Modification of lipid composition of erythrocyte membranes in chronic alcoholism

The lipid composition and microviscosity of erythrocyte membranes have been studied in chronic alcoholics with macrocytosis and minimal liver dysfunction. The findings have been compared with those obtained in subjects with macrocytosis not related to ethanol abuse. In all instances, macrocytosis was accompanied by an increased microviscosity of erythrocyte membranes, together with an increase of the cholesterol/phospholipid and of saturated/unsaturated fatty acids ratio. Both microviscosity and saturated/unsaturated ratio were significantly higher in alcoholics compared to subjects with macrocytosis not related to ethanol abuse. These findings confirm that altered lipid composition and fluidity of erythrocyte membrane may be observed in chronic alcoholics with minimal liver dysfunction, possibly due to the "stabilising" properties of ethanol - among a number of drugs- on biological membranes.     

Increased prolactin reserve in alcoholics

The prolactin response to oral metoclopramide (10 mg) was investigated in 53 chronic alcoholics (26 with alcoholic cirrhosis and 27 without evidence of liver disease) from two to seven days after alcohol suspension. The response appeared significantly higher in patients than in healthy controls and was not related to the presence of liver disease. This finding may depend on the deactivation of the dopaminergic activities secondary to alcohol suspension; alternatively, ethanol could have a direct action on prolactin secretion.     

Effect of chronic ethanol abuse on the physico-chemical properties of erythrocyte membranes in man

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.     

Impairment of hepatic drug metabolism in alcoholics.

1 The effects of chronic ethanol intake on the elimination kinetics of antipyrine were determined in nineteen male alcoholic subjects with comparison made to fourteen male volunteers. 2 Half-lives were longer and clearance values less in the alcoholic group. 3 Significant rank correlations were found between half-life and clearance when compared with various biochemical parameters of liver function measured in the plasma of the alcoholics. 4 These results show that a significant proportion of the alcoholics studied had impaired hepatic drug metabolizing capacity and that the activity of hepatic microsomal enzymes may be related to the extent of ethanol induced liver damage in these subjects.     

Physical properties and lipid composition of brain membranes from ethanol tolerant-dependent mice

DBA/2 mice were made tolerant to and dependent on ethanol by administration of an ethanol-containing liquid diet for 7 days. Fluorescent probe molecules were used to estimate the fluidity and ethanol sensitivity of brain synaptic membranes from these mice. The fluorescence polarization of cis- parinarate , trans- parinarate , and 1,6-diphenyl-1,3,5-hexatriene (probes of the membrane core) and 1-(4- trimethylammoniumphenyl )-6-phenyl-1,3,5-hexatriene (a probe of the membrane surface) was higher in membranes from ethanol tolerant-dependent mice than in membranes from control mice. The decrease in fluorescence polarization produced by in vitro exposure to ethanol was attenuated in membranes from ethanol tolerant-dependent mice when 1,6-diphenyl-1,3,5-hexatriene was used as the probe, but not when 1-(4- trimethylammoniumphenyl )-6-phenyl-1,3,5-hexatriene was used. These results indicate that chronic ingestion of ethanol decreased the fluidity and the ethanol sensitivity of the synaptic membranes. In contrast to the alterations observed with intact membranes, liposomes of lipids extracted from synaptic membranes of control and ethanol tolerant-dependent mice did not differ in their physical properties. Analysis of membrane lipids demonstrated that chronic ethanol treatment selectively decreased the unsaturated acyl groups of phosphatidylserine without altering the acyl composition of other phospholipids or sphingolipids. The amount of each phospholipid was not changed, but membrane cholesterol was decreased by chronic ethanol ingestion. Use of 2-dimensional thin-layer chromatography allowed the quantitation of 10 different gangliosides. The concentrations of these lipids were unchanged in synaptic membranes from ethanol tolerant-dependent mice. Thus, the changes in membrane physical properties produced by chronic ingestion of ethanol may be due, at least in part, to altered acyl composition of phosphatidylserine. The differences observed between intact membranes and extracted lipids suggest, however, that chronic ethanol treatment also produced changes in the lipid arrangement or lipid-protein interactions of the intact membranes.     

Diacetylrhein and rhein: in vivo and in vitro effect on lymphocyte membrane fluidity

The effect of diacetylrhein on lymphocyte membrane fluidity in osteoarthritis patients before and after 10 and 30 days of treatment was studied using the 1,6-diphenyl-1,3,5-hexatriene fluorescence polarization. Moreover we studied the in vitro effect of rhein, the active metabolite of diacetylrhein, on lymphocyte membrane fluidity of controls using the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene and its cationic derivative 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene. Our results showed that the patients with active osteoarthritis have higher fluorescence polarization values than those in the other osteoarthritis patients and in the controls. Moreover after 10 days of diacetylrhein treatment, we observed a significant decrease of fluorescence polarization values only in lymphocytes of the patients who showed active osteoarthritis before therapy. However after 30 days of treatment, significant changes of fluorescence polarization values were observed also in those patients who did not show painful osteoarthritis before diacetylrhein treatment. We observed that in vitro rhein also induces an increase in lymphocyte membrane fluidity, more evident with 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene with respect to 1,6-diphenyl-1,3,5-hexatriene.     

The effects of chronic alcohol ingestion and alcoholic liver disease on binding of drugs to serum proteins

Summary The binding of salicylate, sulphadiazine and phenylbutazone in whole serum of patients with alcohol-induced liver disease has been compared to that of chronic alcoholics with no evidence of liver disease, and normal healthy subjects. Binding of all three drugs was normal in the chronic alcoholic group, but decreased in patients with alcoholic liver disease. In subjects with alcoholic hepatitis, this decrease appeared to be correlated with variations in serum bilirubin and albumin levels. These observations may be of clinical relevance to the distribution of drugs in alcoholic patients with accompanying hepatic disease.     

Control of alcohol addiction by SKV therapy--its action on water, food intake, brain function and cell membrane composition

Alcohol being easily permeable through cell membrane causes toxic damage to many tissues. Rats drinking aqueous ethanol (25% v/v) for 120 days and 240 days showed an initial rise in body weight. The reduced rate in weight gain in chronic alcoholism is associated with a fall in food intake. Ethanol ingesting animals showed slow response to stimuli and increase in blood ethanol and serum GGTP levels. Liver plasma membrane, kidney brush-border membrane and pancreatic plasma membrane from alcoholic rats showed significant alterations in cholesterol/phospholipid molar ratio and membrane ATPases. Water retention with the enlargement of liver and kidney associated with increased fluid consumption are also seen during alcoholism. SKV by breaking alcohol dependence reduces drinking, lowers blood ethanol level and fluid intake without developing withdrawal symptoms. Restriction of ethanol intake by SKV therapy resulted in the reversal of organ enlargement and membrane composition in alcoholics.     

Alcohol dehydrogenase activity of human and animal blood serum in acute and chronic alcoholic intoxication

Alcohol dehydrogenase activity (ADH; KP 1.1.1.1.) in blood serum of rats and rabbits is 1 and 2 orders of magnitude higher than in humans. In chronic alcoholics, blood ADN is activated with an increase in alcoholism standing. Twelve hours after acute alcoholic intoxication alcoholics and heavy drinkers manifest a significant reduction in blood ADH activity. Acute alcoholic intoxication does not influence blood ADH in men who do not abuse alcohol. Chronic exposure of rabbits to ethanol leads to a decrease in ADH activity in the liver and to its rise in the blood. ADH activation is observed only in those animals which demonstrate the signs of fatty and protein liver dystrophy. It is concluded that chronic exposure to ethanol does not induce ADH synthesis in the liver. The blood ADH content ascends as a results of an increase in ADH transport from hepatocytes to the bloodstream.     

Plasma urea and creatinine status in chronic alcoholics

Plasma urea and creatinine concentrations were estimated by Auto-Analyzer in 128 chronic alcoholics (103 males, 25 females; mean age ± SD = 42.73 ± 6.53; age range 20–60 years). Plasma levels of both urea (mean ± SD = 3.46 ± 1.31; normal range 2.0–6.5 mmol/l) and creatinine (mean ± SD = 87.86 ± 15.45; normal range 60–120 μmol/l) were found to be within normal limits. It is concluded from our observations that chronic ethanol ingestion per se is not nephrotoxic. The kidney seems to be the only vital organ generally spared in chronic alcoholics without advanced alcoholic liver disease or hepato-renal syndrome.     

Neurochemical effects of long-term ingestion of ethanol by Sinclair (S-1) swine

Sinclair (S-1) miniature swine were given access to a mixture of ethanol and beer for three years. Control swine were fed an isocaloric diet with corn starch substituted for ethanol. Both groups had free access to tap water. The alcohol group consumed about 4 g ethanol/kg/day (about 50% of their caloric intake) resulting in plasma ethanol concentrations of about 100 mg/dl. Brain membranes were prepared for analysis of neurotransmitter receptor binding, membrane lipid composition and physical properties. Receptor studies demonstrated an increase in the binding of 3H-GABA to cortical and cerebellar membranes from the alcoholic pigs as compared to control. Binding of 3H-ligands to muscarine cholinergic, beta-adrenergic, alpha-adrenergic, dopamine and benzodiazepine receptors was not changed by chronic ethanol ingestion. These results are similar to those obtained in studies of human alcoholics by other investigators. The cholesterol content of myelin and synaptic plasma membranes was not altered by ethanol consumption. The fluorescence polarization of diphenylhexatriene, a measure of membrane order, did not detect any differences in the membranes from control or alcohol-treated swine either before or after in vitro exposure to ethanol. These results are different from those reported for rodents after short-term ethanol treatments and emphasize the importance of evaluating different models of experimental alcoholism.     

Pharmacokinetics of zimeldine in male alcoholics

The pharmacokinetics of zimeldine, a 5-HT reuptake blocker with antidepressive effects, was studied after a single oral dose and after multiple oral administration in 19 alcoholic males, 10 with and 9 without chronic liver damage. The average plasma concentration of zimeldine as assessed by the AUC values (area under the plasma concentration-time curve) was significantly higher in the chronically liver damaged patients than in the patients without chronic liver damage. The plasma half-life of zimeldine was also significantly longer in the chronically liver damaged patients. There were no differences in the obtained pharmacokinetic parameters between the patients having nonchronic liver damage and healthy control subjects. The pharmacokinetics of the active metabolite norzimeldine (resulting from N-demethylation of zimeldine) showed no differences between the two groups of alcoholics and the healthy controls. The IgA values were significantly correlated to both the AUC and plasma half-life of zimeldine. No other correlation between clinical chemistry parameters and pharmacokinetic parameters of zimeldine and norzimeldine were found.     

Effect of antirheumatic drugs on lymphocyte membrane fluidity in rheumatoid arthritis: a fluorescence polarization study

We have demonstrated significant differences in 1,6-diphenyl-1,3,5-hexatriene fluorescence polarization values between lymphocyte membranes of untreated rheumatoid arthritis patients and lymphocyte membranes of patients treated with antirheumatic drugs, such as hydroxychloroquine and auranofin. No difference has been detected in rheumatoid arthritis patients treated with auranofin associated with 6-methylprednisolone. The results indicate that some drugs used in the treatment of rheumatoid arthritis induce changes of lymphocyte membrane fluidity. The positive correlations between fluorescence polarization values and objective indices of the disease activity, as erythrocyte sedimentation rate, C-reactive protein, fibrinogen level, and alpha 2-globulin, suggested that fluorescence polarization could be used in the study of the pharmacological action of antirheumatic drugs and in monitoring antirheumatic therapy.     

Paracetamol, alcohol and the liver

It is claimed that chronic alcoholics are at increased risk of paracetamol (acetaminophen) hepatotoxicity not only following overdosage but also with its therapeutic use. Increased susceptibility is supposed to be due to induction of liver microsomal enzymes by ethanol with increased formation of the toxic metabolite of paracetamol. However, the clinical evidence in support of these claims is anecdotal and the same liver damage after overdosage occurs in patients who are not chronic alcoholics. Many alcoholic patients reported to have liver damage after taking paracetamol with 'therapeutic intent' had clearly taken substantial overdoses. No proper clinical studies have been carried out to investigate the alleged paracetamol-alcohol interaction and acute liver damage has never been produced by therapeutic doses of paracetamol given as a challenge to a chronic alcoholic. The paracetamol-alcohol interaction is complex; acute and chronic ethanol have opposite effects. In animals, chronic ethanol causes induction of hepatic microsomal enzymes and increases paracetamol hepatotoxicity as expected (ethanol primarily induces CYP2E1 and this isoform is important in the oxidative metabolism of paracetamol). However, in man, chronic alcohol ingestion causes only modest (about twofold) and short-lived induction of CYP2E1, and there is no corresponding increase (as claimed) in the toxic metabolic activation of paracetamol. The paracetamol-ethanol interaction is not specific for any one isoform of cytochrome P450, and it seems that isoenzymes other than CYP2E1 are primarily responsible for the oxidative metabolism of paracetamol in man. Acute ethanol inhibits the microsomal oxidation of paracetamol both in animals and man. This protects against liver damage in animals and there is evidence that it also does so in man. The protective effect disappears when ethanol is eliminated and the relative timing of ethanol and paracetamol intake is critical. In many of the reports where it is alleged that paracetamol hepatotoxicity was enhanced in chronic alcoholics, the reverse should have been the case because alcohol was actually taken at the same time as the paracetamol. Chronic alcoholics are likely to be most vulnerable to the toxic effects of paracetamol during the first few days of withdrawal but maximum therapeutic doses given at this time have no adverse effect on liver function tests. Although the possibility remains that chronic consumption of alcohol does increase the risk of paracetamol hepatotoxicity in man (perhaps by impairing glutathione synthesis), there is insufficient evidence to support the alleged major toxic interaction. It is astonishing that clinicians and others have unquestion-ingly accepted this supposed interaction in man for so long with such scant regard for scientific objectivity.     

Adaptation of brain lipid bilayers to ethanol-induced fluidization: Species and strain generality

Membrane lipid compositional changes have recently been shown by us to be at least partially responsible for the apparent tolerance to the membrane-fluidizing effects of ethanol [D. A. Johnson, N. M. Lee, R. Cooke and H. H. Loh, Molec. Pharmac. 15, 739 (1979)]. Because not all effects of ethanol are generalizable to all strains and species, we attempted to determine whether these lipid compositional changes are related to the anesthetic actions of ethanol. Consequently, the effects of ethanol on the fluidity of reconstituted membranes formed from lipid extracts of synaptic membranes from tolerant C57BL/6J mice and Sprague-Dawley rats were assessed by using the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene, incorporated into the membranes, as a relative index of fluidity. We observed apparent tolerance to the fluidizing effects of ethanol in both the C57BL/6J mice and the Sprague-Dawley rats. Acute in vivo ethanol treatment did not alter ethanol-induced fluidity of the reconstituted membranes. The results further support the suggestion that the change in brain membrane lipid composition, responsible for the apparent tolerance to the membrane-fluidizing effects of ethanol, is related to tolerance to the anesthetic actions of ethanol.     

Adaptation to ethanol-induced fluidization of brain lipid bilayers

We have shown that ethanol is less able to fluidize reconstituted membranes prepared from lipid extracts of tolerant mice synaptosomal membranes than those prepared from controls. The effects of ethanol on membrane fluidity were assessed by fluorescence polarization technique. Acute in vivo administration of ethanol did not alter ethanol-induced fluidization of the bilayers. These results suggest that changes in the lipid composition of membranes can account, at least in part, for tissue adaptation to ethanol-induced membrane fluidization. We also discuss the use of reconstituted membranes as a tool both to analyze the significance of changes in membrane composition for the development of tolerance and to refine our concepts concerning the relation between membrane fluidity and anesthetic activity.     

乙醇和乙醛对培养大鼠胚胎卵黄囊细胞膜脂质流动性的影响

为探讨酒精对发育中胚胎卵黄囊 ( VYS)膜功能的影响 .孕 9.5d大鼠胚胎于体外分别给予不同剂量的酒精及其代谢产物乙醛 ,培养 48h后 ,分离胚胎 VYS细胞 .以 1 ,6-二苯己三烯 ( DPH)为荧光探针研究二者对 VYS细胞膜脂质流动性的影响 .结果表明 0 .4g· L-1乙醇 ,2 .0 g· L-1乙醛并不影响 VYS细胞膜脂质的荧光偏振度 ( P)和细胞膜流动度 ( LFU) ,随剂量增高可导致 VYS荧光偏振度降低 ,膜脂质流动度增高 ,相同剂量 ( 2 .0 g· L-1)的乙醇 ,乙醛对 VYS细胞作用无显著性差异 .乙醇 ,乙醛均能改变 VYS细胞膜脂质流动性引起 VYS细胞功能紊乱 ,它很可能在诱发胎儿酒精综合征起重要作用 .     

Altered membrane fluidity occurs during metabolic impairment of cardiac myocytes

The purpose of this study was to evaluate the effect of impaired high energy phosphate metabolism on the membrane fluidity of cardiac myocytes. Cultured neonatal rat cardiac myocytes were treated with the metabolic inhibitor, iodoacetic acid (IAA) (30 microM). Membrane lipid fluidity was assessed by the steady-state fluorescence polarization of 1,6-diphenyl 1-1,3,5-hexatriene (DPH). Metabolic inhibition with IAA resulted in a progressive decrease in fluorescence polarization and calculated microviscosity. Microviscosity was decreased by 11% after 60-90 minutes and by 21% after 120-210 minutes, respectively. These changes are consistent with a progressive increase in membrane fluidity. Pretreatment with the experimental phospholipase inhibitor, U26, 384 (5-10 microM) resulted in a slower onset and less change in membrane fluidity after treatment with IAA. Thus, a) metabolic inhibition in cardiac myocytes induces prominent alterations in membrane fluidity which probably contribute to the membrane dysfunction accompanying myocardial injury and b) phospholipid degradation may be a significant factor in the genesis of altered membrane fluidity.     

Brain membrane disordering related to acute ethanol administration in naive and short-term ethanol-intoxicated rats

Crude synaptic membrane fluidity (checked by fluorescence polarization) together with (Na+ + K+) ATPase activity were examined 18 hours after a single oral ethanol administration (5 g/kg bwt.) to naive rats and to rats previously intubated with ethanol repeatedly during 4 days. The sensibility of both parameters to different concentrations of ethanol added in vitro (0.175 M-1.400 M) was also determined. Although no changes in the basal intrinsic fluidity were found, (Na+ + K+)ATPase activity increased slightly in both conditions. The fluidizing as well as the ATPase inhibiting effects following the addition of ethanol in vitro were markedly increased 18 hours after ethanol administration to naive rats. This hypersensitization was no longer apparent in rats pretreated with ethanol during 4 days. The acute ethanol-induced hypersensitization found in naive rats appears not to be related to an unspecific stress or to changes in body temperature. The disappearance of this hypersensitization in short-term alcohol-intoxicated animals may represent the first stage of tolerance acquisition.     

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-induced decrease in the fluidity of rat liver membranes

1. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCCD)-induced lipid peroxidation has previously been demonstrated by assessing the hepatic content of thiobarbituric acid reactive substances (TBARS) as well as the NADPH-dependent microsomal formation of TBARS as well as the NADPH-dependent microsomal formation of TBARS using malondialdehyde as the standard. 2. Changes in membrane fluidity as a result of lipid peroxidation may occur. Therefore the dose- and time-dependent effects of TCDD on lipid peroxidation in mitochondrial, microsomal, and plasma membranes, and changes in membrane fluidity in these subcellular fractions, were examined. Animals were treated with either 50 or 100 micrograms TCDD/kg orally, and killed 3, 6, or 9 days post-treatment. 3. Time-dependent increases occurred in TBARS content and formation following TCDD administration for all three membranes. Similar results were observed after 50 and 100 micrograms TCDD/kg. 4. Following TCDD administration, fluorescence polarization measurements as determined by the fluorescence polarization (r) and anisotropy parameter (a.p.) values demonstrated significant decreases in membrane fluidity in all membrane fractions, indicative of membrane structural alterations. 5. Excellent inverse correlations between lipid peroxidation and membrane fluidity were observed. Thus, decreased membrane fluidity and increased membrane damage may contribute to the toxic manifestations of TCDD as a consequence of an oxidative stress.