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Knapp CM, Ciraulo DA, Datta S. Mechanisms underlying sleep-wake disturbances in alcoholism: focus on the cholinergic pedunculopontine tegmentum. Behav Brain Res 2014; 274:291-301. [PMID: 25151622 DOI: 10.1016/j.bbr.2014.08.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/11/2014] [Accepted: 08/13/2014] [Indexed: 12/24/2022]
Abstract
Sleep-wake (S-W) disturbances are frequently associated with alcohol use disorders (AUD), occurring during periods of active drinking, withdrawal, and abstinence. These S-W disturbances can persist after months or even years of abstinence, suggesting that chronic alcohol consumption may have enduring negative effects on both homeostatic and circadian sleep processes. It is now generally accepted that S-W disturbances in alcohol-dependent individuals are a significant cause of relapse in drinking. Although significant progress has been made in identifying the socio-economic burden and health risks of alcohol addiction, the underlying neurobiological mechanisms that lead to S-W disorders in AUD are poorly understood. Marked progress has been made in understanding the basic neurobiological mechanisms of how different sleep stages are normally regulated. This review article in seeking to explain the neurobiological mechanisms underlying S-W disturbances associated with AUD, describes an evidence-based, easily testable, novel hypothesis that chronic alcohol consumption induces neuroadaptive changes in the cholinergic cell compartment of the pedunculopontine tegmentum (CCC-PPT). These changes include increases in N-methyl-d-aspartate (NMDA) and kainate receptor sensitivity and a decrease in gamma-aminobutyric acid (GABAB)-receptor sensitivity in the CCC-PPT. Together these changes are the primary pathophysiological mechanisms that underlie S-W disturbances in AUD. This review is targeted for both basic neuroscientists in alcohol addiction research and clinicians who are in search of new and more effective therapeutic interventions to treat and/or eliminate sleep disorders associated with AUD.
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Affiliation(s)
- Clifford M Knapp
- Laboratory of Sleep and Cognitive Neuroscience, Boston University Psychiatry Associates Clinical Studies Unit, Department of Psychiatry, Boston University School of Medicine, 85 East Newton Street, Boston, MA 02118, USA
| | - Domenic A Ciraulo
- Laboratory of Sleep and Cognitive Neuroscience, Boston University Psychiatry Associates Clinical Studies Unit, Department of Psychiatry, Boston University School of Medicine, 85 East Newton Street, Boston, MA 02118, USA
| | - Subimal Datta
- Laboratory of Sleep and Cognitive Neuroscience, Boston University Psychiatry Associates Clinical Studies Unit, Department of Psychiatry, Boston University School of Medicine, 85 East Newton Street, Boston, MA 02118, USA.
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Bertotto ME, Maldonado NM, Bignante EA, Gorosito SV, Cambiasso MJ, Molina VA, Martijena ID. ERK activation in the amygdala and hippocampus induced by fear conditioning in ethanol withdrawn rats: modulation by MK-801. Eur Neuropsychopharmacol 2011; 21:892-904. [PMID: 21315561 DOI: 10.1016/j.euroneuro.2011.01.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 12/08/2010] [Accepted: 01/05/2011] [Indexed: 02/02/2023]
Abstract
The extracellular signal-regulated kinase (ERK) pathway, which can be activated by NMDA receptor stimulation, is involved in fear conditioning and drug addiction. We have previously shown that withdrawal from chronic ethanol administration facilitated the formation of contextual fear memory. In order to explore the neural substrates and the potential mechanism involved in this effect, we examined: 1) the ERK1/2 activation in the central (CeA) and basolateral (BLA) nuclei of the amygdala and in the dorsal hippocampus (dHip), 2) the effect of the NMDA receptor antagonist MK-801 on fear conditioning and ERK activation and 3) the effect of the infusion of U0126, a MEK inhibitor, into the BLA on fear memory formation in ethanol withdrawn rats. Rats made dependent via an ethanol-containing liquid diet were subjected to contextual fear conditioning on day 3 of ethanol withdrawal. High basal levels of p-ERK were found in CeA and dHip from ethanol withdrawn rats. ERK activation was significantly increased both in control (60min) and ethanol withdrawn rats (30 and 60min) in BLA after fear conditioning. Pre-training administration of MK-801, at a dose that had no effect on control rats, prevented the increase in ERK phosphorylation in BLA and attenuated the freezing response 24h later in ethanol withdrawn rats. Furthermore, the infusion of U0126 into the BLA, but not the CeA, before fear conditioning disrupted fear memory formation. These results suggest that the increased fear memory can be linked to changes in ERK phosphorylation, probably due to NMDA receptor activation in BLA in ethanol withdrawn rats.
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Bertotto ME, Bussolino DF, Molina VA, Martijena ID. Increased voluntary ethanol consumption and c-Fos expression in selected brain areas induced by fear memory retrieval in ethanol withdrawn rats. Eur Neuropsychopharmacol 2010; 20:568-81. [PMID: 20400272 DOI: 10.1016/j.euroneuro.2010.02.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 02/19/2010] [Accepted: 02/22/2010] [Indexed: 11/27/2022]
Abstract
Withdrawal from chronic ethanol administration facilitated the formation of contextual fear memory. The effect of fear memory retrieval on subsequent ethanol consumption, by employing a two-bottle free-choice procedure with either water or ethanol (2-8% v/v), was investigated in ethanol withdrawn rats. The effect of fear memory extinction with or without d-cycloserine (DCS, 5mg/kgi.p.) on subsequent ethanol consumption was also evaluated. In addition, we examined c-Fos expression in different brain areas following the fear memory recall. The retrieval of such fear memory induced a significant increase in ethanol consumption in ethanol withdrawn but not in control animals. Regardless of DCS treatment, this increase was attenuated by extinction training. In ethanol withdrawn rats, context-dependent memory retrieval was accompanied by an increased c-Fos expression in the basolateral amygdala, ventrolateral periaqueductal gray, dentate gyrus and dorsomedial periaqueductal gray. Among these brain areas suggested to be implicated in the modulation of motivation and of emotional states, the basolateral amygdala has a crucial role in the emergence of negative affective state during ethanol withdrawal. These data suggest that retrieval of fear memory in ethanol withdrawn rats affected ethanol consumption and that amygdala may be involved in this effect.
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Affiliation(s)
- María Eugenia Bertotto
- IFEC-CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5016 Córdoba, Argentina
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Bertotto ME, Bustos SG, Molina VA, Martijena ID. Influence of ethanol withdrawal on fear memory: Effect of D-cycloserine. Neuroscience 2006; 142:979-90. [PMID: 16934411 DOI: 10.1016/j.neuroscience.2006.07.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 07/13/2006] [Accepted: 07/17/2006] [Indexed: 10/24/2022]
Abstract
Animals made dependent via an ethanol (ETOH) -containing liquid diet (6% v/v) for 14 days were subjected to a contextual fear conditioning paradigm 3 days after the last consumption day. After conditioning, rats were subjected to four extinction trials by exposing the animals to the conditioned context and their freezing was evaluated for each trial. Immediately after the first extinction trial, animals were injected with D-cycloserine (DCS) 5 mg/kg i.p., a dose that did not influence the extinction in control rats. Spontaneous recovery of learned fear was tested seven days after the last extinction trial. The following day, animals were subjected to a reacquisition or a reinstatement procedure and their freezing responses evaluated 24 h later. The present study shows that: 1. discontinuation from chronic ETOH administration facilitated the formation of a new fear memory concomitant with a marked resistance to being extinguished, 2. administration of DCS (5 mg/kg) facilitated the extinction process only in ETOH withdrawn rats, 3. both reinstatement and reacquisition procedures restored the increased freezing in ETOH withdrawn animals after extinction, 4. DCS administered immediately after the first extinction trial prevented the increase in freezing following both reacquisition and reinstatement. The enhanced sensitivity to the facilitatory effect of DCS in ETOH withdrawn animals may be mediated by adaptive changes in N-methyl-D-aspartate (NMDA) receptor provoked by ETOH dependence.
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MESH Headings
- Alcohol-Induced Disorders, Nervous System/physiopathology
- Alcohol-Induced Disorders, Nervous System/psychology
- Animals
- Antimetabolites/pharmacology
- Anxiety Disorders/chemically induced
- Anxiety Disorders/physiopathology
- Anxiety Disorders/psychology
- Brain/drug effects
- Brain/metabolism
- Brain/physiopathology
- Brain Chemistry/drug effects
- Brain Chemistry/physiology
- Central Nervous System Depressants/adverse effects
- Conditioning, Psychological/drug effects
- Conditioning, Psychological/physiology
- Cycloserine/pharmacology
- Disease Models, Animal
- Drug Synergism
- Ethanol/adverse effects
- Extinction, Psychological/drug effects
- Extinction, Psychological/physiology
- Fear/drug effects
- Fear/physiology
- Male
- Memory/drug effects
- Memory/physiology
- Rats
- Rats, Wistar
- Receptors, N-Methyl-D-Aspartate/drug effects
- Receptors, N-Methyl-D-Aspartate/metabolism
- Substance Withdrawal Syndrome/physiopathology
- Substance Withdrawal Syndrome/psychology
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- M E Bertotto
- Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria 5000, Córdoba, Argentina
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Abstract
Symptoms of ethanol withdrawal include heightened responses to sensory stimuli, as well as tremors and convulsions. We tested the hypothesis that repeated episodes of ethanol intake and withdrawal exacerbate the symptoms of alcohol-induced peripheral neuropathy. In contrast to the hyperalgesia produced when an alcohol (6.5%)-containing diet was fed continuously to male rats which took 4 weeks to develop (Dina et al., 2000), feeding alcohol (6.5%) in repeated cycles of 4 days of alcohol followed by 3 days without alcohol resulted in a withdrawal-induced hyperalgesia that began at the end of one weekly cycle and reached a maximum during the fourth cycle. For ethanol withdrawal to produce hyperalgesia, ethanol consumption needed to be terminated for a period of 2 days. Paradoxically, as the amount of alcohol consumed decreased, the hyperalgesia induced by withdrawal developed more rapidly, being maximal between 1.4 and 1.6% ethanol. These results suggest that continued exposure to ethanol also has a neuroprotective effect. Withdrawal-induced hyperalgesia, similar to the hyperalgesia induced by continuous, chronic alcohol intake, was inhibited reversibly by intrathecal administration of an antisense oligodeoxynucleotide to protein kinase C (PKC)epsilon.
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Affiliation(s)
- Olayinka A Dina
- Department of Oral & Maxillofacial Surgery, University of California at San Francisco, CA 94143, USA
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Breese GR, Overstreet DH, Knapp DJ. Conceptual framework for the etiology of alcoholism: a "kindling"/stress hypothesis. Psychopharmacology (Berl) 2005; 178:367-80. [PMID: 15765253 PMCID: PMC2958094 DOI: 10.1007/s00213-004-2016-2] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2003] [Accepted: 08/23/2004] [Indexed: 12/25/2022]
Abstract
RATIONALE The rationale for proposing the "kindling"/stress hypothesis is to provide a conceptual basis for the insidious development and maintenance of alcohol abuse. OBJECTIVE AND RESULTS An objective of the hypothesis is to emphasize how continued alcohol abuse is linked to progressive neural adaptation. Work has shown that repeated withdrawals from chronic low levels of alcohol sensitize ("kindle") anxiety-like behavior ("anxiety") in rats, a finding consistent with multiple withdrawal kindling of seizure activity. Additionally, stress substitutes for initial cycles of the multiple withdrawal protocol to sensitize withdrawal-induced anxiety, which is indicative that stress is capable of facilitating neuroadaptive processes related to withdrawal. The persistence of adaptation caused by stress and multiple withdrawals is revealed by the appearance of withdrawal-induced anxiety following a future re-exposure to a single 5-day period of alcohol. This persisting adaptation also permits stress to induce anxiety during a period of abstinence--a response not observed in animals without previous exposure to alcohol. Furthermore, stress interacts with repeated withdrawals to enhance voluntary alcohol drinking. Results of other preclinical and clinical studies reported in the literature are integrated with these investigations in support of the proposed hypothesis. CONCLUSIONS The "kindling"/stress hypothesis is based on the premise that repeated withdrawals from cycles of chronic alcohol exposure contribute to a progressive development of persisting adaptive change that sensitizes withdrawal-induced anxiety and allows stress to evoke symptoms associated with negative affect during abstinence. Thus, these consequences of repeated withdrawals account for the evolution of major characteristics of alcoholism, which include worsened acute withdrawal symptoms and increased stress-induced negative affect during abstinence, both of which enhance the likelihood of relapse--and with relapse an inability to limit an abusive pattern of alcohol intake. The "kindling"/stress hypothesis provides a clear strategy for future studies to explore the advancing neural adaptation proposed to contribute to the pathogenesis of alcoholism.
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Affiliation(s)
- George R Breese
- Bowles Center for Alcohol Studies, Department of Psychiatry, University of North Carolina School of Medicine, 3007 Thurston-Bowles Building CB-7178, Chapel Hill, NC 27599-7178, USA.
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Breese GR, Knapp DJ, Overstreet DH. Stress sensitization of ethanol withdrawal-induced reduction in social interaction: inhibition by CRF-1 and benzodiazepine receptor antagonists and a 5-HT1A-receptor agonist. Neuropsychopharmacology 2004; 29:470-82. [PMID: 12955093 PMCID: PMC2898195 DOI: 10.1038/sj.npp.1300282] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2003] [Revised: 06/10/2003] [Accepted: 06/13/2003] [Indexed: 11/09/2022]
Abstract
Repeated withdrawals from chronic ethanol sensitize the withdrawal-induced reduction in social interaction behaviors. This study determined whether stress might substitute for repeated withdrawals to facilitate withdrawal-induced anxiety-like behavior. When two 1-h periods of restraint stress were applied at 1-week intervals to rats fed control diet, social interaction was reduced upon withdrawal from a subsequent 5-day exposure to ethanol diet. Neither this ethanol exposure alone nor exposure to three restraint stresses alone altered this measure of anxiety. Further, the repeatedly stressed singly withdrawn rats continued to exhibit a reduction in social interaction 16 days later, upon withdrawal from re-exposure to 5 days of chronic ethanol, consistent with a persistent adaptation by the multiple-stress/withdrawal protocol. Weekly administration of corticosterone in place of stress induced no significant change in social interaction upon withdrawal from the single chronic ethanol exposure, indicative that corticoid release is not responsible for the stress-induced reduction in anxiety-like behavior during withdrawal. In the multiple-withdrawal protocol, stress applied during withdrawal from voluntary ethanol drinking by P-rats facilitated ethanol drinking sufficiently, to induce a withdrawal-induced reduction in social interaction. Administration of a CRF-1 receptor antagonist, a benzodiazepine receptor antagonist, or a 5-HT(1A) receptor agonist prior to each stress minimized sensitization of the withdrawal-induced reduction in anxiety-like behavior. Since these pharmacological consequences on the induction of anxiety-like behavior following the stress/withdrawal protocol are like those previously seen when these drug treatments were given prior to multiple withdrawals, evidence is provided that repeated stresses and multiple withdrawals sensitize the withdrawal reduction in social interaction by similar central adaptive mechanisms.
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Affiliation(s)
- George R Breese
- Department of Psychiatry, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
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De Witte P, Pinto E, Ansseau M, Verbanck P. Alcohol and withdrawal: from animal research to clinical issues. Neurosci Biobehav Rev 2003; 27:189-97. [PMID: 12788332 DOI: 10.1016/s0149-7634(03)00030-7] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The withdrawal syndrome in alcohol-dependent patients appears to be a major stressful event whose intensity increases with repetition of detoxifications according to a kindling process. Disturbances in the balance between excitatory and inhibitory neural processes are reflected in a perturbed physical state while disturbances in the balance between positive and negative reinforcements are reflected in a perturbed mood state. Our purpose is to link the different behavioral outcomes occurring during withdrawal with specific biological brain mechanisms from the animal to the human being. Better understanding of the various biological mechanisms underlying withdrawal from alcohol will be the key to design and to apply appropriate pharmaceutical management, together with appropriate therapy aimed at inducing protracted abstinence.
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Affiliation(s)
- Ph De Witte
- Laboratoire de Biologie du Comportement, Université catholique de Louvain, Place Croix du Sud, 1-Bte 10, B-1348, Louvain-la-Neuve, Belgium.
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Overstreet DH, Knapp DJ, Breese GR. Accentuated Decrease in Social Interaction in Rats Subjected to Repeated Ethanol Withdrawals. Alcohol Clin Exp Res 2002. [DOI: 10.1111/j.1530-0277.2002.tb02665.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Overstreet DH, Knapp DJ, Breese GR. Accentuated decrease in social interaction in rats subjected to repeated ethanol withdrawals. Alcohol Clin Exp Res 2002; 26:1259-68. [PMID: 12198403 PMCID: PMC2865239 DOI: 10.1097/01.alc.0000023983.10615.d7] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2022]
Abstract
BACKGROUND Previous work has shown that repeated withdrawals from chronic ethanol exposure can kindle seizures in rodents. In this article, the effects of a three-cycle model of ethanol exposure and withdrawal on the social interaction test of anxiety are summarized. METHODS Rats were exposed to ethanol (7% or 4.5%) diets over three periods of 5 days, with 2 days of withdrawal between cycles. Between 5 and 6 hr after the ethanol was removed, pairs of rats were placed in open field chambers for the assessment of social interaction behavior and locomotor activity. RESULTS After the third cycle of ethanol (7%) presentation, both male and female rats exhibited lower social interaction behavior (more anxiety) and activity than after a single cycle. Rats exposed to a similar amount of ethanol but tested while ethanol was still available did not exhibit a reduction in social interaction. The decrease in social interaction was still present for up to 24 hr but had disappeared by 48 hr after ethanol was withdrawn. When rats were allowed 8 or 16 days to recover from the effects of the three-cycle protocol, a further exposure to 5 days of 7% ethanol diet resulted in a reduction in social interaction on withdrawal similar to that seen from the three-cycle protocol. In contrast, rats exposed continuously to 7% ethanol diet for 15 consecutive days exhibited higher levels of social interaction when maintained on control diet for 8 or 16 days and then reexposed to ethanol. Rats that were exposed to the three-cycle protocol and allowed 32 days to recover before being reexposed to ethanol still had a partial deficit in social interaction. Finally, animals subjected to repeated withdrawals from 4.5% ethanol exhibited a reduction in social interaction without a change in activity after the final withdrawal from ethanol, whereas rats exposed continuously to a 4.5% ethanol diet did not exhibit a reduction in social interaction or activity. Neither blood ethanol concentrations nor changes in body weight could account for these behavioral differences. CONCLUSION Repeated withdrawal from ethanol can lead to accentuated or more persistent anxiety-like behavior in rats, as indicated by a decrease in social interaction. The withdrawal-induced decrease in locomotor activity is not accentuated by repeated withdrawals. This model of repeated withdrawals from ethanol may prove useful in defining the neurochemical basis of this accentuation.
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Affiliation(s)
- David H Overstreet
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA.
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Knott TK, Dayanithi G, Coccia V, Custer EE, Lemos JR, Treistman SN. Tolerance to Acute Ethanol Inhibition of Peptide Hormone Release in the Isolated Neurohypophysis. Alcohol Clin Exp Res 2000. [DOI: 10.1111/j.1530-0277.2000.tb04653.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Homewood J, Bond NW. Thiamin deficiency and Korsakoff's syndrome: failure to find memory impairments following nonalcoholic Wernicke's encephalopathy. Alcohol 1999; 19:75-84. [PMID: 10487391 DOI: 10.1016/s0741-8329(99)00027-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Prolonged alcohol consumption is associated with a variety of neuropsychiatric conditions, including the dense amnesic disorder known as Korsakoff's syndrome. Korsakoff's syndrome is frequently diagnosed in alcoholics after an episode of acute thiamin deficiency. The accepted view within the medical literature is that the etiology of this disorder lies in thiamin deficiency or Wernicke's encephalopathy. However, examination of the published reports of pure thiamin deficiency unaccompanied by chronic and excessive consumption of alcohol shows that, in this group of patients, the rate of progression to Korsakoff's syndrome is low. This result suggests that the memory impairments associated with alcohol-related brain damage cannot be attributed to thiamin deficiency alone. The etiology of alcohol-related cognitive impairments such as Korsakoff's syndrome is still poorly understood but several lines of evidence suggest multiple causal factors interact to produce deficits in performance. Animal models that manipulate only a single putative etiological factor are unlikely to elucidate the multiple influences that lead to Korsakoff's syndrome. A study of the natural history of alcohol-related brain damage is needed that will allow an assessment of individual risk factors and their interactions.
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Affiliation(s)
- J Homewood
- Department of Psychology, Macquarie University, Sydney, Australia.
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Homewood J, Bond NW, MacKenzie A. The effects of single and repeated episodes of thiamin deficiency on memory in alcohol-consuming rats. Alcohol 1997; 14:81-91. [PMID: 9014028 DOI: 10.1016/s0741-8329(96)00111-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The underlying pathogenesis of Korsakoff's syndrome, an amnesic disorder most commonly found in alcoholics, is not well understood. Chronic alcoholism is associated with thiamin deficiency and current thinking is that this may be the causal factor. In Experiment 1, rats were given a 20% (v/v) ethanol/water mix as their only source of fluid for 156 days. Three groups were made thiamin deficient through the combination of a thiamin-deficient diet and the centrally acting thiamin antagonist pyrithiamin hydrobromide, after 4, 15, and 26 weeks exposure to ethanol, respectively. The control group was given ad lib access to laboratory chow and water throughout this period. There were no differences between groups on either the working or reference versions of the Morris water tank paradigm. In Experiment 2, to test the hypothesis that a single bout of thiamin deficiency, with or without concurrent alcohol intake, is not sufficient to cause severe memory impairments, two groups of rats were subjected to three bouts of thiamin deficiency. One of these groups consumed an ethanol/water mix, the other tap water. A third group was made thiamin deficient on only one occasion. The control group was not made thiamin deficient and consumed lab chow and tap water throughout. Once again, there were no between-group differences in the data derived from testing in either the eight-arm radial maze or the Morris water tank task. These experiments indicate that the aetiology of Korsakoff's syndrome is more complex than previously thought.
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Affiliation(s)
- J Homewood
- Department of Psychology, Macquarie University, Sydney, Australia
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