1
|
Montemitro C, Angebrandt A, Wang TY, Pettorruso M, Abulseoud OA. Mechanistic insights into the efficacy of memantine in treating certain drug addictions. Prog Neuropsychopharmacol Biol Psychiatry 2021; 111:110409. [PMID: 34324921 DOI: 10.1016/j.pnpbp.2021.110409] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 06/23/2021] [Accepted: 07/22/2021] [Indexed: 01/11/2023]
Abstract
The deleterious effects of the drug addiction epidemic are compounded by treatment strategies that are only marginally efficacious. Memantine is a unique glutamatergic medication with proven ability to attenuate drug addiction in preclinical models. However, clinical translational studies are inconsistent. In this review, we summarize preclinical evidences and clinical trials that investigated the efficacy of memantine in treating patients with alcohol, opiate, cocaine, and nicotine use disorders and discuss the results from a mechanistic point of view. Memantine has shown efficacy in reducing alcohol and opiate craving, consumption, and withdrawal severity. However, in cocaine and nicotine use disorders, memantine did not have significant effect on cravings or consumption. Additionally, memantine was associated with increased subjective effects of alcohol, cocaine, and nicotine. We discuss possible mechanisms behind this variability. Since memantine transiently blocks NMDA receptors and protects neurons from overstimulation by excessive synaptic glutamate, its efficacy should be observed in drug phases that cause hyperglutamatergic states, while hypoglutamatergic drug use states would not resolve with blocking NMDA receptors. Second, memantine pharmacokinetic studies have been done in rodents and healthy volunteers, but not in patients with substance use disorder. Memantine, opiates, cocaine, and nicotine share the same transporter family at the blood brain barrier. This shared transport mechanism could impact brain concentrations of memantine and its effects. In conclusion, memantine remains an intriguing compound in our pharmacopeia with controversial results in treating certain aspects of drug addiction. Further studies are needed to understand the clinical and biological correlates of its efficacy.
Collapse
Affiliation(s)
- Chiara Montemitro
- Neuroimaging Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, USA; Department of Neuroscience & Imaging, Università degli Studi G. d'Annunzio Chieti e Pescara, Italy.
| | - Alexandra Angebrandt
- Neuroimaging Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, USA
| | - Tzu-Yun Wang
- Neuroimaging Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, USA; Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Mauro Pettorruso
- Department of Neuroscience & Imaging, Università degli Studi G. d'Annunzio Chieti e Pescara, Italy
| | - Osama A Abulseoud
- Neuroimaging Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, USA; Department of Psychiatry and Psychology, Mayo Clinic, 5777 E Mayo Blvd, Phoenix, AZ, USA.
| |
Collapse
|
2
|
The role of memantine in the treatment of major depressive disorder: Clinical efficacy and mechanisms of action. Eur J Pharmacol 2018; 827:103-111. [PMID: 29551658 DOI: 10.1016/j.ejphar.2018.03.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 03/12/2018] [Accepted: 03/14/2018] [Indexed: 12/22/2022]
Abstract
A developing body of evidence indicates that disturbed glutamate neurotransmission especially through N-methyl-d-aspartate (NMDA) is central to the pathophysiology of major depressive disorder (MDD) and NMDA receptor antagonists have shown therapeutic potential in the MDD treatment. Memantine is an uncompetitive NMDA receptor antagonist, approved for treatment of Alzheimer's disease (AD) that in contrast to other NMDA receptor antagonists at therapeutic doses does not induce highly undesirable side effects. Neuroprotective properties and well tolerability of memantine have been attributed to its unique pharmacological features such as moderate affinity, rapid blocking kinetics and strongly voltage-dependency. In this review we summarized clinical trial evidence of antidepressant effectiveness of memantine and its mechanisms of action. Available data indicate contradictory findings relating to clinical efficacy suggesting further research is necessary in determining as to whether memantine will eventually be an advantageous therapy for MDD. Preclinical data proposed various neurobiological mechanisms underlying antidepressant-like properties of memantine that are responsible for synaptic plasticity and cell survival.
Collapse
|
3
|
Yardley MM, Ray LA. Medications development for the treatment of alcohol use disorder: insights into the predictive value of animal and human laboratory models. Addict Biol 2017; 22:581-615. [PMID: 26833803 DOI: 10.1111/adb.12349] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 11/09/2015] [Accepted: 11/13/2015] [Indexed: 12/20/2022]
Abstract
Development of effective treatments for alcohol use disorder (AUD) represents an important public health goal. This review provides a summary of completed preclinical and clinical studies testing pharmacotherapies for the treatment of AUD. We discuss opportunities for improving the translation from preclinical findings to clinical trial outcomes, focusing on the validity and predictive value of animal and human laboratory models of AUD. Specifically, while preclinical studies of medications development have offered important insights into the neurobiology of the disorder and alcohol's molecular targets, limitations include the lack of standardized methods and streamlined processes whereby animal studies can readily inform human studies. Behavioral pharmacology studies provide a less expensive and valuable opportunity to assess the feasibility of a pharmacotherapy prior to initiating larger scale clinical trials by providing insights into the mechanism of the drug, which can then inform recruitment, analyses, and assessments. Summary tables are provided to illustrate the wide range of preclinical, human laboratory, and clinical studies of medications development for alcoholism. Taken together, this review highlights the challenges associated with animal paradigms, human laboratory studies, and clinical trials with the overarching goal of advancing treatment development and highlighting opportunities to bridge the gap between preclinical and clinical research.
Collapse
Affiliation(s)
- Megan M. Yardley
- Department of Psychology; University of California, Los Angeles; Los Angeles CA USA
| | - Lara A. Ray
- Department of Psychology; University of California, Los Angeles; Los Angeles CA USA
- Department of Psychiatry and Biobehavioral Sciences; University of California, Los Angeles; Los Angeles CA USA
| |
Collapse
|
4
|
Goodwani S, Saternos H, Alasmari F, Sari Y. Metabotropic and ionotropic glutamate receptors as potential targets for the treatment of alcohol use disorder. Neurosci Biobehav Rev 2017; 77:14-31. [PMID: 28242339 DOI: 10.1016/j.neubiorev.2017.02.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/13/2017] [Accepted: 02/22/2017] [Indexed: 12/16/2022]
Abstract
Emerging evidence indicates that dysfunctional glutamate neurotransmission is critical in the initiation and development of alcohol and drug dependence. Alcohol consumption induced downregulation of glutamate transporter 1 (GLT-1) as reported in previous studies from our laboratory. Glutamate is the major excitatory neurotransmitter in the brain, which acts via interactions with several glutamate receptors. Alcohol consumption interferes with the glutamatergic signal transmission by altering the functions of these receptors. Among the glutamate receptors involved in alcohol-drinking behavior are the metabotropic receptors such as mGluR1/5, mGluR2/3, and mGluR7, as well as the ionotropic receptors, NMDA and AMPA. Preclinical studies using agonists and antagonists implicate these glutamatergic receptors in the development of alcohol use disorder (AUD). Therefore, the purpose of this review is to discuss the neurocircuitry involving glutamate transmission in animals exposed to alcohol and further outline the role of metabotropic and ionotropic receptors in the regulation of alcohol-drinking behavior. This review provides ample information about the potential therapeutic role of glutamatergic receptors for the treatment of AUD.
Collapse
Affiliation(s)
- Sunil Goodwani
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA; The Neurodegeneration Consortium, Institute for Applied Cancer Science, The University of Texas MD Anderson Cancer Center, Houston, TX, 77054, USA
| | - Hannah Saternos
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Fawaz Alasmari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA
| | - Youssef Sari
- University of Toledo, College of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology and Experimental Therapeutics, Toledo, OH 43614, USA.
| |
Collapse
|
5
|
Perry CJ, Lawrence AJ. Addiction, cognitive decline and therapy: seeking ways to escape a vicious cycle. GENES BRAIN AND BEHAVIOR 2016; 16:205-218. [DOI: 10.1111/gbb.12325] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/14/2016] [Accepted: 08/25/2016] [Indexed: 12/31/2022]
Affiliation(s)
- C. J. Perry
- Behavioural Neuroscience Division; The Florey Institute of Neuroscience and Mental Health; Melbourne VIC Australia
- Florey Department of Neuroscience and Mental Health; University of Melbourne; Melbourne VIC Australia
| | - A. J. Lawrence
- Behavioural Neuroscience Division; The Florey Institute of Neuroscience and Mental Health; Melbourne VIC Australia
- Florey Department of Neuroscience and Mental Health; University of Melbourne; Melbourne VIC Australia
| |
Collapse
|
6
|
Amin B, Andalib S, Vaseghi G, Mesripour A. Learning and Memory Performance After Withdrawal of Agent Abuse: A Review. IRANIAN JOURNAL OF PSYCHIATRY AND BEHAVIORAL SCIENCES 2016; 10:e1822. [PMID: 27803716 PMCID: PMC5087336 DOI: 10.17795/ijpbs-1822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 01/26/2016] [Accepted: 04/09/2016] [Indexed: 11/25/2022]
Abstract
Context Agent abuse is a dire predicament worldwide. Learning and memory deficits stemming from the withdrawal of such agents is an increasingly burning issue for researchers. Evidence Acquisition The present review revisits the literature generated by far pertaining to the research on memory and cognition deficiencies after withdrawal of agent abuse and corresponding mechanisms. Results Deficiency on spatial memory, episodic memory and working memory are common after withdrawal of agent abuse. Conclusions The present review suggests that memory dysfunction may result from withdrawal of agent abuse.
Collapse
Affiliation(s)
- Bahareh Amin
- Department of Pharmacology and Physiology, School of Medicine, Sabzevar University of Medical Sciences, Sabzevar, IR Iran
| | - Sasan Andalib
- Department of Neurosurgery, Poursina Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, IR Iran
| | - Golnaz Vaseghi
- Applied Physiology Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, IR Iran
| | - Azadeh Mesripour
- Department of Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, IR Iran
| |
Collapse
|
7
|
Idrus NM, McGough NNH, Riley EP, Thomas JD. Administration of memantine during withdrawal mitigates overactivity and spatial learning impairments associated with neonatal alcohol exposure in rats. Alcohol Clin Exp Res 2014; 38:529-37. [PMID: 24428701 DOI: 10.1111/acer.12259] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 07/02/2013] [Indexed: 12/24/2022]
Abstract
BACKGROUND Prenatal alcohol exposure can disrupt central nervous system development, manifesting as behavioral deficits that include motor, emotional, and cognitive dysfunction. Both clinical and animal studies have reported binge drinking during development to be highly correlated with an increased risk of fetal alcohol spectrum disorders (FASD). We hypothesized that binge drinking may be especially damaging because it is associated with episodes of alcohol withdrawal. Specifically, we have been investigating the possibility that NMDA receptor-mediated excitotoxicity occurs during alcohol withdrawal and contributes to developmental alcohol-related neuropathology. Consistent with this hypothesis, administration of the NMDA receptor antagonists MK-801 or eliprodil during withdrawal attenuates behavioral alterations associated with early alcohol exposure. In this study, we investigated the effects of memantine, a clinically used NMDA receptor antagonist, on minimizing ethanol-induced overactivity and spatial learning deficits. METHODS Sprague-Dawley pups were exposed to 6.0 g/kg ethanol via intubation on postnatal day (PD) 6, a period of brain development that models late gestation in humans. Controls were intubated with a calorically matched maltose solution. During withdrawal, 24 and 36 hours after ethanol exposure, subjects were injected with a total of either 0, 20, or 30 mg/kg memantine. The subjects' locomotor levels were recorded in open field activity monitors on PDs 18 to 21 and on a serial spatial discrimination reversal learning task on PDs 40 to 43. RESULTS Alcohol exposure induced overactivity and impaired performance in spatial learning. Memantine administration significantly attenuated the ethanol-associated behavioral alterations in a dose-dependent manner. Thus, memantine may be neuroprotective when administered during ethanol withdrawal. CONCLUSIONS These data have important implications for the treatment of EtOH's neurotoxic effects and provide further support that ethanol withdrawal significantly contributes to FASD.
Collapse
Affiliation(s)
- Nirelia M Idrus
- Center for Behavioral Teratology, Department of Psychology, San Diego State University, San Diego, California
| | | | | | | |
Collapse
|
8
|
Postoperative pain impairs subsequent performance on a spatial memory task via effects on N-methyl-d-aspartate receptor in aged rats. Life Sci 2013; 93:986-93. [DOI: 10.1016/j.lfs.2013.10.028] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 10/03/2013] [Accepted: 10/25/2013] [Indexed: 01/14/2023]
|
9
|
Hashemi Nosrat Abadi T, Vaghef L, Babri S, Mahmood-Alilo M, Beirami M. Effects of different exercise protocols on ethanol-induced spatial memory impairment in adult male rats. Alcohol 2013; 47:309-16. [PMID: 23683528 DOI: 10.1016/j.alcohol.2013.01.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 01/26/2013] [Accepted: 01/28/2013] [Indexed: 12/30/2022]
Abstract
Chronic ethanol consumption is often accompanied by numerous cognitive deficits and may lead to long-lasting impairments in spatial learning and memory. The aim of the present study was to evaluate the therapeutic potential of regular treadmill exercise on hippocampal-dependent memory in ethanol-treated rats. Spatial memory was tested in a Morris Water Maze task. Adult male Wistar rats were exposed to ethanol (4 g/kg, 20% v/v for 4 weeks) and effects of three exercise protocols (pre-ethanol, post-ethanol and pre-to-post-ethanol treatment) were examined. Results showed that ethanol exposure resulted in longer escape latencies during the acquisition phase of the Morris Water Maze task. Moreover, all three exercise protocols significantly decreased the latency to locate the hidden platform. During the probe trial, ethanol led to decreased time spent in the target quadrant. In contrast, performance on the probe trial was significantly better in the rats that had done the post- and pre-to-post-ethanol, but not pre-ethanol, exercises. These findings suggest that treadmill running can attenuate the adverse effects of chronic ethanol exposure on spatial memory, and may serve as a non-pharmacological alcohol abuse treatment.
Collapse
|
10
|
Sabino V, Narayan AR, Zeric T, Steardo L, Cottone P. mTOR activation is required for the anti-alcohol effect of ketamine, but not memantine, in alcohol-preferring rats. Behav Brain Res 2013; 247:9-16. [PMID: 23466691 DOI: 10.1016/j.bbr.2013.02.030] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 02/23/2013] [Accepted: 02/25/2013] [Indexed: 02/06/2023]
Abstract
Glutamate NMDA receptors mediate many molecular and behavioral effects of alcohol, and they play a key role in the development of excessive drinking. Uncompetitive NMDA receptor antagonists may, therefore, have therapeutic potential for alcoholism. The first aim was to compare the effects of the NMDA antagonists memantine and ketamine on ethanol and saccharin drinking in alcohol-preferring rats. The second aim was to determine whether the effects of the two NMDA receptor antagonists were mediated by the mammalian target of rapamycin (mTOR). TSRI Sardinian alcohol-preferring rats were allowed to self-administer either 10% w/v ethanol or 0.08% w/v saccharin, and water. Operant responding and motor activity were assessed following administration of either memantine (0-10mg/kg) or ketamine (0-20mg/kg). Finally, ethanol self-administration was assessed in rats administered with either memantine or ketamine but pretreated with the mTOR inhibitor rapamycin (2.5mg/kg). The uncompetitive NMDA receptor antagonists memantine and ketamine dose-dependently reduced ethanol drinking in alcohol-preferring rats; while memantine had a preferential effect on alcohol over saccharin, ketamine reduced responding for both solutions. Neither antagonist induced malaise, as shown by the lack of effect on water intake and motor activity. The mTOR inhibitor rapamycin blocked the effects of ketamine, but not those of memantine. Memantine and ketamine both reduce alcohol drinking in alcohol-preferring rats, but only memantine is selective for alcohol. The effects of ketamine, but not memantine, are mediated by mTOR. The results support the therapeutic potential of uncompetitive NMDA receptor antagonists, especially memantine, in alcohol addiction.
Collapse
Affiliation(s)
- Valentina Sabino
- Laboratory of Addictive Disorders (LAD), Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA.
| | | | | | | | | |
Collapse
|
11
|
Possible antidepressant effects and mechanisms of memantine in behaviors and synaptic plasticity of a depression rat model. Neuroscience 2011; 182:88-97. [PMID: 21440043 DOI: 10.1016/j.neuroscience.2011.03.026] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 03/09/2011] [Accepted: 03/11/2011] [Indexed: 11/23/2022]
Abstract
Glutamatergic processes are strongly implicated in the pathophysiology and treatment of depression, including the antidepressant effects of N-methyl-D-aspartate (NMDA) receptor antagonists. This study was designed to see whether memantine, a noncompetitive NMDA antagonist, has antidepressant effects in behaviors and synaptic plasticity. Rats were randomly divided into control, stressed, and stressed+memantine groups. The animal model was established by chronic unpredictable stress. Memantine (20 mg/kg) was administrated i.p. for 21 days. Weight, sucrose consumption, water maze behavior and prefrontal cortical long-term potentiation (LTP) were measured, followed by immunohisotchemistry test of NR2B expression. Results showed that rats' weight and sucrose consumption were significantly lower in stressed group than those in control group, while the last time of sucrose consumption was improved by memantine. Rats in stressed group performed worse in reversal learning related stages, while rats in stressed+memantine group performed worse in spatial memory related stages. LTP test showed lower amplitude of field excitatory postsynaptic potential in prefrontal cortex in stressed group. Immunohistochemistry showed lower expression of NR2B receptor in prefrontal cortex in stressed group, and higher expression in hippocampus in stressed+memantine group. In conclusion, memantine in dose of 20 mg/kg improves the sucrose consumption, reversal learning and prefrontal cortical synaptic plasticity, but impairs spatial memory, which is probably due to different extent of up-regulating NR2B receptor expression in prefrontal cortex and hippocampus in stressed rats.
Collapse
|
12
|
Idrus NM, McGough NNH, Riley EP, Thomas JD. Administration of memantine during ethanol withdrawal in neonatal rats: effects on long-term ethanol-induced motor incoordination and cerebellar Purkinje cell loss. Alcohol Clin Exp Res 2010; 35:355-64. [PMID: 21070252 DOI: 10.1111/j.1530-0277.2010.01351.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Alcohol consumption during pregnancy can damage the developing fetus, illustrated by central nervous system dysfunction and deficits in motor and cognitive abilities. Binge drinking has been associated with an increased risk of fetal alcohol spectrum disorders, likely due to increased episodes of ethanol withdrawal. We hypothesized that overactivity of the N-methyl-D-aspartate (NMDA) receptor during ethanol withdrawal leads to excitotoxic cell death in the developing brain. Consistent with this, administration of NMDA receptor antagonists (e.g., MK-801) during withdrawal can attenuate ethanol's teratogenic effects. The aim of this study was to determine whether administration of memantine, an NMDA receptor antagonist, during ethanol withdrawal could effectively attenuate ethanol-related deficits, without the adverse side effects associated with other NMDA receptor antagonists. METHODS Sprague-Dawley pups were exposed to 6.0 g/kg ethanol or isocaloric maltose solution via intubation on postnatal day 6, a period of brain development equivalent to a portion of the 3rd trimester. Twenty-four and 36 hours after ethanol, subjects were injected with 0, 10, or 15 mg/kg memantine, totaling doses of 0, 20, or 30 mg/kg. Motor coordination was tested on a parallel bar task and the total number of cerebellar Purkinje cells was estimated using unbiased stereology. RESULTS Alcohol exposure induced significant parallel bar motor incoordination and reduced Purkinje cell number. Memantine administration significantly attenuated both ethanol-associated motor deficits and cerebellar cell loss in a dose-dependent manner. CONCLUSIONS Memantine was neuroprotective when administered during ethanol withdrawal. These data provide further support that ethanol withdrawal contributes to fetal alcohol spectrum disorders.
Collapse
Affiliation(s)
- Nirelia M Idrus
- Department of Psychology, Center for Behavioral Teratology, San Diego State University, California 92120, USA
| | | | | | | |
Collapse
|
13
|
Rammes G, Danysz W, Parsons CG. Pharmacodynamics of memantine: an update. Curr Neuropharmacol 2010; 6:55-78. [PMID: 19305788 PMCID: PMC2645549 DOI: 10.2174/157015908783769671] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 05/10/2007] [Accepted: 11/05/2007] [Indexed: 01/12/2023] Open
Abstract
Memantine received marketing authorization from the European Agency for the Evaluation of Medicinal Products (EMEA) for the treatment of moderately severe to severe Alzheimer s disease (AD) in Europe on 17(th) May 2002 and shortly thereafter was also approved by the FDA for use in the same indication in the USA. Memantine is a moderate affinity, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist with strong voltage-dependency and fast kinetics. Due to this mechanism of action (MOA), there is a wealth of other possible therapeutic indications for memantine and numerous preclinical data in animal models support this assumption. This review is intended to provide an update on preclinical studies on the pharmacodynamics of memantine, with an additional focus on animal models of diseases aside from the approved indication. For most studies prior to 1999, the reader is referred to a previous review [196].In general, since 1999, considerable additional preclinical evidence has accumulated supporting the use of memantine in AD (both symptomatic and neuroprotective). In addition, there has been further confirmation of the MOA of memantine as an uncompetitive NMDA receptor antagonist and essentially no data contradicting our understanding of the benign side effect profile of memantine.
Collapse
Affiliation(s)
- G Rammes
- Clinical Neuropharmacology, Max Planck Institute of Psychiatry, 80804 Munich, Germany
| | | | | |
Collapse
|
14
|
Malpass GE, Williams HL, McMillen BA. Effects of the non-competitive NMDA receptor antagonist memantine on the volitional consumption of ethanol by alcohol-preferring rats. Basic Clin Pharmacol Toxicol 2010; 106:435-44. [PMID: 20210793 DOI: 10.1111/j.1742-7843.2010.00544.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Potent N-methyl-d-aspartate (NMDA) receptor antagonists decrease volitional consumption of ethanol by rats. This study examined the effects of memantine, a low-affinity, open channel NMDA antagonist, on volitional consumption of ethanol by alcohol-preferring rats and potential locomotor, sedative and hypothermic effects. Volitional consumption of ethanol in a 24-hr two-choice paradigm was determined for male Myers' high-ethanol-preferring (mHEP) rats. Effects of memantine (0.3, 1.0, 3.0 and 10.0 mg/kg, i.p., b.i.d. [twice daily] for 3 days) or vehicle on volitional consumption of ethanol, proportion of ethanol to total fluids consumed, total fluid intake and consumption of food were observed. Potential sedating and locomotor effects of memantine (10.0 mg/kg, i.p., b.i.d.) were determined using an elevated plus maze and an Auto-Track Opto-Varimex activity monitoring system. Rectal temperature was measured to determine if memantine (10.0 mg/kg, i.p.) produces a hypothermic effect. The results indicate that memantine dose-dependently decreased the amount of ethanol and proportion of ethanol to total fluids consumed daily, reaching 48% and 24%, respectively, at the highest dose. These effects did not appear to be anti-caloric. Memantine (10.0 mg/kg) partially reversed both the sedation and the reductions in locomotor activity induced by ethanol. This dose did, however, produce a small, partially reversible hypothermic effect. In conclusion, memantine may decrease ethanol consumption with fewer side effects than other NMDA receptor antagonists, such as phencyclidine (PCP), MK 801 and ketamine.
Collapse
Affiliation(s)
- Gloria E Malpass
- Department of Pharmacology and Toxicology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | | | | |
Collapse
|
15
|
Min JA, Kim DJ, Lee CU. Alcohol and brain health: from mechanisms to interventions. JOURNAL OF THE KOREAN MEDICAL ASSOCIATION 2010. [DOI: 10.5124/jkma.2010.53.12.1115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Jung-Ah Min
- Department of Psychiatry, Seoul St. Mary's Hospital, The Catholic University of Korea School of Medicine, Seoul, Korea
| | - Dai-Jin Kim
- Department of Psychiatry, Seoul St. Mary's Hospital, The Catholic University of Korea School of Medicine, Seoul, Korea
| | - Chang-Uk Lee
- Department of Psychiatry, Seoul St. Mary's Hospital, The Catholic University of Korea School of Medicine, Seoul, Korea
| |
Collapse
|
16
|
The effect of 12-week open-label memantine treatment on cognitive function improvement in patients with alcohol-related dementia. Int J Neuropsychopharmacol 2008; 11:971-83. [PMID: 18346293 DOI: 10.1017/s1461145708008663] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
There is compelling evidence that alcohol-induced neurotoxicity is related to glutamate excitotoxicity. It was hypothesized that the low-affinity NMDA receptor antagonist memantine would improve the cognitive function of patients with alcoholic dementia. The aim of this study was to test this hypothesis and to evaluate the effect of memantine on the cognitive improvement of patients with alcohol-related dementia (ARD). The study was designed as a 12-wk open-label study investigating the efficacy of 20 mg memantine, a low-affinity NMDA receptor antagonist, as a treatment for cognitive and behavioural problems in 19 patients with probable ARD according to the criteria for ARD proposed by Oslin and colleagues. The CERAD-K (Consortium to Establish a Registry for Alzheimer's Disease - Korean version) and several clinical assessment scales were completed before and after the 12-wk memantine treatment period. Significant improvements in the mean scores from baseline to final assessment were observed in the Global Deterioration Scale (p<0.05), Brief Psychiatric Rating Scale (p<0.01), Geriatric Quality of Life - Dementia scale (p<0.01) and Neuropsychiatric Inventory (p<0.01) at the end of week 12. The CERAD-K subscales of word list recall (p<0.05), word list recognition (p<0.05), time orientation (p<0.01), drawing an interlocking pentagon (p<0.05), and the total MMSE-K (Mini Mental State Examination - Korean version) scores (p<0.01) of the patients all showed significant improvement following the memantine trial. In this open-label study, patients with ARD treated with 20 mg/d memantine for 12 wk showed improvement on global cognition, quality of life and behavioural symptoms. The result of this study suggests the possible usefulness of memantine for the treatment of ARD. As this was an open-label study, the possibility that participants improved cognitively on their own due to protracted abstinence from alcohol cannot be discounted.
Collapse
|
17
|
Brooks S, Croft A, Norman G, Shaw S, Little H. Nimodipine prior to alcohol withdrawal prevents memory deficits during the abstinence phase. Neuroscience 2008; 157:376-84. [DOI: 10.1016/j.neuroscience.2008.09.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 08/20/2008] [Accepted: 09/04/2008] [Indexed: 10/21/2022]
|
18
|
Jacquot C, Croft AP, Prendergast MA, Mulholland P, Shaw SG, Little HJ. Effects of the glucocorticoid antagonist, mifepristone, on the consequences of withdrawal from long term alcohol consumption. Alcohol Clin Exp Res 2008; 32:2107-16. [PMID: 18828802 DOI: 10.1111/j.1530-0277.2008.00799.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Studies were carried out to test the hypothesis that administration of a glucocorticoid Type II receptor antagonist, mifepristone (RU38486), just prior to withdrawal from chronic alcohol treatment, would prevent the consequences of the alcohol consumption and withdrawal in mice. MATERIALS AND METHODS The effects of administration of a single intraperitoneal dose of mifepristone were examined on alcohol withdrawal hyperexcitability. Memory deficits during the abstinence phase were measured using repeat exposure to the elevated plus maze, the object recognition test, and the odor habituation/discrimination test. Neurotoxicity in the hippocampus and prefrontal cortex was examined using NeuN staining. RESULTS Mifepristone reduced, though did not prevent, the behavioral hyperexcitability seen in TO strain mice during the acute phase of alcohol withdrawal (4 hours to 8 hours after cessation of alcohol consumption) following chronic alcohol treatment via liquid diet. There were no alterations in anxiety-related behavior in these mice at 1 week into withdrawal, as measured using the elevated plus maze. However, changes in behavior during a second exposure to the elevated plus maze 1 week later were significantly reduced by the administration of mifepristone prior to withdrawal, indicating a reduction in the memory deficits caused by the chronic alcohol treatment and withdrawal. The object recognition test and the odor habituation and discrimination test were then used to measure memory deficits in more detail, at between 1 and 2 weeks after alcohol withdrawal in C57/BL10 strain mice given alcohol chronically via the drinking fluid. A single dose of mifepristone given at the time of alcohol withdrawal significantly reduced the memory deficits in both tests. NeuN staining showed no evidence of neuronal loss in either prefrontal cortex or hippocampus after withdrawal from chronic alcohol treatment. CONCLUSIONS The results suggest mifepristone may be of value in the treatment of alcoholics to reduce their cognitive deficits.
Collapse
Affiliation(s)
- Catherine Jacquot
- Department of Basic Medical Sciences, St George's, University of London, Cranmer Terrace, London, United Kingdom
| | | | | | | | | | | |
Collapse
|
19
|
Krivoy A, Weizman A, Laor L, Hellinger N, Zemishlany Z, Fischel T. Addition of memantine to antipsychotic treatment in schizophrenia inpatients with residual symptoms: A preliminary study. Eur Neuropsychopharmacol 2008; 18:117-21. [PMID: 17728110 DOI: 10.1016/j.euroneuro.2007.07.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 07/06/2007] [Accepted: 07/12/2007] [Indexed: 11/27/2022]
Abstract
BACKGROUND Schizophrenia is comprised of several debilitating symptoms. Antipsychotics offer an effective treatment for positive symptoms, while the negative signs and cognitive deficits are usually treatment-resistant. It was suggested that glutamate dysregulation may be involved in the neuropathology of schizophrenia, mainly through NMDA dysfunction. We hypothesized that addition of memantine, a weak non-selective NMDA receptor antagonist approved for dementia, to antipsychotics would improve the clinical status of un-remitted schizophrenia patients, notably the negative signs and cognitive deficits. METHODS Seven schizophrenia patients, were included in a six-week open-label study, with weekly increasing dosage (5, 10, 15, 20 mg) of memantine added to their on-going antipsychotic treatment. RESULTS We found a significant improvement of the PANSS score (baseline 116.28+/-21.9 vs. 97.86+/-24.48 after six weeks, t=5.98, p<0.001) with the most prominent improvement (21%) in negative signs sub-scale (baseline 40+/-6.38 vs. 31.71+/-7.76 after six weeks, t=5.87, p<0.001). Cognitive status, measured with the Neurobehavioral Cognitive Examination (NCSE) and Clock Drawing Test (CDT) showed no improvement. CONCLUSION Memantine addition to antipsychotic treatment, in schizophrenia patients might improve their clinical status, primarily the negative signs, but not their cognitive deficits. Further research is needed to replicate these observations.
Collapse
Affiliation(s)
- Amir Krivoy
- Geha Mental Health Center, Petach-Tikva, Israel.
| | | | | | | | | | | |
Collapse
|
20
|
Abstract
Abnormalities in hippocampal structure and function are characteristics of early Alzheimer's disease (AD). Behavioral tests measuring hippocampal-dependent memory in rodents are often used to evaluate novel treatments for AD and other dementias. In this study, we review the effects of drugs marketed for the treatment of AD, such as the acetylcholinesterase inhibitors, donepezil, rivastigmine, galantamine and the N-methyl-D-aspartic acid antagonist, memantine, in rodent models of memory impairment. We also briefly describe the effects of novel treatments for cognitive impairment in rodent models of memory impairment, and discuss issues concerning the selection of the animal model and behavioral tests. Suggestions for future research are offered.
Collapse
Affiliation(s)
- Carla M. Yuede
- Department of Psychiatry, Washington University School of Medicine, St Louis, Missouri, USA
| | - Hongxin Dong
- Department of Psychiatry, Washington University School of Medicine, St Louis, Missouri, USA
| | - John G. Csernansky
- Department of Psychiatry, Washington University School of Medicine, St Louis, Missouri, USA
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri, USA
| |
Collapse
|
21
|
Parsons CG, Stöffler A, Danysz W. Memantine: a NMDA receptor antagonist that improves memory by restoration of homeostasis in the glutamatergic system--too little activation is bad, too much is even worse. Neuropharmacology 2007; 53:699-723. [PMID: 17904591 DOI: 10.1016/j.neuropharm.2007.07.013] [Citation(s) in RCA: 464] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 06/19/2007] [Accepted: 07/17/2007] [Indexed: 12/13/2022]
Abstract
The neurotransmitter glutamate activates several classes of metabotropic receptor and three major types of ionotropic receptor--alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and N-methyl-D-aspartate (NMDA). The involvement of glutamate mediated neurotoxicity in the pathogenesis of Alzheimer's disease (AD) is finding increasing scientific acceptance. Central to this hypothesis is the assumption that glutamate receptors, in particular of the NMDA type, are overactivated in a tonic rather than a phasic manner. Such continuous, mild, chronic activation ultimately leads to neuronal damage/death. Additionally, impairment of synaptic plasticity (learning) may result not only from neuronal damage per se but may also be a direct consequence of this continuous, non-contingent NMDA receptor activation. Complete NMDA receptor blockade has also been shown to impair neuronal plasticity, thus, both hypo- and hyperactivity of the glutamatergic system leads to dysfunction. Memantine received marketing authorization from the EMEA (European Medicines Agency) for the treatment of moderate to severe AD in Europe and was subsequently also approved by the FDA (Food and Drug Administration) for use in the same indication in the USA. Memantine is a moderate affinity, uncompetitive NMDA receptor antagonist with strong voltage-dependency and fast kinetics. This review summarizes existing hypotheses on the mechanism of action (MOA) of memantine in an attempt to understand how the accepted interaction with NMDA receptors could allow memantine to provide both neuroprotection and reverse deficits in learning/memory by the same MOA.
Collapse
Affiliation(s)
- Chris G Parsons
- Merz Pharmaceuticals, Eckenheimer Landstrasse 100, 60318 Frankfurt am Main, Germany
| | | | | |
Collapse
|
22
|
Slawecki CJ. Two-choice reaction time performance in Sprague-Dawley rats exposed to alcohol during adolescence or adulthood. Behav Pharmacol 2006; 17:605-14. [PMID: 17021393 DOI: 10.1097/01.fbp.0000236272.10418.62] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Adolescent alcohol abusers display subtle attention impairments. This study used a two-choice reaction time task to examine the effects of ethanol on sustained attention following adult or adolescent exposure. Sprague-Dawley rats were exposed to ethanol vapor for 14 days starting on postnatal day 30 (adolescence) or 60-64 (adulthood) and were then trained to perform the two-choice reaction time task. Ethanol exposure resulted in blood ethanol levels averaging 215 mg/dl. Behavior following adult ethanol exposure was characterized by increased accuracy and omissions during the two-choice reaction time task, reduced fixed ratio lever pressing, and reductions in the highest fixed ratio completed on a progressive ratio schedule. Adolescent ethanol exposure transiently increased two-choice reaction time accuracy and slightly reduced fixed ratio lever presses. Improved accuracy was unexpected, but might be related to ethanol-induced increases in central nervous system arousal and/or mild behavioral perseveration. Increased omissions, reduced lever pressing, and reductions in the highest fixed ratios completed most likely reflect decreased 'motivation to work' and index generalized anhedonia. This study is the first to demonstrate that rats exposed to ethanol during adulthood are more sensitive to the effects of ethanol on sustained attention than rats exposed to ethanol during adolescence and to ethanol-induced anhedonia, as indexed by two-choice reaction time performance.
Collapse
Affiliation(s)
- Craig J Slawecki
- Molecular and Integrative Neuroscience Department, The Scripps Research Institute, La Jolla, California 92037, USA.
| |
Collapse
|
23
|
Hamelink C, Hampson A, Wink DA, Eiden LE, Eskay RL. Comparison of cannabidiol, antioxidants, and diuretics in reversing binge ethanol-induced neurotoxicity. J Pharmacol Exp Ther 2005; 314:780-8. [PMID: 15878999 PMCID: PMC4183207 DOI: 10.1124/jpet.105.085779] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Binge alcohol consumption in the rat induces substantial neurodegeneration in the hippocampus and entorhinal cortex. Oxidative stress and cytotoxic edema have both been shown to be involved in such neurotoxicity, whereas N-methyl-d-aspartate (NMDA) receptor activity has been implicated in alcohol withdrawal and excitoxic injury. Because the nonpsychoactive cannabinoid cannabidiol (CBD) was previously shown in vitro to prevent glutamate toxicity through its ability to reduce oxidative stress, we evaluated CBD as a neuroprotectant in a rat binge ethanol model. When administered concurrently with binge ethanol exposure, CBD protected against hippocampal and entorhinal cortical neurodegeneration in a dose-dependent manner. Similarly, the common antioxidants butylated hydroxytoluene and alpha-tocopherol also afforded significant protection. In contrast, the NMDA receptor antagonists dizocilpine (MK-801) and memantine did not prevent cell death. Of the diuretics tested, furosemide was protective, whereas the other two anion exchanger inhibitors, L-644,711 [(R)-(+)-(5,6-dichloro2,3,9,9a-tetrahydro 3-oxo-9a-propyl-1H-fluoren-7-yl)oxy acetic acid] and bumetanide, were ineffective. In vitro comparison of these diuretics indicated that furosemide is also a potent antioxidant, whereas the nonprotective diuretics are not. The lack of efficacy of L-644,711 and bumetanide suggests that the antioxidant rather than the diuretic properties of furosemide contribute most critically to its efficacy in reversing ethanol-induced neurotoxicity in vitro, in our model. This study provides the first demonstration of CBD as an in vivo neuroprotectant and shows the efficacy of lipophilic antioxidants in preventing binge ethanol-induced brain injury.
Collapse
Affiliation(s)
- Carol Hamelink
- Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulatiuon, National Institute of Mental Health/NIH, Bldg. 49, Room 5A-35, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | | | | | | | | |
Collapse
|
24
|
Rice AC, Bullock MR, Shelton KL. Chronic ethanol consumption transiently reduces adult neural progenitor cell proliferation. Brain Res 2004; 1011:94-8. [PMID: 15140648 DOI: 10.1016/j.brainres.2004.01.091] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2004] [Indexed: 11/24/2022]
Abstract
Adult neural stem/progenitor cells proliferate throughout the life of the animal in the subependymal zone and the subgranular zone of the dentate gyrus (DG). Treatments such as enriched environment, dietary restriction, running and anti-depressants increase proliferation, however, stress and opiates have been shown to decrease proliferation. While models of binge ethanol drinking decreases proliferation, few studies have characterized the effect chronic ethanol usage has on progenitor cell proliferation. In this study, we have examined changes in the progenitor cell proliferation rate following chronic ethanol consumption. Animals were given a nutritionally balanced liquid diet containing 6.5% v/v ethanol or an isocalorically balanced liquid diet. Bromodeoxyuridine (BrdU) was administered (150 mg/kg x 3) and the animals sacrificed 2 h after the last injection on days 3, 10 or 30 of the ethanol diet. Coronal brain blocks were paraffin embedded and 6 microm sections sliced and immunohistochemically stained for BrdU. Quantitation of the number of BrdU-labeled cells in the subgranular zone of the DG revealed a significant decrease only at the 3-day time-point, with recovery by the 10- and 30-day time-points. Thus, the progenitor cell proliferation rate is transiently decreased by chronic ethanol usage. This data suggests that chronic alcohol use results in a compensatory response that restores the progenitor cell proliferation rate.
Collapse
Affiliation(s)
- Ann C Rice
- Department of Neurosurgery, Virginia Commonwealth University, 8th floor West Hospital Box 980631, 1200 E. Broad St., Richmond, VA 23298-0613, USA.
| | | | | |
Collapse
|
25
|
Danysz W, Parsons CG. The NMDA receptor antagonist memantine as a symptomatological and neuroprotective treatment for Alzheimer's disease: preclinical evidence. Int J Geriatr Psychiatry 2003; 18:S23-32. [PMID: 12973747 DOI: 10.1002/gps.938] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
There is increasing evidence for the involvement of glutamate-mediated neurotoxicity in the pathogenesis of Alzheimer's disease (AD). We suggest that glutamate receptors of the N-methyl-D-aspartate (NMDA) type are overactivated in a tonic rather than a phasic manner in this disorder. This continuous mild activation may lead to neuronal damage and impairment of synaptic plasticity (learning). It is likely that under such conditions Mg(2+) ions, which block NMDA receptors under normal resting conditions, can no longer do so. We found that overactivation of NMDA receptors using a direct agonist or a decrease in Mg(2+) concentration produced deficits in synaptic plasticity (in vivo: passive avoidance test and/or in vitro: LTP in the CA1 region). In both cases, memantine-an uncompetitive NMDA receptor antagonists with features of an 'improved' Mg(2+) (voltage-dependency, kinetics, affinity)-attenuated this deficit. Synaptic plasticity was restored by therapeutically-relevant concentrations of memantine (1 microM). Moreover, doses leading to similar brain/serum levels provided neuroprotection in animal models relevant for neurodegeneration in AD such as neurotoxicity produced by inflammation in the NBM or beta-amyloid injection to the hippocampus. As such, if overactivation of NMDA receptors is present in AD, memantine would be expected to improve both symptoms (cognition) and to slow down disease progression because it takes over the physiological function of magnesium.
Collapse
|
26
|
Boulouard M, Lelong V, Daoust M, Naassila M. Chronic ethanol consumption induces tolerance to the spatial memory impairing effects of acute ethanol administration in rats. Behav Brain Res 2002; 136:239-46. [PMID: 12385810 DOI: 10.1016/s0166-4328(02)00134-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A large number of studies in rats have investigated the effects of acute and chronic ethanol administration on performance on many spatial learning and memory tasks. However, no study has addressed the problem of whether chronic ethanol consumption induces tolerance to acute ethanol-induced spatial memory deficits. In this study, we analyzed the behavioral effects of acute ethanol administration on spatial memory and locomotor activity in rats chronically intoxicated by ethanol. Male Sprague-Dawley rats were given as their only available liquid source a 10% (v/v) aqueous ethanol solution for 2 weeks before behavioral testing and during the 1-week behavioral testing period. They were treated intraperitoneally with 1.5 g/kg of ethanol 30 min before daily training in the Morris water maze, a spatial memory task sensitive to hippocampal damage. Our results demonstrate that learning and spatial memory of ethanol-consuming animals were not altered compared with control rats. Chronic ethanol consumption had no effect on spatial reference memory in terms of either the distance traveled to find the hidden platform during the acquisition phase of the experiment, or the time spent in the training quadrant during the retention trial. Acute ethanol administration impaired spatial memory in control rats and this impairment was reversed in chronic ethanol-consuming animals, revealing that chronic ethanol consumption did induce tolerance to the spatial memory deficits induced by acute ethanol injection, although plasma ethanol levels did not differ between the two groups. In contrast, chronic ethanol consumption did not induce tolerance to the acute ethanol-induced stimulatory locomotor activity measured in the same animals. Our results, therefore, indicate that chronic ethanol consumption induces tolerance to the cognitive impairing effects, but not to the locomotor stimulatory effects of acute ethanol administration in rats, suggesting that these two behavioral effects of ethanol do not share a common mechanism in the CNS.
Collapse
Affiliation(s)
- Michel Boulouard
- Laboratoire de Pharmacologie, CERMN, UPRESS EA 2126, Université de Caen, UFR des Sciences Pharmaceutiques, 1, rue Vaubénard, France.
| | | | | | | |
Collapse
|