation of apo E in rat liver. Peritoneal macrophages are another significant apo E synthesis site. The main purpose of this study was to determine the effects of chronic alcohol feeding of rats on the synthesis, sialylation, and sialic acid content of macrophage apo E and its ability to bind to the HDL(3) molecule in vitro. Rats were fed an alcoholic diet or an isoenergetic control diet for 8 wk, after which peritoneal macrophages isolated from them were cultured and analyzed for apo E metabolism. Macrophages from alcohol-fed rats accumulated 33.3% more (P < 0.05) cholesterol than did those from control rats when incubated with acetylated LDL. These macrophages showed a 51-57% lower relative sialylation rate of apo E (P < 0.001) but no significant difference in relative protein synthetic rate. The sialic acid content of the intracellular and secreted forms of apo E was reduced by 41.8% (P < 0.001) and 50.3% (P < 0.001), respectively, with chronic alcohol treatment. Secretion of newly synthesized apo E was impaired by 53.7% (P < 0.001) and 26. 1% (P < 0.001) in the absence and presence of HDL in the medium, respectively. Macrophages of alcohol-treated rats secreted apo E with 47.6-67.2% lower (P < 0.001) HDL(3) binding ability; binding ability was restored completely by resialylation of the desialylated apo E. In rats, an alcohol-mediated decrease in sialylation rate resulting in loss of sialic acid residues in apo E impairs the ability of apo E to bind to HDL and consequently in defective reverse cholesterol transport.

Effect of chronic alcohol feeding on the ultrastructure of rat peripheral blood neutrophils: a morphometric study.

Morphometric methods were used to analyze the ultrastructural characteristics of peripheral blood polymorphonuclear neutrophils (PMN) in 10 rats chronically consuming ethanol and 20 rats fed an isoenergetic standard diet (10 ad libitum and 10 pair fed control rats). Morphometric measurements were made, after a 4-month experimental period, of the following: the profile area of the cell, nucleus and cytoplasm; nucleus to cell profile area; volume density of the nucleus, cytoplasm, mitochondria, Golgi system, endoplasmic reticulum and cytoplasmic granules; number of mitochondria per cell profile; number of cytoplasmic granules per cell profile and per micron2 of cytoplasm, as well as the azurophilic to specific granule ratio and mean diameter of granules. A significant decrease in cell profile area and cytoplasm profile area was shown in ethanol-treated rats. The volume density of mitochondria and endoplasmic reticulum nearly doubled during ethanol abuse. The results also showed that there were highly significant effects of ethanol on the total number of cytoplasmic granules per cell. In addition, changes were observed in mitochondria such as clumping, elongation, swelling and disruption of cristae, as well as changes in the topographic distribution of granules in the cytoplasm such as registration of cytoplasmic areas with numerous granules and areas with a smaller number or without any granules. Some neutrophils of ethanol-treated rats had autophagic vacuoles. The results indicate some ultrastructural abnormalities of PMN in chronic experimental alcoholism that may be related to polymorphonuclear phagocyte dysfunction.

Effects of chronic alcohol feeding and murine AIDS virus infection on liver antioxidant defense systems in mice.

Whether ethanol (ETOH) abuse could contribute to the development of acquired immunodeficiency syndrome (AIDS) among human immunodeficiency virus (HIV)-positive drug abusers is a critical question for which little experimental information is available. This study was designed to determine if chronic ETOH feeding and murine AIDS virus infection cooperatively affected liver antioxidant defense systems in C57B1/6 female mice. Mice were divided into two groups and fed the Lieber-DeCarli liquid ETOH diet containing ETOH at a concentration to provide 31% of total caloric intake or an isocaloric liquid control (control) diet in which dextrin-maltose replaced ETOH. One week after the initiation of ETOH feeding, half of the mice in each diet group (8 mice) were injected intraperitoneally with murine retrovirus (MAIDS) stock. After 3 and 5 weeks of ETOH feeding, half of the mice in each of the four treatment groups (4 mice) were killed, and livers were excised for biochemical analysis. Liver reduced glutathione (GSH) levels and activities of glutathione peroxidase (GP), glutathione reductase (GR), glutathione transferase (GT), catalase and superoxide dismutase (SOD), and serum ETOH concentrations were determined. The results demonstrated that serum ETOH concentrations were significantly elevated in ETOH-MAIDS group when compared with the ETOH group. Moreover, chronic ETOH feeding and MAIDS infection independently depressed liver antioxidant defense capability, and together led to an additive inhibition of GSH and SOD activities. In addition, MAIDS infection inhibited an ETOH-induced increase in catalase and GT activities. These results suggest that alcohol abuse could contribute to the development of AIDS by inhibiting the protective capability of an infected individual against oxidative stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic alcohol feeding on hepatic iron status and ferritin uptake by rat hepatocytes.

Alcohol abuse is known to cause disturbances to iron homeostasis in man and is associated with elevated serum ferritin levels. We have previously shown that ethanol metabolism in the rat hepatocyte is associated with an immediate reduction in ferritin uptake by this cell. In this study we have examined the effect of pair-feeding the Lieber-DeCarli liquid alcohol diet on ferritin uptake by rat hepatocytes. Rat liver ferritin was radiolabeled with 59Fe in vivo and isolated by conventional techniques. Rats were pair-fed the Lieber-DeCarli liquid alcoholic diet for 4-6 weeks. Hepatocytes, isolated from their livers by collagenase perfusion, were incubated with [59Fe]ferritin in L-15 medium at 37 degrees C and 4 degrees to measure ferritin uptake and binding. The in vitro effect of ethanol on these hepatocytes was also studied. Ferritin and iron parameters were measured in the sera and hepatocytes of these animals and a comparable group of normal chow-fed rats. The rate of ferritin uptake by hepatocytes from alcohol-fed rats was significantly faster than that of their pair-fed controls (0.743 +/- 0.061 vs. 0.540 +/- 0.042 ng/min/10(6) cells, p < 0.05). However, the rats on Lieber-DeCarli control diet exhibited a lower hepatocyte ferritin uptake rate than chow-fed animals (79.3 +/- 8.1% of the control values, p < 0.01). In vitro incubation of cells in 100 mM ethanol resulted in less inhibition of ferritin uptake by hepatocytes from alcoholic rats than from their pair-fed controls (11 +/- 7.1% inhibition vs. 43.6 +/- 10.7% for controls, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic alcohol feeding with a low-fat diet on acetyl CoA carboxylase and fatty acid synthase activities in rat liver.

Effect of chronic alcohol feeding with a low-fat diet on acetyl CoA carboxylase and fatty acid synthase activities in rat liver.

Depression of biliary glutathione excretion by chronic ethanol feeding in the rat

The effects of chronic alcohol feeding on biliary glutathione excretion were studied in rats pair fed diets containing either ethanol (36% of total energy) or isocaloric carbodydrate for 4–6 weeks. An exteriorized biliary-duodenal fistula was established and total glutathione (GSH) and oxidized glutathione (GSSG) were measured. A significant decrease was observed in rats fed alcohol chronically compared to their pair fed controls in the biliary excretion of GSH (55.7±37.0 vs 243.1±29.0 μg/ml bile, p<0.025) as well as biliary GSSG (12.5±5.0 vs 49.9±8.0 μg/ml bile, p<0.05) and in bile flow (23.1±1.6 vs 29.2±1.3 μg/min, p<0.05). An acute dose of ethanol tended to exaggerate the decrease on biliary GSH and GSSG in the two groups of animals. The depression in biliary GSH could not be attributed to decreased GSH synthesis since S 35-L-methionine incorporation into hepatic and biliary GSH was unchanged or even increased after chronic ethanol feeding.

The effect of chronic alcohol feeding on lipid peroxidation in microsomes: Lack of relationship to hydroxyl radical generation

Chronic alcohol feeding causes microsomal induction including increased generation of hydroxyl radicals. Ethanol induced liver injury may be mediated by lipid peroxidation for which hydroxyl radicals have been proposed as major mediators. Ethanol promotes lipid peroxidation when given acutely but also may serve as a hydroxyl radical scavenger. Therefore, we studied the acute and chronic effects of alcohol on microsomal lipid peroxidation and hydroxyl radical generation. Chronic alcohol feeding in rats increased microsomal generation of hydroxyl radicals but lipid peroxidation of endogenous lipid was inversely related to hydroxyl radical generation. Ethanol (50mM) had a slight inhibitory effect on hydroxyl radical production in perxidizing microsomes, no effect on endogenous lipid peroxidation and enhanced the lysis of RBCs added as targets of peroxidation. Enhanced microsomal generation of hydroxyl radicals following chronic alcohol feeding is not an important mediator of lipid peroxidation.

Effect of chronic alcohol feeding and withdrawal on rat liver plasma membrane structure and function: a study of binding of [ 3H]prazosin to the membrane bound α1-adrenergic receptor

Effect of chronic alcohol feeding and withdrawal on rat liver plasma membrane structure and function: a study of binding of [ 3H]prazosin to the membrane bound α1-adrenergic receptor

Effects of chronic alcohol feeding on thiamin status: biochemical and neurological correlates

The effects of chronic alcohol feeding on thiamin status are controversial; both adverse and beneficial effects have been reported. In order to study these effects, rats and baboons were pair-fed liquid diets containing thiamin in excess of dietary requirements and either ethanol (rats 36%, baboons 50% of total calories) or the identical diet with ethanol substituted isocalorically by carbohydrate. In the rat, chronic alcohol feeding for up to 6 months had no effects on tissue thiamin measured by transketolase assay, thiamin pyrophosphate effect, or bioassay with Ochromonas danica. Shuttle box avoidance learning in rats was impaired in animals rendered thiamin deficient but not in animals fed control or alcohol-containing liquid diets. In baboons, chronic alcohol feeding for up to 3 yr had no effects on blood levels of thiamin or on urinary excretion of thiamin. Thus, chronic alcohol feeding along with nutritionally supplemented diets does not appear to significantly affect thiamin status.