Ethanol inhibits NMDA receptor-mediated excitotoxicity in rat primary neuronal cultures

Alcohol and the dopamine system

The mesolimbic dopamine pathway plays a major role in drug reinforcement and is likely involved also in the development of drug addiction. Ethanol, like most addictive drugs, acutely activates the mesolimbic dopamine system and releases dopamine, and ethanol-associated stimuli also appear to trigger dopamine release. In addition, chronic exposure to ethanol reduces the baseline function of the mesolimbic dopamine system. The molecular mechanisms underlying ethanol´s interaction with this system remain, however, to be unveiled. Here research on the actions of ethanol in the mesolimbic dopamine system, focusing on the involvement of cystein-loop ligand-gated ion channels, opiate receptors, gastric peptides and acetaldehyde is briefly reviewed. In summary, a great complexity as regards ethanol´s mechanism(s) of action along the mesolimbic dopamine system has been revealed. Consequently, several new targets and possibilities for pharmacotherapies for alcohol use disorder have emerged.

Neuroprotective effect of ethanol and Modafinil on focal cerebral ischemia in rats

Ethanol is known as an effective agent against cerebral lesions after ischemia. Modafinil is a stimulant of the central nervous system (CNS) with antioxidant properties. We assessed the neuroprotective effect of modafinil in combination with ethanol after focal cerebral ischemia. Male wistar rats weighing 280-300 g were divided into nine groups (n = 12 each group): The groups consisted of the MCAO (middle cerebral artery occlusion) group (i.e. ischemia without treatment); the vehicle group(Dimethylsulfoxide); the modafinil group including three subgroups which pretreated with Modafinil (10, 30, 100 mg/kg), respectively, for seven days prior to the induction of MCAO; the ethanol group which received 1.5g/kg ethanol at the time of reperfusion; and modafinil+ethanol group which was divided into three subgroups that received three doses of modanifil (10, 30,100 mg/kg), respectively, for seven days prior to MCAO as well as ethanol at the time of reperfusion. Transient cerebral ischemia was induced by 60-min intraluminal occlusion of the right middle cerebral artery. Edema, infarct volume, glial scar formation (gliosis) and apoptosis were analyzed. The ethanol alone treatment (with a less significant effect), modafinil (in a dose-dependent way), and the combination of modafinil and ethanol significantly decreased the brain infarct volume, edema, apoptosis, and gliosis (P ≤ 0.05). Additionally, modafinil+ethanol mediated the restoration of aerobic metabolism and hyper-glycolysis suppress, thereby resulting in an increase in pyruvate dehydrogenase and a decrease in lactate dehydrogenase activity, respectively, which ultimately reduced oxidative reperfusion injury. These results demonstrate that pretreatment with modafinil (100 mg/kg) and modafinil+ethanol(1.5 g/kg) may prevent ischemic brain injuries.

Low-dose ethanol ameliorates amnesia induced by a brief seizure model: the role of NMDA signaling

Objective: The present study aimed to evaluate the ameliorative effect of low-dose ethanol (Eth) on amnesia induced by a brief seizure model and the role of N-methyl D-aspartate (NMDA) signaling in this event. Materials and Methods: Four groups of rats (total number = 36; n = 9, each group) were used: control, Eth (0.5 g/kg/i.p.), pentylenetetrazole (PTZ) (60 mg/kg/i.p.), and Eth+PTZ. Eth was administered for 6 days before the single injection of PTZ, at minute dose that cannot induce memory impairment. The consequences of Eth pretreatment, coadministered with PTZ, were studied in an inhibitory avoidance (IA) memory model. The PTZ was injected 30 min prior to the IA memory test. Thereafter, locomotion, liver enzymes, and the Real-time PCR for NR1 subunit of NMDA receptor were studied. The statistical analyses were performed using the parametric/nonparametric ANOVA and the post-hoc tests. Results: Our findings revealed that Eth pretreatment significantly improved the IA memory impairment induced by PTZ (P < 0.001), and indicated no change in locomotion and serum ALT, but significantly differed for AST between the PTZ and PTZ groups (P = < 0.05). The Real-time PCR results indicate the decreased NR1 mRNA expression in Eth and PTZ groups and the increased NR1 mRNA expression in Eth+PTZ group, compared to the control group (P < 0.001); however, the NR1 mRNA expression was increased in the Eth+PTZ group, compared to PTZ group (P < 0.001). Conclusion: The present study provides evidence that the low-dose Eth can improve the amnesia induced by a brief seizure model presumably via NMDA signaling in a rat.

Chronic ethanol forced administration from adolescence to adulthood reduces cell density in the rat spinal cord

Ethanol (EtOH) consumption is a risk factor for central nervous system damage, especially during adolescence. This study aimed to investigate the possible effects of chronic EtOH forced administration on gray and white matter of the spinal cord, from adolescence to adulthood. For this, male Wistar rats were administered EtOH by gavage (6.5 g/kg/day; 22.5% w/v) from the 35th to the 90th day of life, while control animals received only distilled water. After exposure, animals were euthanized and their spinal cords processed to obtain cervical and thoracic segments for histological analyses. Quantitative analyses of total cell density and motor neurons of white and gray matter from the ventral horns were evaluated. Forced EtOH administration model showed a decrease in the motoneuron density in the spinal cord in both segments evaluated. Analyses of total cell density showed that the cervical segment was more susceptible to damages promoted by EtOH, with a significant decrease in cell density. Our results showed that chronic EtOH exposure during adolescence could promote injuries to the spinal cord, with neurodegeneration of motoneurons and other cell types present in neural parenchyma.

Acute Ethanol Exposure Promotes Autophagy-Lysosome Pathway-Dependent ASIC1a Protein Degradation and Protects Against Acidosis-Induced Neurotoxicity

Tissue acidosis is a common feature of brain ischemia which causes neuronal injury. Activation of acid-sensing ion channel 1a (ASIC1a) plays an important role in acidosis-mediated neurotoxicity. Acute ethanol administration has been shown to provide neuroprotective effects during ischemic stroke, but the precise mechanisms have yet to be determined. In this study, we investigated the effect of ethanol on the activity/expression of ASIC1a channels and acidosis-induced neurotoxicity. We showed that acute treatment of neuronal cells with ethanol for more than 3 h could reduce ASIC1a protein expression, ASIC currents, and acid-induced [Ca²⁺]_i elevation. We further demonstrated that ethanol-induced reduction of ASIC1a expression is mediated by autophagy-lysosome pathway (ALP)-dependent protein degradation. Finally, we showed that ethanol protected neuronal cells against acidosis-induced cytotoxicity, which effect was mimicked by autophagy activator rapamycin and abolished by autophagy inhibitor CQ. Together, these results indicate that moderate acute ethanol exposure can promote autophagy-lysosome pathway-dependent ASIC1a protein degradation and protect against acidosis-induced neurotoxicity.

Effects of Therapeutic Hypothermia Combined with Other Neuroprotective Strategies on Ischemic Stroke: Review of Evidence

Ischemic stroke is a major cause of death and disability globally, and its incidence is increasing. The only treatment approved by the US Food and Drug Administration for acute ischemic stroke is thrombolytic treatment with recombinant tissue plasminogen activator. As an alternative, therapeutic hypothermia has shown excellent potential in preclinical and small clinical studies, but it has largely failed in large clinical studies. This has led clinicians to explore the combination of therapeutic hypothermia with other neuroprotective strategies. This review examines preclinical and clinical progress towards developing highly effective combination therapy involving hypothermia for stroke patients.

FMRP regulates an ethanol-dependent shift in GABABR function and expression with rapid antidepressant properties

Alcohol promotes lasting neuroadaptive changes that may provide relief from depressive symptoms, often referred to as the self-medication hypothesis. However, the molecular/synaptic pathways that are shared by alcohol and antidepressants are unknown. In the current study, acute exposure to ethanol produced lasting antidepressant and anxiolytic behaviours. To understand the functional basis of these behaviours, we examined a molecular pathway that is activated by rapid antidepressants. Ethanol, like rapid antidepressants, alters γ-aminobutyric acid type B receptor (GABA_BR) expression and signalling, to increase dendritic calcium. Furthermore, new GABA_BRs are synthesized in response to ethanol treatment, requiring fragile-X mental retardation protein (FMRP). Ethanol-dependent changes in GABA_BR expression, dendritic signalling, and antidepressant efficacy are absent in Fmr1-knockout (KO) mice. These findings indicate that FMRP is an important regulator of protein synthesis following alcohol exposure, providing a molecular basis for the antidepressant efficacy of acute ethanol exposure.

Alcohol is thought to lead to neuroadaptive changes, although the underlying molecular mechanisms are unclear. Here, the authors find ethanol treatment alters GABA_B-receptor expression via fragile-X mental retardation protein in mice, leading to antidepressant-like behaviours.

Sub-toxic Ethanol Exposure Modulates Gene Expression and Enzyme Activity of Antioxidant Systems to Provide Neuroprotection in Hippocampal HT22 Cells

Ethanol is known to cause severe systemic damage often explained as secondary to oxidative stress. Brain is particularly vulnerable to ethanol-induced reactive oxygen species (ROS) because the high amounts of lipids, and because nerve cell membranes contain high amounts of peroxidable fatty acids. Usually these effects of ethanol are associated to high and/or chronic exposure to ethanol. However, as we show in this manuscript, a low and acute dose of ethanol trigger a completely different response in hippocampal cells. Thus, we have observed that 0.1% ethanol exposure to HT22 cells, a murine hippocampal-derived cell line, increases the transcriptional expression of different genes belonging to the classical, glutathione/glutaredoxin and thioredoxin/peroxiredoxin antioxidant systems, these including Sod1, Sod2, Gpx1, Gclc, and Txnrd1. Paralleling these changes, enzyme activities of total superoxide dismutase (tSOD), catalase, total glutathione peroxidase (tGPx), glutathione-S-reductase (GSR), and total thioredoxin reductase (tTXNRD), were all increased, while the generation of thiobarbituric acid reactive substances (TBARS), as indicators of lipid peroxidation, and glutathione levels remained unaltered. Ethanol exposure did not affect cell viability or cell growing as assessed by real-time cell culture monitoring, indicating that low ethanol doses are not deleterious for hippocampal cells, but rather prevented glutamate-induced excitotoxicity. In summary, we conclude that sub-toxic exposure to ethanol may well be neuroprotective against oxidative insults in hippocampal cells.

Therapeutic hypothermia for stroke: Where to go?

Ischemic stroke is a major cause of death and long-term disability worldwide. Thrombolysis with recombinant tissue plasminogen activator is the only proven and effective treatment for acute ischemic stroke; however, therapeutic hypothermia is increasingly recognized as having a tissue-protective function and positively influencing neurological outcome, especially in cases of ischemia caused by cardiac arrest or hypoxic-ischemic encephalopathy in newborns. Yet, many aspects of hypothermia as a treatment for ischemic stroke remain unknown. Large-scale studies examining the effects of hypothermia on stroke are currently underway. This review discusses the mechanisms underlying the effect of hypothermia, as well as trends in hypothermia induction methods, methods for achieving optimal protection, side effects, and therapeutic strategies combining hypothermia with other neuroprotective treatments. Finally, outstanding issues that must be addressed before hypothermia treatment is implemented at a clinical level are also presented.

Combination of therapeutic hypothermia and other neuroprotective strategies after an ischemic cerebral insult

Abrupt deprivation of substrates to neuronal tissue triggers a number of pathological events (the “ischemic cascade”) that lead to cell death. As this is a process of delayed neuronal cell death and not an instantaneous event, several pharmacological and non-pharmacological strategies have been developed to attenuate or block this cascade. The most promising neuroprotectant so far is therapeutic hypothermia and its beneficial effects have inspired researchers to further improve its protective benefit by combining it with other neuroprotective agents. This review provides an overview of all neuroprotective strategies that have been combined with therapeutic hypothermia in rodent models of focal cerebral ischemia. A distinction is made between drugs interrupting only one event of the ischemic cascade from those mitigating different pathways and having multimodal effects. Also the combination of therapeutic hypothermia with hemicraniectomy, gene therapy and protein therapy is briefly discussed. Furthermore, those combinations that have been studied in a clinical setting are also reviewed.

The effect of alcohol intoxication on mortality of blunt head injury

Alcohol is found to have neuroprotection in recent studies in head injuries. We investigated the association of blood alcohol concentration (BAC) with mortality of patients with blunt head injury after traffic accident. All patients sustaining blunt head injury caused by traffic accident brought to our emergency department who had obtained a brain computed tomography scans and BAC were analyzed. Patients with unknown mechanisms, transfers from outside hospitals, and incomplete data were excluded. Logistic regression was used to identify independent predictors of mortality. During the study period, 3,628 patients with brain computed tomography (CT) were included. Of these, BAC was measured in 556 patients. Patients with the lowest BAC (less than 8 mg/dl) had lower mortality; intoxicated patients with BAC between 8 and less than 100 mg/dl were associated with significantly higher mortality than those patients in other intoxicated groups. Adjusted logistic regression demonstrated higher BAC group and Glasgow coma scale (GCS) scores, and lower ISS and age were identified as independent predictors of reduced mortality. In our study, we found that patients who had moderate alcohol intoxication had higher risk of mortality. However, higher GCS scores, lower ISS, and younger age were identified as independent predictors of reduced mortality in the study patients.

Chronic ethanol alters network activity and endocannabinoid signaling in the prefrontal cortex

Chronic use of alcohol is associated with structural and functional alterations in brain areas that subserve cognitive processes. Of particular importance is the prefrontal cortex (PFC) that is involved in higher order behaviors such as decision making, risk assessment and judgment. Understanding the mechanisms that underlie alcohol's effects on PFC function is important for developing strategies to overcome the cognitive deficits that may predispose individuals to relapse. Our previous studies showed that acutely applied ethanol inhibits network activity in slices of prefrontal cortex and that exogenous and endogenous cannabinoids modulate up-state dynamics. In the present study, we examined the effects of repeated alcohol exposure on cannabinoid regulation of up-states in slice cultures of the prefrontal cortex. Compared to controls, up-state duration, but not amplitude was enhanced when measured 4 days after a 10 day ethanol exposure (44 mM ethanol; equivalent to 0.2% blood ethanol). Administration of the CB1 agonist WIN 55,212-2 enhanced the amplitude of up-states in control cultures but not in those treated previously with ethanol. This lack of effect occurred in the absence of any noticeable change in CB1 receptor protein expression. Chronic ethanol treatment and withdrawal also blunted WIN's inhibition of electrically evoked GABA IPSCs in layer II/III pyramidal neurons but not those in layer V/VI. WIN inhibited the amplitude of spontaneous GABA IPSCs in both layers and the magnitude of this effect was not altered by ethanol treatment. However, in layer V/VI neurons, WIN's effect on sIPSC frequency was greater in ethanol treated cultures. WIN also inhibited electrically evoked NMDA EPSCs in both layer II/III and V/VI neurons but this action was unaffected by ethanol treatment and withdrawal. Overall, these results suggest that ethanol's down-regulation of cannabinoid signaling results in altered network activity in the prefrontal cortex.

Molecular and genetic determinants of alcohol dependence

Alcohol dependence is a complex disorder affecting all social and ethnic groups. Although the scientific understanding of the mechanism governing this multifactorial disease is still in its infancy, understanding its biological bases, including the potential contribution of genetic factors, is key to characterizing individual's risk and developing efficacious therapeutic target to combat the disease. This review provides an overview of different approaches that are being increasingly integrated to extend our knowledge of the genetic underpinnings of alcohol dependence.

Preconditioning provides neuroprotection in models of CNS disease: paradigms and clinical significance

Preconditioning is a phenomenon in which brief episodes of a sublethal insult induce robust protection against subsequent lethal injuries. Preconditioning has been observed in multiple organisms and can occur in the brain as well as other tissues. Extensive animal studies suggest that the brain can be preconditioned to resist acute injuries, such as ischemic stroke, neonatal hypoxia/ischemia, surgical brain injury, trauma, and agents that are used in models of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Effective preconditioning stimuli are numerous and diverse, ranging from transient ischemia, hypoxia, hyperbaric oxygen, hypothermia and hyperthermia, to exposure to neurotoxins and pharmacological agents. The phenomenon of "cross-tolerance," in which a sublethal stress protects against a different type of injury, suggests that different preconditioning stimuli may confer protection against a wide range of injuries. Research conducted over the past few decades indicates that brain preconditioning is complex, involving multiple effectors such as metabolic inhibition, activation of extra- and intracellular defense mechanisms, a shift in the neuronal excitatory/inhibitory balance, and reduction in inflammatory sequelae. An improved understanding of brain preconditioning should help us identify innovative therapeutic strategies that prevent or at least reduce neuronal damage in susceptible patients. In this review, we focus on the experimental evidence of preconditioning in the brain and systematically survey the models used to develop paradigms for neuroprotection, and then discuss the clinical potential of brain preconditioning.

Acute alcohol intoxication prolongs neuroinflammation without exacerbating neurobehavioral dysfunction following mild traumatic brain injury

Traumatic brain injury (TBI) represents a leading cause of death and disability among young persons with ∼1.7 million reported cases in the United States annually. Although acute alcohol intoxication (AAI) is frequently present at the time of TBI, conflicting animal and clinical reports have failed to establish whether AAI significantly impacts short-term outcomes after TBI. The objective of this study was to determine whether AAI at the time of TBI aggravates neurobehavioral outcomes and neuroinflammatory sequelae post-TBI. Adult male Sprague-Dawley rats were surgically instrumented with gastric and vascular catheters before a left lateral craniotomy. After recovery, rats received either a primed constant intragastric alcohol infusion (2.5 g/kg+0.3 g/kg/h for 15 h) or isocaloric/isovolumic dextrose infusion followed by a lateral fluid percussion TBI (∼1.4 J, ∼30 ms). TBI induced apnea and a delay in righting reflex. AAI at the time of injury increased the TBI induced delay in righting reflex without altering apnea duration. Neurological and behavioral dysfunction was observed at 6 h and 24 h post-TBI, and this was not exacerbated by AAI. TBI induced a transient upregulation of cortical interleukin (IL)-6 and monocyte chemotactic protein (MCP)-1 mRNA expression at 6 h, which was resolved at 24 h. AAI did not modulate the inflammatory response at 6 h but prevented resolution of inflammation (IL-1, IL-6, tumor necrosis factor-α, and MCP-1 expression) at 24 h post-TBI. AAI at the time of TBI did not delay the recovery of neurological and neurobehavioral function but prevented the resolution of neuroinflammation post-TBI.

Effects of ethanol exposure on nervous system development in zebrafish

Alcohol (ethanol) is a teratogen that adversely affects nervous system development in a wide range of animal species. In humans numerous congenital abnormalities arise as a result of fetal alcohol exposure, leading to a spectrum of disorders referred to as fetal alcohol spectrum disorder (FASD). These abnormalities include craniofacial defects as well as neurological defects that affect a variety of behaviors. These human FASD phenotypes are reproduced in the rodent central nervous system (CNS) following prenatal ethanol exposure. While the study of ethanol effects on zebrafish development has been more limited, several studies have shown that different strains of zebrafish exhibit differential susceptibility to ethanol-induced cyclopia, as well as behavioral deficits. Molecular mechanisms underlying the effects of ethanol on CNS development also appear to be shared between rodent and zebrafish. Thus, zebrafish appear to recapitulate the observed effects of ethanol on human and mouse CNS development, indicating that zebrafish can serve as a complimentary developmental model system to study the molecular basis of FASD. Recent studies examining the effect of ethanol exposure on zebrafish nervous system development are reviewed, with an emphasis on attempts to elucidate possible molecular pathways that may be impacted by developmental ethanol exposure. Recent work from our laboratories supports a role for perturbed extracellular matrix function in the pathology of ethanol exposure during zebrafish CNS development. The use of the zebrafish model to assess the effects of ethanol exposure on adult nervous system function as manifested by changes in zebrafish behavior is also discussed.

Neuroinflammation, neurodegeneration, and depression

Neurodegeneration and depression are two common co-morbid conditions, particularly within the aging population. Research has linked neuroinflammation as a major contributing factor to both of these diseases. The key to neuroinflammation effects on neurodegeneration and depression appears to lie within the dysregulation of the control and release of pro- and anti-inflammatory cytokines. This can come from an internal or external insult to the system, or from changes in the individual due to aging that culminate in immune dysregulation. The need to reduce neuroinflammation has led to extensive research into neuroprotectants. We discuss the efficacy found with nicotine, alcohol, resveratrol, curcumin, and ketamine. Our main focus will be on what research tells us about the connections between neuroinflammation, neurodegeneration, and depression, and the hope that neuroprotectants research gives people suffering from neurodegeneration and depression stemming from neuroinflammation. We will conclude by making suggestions for future research in this area.

Independent contributions of alcohol and stress axis hormones to painful peripheral neuropathy

Painful small-fiber peripheral neuropathy is a debilitating complication of chronic alcohol abuse. Evidence from previous studies suggests that neuroendocrine mechanisms, in combination with other, as yet unidentified actions of alcohol, are required to produce this neuropathic pain syndrome. In addition to neurotoxic effects of alcohol, in the setting of alcohol abuse neuroendocrine stress axes release glucocorticoids and catecholamines. Since receptors for these stress hormones are located on nociceptors, at which they can act to cause neuronal dysfunction, we tested the hypothesis that alcohol and stress hormones act on the nociceptor, independently, to produce neuropathic pain. We used a rat model, which allows the distinction of the effects of alcohol from those produced by neuroendocrine stress axis mediators. We now demonstrate that topical application of alcohol and exposure to unpredictable sound stress, each alone, has no effect on the nociceptive threshold. However, when animals that had previous exposure to alcohol were subsequently exposed to stress, they rapidly developed mechanical hyperalgesia. Conversely, sound stress followed by topical alcohol exposure also produced mechanical hyperalgesia. The contribution of stress hormones was prevented by spinal intrathecal administration of oligodeoxynucleotides antisense to β(2)-adrenergic or glucocorticoid receptor mRNA, which attenuates receptor level in nociceptors, as well as by adrenal medullectomy. These experiments establish an independent role of alcohol and stress hormones on the primary afferent nociceptor in the induction of painful peripheral neuropathy.

Alcohol use at time of injury and survival following traumatic brain injury: results from the National Trauma Data Bank

OBJECTIVE

Premised on biological evidence from animal research, recent clinical studies have, for the most part, concluded that elevated blood alcohol concentration levels are independently associated with higher survival or decreased mortality in patients with moderate to severe traumatic brain injury (TBI). This study aims to provide some counterevidence to this claim and to further future investigations.

METHOD

Incident data were drawn from the largest U.S. trauma registry, the National Trauma Data Bank, for emergency department admission years 2002-2006. TBI was identified according to the National Trauma Data Bank's definition using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), codes. To eliminate confounding, the exact matching method was used to match alcohol-positive with alcohol-negative incidents on sex, age, race/ethnicity, and facility. Logistic regression compared in-hospital mortality between 44,043 alcohol-positive and 59,817 matched alcohol-negative TBI incidents, with and without causes and intents of TBI and Injury Severity Score as covariates. A sensitivity analysis was performed within a subsample of isolated moderate to severe TBI incidents.

RESULTS

Alcohol use at the time of injury was found to be significantly associated with an increased risk for TBI. Including varied causes and intents of TBI and Injury Severity Score as potential confounders in the regression model explained away the statistical significance of the seemingly protective effect of alcohol against TBI mortality for all TBIs and for isolated moderate to severe TBIs.

CONCLUSIONS

The null finding shows that the purported reduction in TBI mortality attributed to positive blood alcohol likely is attributable to residual confounding. Accordingly, the risk of TBI associated with alcohol use should not be overlooked.

Alcohol and the head-injured patient

Alcohol intoxication is a major predisposing factor for trauma in general and head injury in particular. The management of the head-injured patient is highly contingent on the accurate assessment of this patient’s consciousness, which is invariably impaired if the patient is intoxicated. This complicates the decision-making process and impedes the promptness needed in management when the head injury is severe. Furthermore, the prognosis of the head injury can depend on the patient’s degree and pattern of intoxication. This article presents some of the latest epidemiological data about the association of alcohol and head injury. It also highlights some of the challenges posed by alcohol intoxication in the management of head-injured patients, and examines the importance of documenting intoxication in head-injured patients.

Repetitive transcranial magnetic stimulation and drug addiction

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that is now being tested for its ability to treat addiction. This review discusses current research approaches and results of studies which measured the therapeutic use of rTMS to treat tobacco, alcohol and illicit drug addiction. The research in this area is limited and therefore all studies evaluating the therapeutic use of rTMS in tobacco, alcohol or illicit drug addiction were retained including case studies through NCBI PubMed ( http://www.ncbi.nlm.nih.gov ) and manual searches. A total of eight studies were identified that examined the ability of rTMS to treat tobacco, alcohol and cocaine addiction. The results of this review indicate that rTMS is effective in reducing the level of cravings for smoking, alcohol, and cocaine when applied at high frequencies to the dorsolateral prefrontal cortex (DLPFC). Furthermore, these studies suggest that repeated sessions of high frequency rTMS over the DLPFC may be most effective in reducing the level of smoking and alcohol consumption. Although work in this area is limited, this review indicates that rTMS is a promising modality for treating drug addiction.

Correlating the Blood Alcohol Concentration with Outcome after Traumatic Brain Injury: Too Much Is Not a Bad Thing

Although recent evidence suggests a beneficial effect of alcohol for patients with traumatic brain injury (TBI), the level of alcohol that confers the protective effect is unknown. Our objective was to investigate the relationship between admission blood alcohol concentration (BAC) and outcomes in patients with isolated moderate to severe TBI. From 2005 to 2009, the Los Angeles County Trauma Database was queried for all patients ≥14 years of age with isolated moderate to severe TBI and admission serum alcohol levels. Patients were then stratified into four levels based on admission BAC: None (0 mg/dL), low (0-100 mg/dL), moderate (100-230 mg/dL), and high (≥230 mg/dL). Demographics, patient characteristics, and outcomes were compared across levels. In evaluating 3794 patients, the mortality rate decreased with increasing BAC levels (linear trend P < 0.0001). In determining the relationship between BAC and mortality, multivariable logistic regression analysis demonstrated a high BAC level was significantly protective (adjusted odds ratio 0.55; 95% confidence interval: 0.38-0.8; P = 0.002). In the largest study to date, a high (≥230 mg/dL) admission BAC was independently associated with improved survival in patients with isolated moderate to severe TBI. Additional research is warranted to investigate the potential therapeutic implications.

Positive and negative effects of alcohol and nicotine and their interactions: a mechanistic review

Nicotine and alcohol are two of the most commonly abused legal substances. Heavy use of one drug can often lead to, or is predictive of, heavy use of the other drug in adolescents and adults. Heavy drinking and smoking alone are of significant health hazard. The combination of the two, however, can result in synergistic adverse effects particularly in incidences of various cancers (e.g., esophagus). Although detrimental consequences of smoking are well established, nicotine by itself might possess positive and even therapeutic potential. Similarly, alcohol at low or moderated doses may confer beneficial health effects. These opposing findings have generated considerable interest in how these drugs act. Here we will briefly review the negative impact of drinking-smoking co-morbidity followed by factors that appear to contribute to the high rate of co-use of alcohol and nicotine. Our main focus will be on what research is telling us about the central actions and interactions of these drugs, and what has been elucidated about the mechanisms of their positive and negative effects. We will conclude by making suggestions for future research in this area.

Alcohol is associated with a lower pneumonia rate after traumatic brain injury

BACKGROUND

Recent evidence supports the beneficial effect of alcohol on patients with traumatic brain injury (TBI). Pneumonia is a known complication following TBI; thus, the purpose of this study was to evaluate the effects of alcohol on pneumonia rates following moderate to severe TBI.

METHODS

From 2005 to 2009, the Los Angeles County Trauma Database was queried for all patients ≥ 14 y of age with isolated moderate to severe TBI and admission serum alcohol levels. The incidence of pneumonia was compared between TBI patients with and without a positive blood alcohol concentration (BAC) level. The study population was then stratified into four BAC levels: None (0 mg/dL), low (0-100 mg/dL), moderate (100-230 mg/dL), and high (≥ 230 mg/dL). Pneumonia rates were compared across these levels.

RESULTS

A total of 3547 patients with isolated, moderate to severe TBI were evaluated. Nearly 66% tested positive for alcohol. The pneumonia rate was significantly lower in the TBI patients who tested positive for alcohol (2.5%) compared with those who tested negative (4.0%, P = 0.017). The pneumonia rate also decreased across increasing BAC levels (linear trend P = 0.03). After logistic regression analysis, a positive ethanol (ETOH) level was associated with a reduced incidence of pneumonia (AOR = 0.62; 95%CI: 0.41-0.93; P = 0.020).

CONCLUSION

A positive serum alcohol level was associated with a significantly lower pneumonia rate in isolated, moderate to severe TBI patients. This may explain the observed mortality reduction in TBI patients who test positive for alcohol. Additional research is warranted to investigate the potential therapeutic implications of this association.

Influence of alcohol on early Glasgow Coma Scale in head-injured patients

BACKGROUND

To assess the depressant effects of alcohol on the level of consciousness of patients admitted with head injuries, this study examined the changes that occur in the Glasgow Coma Scale (GCS) of traumatic brain injury patients over time.

METHODS

The records of 269 head trauma patients consecutively admitted to the neurosurgery intensive care unit were examined retrospectively. Eighty-one patients were excluded because of incomplete data. The remaining 188 patients were further divided into an intoxicated group (blood alcohol concentration [BAC] ≥ 0.08%, n = 100 [53%]) and a nonintoxicated group (BAC <0.08%, n = 88 [47%]). The GCS in the prehospital setting, in the emergency department, and the highest GCS achieved during the first 24 hours postinjury were compared.

RESULTS

The change between emergency department-GCS and the best day 1 GCS in the intoxicated group was greater than the nonintoxicated group and deemed clinically and statistically significant; median change (3 vs. 0) p < 0.001. To assess whether these results were directly related to the BAC%, piecewise regression using a general linear model was used to assess the intercept and slope of alcohol on the changes of GCS with cutting point at BAC% = 0.08. The analysis showed that, in the nonintoxicated range, the effect of alcohol was not significantly related to the changes of GCS. But in the intoxicated range, BAC% was significantly positively related to the changes of GCS.

CONCLUSION

This study concludes that the GCS increases significantly over time in alcohol intoxicated patients with traumatic brain injury.

Serum Ethanol Levels in Patients with Moderate to Severe Traumatic Brain Injury Influence Outcomes: A Surprising Finding

Animal studies routinely demonstrate an alcohol (ETOH) -mediated increase in survival after experimental traumatic brain injury (TBI). Recent clinical studies also suggest ETOH plays a neuroprotective role in moderate to severe TBI. We sought to investigate the relationship between ETOH and outcomes in patients with moderate to severe TBI using a countywide database. The Los Angeles County Trauma System database was queried for all adult (older than 14 years) patients with isolated moderate to severe TBI trauma (head Abbreviated Injury Score [AIS] 3 or greater, all other AIS 3 or less) who had ETOH levels measured on admission between 1998 and 2005. A total of 7304 patients were evaluated with 3219 (44.1%) patients testing positive for serum ETOH. ETOH-positive patients with TBI had a significantly lower mortality rate compared with ETOH negative patients (8.5 vs 10.5%, P = 0.005). Even after logistic regression analysis, a positive ETOH was associated with reduced mortality (adjusted OR 0.82, 95% CI: 0.69-0.99, P = 0.035). Therefore, a positive serum ETOH level was independently associated with significantly improved survival in patients with isolated moderate to severe TBI. The neuroprotective role ETOH plays in TBI is in contrast to previous findings and deserves further attention as a potential therapeutic.

Oxidative stress in anxiety and comorbid disorders

Anxiety disorders, depression, and alcohol use disorder are common neuropsychiatric diseases that often occur together. Oxidative stress has been suggested to contribute to their etiology. Oxidative stress is a consequence of either increased generation of reactive oxygen species or impaired enzymatic or non-enzymatic defense against it. When excessive it leads to damage of all major classes of macromolecules, and therefore affects several fundamentally important cellular functions. Consequences that are especially detrimental to the proper functioning of the brain include mitochondrial dysfunction, altered neuronal signaling, and inhibition of neurogenesis. Each of these can further contribute to increased oxidative stress, leading to additional burden to the brain. In this review, we will provide an overview of recent work on oxidative stress markers in human patients with anxiety, depressive, or alcohol use disorders, and in relevant animal models. In addition, putative oxidative stress-related mechanisms important for neuropsychiatric diseases are discussed. Despite the considerable interest this field has obtained, the detailed mechanisms that link oxidative stress to the pathogenesis of neuropsychiatric diseases remain largely unknown. Since this pathway may be amenable to pharmacological intervention, further studies are warranted.

MK-801 administration during neonatal ethanol withdrawal attenuates interpositus cell loss and juvenile eyeblink conditioning deficits

Binge-level doses of ethanol have been demonstrated to severely disrupt the cerebellum and cerebellum-dependent tasks when administered to rodent subjects during the early postnatal period. N-methyl-d-aspartic acid (NMDA) receptor-mediated excitotoxicity associated with ethanol withdrawal has been implicated as a significant component contributing to neurotoxic effects resulting from early ethanol exposure, and studies using MK-801 (dizocilpine) have reported protection from ethanol-induced damage. The present study examined whether the administration of MK-801 during ethanol withdrawal would ameliorate ethanol-associated cell death in the interpositus nucleus of the cerebellum and behavioral deficits in a cerebellar dependent task. Long Evans rat pups were treated with ethanol (5.25 g/kg) in a binge-like manner on postnatal day 6 using intragastric intubation. Subjects then received an injection of MK-801 (0.5mg/kg) or vehicle during withdrawal, 30h after ethanol exposure. Rats were then trained on an eyeblink classical conditioning task as juveniles (40 days of age), and cerebellar interpositus nucleus numbers were assessed after conditioning. Ethanol-exposed subjects exhibited reductions in neuronal populations and behavioral deficits during eyeblink conditioning. However, MK-801 administration significantly attenuated observed deficiencies, suggesting a protective effect resulting from MK-801 treatment during ethanol withdrawal. These results support the role of NMDA receptor-mediated excitotoxicity as a component mechanism by which ethanol produces teratogenicity. Additionally, our findings support previous reports that have shown correlations between dependent measures of eyeblink classical-conditioning behavior and unbiased cell counts in the interpositus nucleus.

Induction of innate immune gene expression cascades in brain slice cultures by ethanol: key role of NF-κB and proinflammatory cytokines

BACKGROUND

Postmortem human alcoholic brain has increased expression of proinflammatory cytokines (He and Crews, 2007). Nuclear factor kappaB (NF-kappaB) is a transcription factor known to induce proinflammatory cytokine expression. Ethanol exposure increases NF-kappaB-DNA binding in rat brain (Crews et al., 2006) and in brain slice cultures in vitro (Zou and Crews, 2006). Using hippocampal-entorhinal cortex (HEC) brain slice cultures, we explored the effect of ethanol on NF-kappaB-DNA binding, proinflammatory gene expression, and sensitivity to glutamate neurotoxicity.

METHODS

The HEC brain slice cultures are prepared from rats on P7 and used after 2 weeks in culture. NF-kappaB-DNA binding is determined by EMSA, NF-kappaB subunit-DNA binding by ELISA and mRNA by RT-PCR. Multiple antibody immunohistochemistry and confocal microscopy are used to characterize cell types expressing ethanol-induced genes.

RESULTS

Ethanol treatment results in a progressive increase in NF-kappaB-DNA binding that includes large increases in NF-kappaB subunit p50 protein-DNA binding. The expression of NF-kappaB proinflammatory target genes progressively increased with time of ethanol treatment. Ethanol induces proinflammatory cytokines TNFalpha, MCP-1, and IL-1beta, proinflammatory proteases TACE, and tissue plasminogen activator (tPA) as well as inducible nitric oxide synthase. Blockade of NF-kappaB by using NF-kappaB p65 siRNA and BHT reduces ethanol induction of proinflammatory genes. Neutralizing antibody to proinflammatory cytokine TNFalpha reduces ethanol induction of proinflammatory genes, suggesting cytokine propagation of proinflammatory gene induction. Furthermore, neutralizing antibodies to proinflammatory cytokines and protease tPA inhibitors blunt ethanol sensitization to glutamate neurotoxicity.

CONCLUSIONS

These findings indicate that ethanol treatment increases NF-kappaB-DNA binding and proinflammatory gene expression in brain slices. Ethanol-induced innate immune proinflammatory gene induction alters neurotransmission and likely contributes to alcoholic neurodegeneration.

A low ethanol dose affects all types of cells in mixed long-term embryonic cultures of the cerebellum

The beneficial effect of the '1-drink-a-day' lifestyle is suggested by studies of cardiovascular health, and this recommendation is increasingly followed in many countries. The main objective of this study was to determine whether this pattern of ethanol use would be detrimental to a pregnant woman. We exposed a primary culture of rat cerebellum from embryonic day 17 (corresponding to second trimester in humans) to ethanol at a concentration of 17.6 mM which is roughly equivalent to one glass of wine. Acutely, there was no change in cell viability after 5 or 8 days of exposure relative to control. By 11 days, a reduction in the number of viable cells was observed without an accompanying change in caspase-3 activity (marker of apoptotic cell death), suggesting changes in cell proliferation. As the proportion of nestin-positive cells was higher in the ethanol-treated cultures after 5 days, we hypothesized that an increase in differentiation to neurons would compensate for the ongoing neuronal death. However, there were limits to this compensatory ability as the relative proportion of nestin-positive cells was decreased after 11 days. To further illustrate the negative long-term effects of this ethanol dose, cultures were exposed for 30 days. After this period, virtually no neurons or myelinating oligodendrocytes were present in the ethanol-treated cultures. In conclusion, chronic exposure to ethanol, even at small doses, dramatically and persistently affects normal development.

Caffeinol at the receptor level: anti-ischemic effect of N-methyl-D-aspartate receptor blockade is potentiated by caffeine

BACKGROUND AND PURPOSE

Although caffeinol (a combination of a low dose of caffeine and ethanol) was shown to robustly reduce stroke damage in experimental models and is now in clinical evaluation for treatment of ischemic stroke, little is known about the potential mechanism of its action.

METHODS

We used an in vivo excitotoxicity model based on intracortical infusion of N-methyl-D-aspartate (NMDA) and a model of reversible focal ischemia to demonstrate NMDA receptor inhibition as a potential mechanism of caffeinol anti-ischemic activity.

RESULTS

Caffeinol reduced the size of excitotoxic lesion, and substitution of ethanol in caffeinol with the NMDA antagonists CNS-1102 and MK-801 but not with MgSO(4) produced treatment with strong synergistic effect that was at least as robust in reducing ischemic damage as caffeinol. This NMDA receptor antagonist and caffeine combination demonstrated a long window of opportunity, activity in spontaneously hypertensive rats, and, unlike caffeinol, was fully effective in animals chronically pretreated with ethanol.

CONCLUSIONS

Our study suggests that antiexcitotoxic properties may underlie some of the anti-ischemic effect of caffeinol. This study provides strong evidence that the anti-ischemic effect of NMDA receptor blockers in general can be dramatically augmented by caffeine, thus opening a possibility for new use of NMDA-based pharmacology in the treatment of stroke.

Neuro-inflammation induced in the hippocampus of 'binge drinking' rats may be mediated by elevated extracellular glutamate content

The neuropathological and immune changes induced in the brain by 'binge drinking' have been investigated in a rat model. Evidence of neuro-inflammation was identified in the 'binge drinking' rat model of alcohol abuse after 3 weeks of administration of 2 or 3 g/kg ethanol (EtOH), three times per day for two consecutive days, followed by 5 days of abstinence: Firstly, alveolar macrophages, isolated from these animals, showed significant increases in inducible nitric oxide synthase, as assayed by nitrite release, both before and after lipopolysaccaharide stimulation. Secondly, significant numbers of activated microglia were present in the dentate gyrus region of the hippocampus of the 'binge drinking' model, after major histocompatibility complex class II staining, by comparison with the control. Microdialysis studies in the ventral hippocampus identified a significant increase in the basal extracellular concentration of glutamate, in both the 2 and 3 g/kg administered 'binge drinking' rats. In contrast, no changes in the hippocampal extracellular concentrations, of GABA and taurine, or the dopamine and serotonin metabolites were observed under basal conditions. A further dose of EtOH induced a significant decrease in the concentrations of both 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid, whereas glutamate, taurine and GABA levels were unaffected. There was no evidence that EtOH preference was initiated by the 'binge drinking' regimen. Our results suggest that the possible toxicity associated with 'binge drinking' maybe directed by the elevated glutamate levels, which in turn, activate phagocytic cells to release their inflammatory cytokines and chemokines, ultimately leading to neuro-inflammation.

Combined neuroprotective modalities coupled with thrombolysis in acute ischemic stroke: a pilot study of caffeinol and mild hypothermia

BACKGROUND

Both caffeinol and hypothermia are neuroprotective in preclinical models of transient middle cerebral artery occlusion. We tested whether combining caffeinol and hypothermia with tissue plasminogen activator (t-PA) in patients with acute stroke is safe and feasible.

METHODS

Twenty patients with acute ischemic stroke were treated with caffeinol (caffeine 8-9 mg/kg + ethanol 0.4 g/kg intravenously [IV] x 2 hours, started by 4 hours after symptom onset) and hypothermia (started by 5 hours and continued for 24 hours [target temperature 33-35 degrees C] followed by 12 hours of rewarming). IV t-PA was given to eligible patients. Meperidine and buspirone were used to suppress shivering.

RESULTS

All patients received caffeinol, and most reached target blood levels. Cooling was attempted in 18 patients via endovascular (n = 8) or surface (n = 10) approaches. Two patients were not cooled due to catheter or machine failure. Thirteen patients reached target temperature; average time from symptom onset was 9 hours and 43 minutes. The last 5 hypothermia patients received surface cooling with iced saline induction and larger doses of meperidine; all patients reached target temperature, on average within 2 hours and 30 minutes from induction and 6 hours and 21 minutes from symptom onset. Three patients died: one from symptomatic hemorrhage, one from malignant cerebral edema, and one from unrelated medical complications. No adverse events were attributed to caffeinol. One patient had reduced respiratory drive due to meperidine, requiring BiPAP.

DISCUSSION

Combining caffeinol with hypothermia in patients with acute stroke given IV t-PA is feasible. A prospective placebo-controlled randomized study is needed to further assess safety and to test the efficacy of caffeinol, hypothermia, or both.

Biochemical and neurotransmitter changes implicated in alcohol-induced brain damage in chronic or 'binge drinking' alcohol abuse

The brain damage, which occurs after either chronic alcoholization or binge drinking regimes, shows distinct biochemical and neurotransmitter differences. An excessive amount of glutamate is released into specific brain regions during binge drinking (in excess of 4- to 5-fold of the normal basal concentration) that is not evident during periods of excessive alcohol consumption in chronic alcohol abusers. Increases in glutamate release are only observed during the initial stages of withdrawal from chronic alcoholism ( approximately 2- to 3-fold) due to alterations in the sensitivities of the NMDA receptors. Such changes in either density or sensitivity of these receptors are reported to be unaltered by binge drinking. When such excesses of glutamate are released in these two different models of alcohol abuse, a wide range of biochemical changes occur, mediated in part by increased fluxes of calcium ions and/or activation of various G-protein-associated signalling pathways. Cellular studies of alveolar macrophages isolated from these two animal models of alcohol abuse showed enhanced (binge drinking) or reduced (chronic alcoholization) lipopolysaccharide (LPS)-stimulated NO release. Such studies could suggest that neuroadaptation occurs with the development of tolerance to alcohol's effects in both neurotransmitter function and cellular processes during chronic alcoholization that delay the occurrence of brain damage. In contrast, 'binge drinking' induces immediate and toxic effects and there is no evidence of an increased preference for alcohol as seen after withdrawal from chronic alcoholization.

Modulation of ethanol state-dependent learning by dorsal hippocampal NMDA receptors in mice

The possible role of N-methyl-D-aspartate (NMDA) receptors of dorsal hippocampus on ethanol state-dependent learning was studied in adult male mice (Pasteur Institute, Iran). As a model of memory, a single-trial step-down passive avoidance task was used. All animals were bilaterally implanted with cannulae into the CA1 regions of dorsal hippocampi. Results show that intraperitoneal (i.p.) administration of ethanol (0.5 and 1 g/kg) 30 min before training impaired memory performance in animals when tested 24h later. Pretest administration of the same doses of ethanol-induced state-dependent retrieval of the memory acquired under pretraining ethanol (1 g/kg, i.p.) influence. Pretest intra-CA1 microinjection of NMDA (0.001, 0.01, and 0.1 microg/mouse) by itself had no effect on memory retrieval and ethanol-induced amnesia. However, pretest intra-CA1 administration of the same doses of NMDA with an ineffective dose of ethanol (0.25 g/kg, i.p.) significantly restored the retrieval and potentiated ethanol state-dependent learning. On the other hand, pretest administration of a competitive NMDA receptor antagonist D-AP5 (D-(-)-2-Amino-5-phosphonopentanoic acid) (0.01, 0.1, and 1 microg/mouse, intra-CA1) or a noncompetitive NMDA receptor antagonist MK-801 maleate [(5S, 10R)-(+)-5-Methyl-10, 11-dihydro-5H-dibenzo [a, d] cyclohepten-5, 10-imine maleate] (0.25, 0.5, and 1 g/mouse, intra-CA1) 5 min before the administration of ethanol (1 g/kg, i.p.) significantly inhibited ethanol state-dependent learning. Intra-CA1 pretest administration of D-AP5 (0.01, 0.1, and 1 microg/mouse) or MK-801 maleate [5S, 10R)-(+)-5-Methyl-10, 11-dihydro-5H-dibenzo [a, d] cyclohepten-5, 10-imine maleate] (0.25, 0.5, and 1 microg/mouse) alone did not affect memory retention. It may be concluded that dorsal hippocampal NMDA receptors are involved in mediating ethanol state-dependent learning.

Alcohol in moderation, cardioprotection, and neuroprotection: epidemiological considerations and mechanistic studies

In contrast to many years of important research and clinical attention to the pathological effects of alcohol (ethanol) abuse, the past several decades have seen the publication of a number of peer-reviewed studies indicating the beneficial effects of light-moderate, nonbinge consumption of varied alcoholic beverages, as well as experimental demonstrations that moderate alcohol exposure can initiate typically cytoprotective mechanisms. A considerable body of epidemiology associates moderate alcohol consumption with significantly reduced risks of coronary heart disease and, albeit currently a less robust relationship, cerebrovascular (ischemic) stroke. Experimental studies with experimental rodent models and cultures (cardiac myocytes, endothelial cells) indicate that moderate alcohol exposure can promote anti-inflammatory processes involving adenosine receptors, protein kinase C (PKC), nitric oxide synthase, heat shock proteins, and others which could underlie cardioprotection. Also, brain functional comparisons between older moderate alcohol consumers and nondrinkers have received more recent epidemiological study. In over half of nearly 45 reports since the early 1990s, significantly reduced risks of cognitive loss or dementia in moderate, nonbinge consumers of alcohol (wine, beer, liquor) have been observed, whereas increased risk has been seen only in a few studies. Physiological explanations for the apparent CNS benefits of moderate consumption have invoked alcohol's cardiovascular and/or hematological effects, but there is also experimental evidence that moderate alcohol levels can exert direct "neuroprotective" actions-pertinent are several studies in vivo and rat brain organotypic cultures, in which antecedent or preconditioning exposure to moderate alcohol neuroprotects against ischemia, endotoxin, beta-amyloid, a toxic protein intimately associated with Alzheimer's, or gp120, the neuroinflammatory HIV-1 envelope protein. The alcohol-dependent neuroprotected state appears linked to activation of signal transduction processes potentially involving reactive oxygen species, several key protein kinases, and increased heat shock proteins. Thus to a certain extent, moderate alcohol exposure appears to trigger analogous mild stress-associated, anti-inflammatory mechanisms in the heart, vasculature, and brain that tend to promote cellular survival pathways.

Alcohol in moderation, cardioprotection, and neuroprotection: epidemiological considerations and mechanistic studies

In contrast to many years of important research and clinical attention to the pathological effects of alcohol (ethanol) abuse, the past several decades have seen the publication of a number of peer-reviewed studies indicating the beneficial effects of light-moderate, nonbinge consumption of varied alcoholic beverages, as well as experimental demonstrations that moderate alcohol exposure can initiate typically cytoprotective mechanisms. A considerable body of epidemiology associates moderate alcohol consumption with significantly reduced risks of coronary heart disease and, albeit currently a less robust relationship, cerebrovascular (ischemic) stroke. Experimental studies with experimental rodent models and cultures (cardiac myocytes, endothelial cells) indicate that moderate alcohol exposure can promote anti-inflammatory processes involving adenosine receptors, protein kinase C (PKC), nitric oxide synthase, heat shock proteins, and others which could underlie cardioprotection. Also, brain functional comparisons between older moderate alcohol consumers and nondrinkers have received more recent epidemiological study. In over half of nearly 45 reports since the early 1990s, significantly reduced risks of cognitive loss or dementia in moderate, nonbinge consumers of alcohol (wine, beer, liquor) have been observed, whereas increased risk has been seen only in a few studies. Physiological explanations for the apparent CNS benefits of moderate consumption have invoked alcohol's cardiovascular and/or hematological effects, but there is also experimental evidence that moderate alcohol levels can exert direct "neuroprotective" actions-pertinent are several studies in vivo and rat brain organotypic cultures, in which antecedent or preconditioning exposure to moderate alcohol neuroprotects against ischemia, endotoxin, beta-amyloid, a toxic protein intimately associated with Alzheimer's, or gp120, the neuroinflammatory HIV-1 envelope protein. The alcohol-dependent neuroprotected state appears linked to activation of signal transduction processes potentially involving reactive oxygen species, several key protein kinases, and increased heat shock proteins. Thus to a certain extent, moderate alcohol exposure appears to trigger analogous mild stress-associated, anti-inflammatory mechanisms in the heart, vasculature, and brain that tend to promote cellular survival pathways.

Mechanisms of neurodegeneration and regeneration in alcoholism

AIMS

This is a review of preclinical studies covering alcohol-induced brain neuronal death and loss of neurogenesis as well as abstinence-induced brain cell genesis, e.g. brain regeneration. Efforts are made to relate preclinical studies to human studies.

METHODS

The studies described are preclinical rat experiments using a 4-day binge ethanol treatment known to induce physical dependence to ethanol. Neurodegeneration and cognitive deficits following binge treatment mimic the mild degeneration and cognitive deficits found in humans. Various histological methods are used to follow brain regional degeneration and regeneration.

RESULTS

Alcohol-induced degeneration occurs due to neuronal death during alcohol intoxication. Neuronal death is related to increases in oxidative stress in brain that coincide with the induction of proinflammatory cytokines and oxidative enzymes that insult brain. Degeneration is associated with increased NF-kappaB proinflammatory transcription and decreased CREB transcription. Corticolimbic brain regions are most sensitive to binge-induced degeneration and induce relearning deficits. Drugs that block oxidative stress and NF-kappaB transcription or increase CREB transcription block binge-induced neurodegeneration, inhibition of neurogenesis and proinflammatory enzyme induction. Regeneration of brain occurs during abstinence following binge ethanol treatment. Bursts of proliferating cells occur across multiple brain regions, with many new microglia across brain after months of abstinence and many new neurons in neurogenic hippocampal dentate gyrus. Brain regeneration may be important to sustain abstinence in humans.

CONCLUSIONS

Alcohol-induced neurodegeneration occurs primarily during intoxication and is related to increased oxidative stress and proinflammatory proteins that are neurotoxic. Abstinence after binge ethanol intoxication results in brain cell genesis that could contribute to the return of brain function and structure found in abstinent humans.

BHT blocks NF-kappaB activation and ethanol-induced brain damage

BACKGROUND

Binge ethanol administration causes corticolimbic brain damage that models alcoholic neurodegeneration. The mechanism of binge ethanol-induced degeneration is unknown, but is not simple glutamate-N-methyl-D-aspartate (NMDA) excitotoxicity. To test the hypothesis that oxidative stress and inflammation are mechanisms of binge ethanol-induced brain damage, we administered 4 antioxidants, e.g., butylated hydroxytoluene (BHT), ebselen (Eb), vitamin E (VE), and blueberry (BB) extract, during binge ethanol treatment and assessed various measures of neurodegeneration.

METHODS

Adult Sprague-Dawley rats were treated with intragastric ethanol 3 times per day (8-12 g/kg/d) alone or in combination with antioxidants or isocaloric diet for 4 days. Animals were killed, and brains were perfused and extracted for histochemical silver stain determination of brain damage, markers of neurogenesis, or other immunohistochemistry. Some animals were used for determination of nuclear factor kappa B (NF-kappaB)-DNA binding by electrophoretic mobility shift assay (EMSA) or for reverse transcription-polymerase chain reaction (RT-PCR) of cyclooxygenase 2 (COX2).

RESULTS

Binge ethanol induced corticolimbic brain damage and reduced neurogenesis. Treatment with BHT reversed binge induced brain damage and blocked ethanol inhibition of neurogenesis in all regions studied. Interestingly, the other antioxidants studied, e.g., Eb, VE, and BB, did not protect against binge-induced brain damage. Binge ethanol treatment also caused microglia activation, increased NF-kappaB-DNA binding and COX2 expression. Butylated hydroxytoluene reduced binge-induced NF-kappaB-DNA binding and COX2 expression.

CONCLUSIONS

Binge-induced brain damage and activation of NF-kappaB-DNA binding are blocked by BHT. These studies support a neuroinflammatory mechanism of binge ethanol-induced brain damage.

A rational approach to the pharmacotherapy of alcohol dependence

The use of alcohol is widespread in the world, and although there are many regular users, some individuals drink excessively. Understanding the time course of the development and maintenance of alcohol dependence is important in assessing the potential risk/benefit of an intervention and in accurately treating the problem. Most, although not all, literature suggests that alcoholism is a chronic, relapsing disorder and that there is a general progression from less to more severe problems. Understanding the neurobiology that underlies alcohol dependence as it relates to different clinical stages may help in the development of effective targeted pharmacological treatments. Important clinical stages that may be amenable to pharmacological intervention include the transition from alcohol use to heavy drinking particularly in vulnerable individuals, the cessation of heavy drinking in individuals who want to quit, and the prevention of relapse in individuals who have initiated abstinence but may struggle with craving or the desire to resume alcohol use. Neurotransmitter systems implicated in these stages include glutamate, gamma-aminobutyric acid, opioid, and serotonin systems that may act directly or via the indirect modulation of dopamine function. The treatment implications will also be discussed.

Homeostatic plasticity during alcohol exposure promotes enlargement of dendritic spines

Modifications of the size, shape and number of dendritic spines is thought to be an important component of activity-dependent changes of neuronal circuits, and may play an important role in the plasticity of drug addiction. The present study examined whether homeostatic increases in synaptic N-methyl-d-aspartate (NMDA) receptors in response to chronic ethanol exposure is associated with corresponding morphological changes in dendritic spines. Prolonged exposure of rat hippocampal cultures to either the NMDA receptor antagonist d(-)-2-amino-5-phosphono-pentanoic acid or to ethanol increased punctate staining of F-actin and the postsynaptic density protein-95 (PSD-95). The increase in dendritic F-actin occurred only with clusters that co-localized with PSD-95 clusters, indicating that these actin structures likely represent dendritic spines. The ethanol-induced increases in PSD-95 and F-actin clusters were activity-dependent and reversible. Finally, inhibition of protein palmitoylation prevented ethanol-induced increases in synaptic NMDA receptor clustering and F-actin without altering the basal clustering of either F-actin or PSD-95. These observations support a model in which chronic ethanol exposure induces homeostatic increases of NR2B-containing NMDA receptors and PSD-95 to the postsynaptic density. This in turn may provide a scaffolding platform for the subsequent recruitment of actin signaling cascades that alter actin cycling and promote spine enlargement.

CREB and NF-kappaB transcription factors regulate sensitivity to excitotoxic and oxidative stress induced neuronal cell death

1. Glutamate-NMDA receptor excitotoxicity and oxidative stress are two common mechanisms associated with most neurodegenerative diseases. We hypothesize that the vital state of neurons is regulated in part by two key transcription factors, CREB and NF-kappaB. To test this hypothesis we used hippocampal-entorhinal cortex slice cultures. 2. Glutamate neurotoxicity and oxidative stress neurotoxicity, using hydrogen peroxide (H(2)O(2)) are both associated with a decrease in CREB DNA binding and an increase in NF-kappaB DNA binding. 3. Agents that modulate CREB and NF-kappaB DNA-binding activity alter neurotoxicity. Rolipram, a phosphodiesterase IV inhibitor, increased CREB DNA binding activity and decreased toxicity, whereas TNFalpha, increased NF-kappaB DNA-binding activity and increased neurotoxicity to both glutamate and H(2)O(2). Ethanol decreased CREB and increased NF-kappaB DNA-binding activity and increased neurotoxicity to both glutamate and H(2)O(2). 4. Brain-derived neurotrophic factor (BDNF) is a transcriptionally regulated trophic factor whose expression follows sensitivity to toxicity suggesting it is one of the transcriptionally regulated factors that contributes to neuronal vitality secondary to the balance of CREB-NF-kappaB-activated transcription. Together these studies suggest that neurotoxicity through glutamate-NMDA receptors or oxidative stress is dependent upon CREB and NF-kappaB DNA transcription that regulates vitality of neurons.

Chronic ethanol induces synaptic but not extrasynaptic targeting of NMDA receptors

The development of ethanol tolerance and dependence reflects neuroadaptive changes in response to continuous depression in synaptic activity. The present study used confocal imaging and electrophysiology procedures to assess the effects of prolonged ethanol exposure on NMDA receptor trafficking in cultures of hippocampal neurons. Neurons exposed to 50 mm ethanol for 4 d showed an increase in the colocalization of NMDA receptor type 1 (NR1) clusters with the presynaptic marker protein synapsin. This was accompanied by significant increases in the size and density of these synapsin-associated clusters with no change observed in nonsynapsin-associated NR1 clusters. Similar effects were observed with NR2B clustering after chronic ethanol exposure. The increase in synaptic NMDA receptor clustering was prevented by addition of a protein kinase A inhibitor or by coexposure to a low concentration of NMDA and was reversed when ethanol was removed from the cultures. No changes were observed in the synaptic content, cluster size, or density of AMPA receptors after ethanol exposure. Electrophysiological measurements on ethanol-treated neurons revealed a similar enhancement in synaptic NMDA currents with no change in AMPA-mediated events. After isolation of extrasynaptic NMDA receptors by MK801 (+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate (/) trapping, whole-cell responses to NMDA were not different between control and ethanol-treated neurons These observations demonstrate that neuroadaptive changes in NMDA receptors in response to prolonged ethanol exposure occur through activity-dependent processes that regulate their synaptic targeting and localization.

Acute ethanol intoxication in a model of traumatic brain injury: the protective role of moderate doses demonstrated by immunoreactivity of synaptophysin in hippocampal neurons

Although ethanol intoxication is reported to be a complicating factor in traumatic brain injury, some recent studies are indicating its possible protective role especially at lower doses. Ethanol inhibition of NMDA-mediated excitotoxicity which predominates at lower doses is believed to be responsible for this protection. The aim of this study was to demonstrate this neuroprotective role of alcohol using immunoreactivity for synaptophysin as an indirect marker for severity of injury. Acute ethanol intoxication at moderate doses was performed 2 h prior to trauma. Severe traumatic brain injury was administrated using an impact acceleration model in Sprague-Dawley rats. At post-traumatic 48th hour, immunorectivity for synapthophysin in the rat hippocampi was evaluated under light microscopy. According to our results there were slight increases in immunoreactivity for synaptophysin in the stratum oriens and striatum radiatum of CA1 subfield of hippocampus when ethanol was administered prior to trauma comparing to moderate increase in the trauma-only group. On the other hand vacuolar degeneration and red neuron formation was more prominent in the pyramidal cell layer of CA1 and CA3 when ethanol was not administered. Ethanol may have a neuroprotective role when administered at moderate doses prior to traumatic brain injury. This effect of ethanol may primarily be due to inhibition of NMDA receptors.

Ethanol attenuates ischemic and hypoxic injury in rat brain and cultured neurons

Reactive oxygen species play a critical role in ischemic injury and oxidative stress induces apoptosis and triggers inflammation in neural cells. The effect of ethanol on ischemic brain injury was examined. Ethanol attenuated ischemia/reperfusion-induced brain infarction and elevation of inflammatory mediators, including tumor necrosis factor-alpha (TNF-alpha) expression, metalloproteinase-9, and neutrophil-associated myeloperoxidase activities. In cultured neurons, ethanol suppressed combined oxygen and glucose deprivation (COGD)/reoxygenation-induced oxidative stress and neuronal apoptosis. Furthermore, ethanol suppressed COGD/reoxygenation-induced activation of NF-kappaB, a free-radical-sensitive regulator, leading to the attenuation of TNF-alpha expression in glial cultures. We propose that scavenging of free radicals and attenuation of free-radical-induced alterations might account for ethanol's beneficial action against ischemic brain injury.

Alcohol-Induced Neurodegeneration: When, Where and Why?

This manuscript reviews the proceedings of a symposium organized by Drs. Antonio Noronha and Fulton Crews presented at the 2003 Research Society on Alcoholism meeting. The purpose of the symposium was to examine recent findings on when alcohol induced brain damage occurs, e.g., during intoxication and/or during alcohol withdrawal. Further studies investigate specific brain regions (where) and the mechanisms (why) of alcoholic neurodegeneration. The presentations were (1) Characterization of Synaptic Loss in Cerebella of Mature and Senescent Rats after Lengthy Chronic Ethanol Consumption, (2) Ethanol Withdrawal Both Causes Neurotoxicity and Inhibits Neuronal Recovery Processes in Rat Organotypic Hippocampal Cultures, (3) Binge Drinking-Induced Brain Damage: Genetic and Age Related Effects, (4) Binge Ethanol-Induced Brain Damage: Involvement of Edema, Arachidonic Acid and Tissue Necrosis Factor alpha (TNFalpha), and (5) Cyclic AMP Cascade, Stem Cells and Ethanol. Taken together these studies suggest that alcoholic neurodegeneration occurs through multiple mechanisms and in multiple brain regions both during intoxication and withdrawal.