Alcohol-containing Diet Research Articles

Inhibition of muscle protein synthesis by alcohol is associated with modulation of eIF2B and eIF4E.

The present study examined potential mechanisms for the inhibition of protein synthesis in skeletal muscle after chronic alcohol consumption. Rats were maintained on an alcohol-containing diet for 14 wk; control animals were pair fed. Alcohol-induced myopathy was confirmed by a reduction in lean body mass as well as a decrease in the weight of the gastrocnemius and psoas muscles normalized for tibial length. No alcohol-induced decrease in total RNA content (an estimate of ribosomal RNA) was detected in any muscle examined, suggesting that alcohol reduced translational efficiency but not the capacity for protein synthesis. To identify mechanisms responsible for regulating translational efficiency, we analyzed several eukaryotic initiation factors (eIF). There was no difference in the muscle content of either total eIF2alpha or the amount of eIF2alpha in the phosphorylated form between alcohol-fed and control rats. Similarly, the relative amount of eIF2Bepsilon in muscle was also not different. In contrast, alcohol decreased eIF2B activity in psoas (fast-twitch) but not in soleus or heart (slow-twitch) muscles. Alcohol feeding also dramatically influenced the distribution of eIF4E in the gastrocnemius (fast-twitch) muscle. Compared with control values, muscle from alcohol-fed rats demonstrated 1) an increased binding of the translational repressor 4E-binding protein 1 (4E-BP1) with eIF4E, 2) a decrease in the phosphorylated gamma-form of 4E-BP1, and 3) a decrease in eIF4G associated with eIF4E. In summary, these data suggest that chronic alcohol consumption impairs translation initiation in muscle by altering multiple regulatory sites, including eIF2B activity and eIF4E availability.

Differential Effects of Monoaminergic Agonists on Alcohol Intake in Rats Fed a Tryptophan-Enhanced Diet

The goal of the present study was to determine if enhancement of tryptophan levels in a nutritionally balanced liquid diet would affect alcohol intake in a two-bottle choice procedure. Furthermore, the monoaminergic agonists amphetamine, phentermine (dopaminergic- and noradrenergic-releasing drugs), and fenfluramine (a serotonin releaser) were administered to determine if these drugs reduced alcohol intake in animals fed the tryptophan-enhanced diet compared to those fed an alcohol-containing diet without added tryptophan. Amphetamine 0.5 and 2 mg/kg and phentermine 4 mg/kg selectively reduced alcohol intake in animals fed the tryptophan-enhanced diet; higher doses also reduced alcohol intake in animals fed the control alcohol diet. Three hours after drug administration, phentermine 2 and 4 mg/kg produced increases in consumption of the nonalcoholic diet in animals fed the control diet without affecting consumption in animals fed the tryptophan-enhanced diet. Finally, animals in the tryptophan-enhanced group gained less weight than those animals fed an identical diet without the added tryptophan. Neurochemical analysis revealed that the tryptophan-fed groups showed increased 5-HIAA concentrations and serotonin turnover in the striatum, hypothalamus, and frontal cortex compared to animals fed the control diet. The tryptophan-alcohol group also showed almost double the tryptophan levels in the hypothalamus compared to the tryptophan-isocaloric group. These results indicate that, whereas increasing tryptophan levels by itself was not sufficient to alter consumption of an alcohol-containing diet, the administration of monoaminergic agonists significantly interacted with tryptophan in a dose-dependent manner to reduce intake of an alcohol-containing diet without reducing intake of an isocaloric diet.

Lipid peroxidation products and antioxidants in human disease.

Lipid peroxidation (LPO) is a free radical-related process that in biologic systems may occur under enzymatic control, e.g., for the generation of lipid-derived inflammatory mediators, or nonenzymatically. This latter form is associated mostly with cellular damage as a result of oxidative stress, which also involves cellular antioxidants in this process. This article focuses on the relevance of two LPO products, malondialdehyde (MDA) and 4-hydroxynonenal (HNE), to the pathophysiology of human disease. The former has been studied in human serum samples of hepatitis C virus-infected adults and human immunodeficiency virus-infected children. In these two cases it is shown that the specific assay of serum MDA is useful for the clinical management of these patients. The presence of MDA in subretinal fluid of patients with retinal detachment suggests the involvement of oxidative stress in this process. Moreover, we were able to report the dependence of this involvement on the degree of myopia in these patients. The assay of MDA contents in the peripheral nerves of rats fed a chronic alcohol-containing diet or diabetic mice also confirms the pathophysiologic role of oxidative stress in these experimental models. In these two cases, associated with an increase in tissue LPO products content, we detected a decrease of glutathione peroxidase (GSHPx) activity in peripheral nerve, among other modifications. We have demonstrated that in vitro HNE is able to inhibit GSHPx activity in an apparent competitive manner, and that glutathione may partially protect and/or prevent this inactivation. The accumulation of LPO products in the brain of patients with Alzheimer's disease has also been described, and it is on the basis of this observation that we have tried to elucidate the role of oxidative stress and cellular antioxidants in beta-amyloid-induced apoptotic cell death of rat embryo neurons. Finally, we discuss the possible role of the observed vascular effects of HNE on human arteries.

Renal effects of alcohol withdrawal in five-week alcohol-treated rats.

The effects of alcohol withdrawal on renal function following renal ischemia was examined in rats fed a liquid containing ethanol for 5-week alcohol treatment. For alcohol-treated rats, animals were fed with an ethanol-containing diet for 5 weeks. In withdrawal studies, the alcoholic diet was replaced by a regular diet following 5-week alcohol treatment. Renal ischemia was induced by clamping the renal artery for 20 minutes and renal function was evaluated 24 hours later. Alcohol ingestion for 5 weeks did not alter the renal function in the absence of renal ischemia. Mean (+/- SD) glomerular filtration rate (GFR) and renal plasma flow rate (RPFR) measured 24 hours after ischemia in control rats were 430 +/- 29.6 microliters/min/g/kidney weight (gKW) and 1.4 +/- 0.17ml/min/gKW, whereas in alcohol-treated rats, they were 117.2 +/- 35.2 microliters/min/gKW and 0.31 +/- 0.12ml/min/gKW, which values were significantly lower than controls (p < .05). However, when alcohol was withdrawn for 1 week, the renal function of rats after ischemia was no different from that of control rats (GFR = 413.9 +/- 66.3 microliters/min/gKW and RPFR = 2.14 +/- 0.7 ml/min/gKW). As for renal histopathology, tubular damage was milder 1 week after alcohol withdrawal compared to that observed in rats fed the alcohol-containing diet for 5 weeks. The findings suggest renal damage induced in rats by exposure to alcohol for 5 weeks was reversed when alcohol was withdrawn for 1 week before renal ischemia.

Permanent neuronal cell loss in the inferior olive of adult rats exposed to alcohol during the brain growth spurt: a stereological investigation.

The purpose of this study was to examine whether exposure of rat pups to alcohol postnatally over a period of brain development similar to that of the human 3rd trimester results in a permanent loss of cells in the inferior olivary nucleus. It was hypothesized that a deficit of neurons in the inferior olive, the sole source of climbing fibers, may contribute to the cerebellar dysfunction observed following exposure to alcohol during development. Sprague-Dawley rat pups were artificially reared and administered alcohol over postnatal days 4-9. One artificially reared group received a daily alcohol dose of 4.5 g/kg, administered as a 10.2% solution in 2 of 12 daily feedings (10.2% group). This pattern of alcohol administration resulted in high peak blood alcohol concentrations with near total clearance. The other artificially reared group was fed a diet made isocaloric to the alcohol-containing diet (gastrostomy control group). Pups were allowed to grow to adulthood and killed on postnatal day 115. The total number of neurons in the inferior olivary nucleus was estimated using unbiased stereological methods. Exposure to alcohol resulted in a significant deficit in the number of neurons in the inferior olive at 115 days of age. The total number of neurons in the alcohol-exposed group was 40.12 +/- 8.7 x 10(3), compared with 53.37 +/- 3.7 x 10(3) in the artificially reared controls. These results indicate that there is a permanent deficit of neurons in the inferior olive after postnatal exposure to alcohol.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary nonfunction of fatty livers produced by alcohol is associated with a new, antioxidant-insensitive free radical species.

The formation of free radicals after orthotopic liver transplantation in the rat correlates with graft failure. Fatty livers from alcoholics transplant poorly, so these studies were designed to examine the effect of alcohol on free radical formation in a rearterialized rat liver transplantation model. Treatment of rats for 3-5 weeks with either a high-fat or an ethanol-containing liquid diet caused characteristic pericentral lipid accumulation. After storage in University of Wisconsin cold storage solution (UW) and transplantation, a reperfusion injury characterized by increased postoperative AST levels (greater than 1500 U/l in about 3 hours) was observed in rats fed high-fat or alcohol-containing diets, whereas parenchymal cell injury was seen much less in low-fat controls. Survival was around 63% in the low-fat group but decreased to 12 and 18% in the high-fat and alcohol groups, respectively. Furthermore, intracellular lipid content correlated inversely with survival. In untransplanted livers, the spin trap alpha-phenyl N-tert-butylnitrone (PBN) was infused, and blood samples were collected and extracted with chloroform:methanol. Signals indicative of carbon-centered PBN radical adducts were barely detectable in all untransplanted groups studied by electron paramagnetic resonance. In contrast, a robust 6-line complex spectrum was obtained from all groups studied immediately after 48 hours of cold storage in UW solution and transplantation. A mixture of 3 radical species was identified. Two had coupling constants similar to lipid-derived free radicals, whereas the third is a new species with unique coupling constants and is most likely oxygen derived. In low-fat controls, the signal was reduced significantly by superoxide dismutase (SOD)/catalase; however, SOD/catalase had no effect on free radicals in lipid-loaded livers. Thus, both dietary high fat and alcohol exposure produce a unique SOD/catalase-insensitive free radical species that may be involved in the mechanism of failure of fatty livers after orthotopic liver transplantation.

Effect of acute and chronic alcohol administration to rats on the expression of interleukin-6 cell-surface receptors of hepatic parenchymal and nonparenchymal cells.

Rats were treated with alcohol either acutely (continuous, 7-hr intravenous infusion; blood alcohol levels approximately 35 mM) or chronically (liquid diet, 12-14 weeks). Three hr before killing, the animals received Gram-negative bacterial lipopolysaccharide (LPS) or saline. Hepatocytes, Kupffer cells, and liver sinusoidal endothelial cells were isolated by liver collagenase perfusion and centrifugal elutriation, and used for measurements of recombinant human [125I]interleukin-6 binding. Dissociation constant (Kd) and the amount of cell-surface receptors (Bmax) were measured on whole cells, at 4 degrees C. Two binding sites were detected on all three cell types: high-affinity (Kd1, from 20 to 125 pM) and low-affinity (Kd2, from 0.2 to 2 nM), with low Bmax (Bmax, from 0.4 to 12 fmol/10(6) cells) and high Bmax (Bmax2, from 10 to 210 fmol/10(6) cells). Hepatocytes displayed an 8-fold higher binding capacity for high-affinity sites (Bmax1) than the other two cell types. Acute ethanol treatment induced the following significant changes in the binding parameters: a decrease in Kd1 for hepatocytes and Kupffer cells, an increase in Bmax2 for hepatocytes, and a decrease in Bmax1 for Kupffer cells. Although the control (nonalcoholic) liquid diet per se completely suppressed the high-affinity binding sites, alcohol-containing diet induced only one change: a significant increase in Kd2 for hepatocytes. No changes in the binding parameters were seen after LPS administration to the chronically treated group. In the acute group, LPS mimicked alcohol action on hepatocyte binding parameters. Alcohol blunted LPS effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Zonal distribution of protein-acetaldehyde adducts in the liver of rats fed alcohol for long periods

Acetaldehyde, a highly reactive intermediate of alcohol metabolism, has been shown to form adducts with liver proteins in rats fed alcohol for long periods. In this report, the zonal distribution of liver protein-acetaldehyde adducts that formed in vivo was studied by means of histoimmunostaining. Rats were pair-fed alcohol-containing and alcohol-free AIN'76 liquid diets for 2 or 11 wk before they were killed and subjected to whole body perfusion with paraformaldehyde. Each liver was cut into 60-microns-thick slices. Slices were first treated with 10% hydrogen peroxide to eliminate endogenous peroxidase activity. They were then incubated sequentially with rabbit antihemocyanin-acetaldehyde adduct, goat antirabbit serum IgG and rabbit peroxidase-antiperoxidase complex. The liver slices were stained with diaminobenzidine and counterstained with methylgreen. In the livers of rats fed alcohol for 2 wk, peroxidase activity was evident in the perivenous zone but not the periportal zone. No staining was obtained when the primary antibody had been preabsorbed with immobilized hemocyanin-acetaldehyde adduct or if the liver slices were incubated with the unimmunized rabbit IgG. Slight staining of the perivenous zone was seen in the livers of control rats, presumably because of minimal protein-acetaldehyde adduct formation emanating from endogenous acetaldehyde. When rats were fed alcohol for longer periods (e.g., 11 wk), protein-acetaldehyde adducts were still seen predominantly in the perivenous zone, but the distribution pattern was more diffuse than that observed in the livers of rats fed alcohol for only 2 wk. More liver cells produced protein-acetaldehyde adducts when rats were fed the alcohol-containing diet supplemented with cyanamide.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of ethanol on urinary acidification and on gluconeogenesis by isolated renal tubules

Class I alcohol dehydrogenase (ADH) is present in the kidney of rats. Rats fed an alcohol-containing diet long-term had higher urinary pH and reduced titratable acidity compared with pair-fed controls; rates of ammonium excretion were unchanged. The effects of ethanol on the metabolism of isolated renal tubules were then studied. Gluconeogenesis from lactate, pyruvate, or glutamine was not inhibited by 10 mmol/L ethanol during 30- or 60-minute incubations, although there was a trend toward increased lactate/pyruvate ratios at 30 minutes in the presence of ethanol. When the medium was also supplemented with oleate, glucose synthesis from most substrates was decreased, and the addition of ethanol inhibited glucose synthesis dramatically. This interaction between oleate and ethanol was not abolished by 4-methylpyrazole, an inhibitor of ADH. This effect of ethanol was highly dependent on the concentration of oleate present in the medium and was not observed with palmitate or decanoate; the inhibition was reversed by increasing the medium concentration of albumin. We conclude that ethanol may mildly perturb the redox state of isolated kidney tubules without inhibiting glucose synthesis, and that ethanol and oleate interact to inhibit renal gluconeogenesis by a mechanism highly dependent on the fatty acid concentration. The mechanism by which ethanol in the diet reduces renal acid excretion remains unknown.

ETHANOL AND DIET-INDUCED ALTERATIONS IN KUPFFER CELL FUNCTION

The effects of 6 weeks of alcohol feeding on phagocytic, metabolic and secretory functions as well as gene expression of hepatic Kupffer cells were evaluated in vitro using cultured Kupffer cells isolated from male Sprague-Dawley rats. The rats were fed either Teklad pelleted rat chow or the 1982 Lieber-DeCarli liquid diet containing 6% ethanol (36% calories) or the same liquid diet with maltose-dextrin isocalorically substituted for the alcohol. Weight gain was greatest in the chow-fed animals and least in those receiving ethanol. The alcohol-containing diet stimulated Kupffer cell phagocytosis, mitochondrial reduction of MTT, secretion of tumor necrosis factor (TNF) and expression of TNF mRNA. However, each of these cell functions was also enhanced by the control Lieber-DeCarli liquid diet alone and the stimulating effect of the control diet often exceeded that induced by ethanol. The results suggest that early in chronic alcohol consumption, the immune system may be stimulated by ethanol, and that during studies of ethanol-induced changes in immune system function, close attention must be given to potentially confounding effects of the diet.

Effect of Short‐Term Ethanol Feeding on Rat Testes as Assessed by 31P NMR Spectroscopy, 1H NMR Imaging, and Biochemical Methods

31P Nuclear magnetic resonance (NMR) spectroscopy and 1H NMR imaging were used to examine the effect of short-term ethanol feeding on the rat testis. Weanling rats were pair-fed for 10 weeks either on ethanol containing liquid diet (36% ethanol of total calories) or a diet in which dextrimaltose was isocalorically substituted for the ethanol of the alcohol-containing diet. In vivo 31P NMR of the testes was used to determine the intratesticular pH and the relative concentrations of various phosphorus-containing metabolites. The integrity of the blood-testes barrier was evaluated using 1H NMR imaging following a gadolinium diethylene tetramine pentaacetic acid derivative (Gd-DTPA) administration as a vascular contrast agent. After the completion of NMR studies, the testis and the liver were freeze-clamped to allow for the assay of their adenosine-5'-triphosphate (ATP) contents. Serum was assayed for its content of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alcohol and testosterone. Ethanol feeding resulted in the following: (a) a reduction in the body weight (p less than 0.05), (b) a reduction in the testicular phosphodiesters (PDE) PDE/ATP ratio (p less than 0.05), (c) an increased change in the testis image intensity difference between pre- and post-iv Gd-DTPA images, (c) a reduction in the testicular and hepatic content of ATP, and (d) increased serum levels of AST and ALT.(ABSTRACT TRUNCATED AT 250 WORDS)

Sexual orientation in male rats prenatally exposed to ethanol

Previous studies have shown that prenatal ethanol exposure causes feminization of the male offspring, as evidenced by display of female sexual response (lordosis), when mounted by a stud male. In the present study we examined whether or not the feminization induced by prenatal ethanol exposure also affected a different aspect of sexually motivated behavior, namely, the approach towards a receptive female normally displayed by male rats. The testing apparatus consisted of an open-field arena with two small boxes in which were placed the stimulus animals, in one box a male rat, in the other a receptive female. The partition between the stimulus and the experimental animals consisted of a metal net allowing both animals to see and smell each other without actual physical contact. The tendency to approach the receptive female or the male was assessed by the proportion of the observation period the experimental male spent near the receptive female or the male rat, respectively. The experiment was performed on the adult male offspring of mothers consuming a liquid diet containing 5% ethanol, giving rise to a daily ethanol intake of about 14 g/kg. One group of control mothers was given a liquid diet without alcohol but isocaloric with the alcohol-containing diet. Another control group had free access to water and lab chow. The results showed that male offspring of both control groups devoted 29% of the observation period near the receptive female as compared to 13% near the male. The ethanol-exposed males on the other hand devoted as much time, 20%, to the male as to the receptive female. The results indicate that the normal tendency of a male rat to approach a receptive female is attenuated by prenatal ethanol exposure. This observation suggests that the feminization induced in the male by such a treatment is not only restricted to a display of lordotic reactions but also affects the sexual orientation.

Effects of an alcohol diet on locomotor activity and the acquisition of brain self-stimulation in rats

Male rats (n = 45), implanted with stimulating electrodes in the lateral hypothalamus for intracranial self-stimulation (ICSS), were allocated to three groups equalized for body weights. One group was given an alcohol liquid diet (Lieber-DeCarli) diet as the sole source of food; a second group was given a control liquid diet in which carbohydrates were substituted for alcohol; and a third group was maintained on standard laboratory chow and water. After four weeks on these diets, all animals were tested during the fifth week of the diets for locomotor activity in five daily 15-min sessions, and their reactivity to handling was also measured. During the sixth and seventh weeks of the diets, animals were allowed to self-train for ICSS during daily 15-min sessions. In the eighth week blood alcohol levels were measured. There were no differences between groups in locomotor activity or reactivity to handling. However, when tested for the acquisition of ICSS, animals on the diet containing alcohol made fewer responses than did those receiving the two control diets (p less than 0.001). The mean blood level of alcohol in the alcohol-consuming group at the time of day of behavioral testing was 50.6 +/- 5.0 mg/dl. These results suggested that the chronic ingestion of an alcohol-containing diet which resulted in only moderate blood levels of alcohol may not affect simple behavior such as locomotor activity, but may produce decrements in the performance of a more complex task such as lever pressing for ICSS.

Formation of the 37KD Protein‐Acetaldehyde Adduct in Liver During Alcohol Treatment is Dependent on Alcohol Dehydrogenase Activity

Protein-acetaldehyde adducts (protein-AAs) are formed in vivo during chronic alcohol ingestion. These protein-AAs reported thus far include a 37KD protein-AA in liver cytosol, cytP450IIE 1-AA in hepatic microsomes, hemoglobin-AA, and serum protein-AAs. It has been postulated that acetaldehyde or perhaps a reactive acetaldehyde radical generated by the microsomal ethanol oxidizing system (MEOS or cytP450IIE1) explains the formation of the cytP450IIE1-AA. The source of acetaldehyde responsible for the formation of the cytosolic 37KD protein-AA has not been determined. In this report, we have examined the effects of pyrazole (an ADH inhibitor) and cyanamide (an aldehyde dehydrogenase inhibitor) on the formation of the 37KD liver protein-AA in vivo and in vitro. It was found that feeding rats with an alcohol-containing liquid diet supplemented with cyanamide enhanced while a diet supplemented with pyrazole completely abolished the formation of the 37KD liver protein-AA. The liver of rats fed the pyrazole supplemented alcohol-containing diet showed significantly higher content of cytP450IIE1 than that of rats fed the diet containing alcohol alone. On the other hand, feeding the cyanamide supplemented alcohol-containing liquid diet did not further enhance the content of cytP450IIE1. Similarly, adding cyanamide to the culture medium enhanced while adding 4-methylpyrazole inhibited the production of the 37KD protein-AA by cultured hepatocytes even though the combination of alcohol and 4-methylpyrazole increased the content of cytP450IIE1 2-fold over that in control cells. These results demonstrate that the formation of the 37KD liver Protein-AA is dependent on ADH and not on MEOS.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced stimulatory effect of High Density Lipoproteins (HDL) and other agonists on vascular prostacyclin production in rats fed alcohol-containing diets

Chronic administration of liquid diets containing 36% of energy as ethanol to rats increased the serum level of high density lipoproteins (HDL) by 40% and potentiated 2 to 3-fold the stimulatory effect of these lipoporteins on the production of prostacyclin by aortic rings, as compared to pair-fed controls given isocaloric carbohydrate instead of ethanol. Cross-incubations between aortic rings and HDL from either alcohol-fed or pair-fed control rats revealed two factors operating in opposite directions. On the one hand, the predominant mechanism for the potentiation was increased reactivity of the vessel to these lipoproteins. This increased reactivity was also apparent with other agonists of prostacyclin formation. On the other hand, for equal amounts of either cholesterol or protein, the HDL from alcohol-fed rats were less stimulatory than those from controls. This was associated with a smaller content of arachidonate in the HDL of alcohol-fed rats. These ethanol effects on prostacyclin, a potent vasodilator and platelet antiaggregator, may contribute to the decreased incidence of ischemic heart disease observed in moderate alcohol drinkers.

The effect of di-isopropyl 1,3 dithiol-2-ylidenemalonate (Malotilate) on the hepatic changes induced by ethanol administration in the rat

The sulphur-containing drug, di-isopropyl-1,3-dithiol-2-ylidenemalonate (Malotilate) protects against the increase in hepatic triglyceride concentration after acute ethanol administration (either 6 g/kg p.o. or 2 g/kg i.p.)inrats. The compound had no influence on the increased hepatic NADH: NAD ratio (measured as the lactate : pyruvate and 3-hydroxybutyrate : acetoacetate ratios) after acute ethanol dosing (2 g/kg i.p.), but was found to lower hepatic acetaldehyde concentrations and prevent some of the disturbances in lipid metabolism observed in liver slices from ethanol-treated animals (e.g. decreased oxidation of [1- 14C]palmitate to 14CO 2) after this ethanol dose. The drug did not inhibit ethanol metabolism in this acute experiment. Administration of Malotilate to Wistar rats (100 mg/kg/day orally) during chronic feeding of ethanol as 36% of the total calorie intake in a liquid diet, resulted in a lower intake of the alcohol-containing diet by ethanol-fed animals and reduced body weight gain in rats which received the drug, without blood ethanol levels or the ethanol intake (expressed in g/kg body weight/day) being affected. In ethanol-fed animals, Malotilate prevented the production of fatty liver and the adaptive increase in the ethanol elimination rate (EER) normally seen in ethanol-fed animals, although the drug actually caused a slight increase in EER in glucose pair-fed controls. Malotilate did not significantly decrease the degree of induction of microsomal cytochrome P-450 by ethanol, but the increase in aniline hydroxylation was much less marked in animals receiving ethanol and Malotilate, suggesting that the activity of the inducible microsomal ethanol oxidising system (MEOS) may be reduced by the compound. Determination of hepatic acetaldehyde concentrations during ethanol feeding, and during an acute ethanol challenge test following long-term ethanol treatment showed that the compound significantly lowered the level of this ethanol metabolite in the liver under both circumstances. This reduction of hepatic acetaldehyde concentrations, probably resulting in part from the reduced EER as well as increased low- K m aldehyde dehydrogenase activities and glutathione contents seen in the livers of Malotilate-treated rats, are possible mechanisms by which the drug protects against triglyceride accumulation after ethanol administration.

Effect of acute and chronic alcohol feeding on prostaglandin E2 biosynthesis in rat stomach.

The effect of acute and chronic alcohol ingestion on gastric prostaglandin E2 synthesis and the PGE2 content in the stomach was studied in rats. Up to 8 hr following a single oral load of 20% alcohol (v/v; 4 g/kg body weight), the PGE2 synthesis in isolated microsomes from rat stomach remained unchanged as compared with control values. Feeding a liquid alcohol-containing diet (37% of total Joules) for 1, 6, or 12 weeks significantly decreased the rate of PGE2 synthesis (percentage inhibition as compared with control values 39, 27, and 57, respectively). In addition, chronic alcohol feeding led to a drop in the tissue content of PGE2, the decrease being more pronounced after 6 (-49%) and 12 (-58%) weeks than after 1 week (-24%). The results suggest that the inhibition of endogenous PGE2 synthesis in the stomach following ingestion of appreciable quantities of alcohol might play a role in the pathogenesis of alcohol-induced injury of the gastric mucosa.

Enhanced biliary gamma-glutamyltransferase excretion following prolonged alcohol consumption in rats.

In order to study the question of whether chronic ethanol consumption may alter the biliary excretion of gamma-glutamyltransferase (gamma-GT), female rats were pair-fed nutritionally adequate liquid diets containing either ethanol (36% of total calories) or isocaloric carbohydrates for 24 days. Compared to pair-fed controls, the administration of the alcohol-containing diet resulted in an increased biliary excretion of gamma-GT (5.84 +/- 0.73 mU 6 h-1 100 g-1 b.w. vs. 8.82 +/- 0.79, P less than 0.001). This was associated with a corresponding enhanced biliary output of total bile acids. An apparent linear relation between the biliary output rates of gamma-GT and those of total bile acids was observed both in alcohol-fed animals (r = 0.83) and in their pair-fed controls (r = 0.95). In addition, there was a significant increase of gamma-glutamyltransferase activities in the liver homogenate and in liver plasma membranes, both in fractions rich in bile canalicular and basolateral membranes and in those rich in blood sinusoidal site. Serum gamma-glutamyltransferase activities as well as serum bile acid concentrations were also enhanced by 96.8% (P less than 0.001) and 233% (P less than 0.001), respectively. These data show that chronic alcohol consumption enhances hepatic gamma-GT activities, leading to an increased efflux of gamma-GT into the bile and possibly into the blood out of the liver cell. Furthermore, these data suggest the involvement of bile acids with their solubilizing properties for the biliary excretion of gamma-GT.

Alcohol-induced liver injury after jejunoileal bypass operation in rats

The objective of this study was to investigate whether alcohol administration exerts a synergistic effect on jejunoileal bypass-induced liver dysfunction in rats. Male Wistar rats were subjected to 90% jejunoileal bypass or sham operation. For 10 weeks, subgroups were pair-fed either an alcohol-containing (36% of total calories) liquid diet or a liquid diet where alcohol was replaced isocalorically by starch. Alcohol feeding in rats with jejunoileal bypass increased hepatic triglyceride content about 6-fold as compared with bypassed rats receiving control diet. Neither jejunoileal bypass nor alcohol feeding led to significant changes in hepatic DNA and protein contents. Alcohol feeding increased cytochrome P-450 levels both in operated and in sham-operated rats. The administration of alcohol-containing diet decreased the activity of succinic dehydrogenase, the decrease being distinctly more pronounced in rats with jejunoileal bypass than in the sham-operated controls. Light microscopy revealed no significant morphological alterations in liver sections of rats fed the control diet after jejunoileal bypass or of rats receiving either the alcohol-containing diet or the control diet after sham operation. Alcohol feeding in bypassed rats, however, produced marked diffuse accumulation of fat, and regularly led to other histological abnormalities in the liver. These abnormalities included ballooning of hepatocytes and disarray of the trabecular structure of the liver lobule, hyalin inclusions resembling megamitochondria, single-cell necrosis and focal clustering of necrosis, increased number of mitotic figures, and infiltrates with inflammatory cells. The histological lesions of the liver of bypassed rats receiving alcohol exhibited no obvious zonal distribution. The results demonstrate that alcohol feeding to rats subjected to jejunoileal bypass leads to marked liver injury which mimics, at least in part, that of alcohol-induced liver disease in man. Rats subjected to jejunoileal bypass may, therefore, provide a new model for the study of alcoholic liver disease.

Degradation of Acetaldehyde Produced by the Nonalcohol Dehydrogenase Pathway

Acetaldehyde (Ac-CHO) is produced via the oxidation of ethanol by two different pathways; alcohol dehydrogenase (ADH) and non-ADH systems. However, degradation of Ac-CHO in the liver, especially with respect to the relative amounts produced by the two pathways, remains unclear. In order to clarify the metabolic fates of Ac-CHO produced by the two pathways, the ethanol metabolic rate (EMR) and hepatic Ac-CHO levels in the rats fed an alcohol-containing or control diet for 4 weeks were determined after a single administration or constant infusion of ethanol, with or without 4-methylpyrazole pretreatment. The EMR was increased in chronic alcoholic rats and decreased by treatment with 4-methylpyrazole. Consequently, blood and hepatic Ac-CHO levels were low in the pyrazole-treated rats in both the single dose and infusion experiments. Hepatic Ac-CHO levels and EMR were well correlated in both experiments. However, the correlations were curve linear and the slopes of the regression lines in the pyrazole-treated rats were steeper than those in the nontreated rats. When the ratios of hepatic Ac-CHO (subtracted by a constant which was obtained from the correlation equations for the curvilinear fit of hepatic Ac-CHO levels and EMR) to EMR were calculated, they were significantly higher in the pyrazole-treated rats than in the nontreated rats of the perfusion experiment, without relation to chronic alcohol ingestion. These results suggest that Ac-CHO produced by the non-ADH pathway degrades more slowly than that produced by the ADH pathway in the liver.