Binge ethanol treatment causes greater brain damage in alcohol-preferring P rats than in alcohol-nonpreferring NP rats

Sex differences in cholinergic circuits and behavioral disruptions following chronic ethanol exposure with and without thiamine deficiency

BACKGROUND

Few studies have investigated differences in the vulnerabilities of males and females to alcohol use disorder and alcohol-related brain damage (ARBD). According to epidemiological and clinical findings, females appear to be more sensitive to the effects of alcohol and thiamine deficiency and have a worse prognosis in recovery from neurocognitive deficits compared with males. This study aimed to characterize the effects of chronic ethanol (EtOH) toxicity and thiamine deficiency across the sexes using rodent models.

METHODS

Male and female Sprague Dawley rats were assigned to chronic forced EtOH treatment (CET), pyrithiamine-induced thiamine deficiency (PTD), combined CET-PTD, or pair-fed (PF) control treatment conditions. Following treatments, spatial working memory was assessed during a spontaneous alternation task while measuring acetylcholine (ACh) in the prefrontal cortex (PFC) and the hippocampus (HPC). The animals also underwent an operant-based attentional set-shifting task (ASST) for the analysis of behavioral flexibility.

RESULTS

Female and male rats did not differ in terms of EtOH consumption; however, the CET and CET-PTD-treated female rats had lower BECs than male rats. Compared with the PF group, the CET, PTD, and CET-PTD groups exhibited spatial working memory impairments with corresponding reductions in ACh efflux in the PFC and HPC. The ASST revealed that CET-PTD-treated males and females displayed impairments marked by increased latency to make decisions. Thalamic shrinkage was prominent only in the CET-PTD and PTD treatment conditions, but no sex-specific effects were observed.

CONCLUSIONS

Although the CET and CET-PTD-treated females had lower BECs than the males, they demonstrated similar cognitive impairments. These results provide evidence that female rats experience behavioral and neurochemical disruptions at lower levels of alcohol exposure than males and that chronic EtOH and thiamine deficiencies produce a unique behavioral profile.

Sex differences in hippocampal damage, cognitive impairment, and trophic factor expression in an animal model of an alcohol use disorder

Compared to men, women disproportionally experience alcohol-related organ damage, including brain damage, and while men remain more likely to drink and to drink heavily, there is cause for concern because women are beginning to narrow the gender gap in alcohol use disorders. The hippocampus is a brain region that is particularly vulnerable to alcohol damage, due to cell loss and decreased neurogenesis. In the present study, we examined sex differences in hippocampal damage following binge alcohol. Consistent with our prior findings, we found a significant binge-induced decrement in dentate gyrus (DG) granule neurons in the female DG. However, in the present study, we found no significant decrement in granule neurons in the male DG. We show that the decrease in granule neurons in females is associated with both spatial navigation impairments and decreased expression of trophic support molecules. Finally, we show that post-binge exercise is associated with an increase in trophic support and repopulation of the granule neuron layer in the female hippocampus. We conclude that sex differences in alcohol-induced hippocampal damage are due in part to a paucity of trophic support and plasticity-related signaling in females.

Increased DNA double-strand break was associated with downregulation of repair and upregulation of apoptotic factors in rat hippocampus after alcohol exposure

Binge drinking is known to cause damage in critical areas of the brain, including the hippocampus, which is important for relational memory and is reported to be sensitive to alcohol toxicity. However, the roles of DNA double-strand break (DSB) and its repair pathways, homologous recombination (HR), and non-homologous end joining (NHEJ) in alcohol-induced hippocampal injury remain to be elucidated. The purpose of this first study was to assess alcohol-induced DNA DSB and the mechanism by which alcohol affects DSB repair pathways in rat hippocampus. Male Sprague-Dawley rats (8-10 weeks old) were put on a 4-day binge ethanol treatment regimen. Control animals were maintained under similar conditions but were given the vehicle without ethanol. All animals were humanely euthanized 24 h after the last dose of ethanol administration and the hippocampi were dissected for immunoblot and immunohistochemistry analysis. Ethanol exposure caused increased 4-hydroxynonenal (4-HNE) staining as well as elevated γH2AX and 53BP1 foci in hippocampal cells. Immunoblot analysis showed decreased Mre11, Rad51, Rad50, and Ku86 as well as increased Bax and p21 in samples from ethanol-treated rats. Additionally, we also observed increased activated caspase3 staining in hippocampal cells 24 h after ethanol withdrawal. Taken together, our data demonstrated that ethanol concurrently induced DNA DSB, downregulated DSB repair pathway proteins, and increased apoptotic factors in hippocampal cells. We believe these findings will provide the impetus for further research on DNA DSB and its repair pathways in relation to alcohol toxicity in brain.

Reversible loss of reproductive fitness in zebrafish on chronic alcohol exposure

Alcoholism is one of the most prevalent diseases in society and causes significant health and social problems. Alcohol consumption by pregnant women is reported to cause adverse effects on the physical and psychological growth of the fetus. However, the direct effect of chronic alcohol consumption on reproductive fitness has not been tested. In recent years, the zebrafish (Danio rerio) has emerged as a versatile model system to study the effects of alcohol on behavior and embryonic development. We utilized the zebrafish model system to address the effect of chronic alcohol exposure (0.5% alcohol in the holding tank for 9 weeks) on reproductive capacity. We found a dramatic decrease in fecundity, measured by counting the number of eggs laid, when at least one of the parents is subject to chronic alcohol exposure. Interestingly, a 9-week alcohol withdrawal program completely restored the reproductive capacity of the treated subjects. In agreement with observations on fecundity, the chronic alcohol exposure leads to increased anxiety, as measured by the novel-tank diving assay. Conversely, the withdrawal program diminished heightened anxiety in alcohol-exposed subjects. Our results highlight the adverse effects of chronic alcohol exposure on the reproductive capacity of both males and females, and underscore the utility of the zebrafish model system to understand the biology of chronic alcoholism.

Binge ethanol exposure increases the Krüppel-like factor 11-monoamine oxidase (MAO) pathway in rats: Examining the use of MAO inhibitors to prevent ethanol-induced brain injury

Binge drinking induces several neurotoxic consequences including oxidative stress and neurodegeneration. Because of these effects, drugs which prevent ethanol-induced damage to the brain may be clinically beneficial. In this study, we investigated the ethanol-mediated KLF11-MAO cell death cascade in the frontal cortex of Sprague-Dawley rats exposed to a modified Majchowicz 4-day binge ethanol model and control rats. Moreover, MAO inhibitors (MAOIs) were investigated for neuroprotective activity against binge ethanol. Binge ethanol-treated rats demonstrated a significant increase in KLF11, both MAO isoforms, protein oxidation and caspase-3, as well as a reduction in BDNF expression in the frontal cortex compared to control rats. MAOIs prevented these binge ethanol-induced changes, suggesting a neuroprotective benefit. Neither binge ethanol nor MAOI treatment significantly affected protein expression levels of the oxidative stress enzymes, SOD2 or catalase. Furthermore, ethanol-induced antinociception was enhanced following exposure to the 4-day ethanol binge. These results demonstrate that the KLF11-MAO pathway is activated by binge ethanol exposure and MAOIs are neuroprotective by preventing the binge ethanol-induced changes associated with this cell death cascade. This study supports KLF11-MAO as a mechanism of ethanol-induced neurotoxicity and cell death that could be targeted with MAOI drug therapy to alleviate alcohol-related brain injury. Further examination of MAOIs to reduce alcohol use disorder-related brain injury could provide pivotal insight to future pharmacotherapeutic opportunities.

Neurometabolic Effect of Altaian Fungus Ganoderma lucidum (Reishi Mushroom) in Rats Under Moderate Alcohol Consumption

BACKGROUND

The medications produced from natural products are widely used as prophylactics for sickness induced by alcohol consumption. One such prophylactic is produced from the Reishi mushroom, Ganoderma lucidum. Because of the antioxidant properties of these preparations, we expect neuroprotective prophylactic effects of Reishi-based medications in alcohol-treated animals.

METHODS

The Reishi (R) suspension was produced as water extract from Altaian mushrooms. Sprague-Dawley male rats were separated into the following 3 experimental groups: Group A + R received R (6 days per week) starting 1 week before alcohol exposure, and during the next 3 weeks, they received both R and alcohol; group A received alcohol; and group C received water. At the end of experiment, we determined the metabolic profile using proton magnetic resonance spectroscopy ((1) H MRS) of the brain cortex and phosphorus magnetic resonance spectroscopy of the liver. Additionally, the blood cells were collected, and the serum biochemistry and liver histology were performed after euthanasia.

RESULTS

Partial least squares discriminant analysis processing of the brain (1) H MRS gave 2 axes, the Y1 axis positively correlated with the level of taurine and negatively correlated with the level of lactate, and the Y2 axis positively correlated with the content of GABA and glycine and negatively correlated with the sum of the excitatory neurotransmitters, glutamate and glutamine. The Y1 values reflecting the brain energetics for the A + R group exceeded the corresponding values for groups C and A. The maximal level of Y2 reflecting the prevalence of inhibitory metabolites in the brain was observed in the rats exposed to alcohol. Moderate alcohol consumption did not cause significant pathological changes in the livers of the experimental animals. However, 20 days of alcohol consumption significantly increased the number of binuclear hepatocytes compared to the control. This effect was mitigated in the rats that received the Reishi extract.

CONCLUSIONS

Regular administration of the Reishi suspension improved the energy supply to the brain cortex and decreased the prevalence of inhibitory neurotransmitters that are characteristic of alcohol consumption. The alcohol-induced increase in liver proliferation was significantly suppressed by regular administration of the G. lucidum water suspension.

Rat strain differences in brain structure and neurochemistry in response to binge alcohol

RATIONALE

Ventricular enlargement is a robust phenotype of the chronically dependent alcoholic human brain, yet the mechanism of ventriculomegaly is unestablished. Heterogeneous stock Wistar rats administered binge EtOH (3 g/kg intragastrically every 8 h for 4 days to average blood alcohol levels (BALs) of 250 mg/dL) demonstrate profound but reversible ventricular enlargement and changes in brain metabolites (e.g., N-acetylaspartate (NAA) and choline-containing compounds (Cho)).

OBJECTIVES

Here, alcohol-preferring (P) and alcohol-nonpreferring (NP) rats systematically bred from heterogeneous stock Wistar rats for differential alcohol drinking behavior were compared with Wistar rats to determine whether genetic divergence and consequent morphological and neurochemical variation affect the brain's response to binge EtOH treatment.

METHODS

The three rat lines were dosed equivalently and approached similar BALs. Magnetic resonance imaging and spectroscopy evaluated the effects of binge EtOH on brain.

RESULTS

As observed in Wistar rats, P and NP rats showed decreases in NAA. Neither P nor NP rats, however, responded to EtOH intoxication with ventricular expansion or increases in Cho levels as previously noted in Wistar rats. Increases in ventricular volume correlated with increases in Cho in Wistar rats.

CONCLUSIONS

The latter finding suggests that ventricular volume expansion is related to adaptive changes in brain cell membranes in response to binge EtOH. That P and NP rats responded differently to EtOH argues for intrinsic differences in their brain cell membrane composition. Further, differential metabolite responses to EtOH administration by rat strain implicate selective genetic variation as underlying heterogeneous effects of chronic alcoholism in the human condition.

Neuroimmune basis of alcoholic brain damage

Alcohol-induced brain damage likely contributes to the dysfunctional poor decisions associated with alcohol dependence. Human alcoholics have a global loss of brain volume that is most severe in the frontal cortex. Neuroimmune gene induction by binge drinking increases neurodegeneration through increased oxidative stress, particularly NADPH oxidase-induced oxidative stress. In addition, HMGB1-TLR4 and innate immune NF-κB target genes are increased leading to persistent and sensitized neuroimmune responses to ethanol and other agents that release HMGB1 or directly stimulate TLR receptors and/or NMDA receptors. Neuroimmune signaling and glutamate excitotoxicity are linked to alcoholic neurodegeneration. Models of adolescent alcohol abuse lead to significant frontal cortical degeneration and show the most severe loss of hippocampal neurogenesis. Adolescence is a period of high risk for ethanol-induced neurodegeneration and alterations in brain structure, gene expression, and maturation of adult phenotypes. Together, these findings support the hypothesis that adolescence is a period of risk for persistent and long-lasting increases in brain neuroimmune gene expression that promote persistent and long-term increases in alcohol consumption, neuroimmune gene induction, and neurodegeneration that we find associated with alcohol use disorders.

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.

Intermittent hypoxia conditioning protects mitochondrial cytochrome c oxidase of rat cerebellum from ethanol withdrawal stress

Intermittent hypoxia (IH) conditioning minimizes neurocognitive impairment and stabilizes brain mitochondrial integrity during ethanol withdrawal (EW) in rats, but the mitoprotective mechanism is unclear. We investigated whether IH conditioning protects a key mitochondrial enzyme, cytochrome c oxidase (COX), from EW stress by inhibiting mitochondrially directed apoptotic pathways involving cytochrome c, Bax, or phosphor-P38 (pP38). Male rats completed two cycles of a 4-wk ethanol diet (6.5%) and 3 wk of EW. An IH program consisting of 5-10 bouts of 5-8 min of mild hypoxia (9.5-10% inspired O(2)) and 4 min of reoxygenation for 20 consecutive days began 3 days before the first EW period. For some animals, vitamin E replaced IH conditioning to test the contributions of antioxidant mechanisms to IH's mitoprotection. During the second EW, cerebellar-related motor function was evaluated by measuring latency of fall from a rotating rod (Rotarod test). After the second EW, COX activity in cerebellar mitochondria was measured by spectrophotometry, and COX, cytochrome c, Bax, and pP38 content were analyzed by immunoblot. Mitochondrial protein oxidation was detected by measuring carbonyl contents and by immunochemistry. Earlier IH conditioning prevented motor impairment, COX inactivation, depletion of COX subunit 4, protein carbonylation, and P38 phosphorylation during EW. IH did not prevent cytochrome c depletion during EW, and Bax content was unaffected by EW ± IH. Vitamin E treatment recapitulated IH protection of COX, and P38 inhibition attenuated protein oxidation during EW. Thus IH protects COX and improves cerebellar function during EW by limiting P38-dependent oxidative damage.

Binge Drinking: In Search of its Molecular Target via the GABA(A) Receptor

Binge drinking, frequently referred to clinically as problem or hazardous drinking, is a pattern of excessive alcohol intake characterized by blood alcohol levels ≥0.08 g% within a 2-h period. Here, we show that overexpression of α1 subunits of the GABA_A receptor contributes to binge drinking, and further document that this involvement is related to the neuroanatomical localization of α1 receptor subunits. Using a herpes simplex virus amplicon vector to deliver small interference RNA (siRNA), we showed that siRNA specific for the α1 subunit (pHSVsiLA1) caused profound, long-term, and selective reduction of gene expression, receptor density, and binge drinking in high-alcohol drinking rats when delivered into the ventral pallidum (VP). Scrambled siRNA (pHSVsiNC) delivered similarly into the VP failed to alter gene expression, receptor density, or binge drinking. Silencing of the α1 gene in the VP, however, failed to alter binge sucrose or water intake. These results, along with our prior research, provide compelling evidence that the α1-containing GABA_A receptor subunits are critical in the regulation of binge-like patterns of excessive drinking. Collectively, these data may be useful in the development of gene-based and novel pharmacological approaches for the treatment of excessive drinking.

Sleep-wakefulness in alcohol preferring and non-preferring rats following binge alcohol administration

The alcohol-preferring (P) rat is a valid animal model of alcoholism. However, the effect of alcohol on sleep in P or alcohol non-preferring (NP) rats is unknown. Since alcohol consumption has tremendous impact on sleep, the present study compared the effects of binge alcohol administration on sleep-wakefulness in P and NP rats. Using standard surgical procedures, the P and NP rats were bilaterally implanted with sleep recording electrodes. Following post-operative recovery and habituation, pre-ethanol (baseline) sleep-wakefulness was electrographically recorded for 48 h. Subsequently, ethanol was administered beginning with a priming dose of 5 g/Kg followed by two doses of 2 g/Kg every 8 h on the first day and three doses of 3 g/Kg/8 h on the second day. On the following day (post-ethanol), undisturbed sleep-wakefulness was electrographically recorded for 24 h. Our initial results suggest that, during baseline conditions, the time spent in each of the three behavioral states: wakefulness, non-rapid eye movement (NREM) sleep and REM sleep, was comparable between P and NP rats. However, the P rats were more susceptible to changes in sleep-wakefulness following 2 days of binge ethanol treatment. As compared to NP rats, the P rats displayed insomnia like symptoms including a significant reduction in the amount of time spent in NREM sleep coupled with a significant increase in wakefulness on post-ethanol day. Subsequent analysis revealed that binge ethanol induced increased wakefulness and reduced NREM sleep in P rats occurred mainly in the dark period. This is the first study that: (1) demonstrates spontaneous sleep-wake profile in P and NP rats, and (2) compares the effects of binge ethanol treatment on sleep in P and NP rats. Our results suggest that, as compared to NP rats, the P rats were more susceptible to sleep disruptions after binge ethanol treatment. In addition, the P rats exhibited insomnia-like symptoms observed during abstinence from alcohol in human subjects.

Impulsivity, frontal lobes and risk for addiction

Alcohol and substance abuse disorders involve continued use of substances despite negative consequences, i.e. loss of behavioral control of drug use. The frontal-cortical areas of the brain oversee behavioral control through executive functions. Executive functions include abstract thinking, motivation, planning, attention to tasks and inhibition of impulsive responses. Impulsiveness generally refers to premature, unduly risky, poorly conceived actions. Dysfunctional impulsivity includes deficits in attention, lack of reflection and/or insensitivity to consequences, all of which occur in addiction [Evenden JL. Varieties of impulsivity. Psychopharmacology (Berl) 1999;146:348-361.; de Wit H. Impulsivity as a determinant and consequence of drug use: a review of underlying processes. Addict Biol 2009;14:22-31]. Binge drinking models indicate chronic alcohol damages in the corticolimbic brain regions [Crews FT, Braun CJ, Hoplight B, Switzer III RC, Knapp DJ. Binge ethanol consumption causes differential brain damage in young adolescent rats compared with adult rats. Alcohol Clin Exp Res 2000;24:1712-1723] causing reversal learning deficits indicative of loss of executive function [Obernier JA, White AM, Swartzwelder HS, Crews FT. Cognitive deficits and CNS damage after a 4-day binge ethanol exposure in rats. Pharmacol Biochem Behav 2002b;72:521-532]. Genetics and adolescent age are risk factors for alcoholism that coincide with sensitivity to alcohol-induced neurotoxicity. Cortical degeneration from alcohol abuse may increase impulsivity contributing to the development, persistence and severity of alcohol use disorders. Interestingly, abstinence results in bursts of neurogenesis and brain regrowth [Crews FT, Nixon K. Mechanisms of neurodegeneration and regeneration in alcoholism. Alcohol Alcohol 2009;44:115-127]. Treatments for alcoholism, including naltrexone pharmacotherapy and psychotherapy may work through improving executive functions. This review will examine the relationships between impulsivity and executive function behaviors to changes in cortical structure during alcohol dependence and recovery.

Genetic aspects of behavioral neurotoxicology

Considerable progress has been made over the past couple of decades concerning the molecular bases of neurobehavioral function and dysfunction. The field of neurobehavioral genetics is becoming mature. Genetic factors contributing to neurologic diseases such as Alzheimer's disease have been found and evidence for genetic factors contributing to other diseases such as schizophrenia and autism are likely. This genetic approach can also benefit the field of behavioral neurotoxicology. It is clear that there is substantial heterogeneity of response with behavioral impairments resulting from neurotoxicants. Many factors contribute to differential sensitivity, but it is likely that genetic variability plays a prominent role. Important discoveries concerning genetics and behavioral neurotoxicity are being made on a broad front from work with invertebrate and piscine mutant models to classic mouse knockout models and human epidemiologic studies of polymorphisms. Discovering genetic factors of susceptibility to neurobehavioral toxicity not only helps identify those at special risk, it also advances our understanding of the mechanisms by which toxicants impair neurobehavioral function in the larger population. This symposium organized by Edward Levin and Annette Kirshner, brought together researchers from the laboratories of Michael Aschner, Douglas Ruden, Ulrike Heberlein, Edward Levin and Kathleen Welsh-Bohmer conducting studies with Caenorhabditis elegans, Drosophila, fish, rodents and humans studies to determine the role of genetic factors in susceptibility to behavioral impairment from neurotoxic exposure.

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.

Abstinence from moderate alcohol self-administration alters progenitor cell proliferation and differentiation in multiple brain regions of male and female P rats

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 x 1/d x 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 NG(2) 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 NG(2) 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 NG(2) 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 NG(2) 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.

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.

Effects of naltrexone, duloxetine, and a corticotropin-releasing factor type 1 receptor antagonist on binge-like alcohol drinking in rats

A 'binge' is defined by National Institute on Alcohol Abuse and Alcoholism as an excessive pattern of alcohol drinking that produces blood-alcohol levels (BALs) greater than 0.08 g% within a 2-h period and may or may not be associated with dependence. The purpose of this investigation was to explore the effects of several neuropharmacological agents in an animal model in which outbred rats voluntarily and orally self-administer pharmacologically meaningful alcohol doses that produce BALs >or=0.08 g% in daily limited access two-bottle choice and operant drinking sessions. Rats were trained to self-administer either 10% (w/v) alcohol solution sweetened with 'supersac' (3% glucose+0.125% saccharin) or supersac alone versus water in a two-bottle choice or operant situation during 30-min daily sessions. Rats were then injected systemically with multiple doses of duloxetine, naltrexone, and the corticotropin-releasing factor antagonist, MPZP, in Latin-square designs. Alcohol binge drinkers reliably consumed amounts of alcohol sufficient to produce BALs >or=0.08 g%. Duloxetine dose-dependently suppressed two-bottle choice alcohol binge drinking and operant alcohol responding as well as operant supersac responding, but did not affect two-bottle choice supersac drinking. Naltrexone-suppressed alcohol binge drinking at very low doses and suppressed supersac drinking at moderate-to-high doses. MPZP did not affect alcohol or supersac consumption. Different profiles for drugs that suppress binge-like alcohol drinking compared with dependence-induced drinking provide a heuristic foundation for future medications development.

Adolescence: Booze, Brains, and Behavior

This article represents the proceedings of a symposium at the 2004 Research Society on Alcoholism meeting in Vancouver, British Columbia, Canada, organized and chaired by Peter M. Monti and Fulton T. Crews. The presentations and presenters were (1) Introduction, by Peter M. Monti; (2) Adolescent Binge Drinking Causes Life-Long Changes in Brain, by Fulton T. Crews and Kim Nixon; (3) Functional Neuroimaging Studies in Human Adolescent Drinkers, by Susan F. Tapert; (4) Abnormal Emotional Reactivity as a Risk Factor for Alcoholism, by Robert Miranda, Jr.; (5) Alcohol-Induced Memory Impairments, Including Blackouts, and the Changing Adolescent Brain, by Aaron M. White and H. Scott Swartzwelder; and (6) Discussion, by Kenneth Sher.

CREB Gene Transcription Factors: Role in Molecular Mechanisms of Alcohol and Drug Addiction

This article presents the proceedings of a symposium presented at the meeting of the Research Society on Alcoholism, held in Vancouver, British Columbia, Canada, in June 2004. The organizers and chairpersons were Subhash C. Pandey and Fulton Crews. The presentations were (1) Ethanol Modulation of CREB: Role in Dependence and Withdrawal, by Fulton Crews; (2) Effects of D1 Dopamine Receptor Activation During Withdrawal From Chronic Morphine: Enhanced CREB Activation and Decreased Conditioned Place Aversion, by Elena H. Chartoff; (3) CREB-Haplodeficient Mice: Role in Anxiety and Alcohol-Drinking Behaviors, by Subhash C. Pandey; and (4) A Role for CREB in Stress and Drug Addiction, by Julie A. Blendy.

Sugar-dependent rats show enhanced intake of unsweetened ethanol

Rats show signs of dependence on sugar when it is available intermittently, including bingeing, withdrawal, and cross-sensitization with amphetamine. In the current study, we sought to determine whether sugar-dependent rats would show increased intake of unsweetened ethanol and, conversely, whether intermittent access to ethanol would augment sugar consumption. In Experiment 1, with intermittent versus ad libitum access to ethanol, Sprague-Dawley rats were given escalating concentrations of ethanol (1%, 2%, 4%, 7%, and 9%) over the course of 20 days. Rats in the intermittent ethanol access group, with 12-h daily access, consumed more 4%, 7%, and 9% ethanol during the first hour of access, and more 9% ethanol daily, than did rats in the ad libitum ethanol access group. In Experiment 2, with ethanol as a gateway to sugar intake, the rats from Experiment 1 were switched to 10% sucrose with 12-h daily access for 1 week. Rats in the intermittent ethanol access group consumed significantly more sugar than was consumed by rats in a control group with no prior ethanol experience. In Experiment 3, with sugar as a gateway to ethanol to determine whether sugar dependence leads to increased ethanol intake, four groups were maintained for 21 days according to the following designations: intermittent access to sugar and chow, ad libitum access to sugar and chow, intermittent access to chow, or ad libitum access to chow. Four days later, all groups were switched to intermittent ethanol access, as described in Experiment 1. The group with intermittent access to sugar and chow consumed the most 9% ethanol, supporting the suggestion that sugar dependence alters a rat's proclivity to drink ethanol. These results may relate to the co-morbidity between binge-eating disorders and alcohol intake and the tendency of people abstaining from alcohol to consume excessive amounts of sugar. In conclusion, bingeing on either ethanol or sugar fosters intake of the other.

Risk factors for alcoholic liver disease in China

AIM: To examine the association of daily alcohol intake, types of alcoholic beverage consumed, drinking patterns and obesity with alcoholic liver disease in China.

METHODS: By random cluster sampling and a 3-year follow-up study, 1 270 alcohol drinkers were recruited from different occupations in the urban and suburban areas of Xi’an City. They were examined by specialists and inquired for information on: Medical history and family medical history, alcohol intake, types of alcoholic beverage consumed, drinking patterns by detailed dietary questionnaires. Routine blood tests and ultrasonography were done.

RESULTS: Multivariate analysis showed that: (1) The risk threshold for developing alcoholic liver disease was ingestion of more than 20 g alcohol per day, keeping on drinking for over 5 years in men. The highest OR was at the daily alcohol consumption > / = 160 g, the occurrence rate of ALD amounted to 18.7% (P < 0.01). No ALD occurred when ingestion of alcohol was less than 20 g per day. (2) 87.9% of all drank only at mealtimes. The cumulative risk of developing ALD was significantly higher in those individuals who regularly drank alcohol without food than in those who drank only at mealtimes, especially for those who regularly drank hard liquors only and multiple drinks (P < 0.05). (3) The alcohol consumption in those with BMI > / = 25 was lower than in those with BMI < 25, but the risk increased to 11.5%, significantly higher than that of general population, 6.5% (P < 0.01). (4) Abstinence and weight reduction could benefit the liver function recovery.

CONCLUSION: In the Chinese population the ethanol risk threshold for developing ALD is 20 g per day, and this risk increases with increased daily intake. Drinking 20 g of ethanol per day and for less than 5 years are safe from ALD. Drinking alcohol outside mealtimes and drinking hard liquors only and multiple different alcohol beverages both increase the risk of developing ALD. Obesity also increases the risk. Abstinence and weight reduction will directly affect the prognosis of ALD. Doctor’s strong advice might influence the prognosis indirectly.

Consequences of Multiple Withdrawals From Alcohol

This article represents the proceedings of a symposium at the 2003 annual meeting of the Research Society on Alcoholism in Fort Lauderdale, FL, organized by Theodora Duka and chaired by Dai Stephens. The purpose of the symposium was to examine the effects of multiple experiences of withdrawal from alcohol in animals made dependent on alcohol and in humans who are alcohol dependent. Parallels were drawn to the effects of repeated short-lived high-content alcohol exposures in animals and in humans who are social drinkers but indulge in binge drinking. The presentations were (1) Multiple detoxifications and risk of relapse in abstinent alcoholics, by John Gentry and Robert Malcolm; (2) Emotional and cognitive impairments after long-term use of alcohol: relationship to multiple detoxifications and binge drinking, by Theodora Duka; (3) The effect of repeated withdrawal from ethanol on conditioning to appetitive stimuli, by Tamzin Ripley, Gilyanna Borlikova, and Dai Stephens; (4) Alcohol withdrawal kindling: electrographic measures in a murine model of behavioral seizure sensitization, by Lynn Veatch and Howard Becker; and (5) Binge drinking induced changes in CNS, by Fulton Crews.

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.