Unpredictable cold-immobilization stress effects on voluntary ethanol consumption in rats

The effects of exposure to a schedule of unpredictable cold-immobilization stress on voluntary ethanol consumption were examined. Following testing for ethanol preference, rats were divided into high, medium and low ethanol consuming groups on the basis of daily ethanol intake (g/kg/day) and exposed to immobilization stress over an 18 day period. Voluntary ethanol consumption was monitored during the stress period and for an additional 36 days post-stress. Results indicated a differential effect of stress on ethanol intake in that low ethanol consuming rats increased their ethanol intake during the stress period and maintained this increase throughout the entire post-stress period as compared to non-stressed controls. High ethanol consuming groups demonstrated a small (marginally significant) decrease in ethanol intake during the stress period as compared to baseline levels. No change in ethanol intake was observed for the medium ethanol consuming groups. The results suggest that unpredictable immobilization stress has a differential effect on ethanol intake depending upon pre-stress levels of ethanol consumption.     

Ethanol preference in C. elegans

Caenorhabditis elegans senses multiple environmental stimuli through sensory systems and rapidly changes its behaviors for survival. With a simple and well-characterized nervous system, C. elegans is a suitable animal model for studying behavioral plasticity.
Previous studies have shown acute neurodepressive effects of ethanol on multiple behaviors of C. elegans similar to the effect of ethanol on other organisms. Caenorhabditis elegans also develops ethanol tolerance during continuous exposure to ethanol. In mammals, chronic ethanol exposure leads to ethanol tolerance as well as increased ethanol consumption. Ethanol preference is associated with the development of tolerance and may lead to the development of ethanol dependence.
In this study, we show that C. elegans is a useful model organism for studying chronic effects of ethanol, including the development of ethanol preference. We designed a behavioral assay for testing ethanol preference after prolonged ethanol exposure. Despite baseline aversive responses to ethanol, animals show ethanol preference after 4 h of pre-exposure to ethanol and exhibit significantly enhanced preference for ethanol after a lifetime of ethanol exposure. The cat-2 and tph-1 mutant animals have defects in the synthetic enzymes for dopamine and serotonin, respectively. These mutants are deficient in the development of ethanol preference, indicating that dopamine and serotonin are required for this form of behavioral plasticity.     

Investigations of the effects of ethanol on warfarin binding to human serum albumin

Ethanol effects on warfarin binding to human serum albumin (HSA) have been studied by equilibrium dialysis and fluorescence methods at pH 7.4 in phosphate-buffered saline at 37 degrees C. In the presence of various amounts of ethanol fluorescence intensity of bound warfarin decreased significantly but this intensity reduction was not solely from displacement of bound warfarin from HSA. By comparing fluorescence and equilibrium dialysis data we concluded that fluorescence intensity reduction of warfarin was mainly the result of changes in the surrounding environment of the warfarin binding site by ethanol interaction with HSA and that displacement of bound warfarin was not significant compared to the fluorescence intensity changes. The dissociation constant of warfarin binding to HSA decreased with an increasing amount of ethanol. From the changes in fluorescence intensity upon warfarin binding to HSA with the presence of ethanol ranging from 0 to 5.0% the following dissociation constants (Kd) were determined: 0% ethanol 5.39 +/- 0.2 microM, 0.1% ethanol 5.86 +/- 0.1 microM, 0.3% ethanol 5.83 +/- 0.2 microM, 0.5% ethanol 6.76 +/- 0.1 microM, 1% ethanol 7.01 +/- 0.1 microM, 3% ethanol 9.9 +/- 0.7 microM, 5% ethanol 13.01 +/- 0.1 microM. From the equilibrium dialysis with the same ranges of ethanol presence the following Kd values were obtained: 0% ethanol 6. 62 +/- 1.6 microM, 0.1% ethanol 6.81 +/- 1.1 microM, 0.3% ethanol 8. 26 +/- 2.5 microM, 0.5% ethanol 8.86 +/- 1.9 microM, 1% ethanol 11. 01 +/- 4.2 microM, 3% ethanol 20.75 +/- 2.4 microM, 5% ethanol 21.67 +/- 2.2 microM. The results suggest that warfarin bound to HSA was displaced by ethanol. These data indicate that ethanol influence on warfarin binding to HSA may alter the pharmacokinetics of warfarin.     

Ethanol tolerance of yeast

The ethanol tolerance mechanism in yeasts is not very well understood. This may result from the complex inhibitory mechanisms of ethanol, the lack of a universally accepted definition and method to measure ethanol tolerance, and its complex polygenic characteristic. Recently, there has been some progress in understanding ethanol tolerance. Plasma membrane phospholipids have been shown to play an important role in the ethanol tolerance mechanism. Increases in membrane unsaturated fatty acids result in increased yeast ethanol tolerance. Supplementation of growth media with combinations of unsaturated fatty acids, vitamins and proteins also enhance ethanol tolerance. Physiological factors such as mode of substrate feeding, intracellular ethanol accumulation, temperature and osmotic pressure all contribute to the ethanol tolerance of yeast. The complex nature of ethanol toxicity suggests that a number of different genes are likely to be involved in the ethanol tolerance mechanism. Genetic approaches such as spheroplast or protoplast fusion, hybridization and continuous culture selection have been used to obtain ethanol tolerant yeasts. Isolation and characterization of such strains may provide a better understanding of ethanol tolerance.     

Direct and correlated responses to selection for larval ethanol tolerance in Drosophila melanogaster

Ethanol is an important larval resource and toxin for natural Drosophila melanogaster populations, and ethanol tolerance is genetically variable within and among populations. If ethanol‐tolerant genotypes have relatively low fitness in the absence of ethanol, as suggested by the results of an earlier study, genetic variation for ethanol tolerance could be maintained by variation in ethanol levels among breeding sites. I selected for ethanol tolerance in large laboratory populations by maintaining flies on ethanol‐supplemented media. After 90 generations, the populations were compared with control populations in egg‐to‐adult survival and development rate on ethanol‐supplemented and unsupplemented food. When compared on ethanol‐supplemented food, the ethanol‐selected populations had higher survival and faster development than the control populations, but on unsupplemented food, the populations did not differ in either trait. These results give no evidence for a ‘trade‐off’ between the ability to survive and develop rapidly in the presence of ethanol and the ability to do so in its absence. The effect of physiological induction of ethanol tolerance by exposing eggs to ethanol was also investigated; exposing eggs to ethanol strongly increased subsequent larval survival on ethanol‐supplemented food, but did not affect survival on regular food, and slowed development on both ethanol‐supplemented and regular food, partly by delaying egg hatch.     

Neuropeptide Y modulation of ethanol intake: effects of ethanol drinking history and genetic background

Intracerebroventricular administration of NPY suppresses ethanol intake in selectively bred alcohol-preferring rat lines, but not in rats selectively bred for low ethanol drinking or in unselected Wistar rats, when access to ethanol is limited to 2h/day. However, when rats undergo chronic (24h/day) ethanol drinking (or exposure to ethanol by vapor inhalation) and have periods of imposed ethanol abstinence, the reductions in ethanol drinking following NPY administration are enhanced in alcohol-preferring rats and are also observed in unselected Wistar rats. Thus, sensitivity to the effects of NPY on ethanol drinking appears to be altered by selective breeding for ethanol preference and by a prior history of chronic but intermittent exposure to ethanol.     

Aeration alleviates ethanol inhibition and glycerol production during fed-batch ethanol fermentation

In this study, we investigated the effects of aeration on ethanol inhibition and glycerol production during fed-batch ethanol fermentation. When aeration was conducted at 0.13, 0.33, and 0.8 vvm, the ethanol productivity, specific ethanol production rate, and ethanol yield in the presence of greater than 100 g/L of ethanol were higher than when aeration was not conducted. In addition, estimation of the parameters (α and β) in a model equation of ethanol inhibition kinetics indicated that aeration alleviated ethanol inhibition against the specific growth rate and the specific ethanol production rate. Specifically, when aeration was conducted, the glycerol yield and specific glycerol production rate decreased approximately 50 and 70%, respectively. Finally, the results of this study indicated that aeration during fed-batch ethanol fermentation may improve the ethanol concentration in the final culture broth, as well as the ethanol productivity.     

The ethanol tolerance of Pichia stipitis Y 7124 grown on a d-xylose,d-glucose and l-arabinose mixture

The tolerance of Pichia stipitis Y 7124 to initial added ethanol was evaluated in anaerobic and microaerobic conditions, during the fermentation of a sugar mixture (d-glucose 20%, d-xylose 75%, l-arabinose 5%). The ethanol tolerance depends on the presence of oxygen. In microaerobiosis, the fermentative capacity of P. stipitis is not inhibited when the initial ethanol concentration does not exceed 20 g/l; in this added ethanol range, the strain produced ethanol with a yield up to 0.40 g/g and a specific rate of 0.1 g/g·h. An increase of the initial ethanol level decreases the rate of ethanol production but the ethanol yield appears to be less sensitive to ethanol inhibition. In anaerobiosis, maximum fermentative performances are obtained in the zero initial ethanol culture. When initial ethanol increases, growth and ethanol production decline gradually. But P. stipitis produces ethanol at an initial ethanol level of 50 g/l, even though this totally inhibits the strain activity in microaerobiosis.     

Saturable ethanol binding in rat liver mitochondria

The binding of ethanol to rat liver mitochondria is shown to be saturable at physiologically relevant ethanol concentrations. This effect is reversible and is not observed in extracted mitochondrial phospholipids. Brief exposure of the mitochondria to heat abolishes saturable ethanol binding. Previously, saturable ethanol binding was reported in rat liver microsomes. Taken together, the studies indicate that saturable ethanol binding motifs may be widespread in cellular membranes. The possibility is raised that incomplete expression of the hydrophobic effect in membrane assembly results in the expression of amphipathic packing defects which display an affinity for and a sensitivity to ethanol. The presence of saturable binding modalities is reconciled with the long-standing consensus on the biodistribution of ethanol - that ethanol's interactions with tissue are negligible - on the grounds that the affinities of ethanol and of water for membranes are similar; consequently, free ethanol concentrations are insensitive to the presence of tissue despite significant ethanol binding. A fraction of the binding sites possess submillimolar affinities for ethanol consistent with published functional studies, both in vitro and in vivo, that reported submillimolar efficacies for ethanol.     

Intragastric self-infusion of ethanol in high- and low-drinking mouse genotypes after passive ethanol exposure

Two experiments examined the effect of 5 days of passive exposure to ethanol (or water) on later self-infusion of ethanol or water via surgically implanted intragastric (IG) catheters in mouse genotypes previously shown to drink high (C57BL/6J, HAP2) or low (DBA/2J, LAP2) amounts of ethanol in home-cage continuous-access two-bottle choice procedures. Intragastric ethanol self-infusion was affected by both genotype and a history of passive ethanol exposure, with greater intakes in the high-drinking genotypes and in groups that received passive exposure to ethanol. Passive ethanol exposure also increased preference for the flavor that signaled ethanol infusion (S+), eliminating genetic differences in this measure. The increases in ethanol intake and S+ preference induced by ethanol exposure might have been mediated jointly by development of tolerance to aversive post-absorptive ethanol effects and negative reinforcement because of alleviation of withdrawal. Bout analyses indicated that ethanol exposure increased ethanol self-infusion by increasing the total number of daily bouts rather than by increasing bout size. These analyses also showed that DBA/2J mice infused larger ethanol bouts and a greater percentage of their total intakes in large bouts than C57BL/6J mice. Overall, these studies suggest that the IG self-infusion procedure is a potentially useful new tool for studying genetic and environmental influences on excessive ethanol intake and preference in mice.     

Differences in hepatic and metabolic changes after acute and chronic alcohol consumption.

Hepatic metabolism of ethanol to acetaldehyde by the alcohol dehydrogenase pathway is associated with the generation of reducing equivalents as NADH. Conversely, reducing equivalents are consumed when ethanol oxidation is catalyzed by the NADPH dependent microsomal ethanol oxidizing system. Since the major fraction of ethanol metabolism proceeds via alcohol dehydrogenase and since the oxidation of acetaldehyde also generates NADH, an excess of reducing equivalents is produced. This explains a variety of effects following acute ethanol administration, including hyperlactacidemia, hyperuricemia, enhanced lipogenesis and depressed lipid oxidation. To the extent that ethanol is oxidized by the alternate microsomal ethanol oxidizing system pathway, it slows the metabolism of other microsomal substrates. Following chronic ethanol consumption, adaptive microsomal changes prevail, which include enhanced ethanol and drug metabolism, and increased lipoprotein production. Severe hepatic lesions (alcoholic hepatitis and cirrhosis) develop after prolonged ethanol consumption in baboons. These injurious alterations are not prevented by nutritionally adequate diets and can therefore be ascribed to ethanol rather than to dietary inadequacy.     

外加肌醇和钙离子对酿酒酵母乙醇发酵的影响

酒精发酵是重要的发酵工业之一,在传统的酒精发酵过程中,菌种的酒精发酵浓度低,原料的利用率和酒精的转化率也低,能量消耗大,导致生产效率较差［１］。近年来国内外许多研究者致力于筛选和构建能产高浓度酒精和耐高浓度酒精的菌种,并把这些酿酒酵母应用于浓醪发酵生...     

Effect of Withania somnifera Dunal in ethanol-induced anxiolysis and withdrawal anxiety in rats

Withania somnifera (WS) or its psychotropic preparation is known to play a critical role in morphine, alcohol and benzodiazepines addiction. This study investigates the role of WS in acute ethanol and withdrawal from chronic ethanol consumption using elevated plus maze paradigm in rats. Acute administration of ethanol (1.5-2 g/kg, ip) triggered anxiolytic effect and withdrawal from prolonged ethanol (9% v/v ethanol, 15 days) consumption elicited enhanced behavioral despair (anxiety). Acute administration of WS (50 mg/kg, oral) potentiated the anxiolytic action of subeffective dose of ethanol (0.5 or 1 g/kg, ip). Moreover, the ethanol withdrawal anxiety was markedly antagonized in dose dependent manner by WS at 200 and 500 mg/kg or higher dose of ethanol (2.5 g/kg). However, co-administration of subeffective doses of WS (50 mg/kg, oral) and ethanol also attenuated withdrawal-induced anxiety due to chronic ethanol (9% v/v ethanol, 15 days) consumption. The results suggest the protective effect of WS in the management of ethanol withdrawal reactions.     

The role of fetal urinary excretion in the transfer of ethanol into amniotic fluid after maternal administration of ethanol to the near-term pregnant ewe

The objective of this study was to determine whether fetal urinary excretion is a major route of ethanol transfer into the amniotic fluid surrounding the fetus following maternal administration of ethanol. Conscious instrumented pregnant ewes between 130 and 137 days' gestation (term, 147 days) with (n = 3) or without (n = 3) a catheter in the fetal bladder were administered 1 g ethanol/kg maternal body weight as a 1-h maternal intravenous infusion. Maternal blood, fetal blood, and amniotic fluid samples were collected at selected times, and fetal urine was collected continuously from the bladder-cannulated fetus during the 14-h study for the determination of ethanol concentrations. Fetal urinary excretion of ethanol occurred, and the total amount of ethanol excreted represented 0.30 +/- 0.07 (SD)% of the maternal ethanol dose. The renal clearance of ethanol by the fetus was 0.43 +/- 0.06 mL/min. The pharmacokinetics of ethanol in the maternal-fetal unit and the amniotic fluid for the bladder-cannulated fetal preparation were similar to the data for the nonbladder-cannulated preparation. The data indicate that fetal urinary excretion of ethanol is a secondary route of ethanol transfer into the amniotic fluid. It would appear that diffusion of ethanol across membranes from the maternal and fetal circulations is a major route of ethanol transfer into this intrauterine compartment.     

Vasopressin and ethanol preference. I. Effects of vasopressin and the fragment DGAVP on altered ethanol preference in Brattleboro diabetes insipidus rats

Preference for concentrations of ethanol between 2.2 and 10 percent versus tap water was studied in Brattleboro rats homozygous for diabetes insipidus (di/di), heterozygous (di/+) or normal (+/+). The di/di rats, totally lacking in vasopressin, had greatly reduced preference scores for all concentrations of ethanol. Their intake of ethanol (g/day) was higher than heterozygotes or normals, but only when 2.2 percent ethanol was offered as a choice. Administration of lysine vasopressin or the vasopressin fragment des-9-Glycinamide-[Arginine8] vasopressin (DGAVP) using osmotic minipumps enhanced ethanol preference scores, reduced ethanol (g/day) intake, and restored total daily fluid intake in di/di rats. When di/di and di/+ rats were first allowed to develop stable ethanol preference before treatment with DGAVP, the peptide had no effect on preference scores. Thus, no treatment was effective in dissociating polydipsia from reduced ethanol preference and increased ethanol intake. While these results cannot exclude a possible regulatory role for endogenous vasopressin in ethanol preference drinking, they more strongly suggest that reduced preference for ethanol and increased ethanol intake are epiphenomena secondary to a polydipsic state.     

急、慢性乙醇处理后大鼠伏核内cAMP反应元件结合蛋白磷酸化的变化

采用免疫组织化学的方法,检测急性、慢性乙醇作用及戒断后大鼠伏核内cAMP反应元件结合蛋白(cAMP response element binding protein,CREB)磷酸化的变化。结果显示,急性腹腔注射乙醇后15min,伏核内磷酸化CREB(Phospho-CREB,p-CREB)蛋白明显增加,30min后达高峰,至1和6h后仍明显高于对照组。而慢性饮乙醇溶液显著降低大鼠伏核内P—CREB蛋白含量,在撤除乙醇后24、72h时,伏核内p—CREB蛋白含量仍明显较低,戒断后7d,恢复到正常水平。结果表明,急性乙醇处理增加伏核内CREB磷酸化作用,而慢性乙醇作用则降低伏核内CREB磷酸化作用,这可能是乙醇依赖的分子机制之一。     

Acquired resistance to severe ethanol stress-induced inhibition of proteasomal proteolysis in Saccharomyces cerevisiae

BackgroundAlthough the budding yeast, Saccharomyces cerevisiae, produces ethanol via alcoholic fermentation, high-concentration ethanol is harmful to yeast cells. Severe ethanol stress (> 9% v/v) inhibits protein synthesis and increases the level of intracellular protein aggregates. However, its effect on proteolysis in yeast cells remains largely unknown.MethodsWe examined the effects of ethanol on proteasomal proteolysis in yeast cells through the cycloheximide-chase analysis of short-lived proteins. We also assayed protein degradation in the auxin-inducible degron system and the ubiquitin-independent degradation of Spe1 under ethanol stress conditions.ResultsWe demonstrated that severe ethanol stress strongly inhibited the degradation of the short-lived proteins Rim101 and Gic2. Severe ethanol stress also inhibited protein degradation in the auxin-inducible degron system (Paf1-AID*-6FLAG) and the ubiquitin-independent degradation of Spe1. Proteasomal degradation of these proteins, which was inhibited by severe ethanol stress, resumed rapidly once the ethanol was removed. These results suggested that proteasomal proteolysis in yeast cells is reversibly inhibited by severe ethanol stress. Furthermore, yeast cells pretreated with mild ethanol stress (6% v/v) showed proteasomal proteolysis even with 10% (v/v) ethanol, indicating that yeast cells acquired resistance to proteasome inhibition caused by severe ethanol stress. However, yeast cells failed to acquire sufficient resistance to severe ethanol stress-induced proteasome inhibition when new protein synthesis was blocked with cycloheximide during pretreatment, or when Rpn4 was lost.Conclusions and general significanceOur results provide novel insights into the adverse effects of severe ethanol stress on proteasomal proteolysis and ethanol adaptability in yeast.     

The influence of fructose and its metabolites on ethanol metabolism in vitro

1. Fructose caused an increase in the rate of ethanol oxidation by rat-liver slices, and d-glyceraldehyde was found to have a similar effect. 2. Addition of glycerol lowered the rate of ethanol oxidation if the incubation medium contained fructose and ethanol, but no such effect was found if it contained glucose and ethanol. 3. The formation of glycerol by the slices during incubation and the concentration of alpha-glycerophosphate in the slices were highest in medium containing fructose and ethanol. 4. In experiments without ethanol in the incubation medium, fructose strongly increased the pyruvate concentration, which resulted in a decrease of the lactate/pyruvate concentration ratio. Addition of ethanol to the medium resulted in a marked decrease in pyruvate concentration. 5. Oxygen consumption is greater in slices incubated in medium containing fructose and ethanol than in slices incubated in medium containing glucose and ethanol.     

The inhibition of the maximum specific growth and fermentation rate of Zymomonas mobilis by ethanol

The inhibition of the maximum specific growth and fermentation rate of Zymomonas mobilis by ethanol was studied in turbidostat cultures at constant and stepwise changed ethanol concentrations. Up to 50 g/L ethanol, the inhibition kinetics can be approximated by a linear relationship between the specific growth rate and the ethanol concentration. Above this level, deviations from this linearity are observed. The specific fermentation rates were less inhibited by ethanol than was the specific growth rate. The maximum ethanol concentration achieved was 72 g/L.The response time for the adaptation of a turbidstat culture to step changes in the ethanol concentration was markedly dependent on the concentration level, the response time being large at high ethanol concentrations.     

The contribution of the stomach to ethanol oxidation in the rat

To estimate the amount of ethanol that can be oxidized in the stomach, steady-state conditions were created in a group of fed rats by giving a loading dose of ethanol (2 g/kg body wt I.V.) followed by continuous infusion either intravenously or intragastrically. The rate of ethanol oxidation was calculated from the rate of infusion required to maintain steady blood levels of approximately 30 mM for at least 3 hours. Gastrointestinal ethanol concentrations and total contents also remained steady. The rate of ethanol oxidation was 19.3% faster during intragastric than during intravenous infusion (p less than 0.01). When measured at the prevailing luminal ethanol concentration (145 mM) and expressed per body weight, the gastric ADH activity represented 14% of the hepatic activity at 30 mM ethanol, suggesting that gastric ADH activity could account for most of the increased rate of oxidation when ethanol is given intragastrically. Thus, gastric ethanol oxidation by a high Km ADH in the rat represents a significant fraction of the total rate of ethanol oxidation and it is therefore one of the factors which determines the bioavailability of orally administered ethanol.