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Chronic Ethanol Exposure (chronic + ethanol_exposure)

Distribution by Scientific Domains

Medical Sciences	96%

Selected Abstracts

Differential Effects of Acute and Chronic Ethanol Exposure on Orexin Expression in the Perifornical Lateral Hypothalamus

ALCOHOLISM, Issue 5 2010
Irene Morganstern
Background:, Recent reports support the involvement of hypothalamic orexigenic peptides in stimulating ethanol intake. Our previous studies have examined the effects of ethanol on hypothalamic peptide systems of the paraventricular nucleus (PVN) and identified a positive feedback loop in which PVN peptides, such as enkephalin and galanin, stimulate ethanol intake and ethanol, in turn, stimulates the expression of these peptides. Recently, orexin (OX), a peptide produced mainly by cells in the perifornical lateral hypothalamus (PFLH), has been shown to play an important role in mediating the rewarding aspects of ethanol intake. However, there is little evidence showing the effects that ethanol itself may have on the OX peptide system. In order to understand the feedback relationship between ethanol and the OX system, the current investigation was designed to measure OX gene expression in the PFLH following acute as well as chronic ethanol intake. Methods:, In the first experiment, Sprague,Dawley rats were trained to voluntarily consume a 2 or 9% concentration of ethanol, and the expression of OX mRNA in the PFLH was measured using quantitative real-time polymerase chain reaction (qRT-PCR). The second set of experiments tested the impact of acute oral gavage of 0.75 and 2.5 g/kg ethanol solution on OX expression in the PFLH using qRT-PCR, as well as radiolabeled in situ hybridization. Further tests using digoxigenin-labeled in situ hybridization and immunofluorescence histochemistry allowed us to more clearly distinguish the effects of acute ethanol on OX cells in the lateral hypothalamic (LH) versus perifornical (PF) regions. Results:, The results showed chronic consumption of ethanol versus water to dose-dependently reduce OX mRNA in the PFLH, with a larger effect observed in rats consuming 2.5 g/kg/d (,70%) or 1.0 g/kg/d (,50%) compared to animals consuming 0.75 g/kg/d (,40%). In contrast to chronic intake, acute oral ethanol compared to water significantly enhanced OX expression in the PFLH, and this effect occurred at the lower (0.75 g/kg) but not higher (2.5 g/kg) dose of ethanol. Additional analyses of the OX cells in the LH versus PF regions identified the former as the primary site of ethanol's stimulatory effect on the OX system. In the LH but not the PF, acute ethanol increased the density of OX-expressing and OX-immunoreactive neurons. The increase in gene expression was detected only at the lower dose of ethanol (0.75 g/kg), whereas the increase in OX peptide was seen only at the higher dose of ethanol (2.5 g/kg). Conclusion:, These results lead us to propose that OX neurons, while responsive to negative feedback signals from chronic ethanol consumption, are stimulated by acute ethanol administration, most potently in the LH where OX may trigger central reward mechanisms that promote further ethanol consumption. [source]

Intensity and Duration of Chronic Ethanol Exposure Is Critical for Subsequent Escalation of Voluntary Ethanol Drinking in Mice

ALCOHOLISM, Issue 11 2009
William C. Griffin III
Background:, Excessive alcohol drinking continues to be an important health problem. Recent studies from our laboratory and others have demonstrated that animal models of ethanol dependence and relapse can contribute to understanding factors that contribute to excessive drinking. In this study, we tested the hypothesis that the amount and duration of ethanol exposure is critical for promoting the escalation in drinking by mice given access to ethanol in a limited access paradigm. Methods:, We used several methods of chronic intermittent ethanol exposure in male C57BL/6J mice that would vary in the amount and duration of exposure to ethanol as indicated by blood ethanol concentrations (BEC). After establishing baseline drinking in the mice using a 2 hours, 2 bottle choice drinking paradigm, each study involved alternating between periods of ethanol exposure and periods of limited access to ethanol (1 cycle) for a total of 3 cycles. In Study 1, mice were allowed extended access (16 hours) to ethanol for oral consumption or remained in the home cage. In Study 2, the ethanol exposure consisted of intragastric gavage of increasing doses of ethanol or isocaloric sucrose as the control. Study 3 compared intragastric gavage combined with pyrazole, an alcohol dehydrogenase inhibitor, with vapor inhalation of ethanol using procedures known to lead to increased drinking in mice. Finally, Study 4 was a retrospective review of several studies conducted in our laboratory using inhalation procedures. The retrospective review encompassed a range of postvapor chamber BEC values and ethanol intakes that would allow a relationship between increased drinking and BEC to be examined. Results:, Allowing mice to drink for longer periods of time did not cause increased drinking in subsequent limited access sessions. Likewise, gastric intubation of ethanol which produced high BEC (>300 mg/dl) with or without pyrazole did not increase drinking. Only the vapor inhalation procedure, which was associated with sustained BEC above 175 mg/dl for the entire exposure period resulted in increased drinking. The retrospective study provided further evidence that sustained BEC levels above 175 mg/dl was critical to the escalation in drinking. Conclusions:, We found that the intensity (amount) and duration of ethanol exposure, indexed by BEC, is critical to produce increased drinking in mice. Specifically, BEC must regularly exceed 175 mg/dl for the escalation in drinking to occur. Future studies will examine neurobiological adaptations that may underlie the increased drinking behavior caused by chronic intermittent ethanol exposure. [source]

Alterations of Rat Corticostriatal Synaptic Plasticity After Chronic Ethanol Exposure and Withdrawal

ALCOHOLISM, Issue 5 2006
Jian Xun Xia
Background: The purpose of this study was to investigate the effects of chronic ethanol exposure (CEE) and withdrawal on corticostriatal plasticity in rats. Methods: We established an animal model of alcoholism using the method of Turchan et al. (1999). A synaptic model of long-term memory (long-term depression, LTD) was used as an index and the striatum, which is related to habit learning, was selected as a target region in the present study. The effects of CEE and withdrawal on the LTD were studied in striatal slices of ethanol-dependent rats using the extracellular recording method. Results: A stable LTD can be induced after high-frequency stimulation (HFS) in the slices of control rats. Chronic ethanol exposure and withdrawal suppressed the induction of corticostriatal LTD to different extents, with the strongest suppressive effects on LTD occurring in the slices of rats exposed to ethanol for 10 days and in those withdrawn from ethanol for 1 day. Notably, 3 days of withdrawal resulted in the shift of corticostriatal synaptic plasticity from LTD to long-term potentiation, and the peak latencies of the population spikes were obviously shortened compared with those of control rats. After 7 days of withdrawal, ethanol's effects tended to disappear. Conclusions: These results suggest that the alterations of corticostriatal synaptic plasticity produced by CEE and withdrawal may play a prominent role in alcohol abuse and alcoholism. [source]

Ethanol Attenuates Spatial Memory Deficits and Increases mGlu1a Receptor Expression in the Hippocampus of Rats Exposed to Prenatal Stress

ALCOHOLISM, Issue 8 2009
Vincent Van Waes
Background:, Although it is generally believed that chronic ethanol consumption impairs learning and memory, results obtained in experimental animals are not univocal, and there are conditions in which ethanol paradoxically improves cognitive functions. In the present work, we investigated the effects of prenatal stress and of chronic ethanol exposure during adulthood on spatial memory in rats. Methods:, Rats were subjected to a prenatal stress delivered as 3 daily 45-minute sections of restraint stress to the mothers during the last 10 days of pregnancy (PRS rats). After 7 months of ethanol exposure (ethanol 10%, oral intake), memory performances were evaluated in a spatial discrimination test in control and PRS male rats. Then, the oxidative damages and the expression of metabotropic glutamate (mGlu) receptors were assessed in their hippocampus. Results:, Chronic ethanol exposure resulted in a reduced performance in a spatial recognition task in control animals. Unexpectedly, however, the same treatment attenuated spatial memory deficits in rats that had been subjected to prenatal stress. This paradigm of ethanol administration did not produce detectable signs of oxidative damage in the hippocampus in either unstressed or PRS rats. Interestingly, ethanol intake resulted in differential effects in the expression of mGlu receptor subtypes implicated in mechanisms of learning and memory. In control rats, ethanol intake reduced mGlu2/3 and mGlu5 receptor levels in the hippocampus; in PRS rats, which exhibited a constitutive reduction in the levels of these mGlu receptor subtypes, ethanol increased the expression of mGlu1a receptors but did not change the expression of mGlu2/3 or mGlu5 receptors. Conclusion:, Our findings support the idea that stress-related events occurring before birth have long-lasting effects on brain function and behavior, and suggest that the impact of ethanol on cognition is not only dose- and duration-dependent, but also critically influenced by early life experiences. [source]

Long-Term Ethanol Exposure Impairs Neuronal Differentiation of Human Neuroblastoma Cells Involving Neurotrophin-Mediated Intracellular Signaling and in Particular Protein Kinase C

ALCOHOLISM, Issue 3 2009
Julian Hellmann
Background:, Revealing the molecular changes in chronic ethanol-impaired neuronal differentiation may be of great importance for understanding ethanol-related pathology in embryonic development but also in the adult brain. In this study, both acute and long-term effects of ethanol on neuronal differentiation of human neuroblastoma cells were investigated. We focused on several aspects of brain-derived neurotrophic factor (BDNF) signaling because BDNF activates the extracellular signal-regulated kinase (ERK) cascade, promoting neuronal differentiation including neurite outgrowth. Methods:, The effects of ethanol exposure on morphological differentiation, cellular density, neuronal marker proteins, basal ERK activity, and ERK responsiveness to BDNF were measured over 2 to 4 weeks. qRT-PCR and Western blotting were performed to investigate the expression of neurotrophin receptor tyrosin kinase B (TrkB), members of the ERK-cascade, protein kinase C (PKC) isoforms and Raf-Kinase-Inhibitor-Protein (RKIP). Results:, Chronic ethanol interfered with the development of a neuronal network consisting of cell clusters and neuritic bundles. Furthermore, neuronal and synaptic markers were reduced, indicating impaired neuronal differentiation. BDNF-mediated activation of the ERK cascade was found to be continuously impaired by ethanol. This could not be explained by expressional changes monitored for TrkB, Raf-1, MEK, and ERK. However, BDNF also activates PKC signaling which involves RKIP, which finally leads to ERK activation as well. Therefore, we hypothesized that ethanol impairs this branch of BDNF signaling. Indeed, both PKC and RKIP were significantly down-regulated. Conclusions:, Chronic ethanol exposure impaired neuronal differentiation of neuroblastoma cells and BDNF signaling, particularly the PKC-dependent branch. RKIP, acting as a signaling switch at the merge of the PKC cascade and the Raf/MEK/ERK cascade, was associated with neuronal differentiation and significantly reduced in ethanol treatment. Moreover, PKC expression itself was even more strongly reduced. In contrast, members of the Raf-1/MEK/ERK cascade were less affected and the observed changes were not associated with impaired differentiation. Thus, reduced RKIP and PKC levels and subsequently reduced positive feedback on ERK activation provide an explanation for the striking effects of long-term ethanol exposure on BDNF signal transduction and neuronal differentiation, respectively. [source]

Alterations of Rat Corticostriatal Synaptic Plasticity After Chronic Ethanol Exposure and Withdrawal

Chronic Intermittent Ethanol Exposure During Adolescence Blocks Ethanol-Induced Inhibition of Spontaneously Active Hippocampal Pyramidal Neurons

ALCOHOLISM, Issue 1 2006
Sayaka Tokunaga
Background: Binge alcohol drinking among adolescents has been a serious public health problem. A model of binge alcohol, chronic intermittent ethanol exposure (CIEE), during adolescence significantly attenuates ethanol-induced spatial memory deficits in rats. However, the attenuation was absent following a 12-day ethanol-free period. Since spatial memory is hippocampal dependent, a reduction in ethanol-induced spatial memory impairments may be due to a reduction in the ability of ethanol to inhibit the firing rate of single hippocampal pyramidal neurons following CIEE. Methods: Beginning on postnatal day 30 (P30), male adolescent Sprague-Dawley rats (Harlan) were administered 5.0 g/kg ethanol (n=10, CIEE-treated group) or an equivolume saline (n=10, CISE-treated group) every 48 hours for 20 days. Single hippocampal pyramidal neurons from 5 CIEE-treated rats and 5 CISE-treated rats were recorded on the day following completion of the chronic intermittent exposure procedure (animals now P50). Additionally, neurons from 5 CIEE-treated rats and 5 CISE-treated rats were recorded 12 days after the completion of the chronic intermittent exposure procedure (animals now P62). Results: Ethanol exposure during adolescence completely blocked ethanol-induced inhibition of hippocampal pyramidal neurons in rats that were CIEE exposed. However, the effect of CIEE on hippocampal neurophysiology was time dependent. Specifically, neurons recorded from CIEE-treated rats after a 12-day ethanol-free period had similar maximal inhibition as neurons from CISE-treated animals, although the time to reach inhibition was significantly greater in neurons from CIEE-treated rats. Conclusion: Chronic ethanol exposure during adolescence produces a reduction, or tolerance, to ethanol-induced inhibition of hippocampal pyramidal neural activity. Although the tolerance was greatly reversed after a 12-day ethanol-free period, neurons from CIEE animals inhibited slower than neurons from CISE animals. Since the hippocampus is known to be involved not only in spatial memory, but also in many other types of memory formation, the altered hippocampal functions because of CIEE during adolescence should be taken as a serious warning for society. [source]

Effect of Chronic Ethanol Ingestion and Gender on Heart Left Ventricular p53 Gene Expression

ALCOHOLISM, Issue 8 2005
Heidi Jänkälä
Background: Although the beneficial effects of mild to moderate ethanol consumption have been implied with respect to heart, alcohol abuse has proven to be a major cause of nonischemic cardiomyopathy in Western society. However, the biochemical and molecular mechanisms, which mediate the pathologic cardiac effects of ethanol, remain largely unknown. The aim of the present study was to explore the effects of chronic ethanol exposure on cardiac apoptosis and expression of some of the genes associated with cardiac remodeling in vivo. Methods: Alcohol-avoiding Alko Non Alcohol rats of both sexes were used. The ethanol-exposed rats (females, n= 6; males, n= 8) were given 12% (v/v) ethanol as the only available fluid from age of three to 24 months of age. The control rats (females, n= 7; males, n= 5) had only water available. At the end of the experiment, free walls of left ventricles of hearts were immediately frozen. Cytosolic DNA fragmentation, reflecting apoptosis, was measured using a commercial quantitative sandwich enzyme-linked immunosorbent assay kit, and mRNA levels were analyzed using a quantitative reverse transcriptase,polymerase chain reaction method. Results: Ethanol treatment for two years increased cardiac left ventricular p53 mRNA levels significantly (p= 0.014) compared with control rats. The gene expression was also dependent on the gender (p= 0.001), so that male rats had higher left ventricular p53 mRNA levels than female rats. However, no significant differences in levels of DNA fragmentation were detected. Conclusions: Chronic ethanol exposure in vivo induces rat cardiac left ventricular p53 gene expression. Expression of p53 is also gender-dependent, males having higher p53 mRNA levels than females. This preliminary finding suggests a role for the p53 gene in ethanol-induced cardiac remodeling. The results might also have some relevance for the known gender-dependent differences in propensity to cardiovascular disease. [source]

No change in apoptosis in skeletal muscle exposed acutely or chronically to alcohol

ADDICTION BIOLOGY, Issue 1 2003
AG PAICE
The pathogenic mechanisms responsible for the deleterious changes in ethanol-exposed skeletal muscle are unknown, although apoptosis may be a causal process. We therefore investigated the responses of skeletal muscle to acute or chronic ethanol exposure in male Wistar rats. In acute studies, rats were dosed with ethanol (75 mmol (3.46 g)/kg BW) and killed after either 2.5 or 6 hours. In chronic studies, rats were fed ethanol as 35% of total dietary energy for 6 weeks. Apoptosis was determined by either DNA fragmentation or TUNEL (terminal deoxynucleotidyl transferase mediated dUTP nick end labelling) assays. The results showed that apoptosis was not increased in the ethanol-exposed muscle in both acute and chronic studies compared to appropriate controls. [source]

Synergistic premalignant effects of chronic ethanol exposure and insulin receptor substrate-1 overexpression in liver

HEPATOLOGY RESEARCH, Issue 9 2008
Lisa Longato
Aim:, Insulin receptor substrate, type 1 (IRS-1) transmits growth and survival signals, and is overexpressed in more than 90% of hepatocellular carcinomas (HCCs). However, experimental overexpression of IRS-1 in the liver was found not to be sufficient to cause HCC. Since chronic alcohol abuse is a risk factor for HCC, we evaluated potential interactions between IRS-1 overexpression and chronic ethanol exposure by assessing premalignant alterations in gene expression. Methods:, Wild-type (wt) or IRS-1 transgenic (Tg) mice, constitutively overexpressing the human (h) transgene in the liver, were pair-fed isocaloric liquid diets containing 0% or 24% ethanol for 8 weeks. The livers were used for histopathologic study and gene expression analysis, focusing on insulin, insulin-like growth factor (IGF) and wingless (WNT),Frizzled (FZD) pathways, given their known roles in HCC. Results:, In wt mice, chronic ethanol exposure caused hepatocellular microsteatosis with focal chronic inflammation, reduced expression of proliferating cell nuclear antigen (PCNA) and increased expression of IGF-I and IGF-I receptor. In hIRS-1 Tg mice, chronic ethanol exposure caused hepatic micro- and macrosteatosis, focal chronic inflammation, apoptosis and disordered lobular architecture. These effects of ethanol in hIRS-1 Tg mice were associated with significantly increased expression of IGF-II, insulin, IRS-4, aspartyl,asparaginyl , hydroxylase (AAH), WNT-1 and FZD 7, as occurs in HCC. Conclusion:, In otherwise normal liver, chronic ethanol exposure mainly causes liver injury and inflammation with impaired DNA synthesis. In contrast, in the context of hIRS-1 overexpression, chronic ethanol exposure may serve as a cofactor in the pathogenesis of HCC by promoting expression of growth factors, receptors and signaling molecules known to be associated with hepatocellular transformation. [source]

Ethanol Acutely Modulates mGluR1-Dependent Long-Term Depression in Cerebellum

ALCOHOLISM, Issue 7 2010
Li-Da Su
Background:, Acute and chronic ethanol exposure produces profound impairments in motor functioning. Individuals with lower sensitivity to the acute motor impairing effects of ethanol have an increased risk of developing alcohol dependence and abuse, and infants with subtle delays in motor coordination development may have an increased risk for subsequently developing alcoholism. Thus, understanding the mechanism by which ethanol disrupts motor functioning is very important. Methods:, Parasagittal slices of the cerebellar vermis (250 ,M thick) were prepared from P17 to 20 Sprague,Dawley rats. Whole-cell recordings of Purkinje cells were obtained with an Axopatch 200B amplifier. Parallel fiber-Purkinje cell synaptic currents were sampled at 1 kHz and digitized at 10 kHz, and synaptic long-term depression (LTD) was observed in either external or internal application of ethanol for comparison. Results:, We determined whether ethanol acutely affects parallel fiber LTD using whole-cell patch-clamp recordings from Purkinje cells. Application of ethanol both externally (50 mM) and internally (17 and 10 mM) significantly suppressed mGluR-mediate slow currents. Short-term external ethanol exposure (50 but not 17 mM) during tetanus blocked mGluR-dependent parallel fiber LTD. Furthermore, internal 17 and 10 mM ethanol completely inhibited this LTD. Conclusions:, The results of the current study demonstrate that ethanol acutely suppresses parallel fiber LTD and may influence the mGluR-mediated slow current intracellularly. This study, plus previous evidence by Carta and colleagues (2006) and Belmeguenai and colleagues (2008), suggests significant actions of ethanol on mGluR-mediated currents and its dependent plasticity in brain. [source]

A Critical Evaluation of Influence of Ethanol and Diet on Salsolinol Enantiomers in Humans and Rats

ALCOHOLISM, Issue 2 2010
Jeongrim Lee
Background:, (R/S)-Salsolinol (SAL), a condensation product of dopamine (DA) with acetaldehyde, has been speculated to have a role in the etiology of alcoholism. Earlier studies have shown the presence of SAL in biological fluids and postmortem brains from both alcoholics and nonalcoholics. However, the involvement of SAL in alcoholism has been controversial over several decades, since the reported SAL levels and their changes after ethanol exposure were not consistent, possibly due to inadequate analytical procedures and confounding factors such as diet and genetic predisposition. Using a newly developed mass spectrometric method to analyze SAL stereoisomers, we evaluated the contribution of ethanol, diet, and genetic background to SAL levels as well as its enantiomeric distribution. Methods:, Simultaneous measurement of SAL enantiomers and DA were achieved by high performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS). Plasma samples were collected from human subjects before and after banana (a food rich in SAL) intake, and during ethanol infusion. Rat plasma and brain samples were collected at various time points after the administration of SAL or banana by gavage. The brain parts including nucleus accumbens (NAC) and striatum (STR) were obtained from alcohol-non-preferring (NP) or alcohol-preferring (P) rats as well as P-rats which had a free access to ethanol (P-EtOH). Results:, Plasma SAL levels were increased significantly after banana intake in humans. Consistently, administration of banana to rats also resulted in a drastic increase of plasma SAL levels, whereas brain SAL levels remained unaltered. Acute ethanol infusion did not change SAL levels or R/S ratio in plasma from healthy humans. The levels of both SAL isomers and DA were significantly lower in the NAC of P rats in comparison to NP rats. The SAL levels in NAC of P rats remained unchanged after chronic free-choice ethanol drinking. There were decreasing trends of SAL in STR and DA in both brain regions. No changes in enantiomeric ratio were observed after acute or chronic ethanol exposure. Conclusions:, SAL from dietary sources is the major contributor to plasma SAL levels. No significant changes of SAL plasma levels or enantiomeric distribution after acute or chronic ethanol exposure suggest that SAL may not be a biomarker for ethanol drinking. Significantly lower SAL and DA levels observed in NAC of P rats may be associated with innate alcohol preference. [source]

Schedule of Passive Ethanol Exposure Affects Subsequent Intragastric Ethanol Self-Infusion

ALCOHOLISM, Issue 11 2009
Tara L. Fidler
Background:, Many studies have shown that chronic ethanol exposure can enhance later self-administration of ethanol, but only a few studies have identified critical parameters for such exposure. The present studies examined temporal and other parameters of chronic ethanol exposure on subsequent intragastric (IG) self-infusion of ethanol. Methods:, Sprague,Dawley rats implanted with IG catheters were passively infused with ethanol for 5 to 6 days and then allowed to self-infuse ethanol or water using a procedure in which infusions were contingent upon licking fruit-flavored solutions. Experiment 1 examined the time interval between consecutive periods of passive infusion (Massed Group: 12 hours vs. Spaced Group: 36 hours). Experiment 2 studied the interval between the final passive infusion and onset of self-infusion (12 vs. 36 hours). Finally, Experiment 3 tested the effect of inserting self-infusion days within the passive infusion phase. Results:, Passive ethanol exposure on consecutive days induced relatively large amounts of ethanol self-infusion (4.1 to 7.9 g/kg/d). Increasing the duration of the ethanol-free interval between periods of passive exposure to 36 hours significantly reduced ethanol self-infusion (2.2 g/kg/d; Exp. 1). The time delay between the last passive ethanol exposure and onset of self-infusion had no effect on self-infusion (Exp. 2). Moreover, inserting no-choice self-infusion days between the last few passive exposure days did not increase self-infusion (Exp. 3). Conclusions:, Measurement of withdrawal signs indicated that Massed passive exposure produced stronger dependence than Spaced passive exposure, suggesting that enhanced ethanol self-infusion in Massed Groups might be explained by the opportunity for greater negative reinforcement by ethanol. Although enhanced negative reinforcement might also explain why the Massed Group showed a weaker aversion for the ethanol-paired flavor than the Spaced Group, this observation could also be explained by the development of greater tolerance to ethanol's aversive pharmacological effects in the Massed Group. [source]

Ethanol Attenuates Spatial Memory Deficits and Increases mGlu1a Receptor Expression in the Hippocampus of Rats Exposed to Prenatal Stress

Ethanol-Sensitive Brain Regions in Rat and Mouse: A Cartographic Review, Using Immediate Early Gene Expression

ALCOHOLISM, Issue 6 2009
Catherine Vilpoux
Background:, Ethanol addiction has been conceptualized as a progression from occasional, impulsive use to compulsive behavior. Ethanol-dependence is a chronic pathology with repeated cycles of withdrawal, craving, and relapse. Specific molecular and cellular mechanisms underlie these transition stages. Methods:, This review aimed at elucidating whether there are also adaptations in the pattern of brain regions responding to ethanol. This paper reviews the evidence in rodents for activation of specific brain regions, assessed by induction of IEG expression, following acute and chronic ethanol exposure. Results:, The review sheds light on the specific patterns of response in regions of the brain to different types of ethanol exposure and shows that activation of specific brain regions may occur in particular phases of the development of ethanol addiction. Some brain regions respond consistently following acute or chronic treatments or withdrawal: the prefrontal cortex; nucleus accumbens; lateral septum; hippocampus; perioculomotor urocortin-containing cells population (pIIIu), also known as Edinger-Westphal nucleus; central nucleus of the amygdale; and the paraventricular nucleus of hypothalamus. The two last brain areas are particularly activated by relapse-inducing stressors. It is of interest that the amygdala, hippocampus, and prefrontal cortex, which belong to the reward system, are activated by cue-induced relapse to ethanol self-administration in rodents and humans, while activation of these regions is reversed with anticraving compounds. Following chronic exposure, IEG induction desensitizes while withdrawal reactivates these regions. Discussion:, Some responding regions are implicated in reward related processes (VTA, extended amygdala, hypothalamus, hippocampus, prelimbic cortex, ventral part of lateral septum) and some others in aversive-related processes (area postrema, nucleus of solitary tract). Conclusion:, A better understanding of the neural circuits affected by ethanol and their adaptations during the development of ethanol addiction will provide new opportunities for developing appropriate therapies. [source]

Abstinence From Moderate Alcohol Self-Administration Alters Progenitor Cell Proliferation and Differentiation in Multiple Brain Regions of Male and Female P Rats

ALCOHOLISM, Issue 1 2009
Jun He
Background:, Acute and chronic ethanol exposure has been found to decrease hippocampal neurogenesis, reduce dendritic differentiation of new neurons, and increase cell death. Interestingly, abstinence from such treatment increases hippocampal neurogenesis and microglial genesis across several brain regions. The goal of the current investigation was to study cellular alterations on neuro- and cell-genesis during abstinence following alcohol self-administration using alcohol-preferring rats (P rats). Methods:, Male and female P rats were given the choice of drinking 10% alcohol in water or pure water for 7 weeks. Social interaction behavioral assessments were conducted at 5 hours upon removal of alcohol, followed by bromo-deoxyuridine (BrdU, 150 mg/kg × 1/d × 14 d) injections to label proliferating cells. Animals were then killed 4 weeks later to conduct immunohistochemical and confocal analyses using antibodies against BrdU and other phenotypic markers (NeuN for mature neurons; Iba-1 for microglia; GFAP for astrocytes; and NG2 for oligodendrocyte progenitors). Results:, Mild alcohol withdrawal anxiety was detected by reduction in social interactions. The number of hippocampal BrdU+ cells was increased approximately 50% during alcohol abstinence (26 ± 2.8 in controls vs. 39 ± 4 in alcohol group). BrdU+ cells were also increased in the substantia nigra (SN) approximately 65% in the alcohol abstinent group (12 ± 1 in controls vs. 19 ± 1.5 in alcohol group). No gender differences were found. Confocal analyses indicated that approximately 75% of co-localization of BrdU+ cells with NeuN in the hippocampal dentate gyrus (DG) resulting a net increase in neurogenesis in the alcohol abstinent group compared to controls. In cingulum, greater proportion of BrdU+ cells were co-localized with NG2 in the alcohol abstinent group indicating increased differentiation toward oligodendrocyte progenitors in both genders. However, the phenotype of the BrdU+ cells in SN and other brain regions were not identified by NeuN, Iba-1, GFAP, or NG2 suggesting that these BrdU+ cells probably remain in a nondifferentiated stage. Conclusions:, These data indicate that abstinence from moderate alcohol drinking increases hippocampal neurogenesis, cingulate NG2 differentiation, and SN undifferentiated cell proliferation in both males and females. Such cellular alteration during abstinence could contribute to the spontaneous partial restoration of cognitive deficits upon sobriety. [source]

Inhibition of the Activity of Excitatory Amino Acid Transporter 4 Expressed in Xenopus Oocytes After Chronic Exposure to Ethanol

ALCOHOLISM, Issue 7 2008
Seung-Yeon Yoo
Background:, The extracellular glutamate concentration is tightly controlled by excitatory amino acid transporters (EAATs). EAAT4 is the predominant EAAT in the cerebellar Purkinje cells. Purkinje cells play a critical role in motor coordination and may be an important target for ethanol to cause motor impairments. We designed this study to determine the effects of chronic ethanol exposure on the activity of EAAT4 and evaluate the involvement of protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3K) in these effects. Methods:, EAAT4 was expressed in Xenopus oocytes following injection of EAAT4 mRNA. Oocytes were incubated with ethanol-containing solution for 24 to 96 hours. Membrane currents induced by l -aspartate were recorded using 2-electrode voltage clamps. Responses were quantified by integration of the current trace and reported in microCoulombs (,C). Results:, Ethanol dose- and time-dependently reduced EAAT4 activity. EAAT4 activity after a 96-hour exposure was significantly decreased compared to the control values at all concentrations tested (10 to 100 mM). Ethanol (50 mM) significantly decreased the Vmax (2.2 ± 0.2 ,C for control vs. 1.6 ± 0.2 ,C for ethanol, n = 18, p < 0.05) of EAAT4 for l -aspartate. Preincubation of ethanol-treated (50 mM for 96 hours) oocytes with phorbol-12-myrisate-13-acetate (100 nM for 10 minutes) abolished the ethanol-induced decrease in EAAT4 activity. While staurosporine (2 ,M for 1 hour) or chelerythrine (100 ,M for 1 hour) significantly decreased EAAT4 activity, no difference was observed in EAAT4 activity among the staurosporine, ethanol, or ethanol plus staurosporine groups. Similarly, EAAT4 activity did not differ among the chelerythrine, ethanol, or ethanol plus chelerythrine groups. Pretreatment of the oocytes with wortmannin (1 ,M for 1 hour) also significantly decreased EAAT4 activity. However, no difference was observed in the wortmannin, ethanol, or ethanol plus wortmannin groups. Conclusions:, The results of this study suggest that chronic ethanol exposure decreases EAAT4 activity and that PKC and PI3K may be involved in these effects. These effects of ethanol on EAAT4 may cause an increase in peri-Purkinje cellular glutamate concentration, and may be involved in cerebellar dysfunction and motor impairment after chronic ethanol ingestion. [source]

Disruptions in Sleep Time and Sleep Architecture in a Mouse Model of Repeated Ethanol Withdrawal

ALCOHOLISM, Issue 7 2006
Lynn M. Veatch
Background: Insomnia and other sleep difficulties are perhaps the most common and enduring symptoms reported by alcoholics undergoing detoxification, especially those alcoholics with a history of multiple detoxifications. While some studies have reported sleep disruptions in animal models after chronic ethanol exposure, the reports are inconsistent and few address sleep architecture across repeated ethanol exposures and withdrawals. The present study evaluated sleep time and architecture in a well-characterized mouse model of repeated chronic ethanol exposure and withdrawal. Methods: C57BL6/J mice were fitted with electrodes in frontal cortex, hippocampus, and nuchal muscle for collection of continuous electroencephalogram (EEG)/electromyogram (EMG) data. Baseline data were collected, after which mice received 4 cycles of 16-hour exposure to alcohol (ethanol: EtOH) vapor separated by 8-hour periods of withdrawal or similar handling in the absence of EtOH vapor. Ethanol-exposed mice attained a blood ethanol concentration of 165 mg%. Upon completion of vapor exposure, EEG/EMG data were again collected across 4 days of acute withdrawal. Data were subjected to automated analyses classifying 10-second epochs into wake, non,rapid eye movement (REM) sleep, or REM sleep states. Results: Mice in withdrawal after chronic EtOH exposure showed profound disruptions in the total time asleep, across the acute withdrawal period. Sleep architecture, the composition of sleep, was also disrupted with a reduction in non-REM sleep concomitant with a profound increase in REM sleep. While altered sleep time and non-REM sleep loss resolved by the fourth day of withdrawal, the increase in REM sleep ("REM rebound") persisted. Conclusions: These results mirror those reported for the human alcoholic and demonstrate that EtOH withdrawal,induced sleep disruptions are evident in this mouse model of alcohol withdrawal,induced sensitization. This mouse model may provide mechanisms to investigate fully the high correlation between unremitting sleep problems and increased risk of relapse documented clinically. [source]

Alterations of Rat Corticostriatal Synaptic Plasticity After Chronic Ethanol Exposure and Withdrawal

Effect of Chronic Ethanol Ingestion and Gender on Heart Left Ventricular p53 Gene Expression

Ethanol Modulation of TNF-alpha Biosynthesis and Signaling in Endothelial Cells: Synergistic Augmentation of TNF-alpha Mediated Endothelial Cell Dysfunctions by Chronic Ethanol

ALCOHOLISM, Issue 6 2005
Corinne Luedemann
Despite reported cardio-protective effects of low alcohol intake, chronic alcoholism remains a risk factor in the pathogenesis of coronary artery disease. Dose related bimodal effects of alcohol on cardiovascular system might reflect contrasting influences of light versus heavy alcohol consumption on the vascular endothelium. Chronic ethanol induced damage to various organs has been linked to the increased release of TNF-alpha (TNF). We have previously shown that TNF, expressed at the sites of arterial injury, suppresses re-endothelialization of denuded arteries and inhibits endothelial cell (EC) proliferation in vitro. Here we report that in vitro chronic ethanol exposure enhances agonist-induced TNF mRNA and protein expression in EC. Ethanol-mediated increment in TNF expression involves increased de novo transcription without affecting mRNA stability. DNA binding assays revealed that ethanol-induced TNF up regulation was AP1 dependent. Functionally, TNF induced EC dysfunction, including reduced proliferation, migration and cyclin A expression, were all markedly enhanced in the presence of ethanol. Additionally, expression of cyclin D1 was significantly attenuated in cells co-treated with TNF and ethanol while each treatment alone had little effect on cyclin D1 expression. Furthermore, exposure to ethanol potentiated and prolonged agonist-induced activation of JNK. Inhibition of JNK by over-expression of dominant negative JNK1 substantially reversed ethanol/TNF-mediated inhibition of cyclin A expression and EC proliferation, suggesting modulation of JNK1 signaling as the mechanism for ethanol/TNF-induced EC dysfunctions. Taken together, these data indicate that chronic ethanol consumption may negatively influence post angioplasty re-endothelialization thereby contributing to the development of restenosis. [source]

Differential Adaptations in GABAergic and Glutamatergic Systems During Ethanol Withdrawal in Male and Female Rats

ALCOHOLISM, Issue 6 2005
P E. Alele
Background: There are significant and consistent sex differences in recovery from ethanol withdrawal in our animal model of ethanol dependence. We have also observed significant and varied sex differences in subunit protein levels of ,-aminobutyric acid A (GABAA) and the N-metheyl-D-aspartate subtype of glutamate receptors occurring with ethanol dependence and withdrawal. Considering the major role of these two systems as targets of ethanol, we wanted to explore additional possible mechanisms underlying changes in GABAergic and glutamatergic responses after chronic ethanol exposure. Therefore, the objective of the present study was to examine GABAergic- and glutamatergic-associated proteins at three days of ethanol withdrawal, when female rats appear to have largely recovered but male rats still display robust signs of withdrawal. Methods: Male and female rats were fed 6% ethanol in a nutritionally complete liquid diet for 14 days according to a pair-fed design; withdrawal was initiated by replacement of the diet with chow. At three days of withdrawal, the cerebral cortex and hippocampus were dissected for use in Western blot analysis. The paired design was maintained throughout all experimental procedures. Results: At three days of ethanol withdrawal, we found region-specific and sex-selective alterations in levels of GAD (glutamic acid decarboxylase, GABA synthetic enzyme), GABA and glutamate transporters, and the synapse-associated proteins HSP70, PSD-95, and synaptophysin. There were also several significant differences in transporter function at this time that varied between males and females. Conclusions: Taken together, these findings show differential adaptations of GABAergic and glutamatergic neurotransmission between female and male rats that are associated with withdrawal recovery. This suggests that selective withdrawal-induced neuroadaptations in regulation of these systems' activities underlie, at least in part, sex differences in withdrawal recovery between male and female rats. [source]

Alcohol and Mitochondria in Cardiac Apoptosis: Mechanisms and Visualization

ALCOHOLISM, Issue 5 2005
György Hajnóczky
Apoptosis of myocytes is likely to contribute to a variety of heart conditions and could also be important in the development of alcoholic heart disease. A fundamental pathway to apoptosis is through mitochondrial membrane permeabilization and release of proapoptotic factors from the mitochondrial intermembrane space to the cytosol. The authors' results show that prolonged exposure of cultured cardiac cells to ethanol (35 mM for 48 hr) promotes Ca2+ -induced activation of the mitochondrial permeability transition pore (PTP). PTP-dependent mitochondrial membrane permeabilization is followed by release of cytochrome c and execution of apoptosis. The authors propose that chronic ethanol exposure, in combination with other stress signals, may allow for activation of the PTP by physiological calcium oscillations, providing a trigger for cardiac apoptosis during chronic alcohol abuse. Coincidence of apoptosis promoting factors occurs in only a small fraction of myocytes, but because of the absence of regeneration, even a modest increase in the rate of cell death may contribute to a decrease in cardiac contractility. Detection of apoptotic changes that are present in only a few myocytes at a certain time in the heart is not feasible with most of the apoptotic assays. Fluorescence imaging is a powerful technology to visualize changes that are confined to a minor fraction of cells in a tissue, and the use of multiphoton excitation permits imaging in situ deep in the wall of the intact heart. This article discusses potential mechanisms of the effect of alcohol on mitochondrial membrane permeabilization and visualization of mitochondria-dependent apoptosis in cardiac muscle. [source]

Ethanol Treatment Reduces Bovine Bronchial Epithelial Cell Migration

ALCOHOLISM, Issue 4 2005
John R. Spurzem
Background: Chronic ethanol abuse is associated with significant lung disease. Excessive alcohol intake increases risk for a variety of respiratory tract diseases, including pneumonia and bronchitis. Damage to airway epithelium is critical to the pathogenesis of airway disorders such as chronic bronchitis and chronic obstructive pulmonary disease. The ability of the airway epithelium to repair itself is an important step in the resolution of airway inflammation and disease. Ethanol exposure is known to modulate signaling systems in bronchial epithelial cells. We hypothesize that chronic ethanol exposure down-regulates the adenosine 3,:5,-cyclic monophosphate signaling cascade in airway epithelial cells, resulting in decreased epithelial cell migration and repair. Methods: We evaluated the effect of ethanol on primary cultures of bovine bronchial epithelial cells in in vitro models of cell migration, wound repair, cell attachment, and cell spreading. Results: Ethanol causes a concentration-dependent effect on closure of mechanical wounds in cell monolayers. Pretreatment of cells with 100 mm ethanol for 24 hr further slows wound closure. Ethanol pretreatment also reduced the protein kinase A response to wounding and made the cells unresponsive to stimuli of protein kinase A that accelerate wound closure. The effects of ethanol on cell migration in wound closure were confirmed in another assay of migration, the Boyden chamber cell migration assay. Prolonged treatment with ethanol also reduced other cell functions, such as spreading and attachment, which are necessary for epithelial repair. Conclusions: Ethanol modulates signaling systems that are relevant to airway injury and repair, suggesting that chronic, heavy ethanol ingestion has a detrimental impact on airway repair. Impaired response to inflammation and injury may contribute to chronic airway disease. [source]

Cellular Adaptation to Chronic Ethanol Results in Altered Compartmentalization and Function of the Scaffolding Protein RACK1

ALCOHOLISM, Issue 10 2003
Alicia J. Vagts
Background: Previously, we found that acute ethanol induces the translocation of the scaffolding protein RACK1 to the nucleus. Recently, we found that nuclear RACK1 mediates acute ethanol induction of immediate early gene c-fos expression. Alterations in gene expression are thought to lead to long-term changes that ultimately contribute to the development of alcohol addiction and toxicity. Therefore, we sought to determine the effects of chronic exposure of cells to ethanol on the cellular compartmentalization of RACK1 and on c-fos messenger RNA (mRNA) and protein expression. Methods: Rat C6 glioma cells were used as the cell culture model. Immunohistochemistry was implemented to visualize the localization of RACK1 and to monitor the protein level of c-fos. Reverse-transcription polymerase chain reaction was used to measure c- fos mRNA levels. The Tat-protein transduction method was used to transduce recombinant Tat-RACK1 into cells as previously described. Results: Chronic exposure of cells to 200 mM ethanol for 24 and 48 hr resulted in the gradual re-distribution of RACK1 out of the nucleus. It is interesting to note that acute ethanol re-challenge immediately after chronic treatment did not result in RACK1 translocation to the nucleus, and nuclear compartmentalization of RACK1 in response to acute ethanol was detected only after 24 hr of withdrawal. Similar patterns were obtained for c-fos expression. Chronic exposure to ethanol did not result in an increase in mRNA or protein levels of c-fos. Furthermore, acute ethanol exposure did not increase c-fos protein levels in cells that were first treated chronically with ethanol. However, transduction of exogenous RACK1 expressed as a Tat-fusion protein was able to rescue c- fos mRNA expression after chronic ethanol exposure. Conclusions: Our data suggest that RACK1 nuclear compartmentalization and ethanol-induced c-fos expression are transient and are desensitized to ethanol during prolonged exposure to high concentrations. The desensitization is temporary, and RACK1 can respond to acute ethanol treatment after a 24-hr withdrawal period. Our data further suggest that the altered compartmentalization of RACK1 leads to differences in c-fos expression upon acute or chronic exposure to ethanol. In summary, RACK1 is an important molecular mediator of the acute and chronic actions of ethanol on the expression of c-fos. These findings could have implications for the molecular signaling pathways leading to pathologic states associated with alcoholism, including toxicity. [source]

GABAA -Receptor , Subunit Knockout Mice Have Multiple Defects in Behavioral Responses to Ethanol

ALCOHOLISM, Issue 12 2001
Robert M. Mihalek
Background: The ,-aminobutyric acid type A receptors (GABARs) are involved in mediating some of the behavioral effects of beverage alcohol (ethanol). However, the unique pharmacological and behavioral responses conferred by each of the various receptor subunits are not well understood. Methods: To address the role of the GABAR , subunit in mediating ethanol responses, gene knockout mice that lack this subunit were tested for a variety of ethanol-induced behavioral responses. Results: Our results indicate that, compared with controls, ,-deficient mice (,,/,) have (1) reduced ethanol consumption, (2) attenuated withdrawal from chronic ethanol exposure, and (3) reduced anticonvulsant (seizure-protective) effects of ethanol. These mice demonstrate a normal anxiolytic response to ethanol and a normal hypothermic response to ethanol, and they develop both chronic and acute tolerance. Conclusions: These results further establish the link between GABARs and specific behavioral responses to ethanol and begin to reveal the role of the , subunit in these responses. [source]

Ethanol Dependence Has Limited Effects on GABA or Glutamate Transporters in Rat Brain

ALCOHOLISM, Issue 4 2001
Leslie L. Devaud
Background: Neuroadaptations of GABAergic and glutamatergic systems appear to play an important role in both the acute as well as chronic effects of ethanol. Chronic ethanol intake leads to the development of ethanol tolerance and dependence that is associated with a decrease in GABAergic and an increase in glutamatergic function. The present report assessed the involvement of GABA and glutamate transporters in the chronic ethanol-induced adaptations of these two neuronal systems. Methods: Male and female rats were made ethanol dependent by 2-week administration of ethanol in a liquid diet. Levels of GABA (GAT-1, GAT-3) and glutamate (GLT-1, EAAC-1) transporters were assayed by immunoblotting. Transporter function was assessed by [3H]GABA and [3H]glutamate uptake assays. Results: Ethanol dependence did not alter levels of GABA or glutamate transporters in cerebral cortex compared with pair-fed control values. There were increases in some, but not all, transporter levels in hippocampus and hypothalamus with the development of ethanol dependence. A decreased rate of uptake was observed for GABA in cerebral cortex. There was no change in maximal GABA uptake or in glutamate uptake (Vmax). Conclusions: These results suggest that alterations in GABA and glutamate transporters have only a limited role in neuroadaptations to chronic ethanol intake in rats. However, the observed alterations were region-specific, supporting the complex responses to chronic ethanol exposure and suggesting that neuroadaptations of GABAergic and glutamatergic systems vary across the brain. [source]

Ethanol Exposure Enhances Apoptosis Within the Testes

ALCOHOLISM, Issue 10 2000
Qianlong Zhu
Background: Chronic ethanol abuse causes testicular atrophy and male infertility in alcoholic men. It is well known that ethanol exposure disrupts the hypothalamic-pituitary-gonadal axis, adversely affects the secretory function of Sertoli cells, and produces oxidative stress within the testes. It is still not clear what cellular mechanisms are responsible for the morphologic alteration of the testes that results in a reduction of testicular mass as a consequence of ethanol exposure. The hypothesis tested was that ethanol enhances apoptosis of testicular germ cells. Methods: In the experiments of chronic ethanol exposure, male Sprague Dawley® rats (Harlan Sprague Dawley, Inc., Indianapolis, IN) were fed Liber-Decarlie liquid diet for 9 weeks. In the experiments of acute ethanol exposure, a small volume of 20% ethanol solution was administered by intratesticular injection. Both 3,-end labeling of isolated testicular deoxyribonucleic acid (DNA) and labeling of apoptotic cells in situ by the terminal deoxynucleotidyl transferase-mediated deoxyuridine 5,-triphosphate nick end-labeling method were used to determine apoptosis rates within the testes. The expression of proteins involved in apoptosis was assessed by reverse transcription-polymerase chain reaction and by Western blotting. Results: The testes of rats that were fed an ethanol-containing liquid diet had more testicular DNA fragmentation than did those of animals that were fed an isocaloric control diet. Ethanol increased the number of apoptotic spermatogonia as well as spermatocytes. Direct intratesticular injections of ethanol solution enhanced testicular DNA fragmentation, suggesting an increase in apoptosis. Moreover, Fas ligand levels were increased within the testes of rats that were chronically fed ethanol. In vitro, ethanol treatment of cultured Sertoli cells enhanced the production of Fas ligand. In addition, testicular levels of p53 messenger ribonucleic acid were increased in rats that were chronically fed ethanol. Conclusions: All of these observations suggest that ethanol enhances testicular germ cell apoptosis. [source]