Chronic memantine decreases nicotine self-administration in rats.
Neurobehavioral bases of tobacco addiction and nicotine reinforcement are complex, involving more than only nicotinic cholinergic or dopaminergic systems. Memantine is an NMDA glutamate antagonist used to improve cognitive function in people with Alzheimer's disease. Glutamate may be an important component of the reinforcing effects of nicotine, so memantine was evaluated as a potential smoking cessation aid. Two studies were conducted with adult female rats, one testing acute effects of memantine over a range of doses for changing nicotine self-administration and the other testing the chronic effects of memantine to reduce nicotine self-administration. Acute memantine injections slightly, but significantly, increased nicotine self-administration in a dose-related manner. In contrast, chronic memantine treatment significantly reduced nicotine self-administration. During the first day of memantine administration in the chronic study, nicotine self-administration was significantly elevated replicating the acute study. Starting in the second week of treatment there was a significant reduction of nicotine self-administration relative to controls. This was seen because memantine treatment prevented the increase in nicotine self-administration shown by controls. There even continued to be a memantine-induced lowered nicotine self-administration during the week after the cessation of memantine treatment. Memantine or other drugs affecting NMDA glutamate receptors may be useful aids to smoking cessation. Full efficacy for reducing nicotine self-administration was seen as the NMDA drug treatment is given chronically. Importantly, the effect persisted even after treatment is ended, indicating the high potential for NMDA glutamate receptors to impact nicotine addiction.
Published Version (Please cite this version)
Levin, Edward D, Corinne Wells, Leah Yao, Wendi Guo, Anica Nangia, Sarah Howard, Erica Pippen, Andrew B Hawkey, et al. (2019). Chronic memantine decreases nicotine self-administration in rats. European journal of pharmacology, 861. p. 172592. 10.1016/j.ejphar.2019.172592 Retrieved from https://hdl.handle.net/10161/29509.
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Dr. Levin is Chief of the Neurobehavioral Research Lab in the Psychiatry Department of Duke University Medical Center. His primary academic appointment is as Professor in the Department of Psychiatry and Behavioral Sciences. He also has secondary appointments in the Department Pharmacology and Cancer Biology, the Department of Psychological and Brain Sciences and the Nicholas School of the Environment at Duke. His primary research effort is to understand basic neural interactions underlying cognitive function and addiction and to apply this knowledge to better understand cognitive dysfunction and addiction disorders and to develop novel therapeutic treatments.
The three main research components of his laboratory are focused on the themes of the basic neurobiology of cognition and addiction, neurobehavioral toxicology and the development of novel therapeutic treatments for cognitive dysfunction and substance abuse. Currently, our principal research focus concerns nicotine. We have documented the basic effects of nicotine on learning memory and attention as well as nicotine self-administration. We are continuing with more mechanistic studies in rat models using selective lesions, local infusions and neurotransmitter interaction studies. We have found that nicotine improves memory performance not only in normal rats, but also in rats with lesions of hippocampal and basal forebrain connections. We are concentrating on alpha7 and alpha4beta2 nicotinic receptor subtypes in the hippocampus, amygdala , thalamus and frontal cortex and how they interact with dopamine D1 and D2 and glutamate NMDA systems with regard to memory and addiction. I am also conducting studies on human cognitive behavior. We have current studies to assess nicotine effects on attention, memory and mental processing speed in schizophrenia, Alzheimer's Disease and Attention Deficit Hyperactivity Disorder. In the area of neurobehavioral toxicology, I have continuing projects to characterize the adverse effects of prenatal and adolescent nicotine exposure. Our primary project in neurobehavioral toxicology focuses on the cognitive deficits caused by the marine toxins. The basic and applied aims of our research complement each other nicely. The findings concerning neural mechanisms underlying cognitive function help direct the behavioral toxicology and therapeutic development studies, while the applied studies provide important functional information concerning the importance of the basic mechanisms under investigation.
We are pursuing three main lines of research:
1) Brain imaging of the effects of nicotine and cigarette smoking: We have used Positron Emission Tomography (PET) methods to analyze regional cerebral blood flow responses to nicotine, administered either intravenously or inhaled in cigarettes. Our aim is to identify brain substrates mediating the addictive properties of nicotine. Preliminary results have shown alterations in the pattern of regional cerebral blood flow, involving frontal cortex, amygdala and other brain regions. We will continue to delineate the similarities and differences between the effects of nicotine and other drugs on regional brain activity, and plan to monitor the changes in response to nicotine after smoking cessation with nicotine antagonist treatment.
2) Analysis of airway sensory components of smoking reinforcement: We have continued the study the role of sensorimotor aspects of cigarette smoking in relieving craving for cigarettes and regulating smoke intake. We completed a study of the effects of intravenous nicotine presented alone or in combination with the sensorimotor aspects of smoking using de-nicotinized cigarette smoke. Craving for cigarettes was relieved more effectively by the de-nicotinized smoke than by the intravenous nicotine. Current studies underway at the Clinical Research Unit will further investigate the subjective effects of i.v. nicotine and de-nicotinized cigarette smoke, using a wider range of nicotine doses. Possible predictors of clinical outcome following nicotine skin patch treatment will be identified based on acute responses to the pharmacologic effects of nicotine in the laboratory.
We are also continuing to further the clinical application of these findings by developing substitutes that provide the airways sensory effects of smoking (e.g. citric acid aerosol).
3) Agonist/antagonist combination treatment for drug dependence: In a double blind smoking cessation trial using mecamylamine, a nicotinic antagonist, in combination with nicotine skin patches, we found that addition of the antagonist substantially increases smoking abstinence throughout the 1 year follow-up. Two additional studies that we conducted support the view that pre-treatment with mecamylamine prior to smoking cessation may be a critical factor in achieving high success rates. By blocking reinforcing effects of nicotine, smoking behavior may be partially extinguished, thereby facilitating subsequent smoking cessation. We recently completed a Phase II FDA trial evaluating a transdermal patch delivering nicotine and mecamylamine, which replicated our previous results. It is anticipated that an NDA pertaining to the new skin patch will be submitted in 1997. Continuing studies in our program will determine the optimal dose and duration of treatment. We also have initiated studies to extend this approach to the treatment of other drug dependencies, including cocaine.
My research and teaching interests have been primarily focused on the following areas:
Alcoholism: I work with "alcoholic" rats with genetic predisposition!" We use selectively-bred alcohol preferring rats as an animal model of human alcoholism for developing better pharmacological treatments for alcoholism. Recently, we are working on several novel promising "anti-craving" compounds for the treatment of alcoholism. We are also studying the interaction between alcohol drinking and nicotine intake.
Nicotine Addiction: We have been studying age and sex differences in i.v. nicotine self-administration in rats. We have found that pattern of drug intake is both age- and sex-dependent. Our lab is also exploring different neuronal targets for developing better pharmacologic treatment for nicotine addiction.
Sustained Attention: Another aspect of our research is studying the role of the neuronal nicotinic and other neuronal systems in sustained attention using a rodent model. We have shown, nicotine (not smoking!) and nicotinic compounds improve attention in rats. A majority of people with schizophrenia smoke and they smoke heavily. Thus, it is important to understand the interaction of antipsychotic medications and nicotine in sustained attention. This has been another aspect of our research with interesting results. Presently, we are testing novel nicotinic compounds for improving pharmacologically-impaired sustained attention.
Teaching: I love to teach and interact with students. Since arriving at Duke in 1999, I have been team-teaching the popular alcohol course (Psych 206-01R; Alcohol: Brain, Society and Individual). I also enjoy mentoring undergrad students who are interested in science and enjoy working in the lab with cute little creatures!.
Community: I am a member of the Board of Directors of Triangle Residential Options for Substance Abusers (TROSA), a self-supported therapeutic community in Durham. I also give seminars and workshops on addiction around the country.
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