Ethanol-induced adaptation in biological membranes

OMEGA-3 Interventions in Alcohol Dependence and Related Outcomes: A Systematic Review and Propositions

BACKGROUND

Pharmacological treatment for alcohol dependence has only three approved drugs: disulfiram, naltrexone and acamprosate. The effects of these drugs are, however, limited, presenting several side effects and a modestly higher efficacy compared to placebo. The administration of omega-3 might bring new perspectives to relapse prevention.

METHODS

This systematic review aimed to analyze the available literature, compiling the studies that used omega-3 to prevent relapse in alcohol dependents.

RESULTS

The databases used were PubMed and Web of Science. We identified 2,231 studies and only five articles addressed the administration of omega-3 and alcoholism. Preclinical studies evaluating the effects of PUFAs related to chronic alcohol administration showed improvements in behavioral, cellular and molecular levels. The clinical trial yielded inconclusive results.

CONCLUSION

Despite the reduced number of studies, omega-3 interventions seem to be promising for controlling issues related to alcohol dependence.

The role of polyunsaturated fatty acids (PUFAs) in development, aging and substance abuse disorders: review and propositions

The polyunsaturated fatty acids (PUFAs), especially omega-3 and -6, play an important role in the functioning of membranes. Therefore, changes in their physical properties might entail impairment of the neurotransmission between cells. Studies emphasize the importance of omega-3 intakes, but they also highlight the need of a balance between omega-6 and -3, whose ideal ratio should be 4:1. The Western diet has very high amounts of saturated fat and omega-6, which might contribute, at least partially, to physiopathologies and high incidence as well as prevalence of psychiatric and neurodegenerative diseases. This narrow review aimed at systematizing the studies on the importance of PUFAs in some particular cases, that is, the extremes of life: pre- and post-natal development, and cognitive aging. Additionally, it aimed at studying the association between PUFAs and substance abuse disorders. We used the databases LILACs, MEDLINE and PUBMED.

Ethanol induces oxidative stress in primary rat hepatocytes through the early involvement of lipid raft clustering

The role of the hepatocyte plasma membrane structure in the development of oxidative stress during alcoholic liver diseases is not yet fully understood. Previously, we have established the pivotal role of membrane fluidity in ethanol-induced oxidative stress, but no study has so far tested the involvement of lipid rafts. In this study, methyl-beta-cyclodextrin or cholesterol oxidase, which were found to disrupt lipid rafts in hepatocytes, inhibited both reactive oxygen species production and lipid peroxidation, and this suggested a role for these microstructures in oxidative stress. By immunostaining of lipid raft components, a raft clustering was detected in ethanol-treated hepatocytes. In addition, we found that rafts were modified by formation of malondialdehyde adducts and disulfide bridges. Interestingly, pretreatment of cells by 4-methyl-pyrazole (to inhibit ethanol metabolism) and various antioxidants prevented the ethanol-induced raft aggregation. In addition, treatment of hepatocytes by a stabilizing agent (ursodeoxycholic acid) or a fluidizing compound [2-(2-methoxyethoxy)ethyl 8-(cis-2-n-octylcyclopropyl)octanoate] led to inhibition or enhancement of raft clustering, respectively, which pointed to a relationship between membrane fluidity and lipid rafts during ethanol-induced oxidative stress. We finally investigated the involvement of phospholipase C in raft-induced oxidative stress upon ethanol exposure. Phospholipase C was shown to be translocated into rafts and to participate in oxidative stress by controlling hepatocyte iron content.

CONCLUSION

Membrane structure, depicted as membrane fluidity and lipid rafts, plays a key role in ethanol-induced oxidative stress of the liver, and its modulation may be of therapeutic relevance.

Acute alcohol activates STAT3, AP-1, and Sp-1 transcription factors via the family of Src kinases to promote IL-10 production in human monocytes

Alcohol consumption is associated with an imbalance in pro- and anti-inflammatory cytokines and immunosuppression, partially as a result of enhanced IL-10 production. The mechanisms of IL-10 induction by alcohol remain poorly understood. We identified that increased IL-10 production in human monocytes after acute in vivo alcohol consumption or in vitro alcohol treatment was associated with increased STAT3 activation. Alcohol alone induced and in combination with LPS augmented STAT3 phosphorylation at tyrosine 705 (tyr705) and serine 727 (ser727) residues and increased STAT3 binding to DNA. Upstream, alcohol activated the Src kinases, as indicated by an increase in phosphorylated and a decrease in nonphosphorylated Src proteins. STAT3 activation by Src kinases occurred directly at the tyr705 residue and indirectly at the ser727 residue via JNK MAPKs. Using specific Src (PP2), JNK1/2 (SB600125), or p38 (SB203580) inhibitors, we determined that alcohol treatment alone induced and together with LPS, augmented the DNA-binding capacity of the specificity protein-1 (Sp-1) and AP-1 transcription factors involved in IL-10 production via Src-mediated activation of p38 MAPK and JNK, respectively. Our data suggest that acute alcohol activates Src/STAT3 and Src/MAPK/STAT3, AP-1, and Sp-1 pathways as important mechanisms for IL-10-mediated immunomodulation after acute alcohol use.

Ethanol alters cellular activation and CD14 partitioning in lipid rafts

Alcohol consumption interferes with innate immunity. In vivo EtOH administration suppresses cytokine responses induced through Toll-like receptor 4 (TLR4) and inhibits TLR4 signaling. Actually, EtOH exhibits a generalized suppressive effect on signaling and cytokine responses induced by through most TLRs. However, the underlying mechanism remains unknown. RAW264.7 cells were treated with LPS or co-treated with EtOH or with lipid raft-disrupting drugs. TNF-alpha production, IRAK-1 activation, and CD14 partition were evaluated. EtOH or nystatin, a lipid raft-disrupting drug, suppressed LPS-induced production of TNF-alpha. The suppressive effect of EtOH on LPS-induced TNF-alpha production was additive with that of methyl-beta-cyclodextrin (MCD), another lipid raft-disrupting drug. EtOH interfered with IRAK-1 activation, an early TLR4 intracellular signaling event. Cell fractionation analyses show that acute EtOH altered LPS-related partition of CD14, a critical component of the LPS receptor complex. These results suggest a novel mechanism of EtOH action that involves interference with lipid raft clustering induced by LPS. This membrane action of EtOH might be one of the mechanisms by which EtOH acts as a generalized suppressor for TLR signaling.

Red blood cell fatty acid ethyl esters: a significant component of fatty acid ethyl esters in the blood

Although alcohol abuse is known to cause an array of ethanol-induced red blood cell (RBC) abnormalities, the underlying molecular mechanisms remain poorly understood. Fatty acid ethyl esters (FAEEs) are toxic, nonoxidative ethanol metabolites that have been found in blood, plasma, and tissues. Because FAEEs have been shown to be incorporated into phospholipid bilayers, we conducted a controlled ethanol intake study to test the hypothesis that FAEEs accumulate and persist within RBCs following ethanol ingestion. We demonstrated that RBC FAEEs account for approximately 5% to 20% of total whole-blood FAEEs, and that the fatty acid composition of FAEEs in RBCs and plasma are different and vary differently over time. These data indicate that a significant percentage of FAEEs in the blood is associated with RBCs and that the metabolism of RBC FAEEs and that of plasma FAEEs (bound to albumin or lipoproteins) are largely independent.

Effect of ethanol on regulation of (Na + K)-adenosine triphosphatase by aldosterone and dexamethasone in cultured renal papillary collecting duct cells

Chronic ethanol exposure causes alterations in biologic membranes of different cell types. (Na + K) adenosine triphosphatase (ATPase), a membrane-bound enzyme inhibited by the acute presence of ethanol, increases its activity in rat kidney after chronic ethanol consumption. The aim of this investigation was to evaluate the effect of ethanol on the modulation of (Na + K)-ATPase by glucocorticoids and mineralocorticoids in renal papillary collecting duct cells. Cultured renal papillary collecting duct cells were exposed to a medium containing 150 mM ethanol plus either 100 nM aldosterone or 10 nM dexamethasone. Control groups were cultured in the absence of ethanol and/or the hormones. Mg(2+)-ATPase was used as control enzyme. The activity of ATPases was measured by ATP hydrolysis. Ethanol increased the activities of (Na + K)-ATPase and Mg(2+)- ATPase in 29 and 33% of controls, respectively; only (Na + K)-ATPase activity was elevated in the presence of aldosterone or dexamethasone, whereas Mg(2+)-ATPase was unaltered by these hormones. The effects of aldosterone and dexamethasone on (Na + K)-ATPase activity were augmented by ethanol in 50 and 19% of controls, respectively. These results suggest that ethanol treatment enhances the upregulation of (Na + K)-ATPase activity by both aldosterone and dexamethasone, in cultured renal papillary collecting duct cells.

Alcohol, injury, and cellular immunity

It is widely accepted that alcohol exposure is a causative factor in the occurrence of burn or other traumatic injury. It is less well known that individuals who have consumed alcohol before sustaining an injury suffer from increased morbidity and mortality compared with the morbidity and mortality of non-alcohol-consuming subjects with similar injuries. Complications due to bacterial infection are the most common burn sequelae in injured patients and are frequently associated with depressed immunity. Independently, alcohol exposure and injury have been shown to influence cellular immunity negatively. These changes in immunity are closely linked to injury- or alcohol-induced alterations in the cytokine milieu in both clinical studies and animal models. Not surprisingly, the combination of insult of alcohol exposure and burn injury results in immune suppression that is greater in magnitude and duration compared with either insult alone. The combined effects of alcohol and injury on immunity have been examined in a limited number of studies. However, results of these studies support the suggestion that altered cytokine production is an integral part of the immune dysregulation and increased mortality that is observed. In particular, the increased presence of macrophage-derived mediators observed after burn or alcohol exposure alone seems to be synergistically increased in a combined injury model. Although more research is needed, it is likely that therapeutic modalities that include manipulation of cytokine networks to boost cellular immunity may improve outcome for patients who sustain injuries subsequent to consuming alcohol.

Effects of ethanol on plasma chloroquine, arginine vasopressin (AVP) concentrations and renal hydro-electrolyte handling in the rat

Current evidence in literature suggests that acute effects of either chloroquine or ethanol on kidney function partly depend on influencing plasma concentrations of arginine vasopressin (AVP). Therefore, the goal of the current study was to explore the effects of chloroquine and/or various doses of ethanol on plasma AVP levels and associated effects on renal hydro-electrolyte handling. Separate groups of male anaesthetized Sprague-Dawley rats were placed on a continuous jugular infusion of 0.077 M NaCl at 150 microL/min(-1). After 3 h equilibration period, consecutive 20 min urine collections were made over the subsequent 4 h of 1 h control, 1 h 20 min treatment and 1 h 40 min postequilibration periods for measurements of urine flow and Na+ and K+ excretion rates. Chloroquine (0.06 microg/min(-1)) and/or ethanol at either 2.4, 6, 18 or 24 microg/min(-1) were added to the infusate during the treatment period. Trunk blood was collected after the treatment period from parallel groups for AVP, ethanol and chloroquine measurements. Vehicle infused animals acted as control animals. Infusion of ethanol at low rate of 2.4 microg/min(-1) increased Na+ excretion rates, but high rates (6-24 microg/min(-1)) did not elicit such effects. Plasma ethanol concentrations were undetectable following administration of ethanol alone at 2.4 or 6 microg/min(-1). However, ethanols were measurable following co-infusion of chloroquine and ethanol at 6 microg/min(-1) (6+/-1 mg/dL(-1)). Concurrent chloroquine and ethanol (24 microg/min(-1)) administration elevated plasma ethanol concentrations by 26% by comparison with that of ethanol alone at the same dose. Chloroquine and ethanol infusion at all doses significantly (p < 0.01) increased plasma chloroquine concentrations. Intravenous infusion of ethanol increased plasma AVP concentrations in a dose-dependent manner. The observations of this study suggest that acute ethanol increases plasma AVP levels in a dose-dependent manner to affect hydro-electrolyte balance.

Alcohol abuse, alcoholism, and damage to the immune system--a review

Chronic alcohol abuse exacts a major social and medical toll in the United States and other Western countries. One of the least appreciated medical complications of alcohol abuse is altered immune regulation leading to immunodeficiency and autoimmunity. The consequences of the immunodeficiency include increased susceptibility to bacterial pneumonia, tuberculosis, and other infectious diseases. In addition, the chronic alcoholic often has circulating autoantibodies, and recent investigations indicate that the most destructive complications of alcoholism, such as liver disease and liver failure, may have a component of autoimmunity. Current research on altered cytokine balance produced by alcohol is leading to new insights on the regulation of the immune system in the chronic alcoholic. There is also recent development of exciting new techniques designed to improve or restore immune function by manipulation of cytokine balance. Although much remains to be learned, both in the abnormalities produced by alcohol and in the techniques to reverse those abnormalities, current progress reflects a rapidly improving understanding of the basic immune disorders of the alcoholic.

Effects of ethanol on mitogen-activated protein kinase and stress-activated protein kinase cascades in normal and regenerating liver

To understand the mechanisms by which ethanol inhibits hepatocyte proliferation, we studied the effects of ethanol on p42/44 mitogen-activated protein kinase (MAPK), p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK) in normal and regenerating rat liver. Treatment of rat hepatocytes with 100 mM ethanol in vitro for 16 h prolonged the activation of p42/44 MAPK and p38 MAPK induced by various agonists. Such treatment also increased basal JNK activity, but did not potentiate or prolong agonist-induced JNK activation. Ethanol potentiation of the activation of p42/44 MAPK was abolished by pertussis toxin. In contrast, chronic ethanol consumption in vivo inhibited the activation of p42/44 MAPK, p38 MAPK and JNK induced either by partial hepatectomy or by various agonists. However, both acute and chronic ethanol inhibited hepatocyte proliferation induced by insulin and epidermal growth factor. A selective inhibitor of p42/44 MAPK partially prevented the inhibition of hepatocyte proliferation caused by acute, but not by chronic, ethanol exposure, whereas a selective inhibitor of p38 MAPK further inhibited hepatocyte proliferation under both conditions. These data suggest that acute and chronic ethanol inhibit hepatocyte proliferation by different mechanisms. The effect of acute ethanol may be related to the prolongation of p42/44 MAPK activation, whereas inhibition of hepatocyte proliferation by chronic ethanol may be due to inhibition of p38 MAPK activation.

Effects of chronic and acute ethanol exposure on renal (Na + K)-ATPase in the rat

1. We evaluated the effects of chronic ethanol consumption on the kinetic properties of renal (Na + K)-ATPase and compared them with acute inhibition by ethanol in vitro. 2. When adult rats were fed 20% ethanol for 10 weeks, renal (Na + K)-ATPase activity increased but the sensitivity of the enzyme to ethanol inhibition in vitro was not altered. 3. Vmax was increased by ethanol consumption, whereas K0.5 and nH were not changed. The kinetic parameters of Mg(2+)-ATPase were not affected under the same conditions. 4. We concluded that ethanol-induced tolerance or enhancement of renal (Na + K)-ATPase or both can be explained on the basis of an increase in Vmax.

In vivo proton magnetic resonance spectroscopy detection of human alcohol tolerance

Alcohol tolerance was ascertained with in vivo proton magnetic resonance spectroscopy (MRS) in men who regularly consumed either large (10-20 drinks/week) or small (2-4 drinks/weeks) amounts of beverage alcohol. Brain ethanol concentrations were determined by MRS, and blood ethanol levels were measured by gas chromatography after controlled ethanol administration (0.8 g/kg). Brain-blood ethanol concentration ratios for heavy drinkers were significantly greater than ratios for occasional drinkers (P < 0.002). Inasmuch as ethanol tolerance covaries with the severity of dependence, MRS procedures may facilitate our understanding of alcohol tolerance and treatment of alcoholism.

Lipid-protein interactions and protein dynamics in vesicles containing the nicotinic acetylcholine receptor: a study with ethanol

Electron paramagnetic resonance (EPR) spectroscopy was used to study the action of ethanol on the protein side chain motions of the nicotinic acetylcholine receptor (nAcChoR) in alkaline extracted membranes from Torpedo nobiliana. EPR spectra of the nAcChoR derivatized with maleimide spin label contain both strongly and weakly immobilized components. The rotational correlation time of the strongly immobilized component decreases by a factor of 2-3-fold with the addition of 1.6 M ethanol, while that of the weakly immobilized component is not significantly altered. EPR spectroscopy was also used to probe the lipid environment immediately surrounding the nAcChoR with stearic acid and phosphatidylcholine spin labeled at the fourteenth acyl carbons (14-SASL and 14-PCSL, respectively), and the steroid spin label androstanol (ASL). EPR spectra of these probes reveal a component corresponding to lipids that are motionally restricted by the receptor (annular lipids) in addition to a more fluid component arising from bulk lipid. Using spectral subtraction, the order of selectivity of these spin labels for the nAcChoR was determined to be ASL > or = 14-SASL > 14-PCSL. The estimated rotational correlation times of the high affinity 14-SASL and ASL probes ranged from approx. 20 to 35 ns. The correlation times of the lower affinity 14-PCSL were generally shorter than those for 14-SASL and ASL and ranged from about 10 to 25 ns. The addition of up to 0.9 M ethanol altered neither the affinity nor the mobility of the motionally restricted EPR component. This suggests that ethanol's actions on the nAcChoR are not mediated via changes at the lipid/protein interface near the center of the bilayer.

Effects of ethanol on Na+-dependent amino acid uptake: dependence on rat age and Na+, K+-ATPase activity

Acute effects of ethanol on Na(+)-dependent transport of gamma-aminobutyric acid (GABA) and glutamic acid (GLU) were investigated in crude synaptosomal preparations from rat cerebral cortex. In experiments with 30-40-day-old (peripubertal) rats, the overall dose responses of the GABA and GLU transport systems to ethanol were biphasic. Stimulation was observed at ethanol concentrations (40-160 mM) relevant to intoxication. Inhibition was observed at higher concentrations of ethanol. The stimulatory phase of the dose response was not observed in 60-100-day-old (adult) rats. In preparations from peripubertal rats, other alcohols also had biphasic dose response curves with stimulation at low alcohol concentrations. The relative efficacy of the different alcohols appeared to correlate with the relative membrane-buffer partition coefficient. In synaptosomal membrane vesicles, where artificial ion concentration gradients rather than Na+,K(+)-ATPase activity provide the driving force for uptake, ethanol did not stimulate GABA uptake. In direct measures of Na+,K(+)-ATPase activity, both Rb+ uptake and ATP hydrolysis were enhanced by 80 mM ethanol. We conclude that stimulation of Na(+)-dependent uptake of amino acids by ethanol was secondary to enhanced Na+,K(+)-ATPase activity and may be associated with a specific developmental stage in the rat.

A deuterium NMR and steady-state fluorescence anisotropy study of the effects of cholesterol on the lipid membrane-disordering actions of ethanol

We examined the effects of cholesterol on the membrane-disordering action of ethanol by using deuterium nuclear magnetic resonance (2H-NMR) and fluorescence spectroscopy. Specifically, the effects of ethanol were measured on the 2H-NMR spectra of di(perdeuteropalmitoyl)phosphatidylcholine (DPPC-d62) and on the steady-state emission anisotropy of diphenylhexatriene (DPH) incorporated into hydrated egg phosphatidylcholine (eggPC)/cholesterol dispersions. Analysis of the 2H-NMR spectra of DPPC-d62 incorporated into eggPC liposomes showed that the addition of cholesterol up to 30 mol% enhanced the ability of ethanol to disorder methylene groups all along the phospholipid acyl chains. This effect was somewhat greater toward the terminal methyl groups. However, above 30 mol% cholesterol, the bilayer-disordering action of ethanol on both the upper and lower portions of the acyl chains decreased to an apparent constant change up to the highest cholesterol content examined (50 mol%). Analysis of the fluorescence anisotropy of DPH, on the other hand, suggested that cholesterol attenuated the ability of ethanol to disorder the bilayers, which is in agreement with a previous EPR study [Chin and Goldstein, Mol Pharmacol 19: 425-431, 1981]. Re-analysis of our previous fluorescence anisotropy results with DPH incorporated into dispersions of brain-lipid extracts as a percent change [Johnson et al., Mol Pharmacol 15: 739-746, 1979] indicated that the chemical composition of the lipid bilayers also affects the apparent ability of cholesterol to modulate the membrane-disordering action of ethanol, because the addition of cholesterol to brain-lipid extracts had no significant effect on the membrane-disordering action of ethanol. Given the greater likelihood that the 2H-NMR probes accurately monitor bulk phospholipid properties, some caution is required in the analysis of the membrane-disordering actions of drugs using EPR and fluorescence spectroscopy.

Rat synaptic membrane fluidity parameters after intermittent exposures to ethanol in vivo

Differentiated membrane alterations correlate with the development of functional tolerance or dependence during chronic alcohol intoxication in humans as well as in animals. In animal studies, a single period of continuous exposure was generally used. In humans, the consumption can be more episodic with heavier weekend drinking. How a heavy but intermittent alcohol exposure over 4 weeks affects the synaptic membrane fluidity and sensitivity was examined in male and female adult rats. No differences were seen between membranes from males and females. Alterations were found in the negative polar membrane region probed by TMA-DPH and the sensitivity to acute ethanol was significantly reduced in the DPH (lipid core) and TMA-DPH probed membrane regions. Tolerance to the hypothermic effect of ethanol has developed and could be correlated with the resistance of the membrane lipid core to ethanol. Intermittent exposures to ethanol, as continuous ones, can result in development of functional and membrane tolerance and in specific alterations in the fluidity of the polar part of the membrane, probably in relation with dependence.

Histomorphometric analysis of the epiphyseal growth plate in rats after prenatal alcohol exposure

We studied the effect of prenatal alcohol exposure on growth in the proximal tibial growth plate in 0- and 15-day-old rats, using histomorphometric methods. Body weight and tibial length were reduced in all alcohol-exposed rats. In 15-day-old rats, these parameters were lower than in the 15-day-old controls, thus showing a persistence of the effects of ethanol. The proximal tibial growth plate showed alterations, principally in 15-day-old rats. The most notable of these was a decrease in growth plate height produced by a significant reduction in hypertrophic zone height. Likewise, there were fewer cells in this zone in alcohol-exposed rats than in controls. This work shows that prenatal ethanol exposure induces growth retardation which may be due to growth plate alterations that might reflect impaired cell function.

Adaptation of gastric mucosa to chronic alcohol administration is associated with increased mucosal expression of growth factors and their receptor

In our previous study we found that chronic, intragastric administration of ethanol to rats produces adaptation of the gastric mucosa to subsequent challenge with an acute dose of 50% ethanol. The mechanism of this mucosal tolerance remains unexplained. Epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) stimulate cells growth and proliferation in the gastric mucosa with noted trophic effect, protect the gastric mucosa against acute injury and accelerate healing of injured mucosa. Many of these effects are exerted through EGF and TGF alpha action on their common receptor (EGFR). The aim of the present study was to determine the effect of chronic alcohol administration on cell proliferation and gastric mucosal expression and distribution of EGF, TGF alpha and EGFR. Chronic administration of ethanol (1 ml, 50% ethanol, twice daily) significantly increased the extent of gastric mucosal mucous and proliferative cell zones, the number of proliferating (DNA synthesizing) cells and mucosal expression of EGF, TGF alpha and EGFR by 13, 6, and 20-fold, respectively. Thus, adaptation of gastric mucosa to chronic alcohol administration is associated with increased cell proliferation and increased expression of mucosal EGF, TGF alpha and EGFR.

Effect of chronic ethanol consumption on postnatal development of renal (Na + K)-ATPase in the rat

Renal (Na + K)-ATPase was studied to ascertain whether it follows the pattern of adaptation of membrane-bound enzymes that are inhibited by acute ethanol exposure and develop greater activity after chronic ethanol treatment. A colony of rats was given 20 per cent (v/v) ethanol as sole drinking solution throughout gestation, lactation and following weaning. (Na + K)-ATPase and ouabain-insensitive Ca(2+)-ATPase activities were determined; regional distribution of these enzymes was assessed in renal cortex and outer medulla. Control rats drank tap water. (Na + K)-ATPase in whole homogenate of kidney increased with age in controls and ethanol-fed rats, but the latter showed higher values at every age studied. Between 15 and 60 days of age, the control group showed 2-fold increases in cortex and 5-fold in outer medulla, whereas ethanol-fed rats reached a 3-fold increase in the enzyme activity in both renal regions. Ca(2+)-ATPase showed the same time course in developing kidney of both groups. Chronic ethanol treatment of adult rats resulted in an increase of (Na + K)-ATPase activity in cortex and outer medulla, but no change in other ATPases. Since an earlier maturational development of renal (Na + K)-ATPase was displayed by ethanol-fed rats, underlying mechanisms that may account for these results are discussed.

Follow-up of a cohort of alcoholic patients through 12 months of comprehensive biobehavioral treatment

One hundred and eleven socially stable alcoholic patients were subjected to a comprehensive diagnostic and treatment protocol based on a biobehavioral model of alcoholism. Physical pathology, malnutrition, and toxicity were prevalent throughout the sample. After a period of inpatient care, subjects were treated for a period of 12 months with a combination of medical, nutritional, behavioral, and psychological support and care. At the end of the study period, 91 subjects (81.9%) remained in treatment contact. Sixty seven subjects (60.4%) were abstinent and physically stable at the 12-month date. Elevations of three scales of the MMPI were significantly predictive of treatment outcome.

[Biophysical membrane correlates of tolerance and dependence on alcohol]

A large number of studies have given clear indications that ethanol does affect the physicochemical properties of the membrane. Membrane reorganization and adaptation can develop against the acute disordering effect of ethanol during chronic intoxication. Nevertheless, there has been so far no direct evidence of correlations between functional tolerance or dependence and membrane physical states. Membrane physical state can be assessed by fluorescence polarization of DPH in the absence (measure of membrane 'fluidity') or presence (measured of membrane sensitivity) of ethanol added in vitro. Functional tolerance has been already correlated with a reduced synaptic membrane sensitivity to ethanol (membrane tolerance). Behavioural dependence was shown to be quantifiable by measurement of alcohol intake in a free choice situation (water/alcohol) solution). This dependence model allowed us to define a membrane dependence which consists in an increased membrane rigidity (or decrease in 'fluidity') persistent after withdrawal, and which was correlated to the intensity of the behavioural dependence. This biophysical expression of dependence seems rather independent of the biophysical membrane tolerance (resistance to the acute ethanol fluidizing effect), which was found to be rapidly reversible after withdrawal and re-induced by alcohol re-intake, requiring recent periods of current abuse to be expected.

Cellular and molecular mechanisms of drug dependence

The molecular and cellular actions of three classes of abused drugs--opiates, psychostimulants, and ethanol--are reviewed in the context of behavioral studies of drug dependence. The immediate effects of drugs are compared to those observed after long-term exposure. A neurobiological basis for drug dependence is proposed from the linkage between the cellular and behavioral effects of these drugs.

Ethanol-induced modifications to membrane lipid structure: effect on phospholipase A2-membrane interactions

Chronic ethanol intoxication leads to the development of a resistance to lipid disordering by ethanol, a phenomenon known as "membrane tolerance". In the absence of the added ethanol, the lipid order, as measured by ESR and fluorescence techniques, does not necessarily change as a result of chronic ethanol ingestion (as in liver microsomes, for example). This suggests that the spectroscopic techniques detect tolerance somewhat indirectly, in that the modification responsible may reside in a region distinct from that being probed and also raises the question of whether membrane tolerance is necessarily associated with an alteration in the membrane lipid structure. Here we show that liver microsomes from rats treated chronically with ethanol are rendered relatively resistant to the hydrolytic action of exogenous phospholipase A2, compared to preparations from control animals. This resistance persists in reconstituted lipid vesicles prepared from extracted phospholipids. Since the same substrate (1-palmitoyl-2-N-(4-nitrobenzo-2-oxa-1,3-diazole)amino caproylphosphatidylcholine) was used in both membranes from ethanol-treated animals and controls, the modification appears to reside in the structure and/or organization of the membrane. Further evidence that the lipid structure is modified by chronic ethanol treatment is provided by the observation that perturbance of the membrane structural integrity by increasing levels of oleic acid led to a progressive loss of the ethanol-induced relative resistance to hydrolysis by phospholipase A2. The results of this study support the idea that membrane tolerance involves a modification to lipid structure probably at the bilayer surface. The use of exogenous phospholipase A2 provides a new method for probing the structural modifications induced by chronic ethanol ingestion.

The emerging pharmacology of ethanol

Historically, alcohol (ethanol) has been viewed as a non-specific CNS depressant, presumed to act equally on all bioelectric membranes. In contrast to this view, cellular electrophysiological studies, supported by anatomic and neurochemical evidence, support the emergence of a more specific pharmacological profile. Four regions of the rodent brain (cerebellum, hippocampus, locus coeruleus and inferior olive) have so far been examined. The effects of acute parenteral ethanol on specific identifiable neurons within these four regions are highly consistent, dose-related, and spontaneously reversible. Nevertheless, different patterns of effects are seen in each responsive region, ranging from general increased firing in inferior olive to generally depressed synaptic transmission in hippocampus, and with more subtle effects within the cerebellum and within the locus ceruleus. This survey of consistent but differing patterns of responsiveness to ethanol at specific time points after acute exposure, suggests that the global effects of ethanol on movement, on arousal and on emotions and memory must be composed of several distinct effects both within and across many cellular systems.