501
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Priddy BM, Carmack SA, Thomas LC, Vendruscolo JCM, Koob GF, Vendruscolo LF. Sex, strain, and estrous cycle influences on alcohol drinking in rats. Pharmacol Biochem Behav 2016; 152:61-67. [PMID: 27498303 DOI: 10.1016/j.pbb.2016.08.001] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 08/01/2016] [Accepted: 08/03/2016] [Indexed: 11/24/2022]
Abstract
Although women appear to be more vulnerable to alcohol-induced pathophysiology than men, the neurobiological basis for sex differences is largely unknown, partially because most studies on alcohol drinking are conducted in male subjects only. The present study examined sex differences in alcohol consumption in two rat strains, Long Evans and Wistar, using multiple behavioral paradigms. The effects of the estrous cycle on alcohol consumption were monitored throughout the study. The results indicated that females drank more alcohol than males when given either continuous or intermittent access to alcohol (vs. water) in their home cages (voluntary drinking). Under operant conditions, no sex or strain differences were found in drinking prior to development of alcohol dependence. However, upon dependence induction by chronic, intermittent alcohol vapor exposure, Wistar rats of both sexes substantially escalated their alcohol intake compared with their nondependent drinking levels, whereas Long Evans rats only exhibited a moderate escalation of drinking. Under these conditions, the estrous cycle had no effect on alcohol drinking in any strain and drinking model. Thus, strain, sex, and drinking conditions interact to modulate nondependent and dependent alcohol drinking. The present results emphasize the importance of including sex and strain as biological variables in exploring individual differences in alcohol drinking and dependence.
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Affiliation(s)
- Brittany M Priddy
- Neurobiology of Addiction Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Stephanie A Carmack
- Neurobiology of Addiction Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Lisa C Thomas
- Neurobiology of Addiction Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Janaina C M Vendruscolo
- Neurobiology of Addiction Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - George F Koob
- Neurobiology of Addiction Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Leandro F Vendruscolo
- Neurobiology of Addiction Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA.
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502
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Cao J, Dorris DM, Meitzen J. Neonatal Masculinization Blocks Increased Excitatory Synaptic Input in Female Rat Nucleus Accumbens Core. Endocrinology 2016; 157:3181-96. [PMID: 27285859 PMCID: PMC4967116 DOI: 10.1210/en.2016-1160] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/04/2016] [Indexed: 01/18/2023]
Abstract
Steroid sex hormones and genetic sex regulate the phenotypes of motivated behaviors and relevant disorders. Most studies seeking to elucidate the underlying neuroendocrine mechanisms have focused on how 17β-estradiol modulates the role of dopamine in striatal brain regions, which express membrane-associated estrogen receptors. Dopamine action is an important component of striatal function, but excitatory synaptic neurotransmission has also emerged as a key striatal substrate and target of estradiol action. Here, we focus on excitatory synaptic input onto medium spiny neurons (MSNs) in the striatal region nucleus accumbens core (AcbC). In adult AcbC, miniature excitatory postsynaptic current (mEPSC) frequency is increased in female compared with male MSNs. We tested whether increased mEPSC frequency in female MSNs exists before puberty, whether this increased excitability is due to the absence of estradiol or testosterone during the early developmental critical period, and whether it is accompanied by stable neuron intrinsic membrane properties. We found that mEPSC frequency is increased in female compared with male MSNs before puberty. Increased mEPSC frequency in female MSNs is abolished after neonatal estradiol or testosterone exposure. MSN intrinsic membrane properties did not differ by sex. These data indicate that neonatal masculinization via estradiol and/or testosterone action is sufficient for down-regulating excitatory synaptic input onto MSNs. We conclude that excitatory synaptic input onto AcbC MSNs is organized long before adulthood via steroid sex hormone action, providing new insight into a mechanism by which sex differences in motivated behavior and other AbcC functions may be generated or compromised.
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Affiliation(s)
- Jinyan Cao
- Department of Biological Sciences (J.C., D.M.D., J.M.), North Carolina State University, Raleigh, North Carolina 27695; W.M. Keck Center for Behavioral Biology (J.C., J.M.), North Carolina State University, Raleigh, North Carolina 27695; Center for Human Health and the Environment (J.M.), North Carolina State University, Raleigh, North Carolina 27695; and Comparative Medicine Institute (J.M.), North Carolina State University, Raleigh, North Carolina 27695
| | - David M Dorris
- Department of Biological Sciences (J.C., D.M.D., J.M.), North Carolina State University, Raleigh, North Carolina 27695; W.M. Keck Center for Behavioral Biology (J.C., J.M.), North Carolina State University, Raleigh, North Carolina 27695; Center for Human Health and the Environment (J.M.), North Carolina State University, Raleigh, North Carolina 27695; and Comparative Medicine Institute (J.M.), North Carolina State University, Raleigh, North Carolina 27695
| | - John Meitzen
- Department of Biological Sciences (J.C., D.M.D., J.M.), North Carolina State University, Raleigh, North Carolina 27695; W.M. Keck Center for Behavioral Biology (J.C., J.M.), North Carolina State University, Raleigh, North Carolina 27695; Center for Human Health and the Environment (J.M.), North Carolina State University, Raleigh, North Carolina 27695; and Comparative Medicine Institute (J.M.), North Carolina State University, Raleigh, North Carolina 27695
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503
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Spear LP. Consequences of adolescent use of alcohol and other drugs: Studies using rodent models. Neurosci Biobehav Rev 2016; 70:228-243. [PMID: 27484868 DOI: 10.1016/j.neubiorev.2016.07.026] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Revised: 07/08/2016] [Accepted: 07/22/2016] [Indexed: 10/21/2022]
Abstract
Studies using animal models of adolescent exposure to alcohol, nicotine, cannabinoids, and the stimulants cocaine, 3,4-methylenedioxymethampethamine and methamphetamine have revealed a variety of persisting neural and behavioral consequences. Affected brain regions often include mesolimbic and prefrontal regions undergoing notable ontogenetic change during adolescence, although it is unclear whether this represents areas of specific vulnerability or particular scrutiny to date. Persisting alterations in forebrain systems critical for modulating reward, socioemotional processing and cognition have emerged, including apparent induction of a hyper-dopaminergic state with some drugs and/or attenuations in neurons expressing cholinergic markers. Disruptions in cognitive functions such as working memory, alterations in affect including increases in social anxiety, and mixed evidence for increases in later drug self-administration has also been reported. When consequences of adolescent and adult exposure were compared, adolescents were generally found to be more vulnerable to alcohol, nicotine, and cannabinoids, but generally not to stimulants. More work is needed to determine how adolescent drug exposure influences sculpting of the adolescent brain, and provide approaches to prevent/reverse these effects.
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Affiliation(s)
- Linda Patia Spear
- Department of Psychology, Developmental Exposure Alcohol Research Center (DEARC), Binghamton University, Binghamton, NY, United States.
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504
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Zakiniaeiz Y, Cosgrove KP, Potenza MN, Mazure CM. Balance of the Sexes: Addressing Sex Differences in Preclinical Research. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2016; 89:255-9. [PMID: 27354851 PMCID: PMC4918870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Preclinical research is fundamental for the advancement of biomedical sciences and enhancing healthcare. Considering sex differences in all studies throughout the entire biomedical research pipeline is necessary to adequately inform clinical research and improve health outcomes. However, there is a paucity of information to date on sex differences in preclinical work. As of 2009, most (about 80 percent) rodent studies across 10 fields of biology were still conducted with only male animals. In 2016, the National Institutes of Health implemented a policy aimed to address this concern by requiring the consideration of sex as a biological variable in preclinical research grant applications. This perspective piece aims to (1) provide a brief history of female inclusion in biomedical research, (2) describe the importance of studying sex differences, (3) explain possible reasons for opposition of female inclusion, and (4) present potential additional solutions to reduce sex bias in preclinical research.
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Affiliation(s)
- Yasmin Zakiniaeiz
- Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT,To whom all correspondence should be addressed: Yasmin Zakiniaeiz, 1 Church Street, Suite 721, New Haven, CT 06510; Tel: 203-737-3448;
| | - Kelly P. Cosgrove
- Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT,Department of Radiology and Bioimaging, Yale University, New Haven, CT,Department of Psychiatry, Yale University, New Haven, CT,Department of Neuroscience, Yale University School of Medicine, New Haven, CT
| | - Marc N. Potenza
- Department of Psychiatry, Yale University, New Haven, CT,Department of Neuroscience, Yale University School of Medicine, New Haven, CT,Child Study Center, Yale University School of Medicine, New Haven, CT,CASAColumbia, Yale University School of Medicine, New Haven, CT,Connecticut Mental Health Center, New Haven, CT,Women’s Health Research at Yale, New Haven, CT
| | - Carolyn M. Mazure
- Department of Psychiatry, Yale University, New Haven, CT,Women’s Health Research at Yale, New Haven, CT
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505
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Hamson DK, Roes MM, Galea LAM. Sex Hormones and Cognition: Neuroendocrine Influences on Memory and Learning. Compr Physiol 2016; 6:1295-337. [DOI: 10.1002/cphy.c150031] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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506
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Lacy RT, Brown RW, Morgan AJ, Mactutus CF, Harrod SB. Intravenous Prenatal Nicotine Exposure Alters METH-Induced Hyperactivity, Conditioned Hyperactivity, and BDNF in Adult Rat Offspring. Dev Neurosci 2016; 38:171-185. [PMID: 27287203 DOI: 10.1159/000446563] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 04/26/2016] [Indexed: 01/01/2023] Open
Abstract
In the USA, approximately 15% of women smoke tobacco cigarettes during pregnancy. In utero tobacco smoke exposure produces somatic growth deficits like intrauterine growth restriction and low birth weight in offspring, but it can also negatively influence neurodevelopmental outcomes in later stages of life, such as an increased incidence of obesity and drug abuse. Animal models demonstrate that prenatal nicotine (PN) alters the development of the mesocorticolimbic system, which is important for organizing goal-directed behavior. In the present study, we determined whether intravenous (IV) PN altered the initiation and/or expression of methamphetamine (METH)-induced locomotor sensitization as a measure of mesocorticolimbic function in adult rat offspring. We also determined whether PN and/or METH exposure altered protein levels of BDNF (brain-derived neurotrophic factor) in the nucleus accumbens, the dorsal striatum, and the prefrontal cortex of adult offspring. BDNF was of interest because of its role in the development and maintenance of the mesocorticolimbic pathway and its ability to modulate neural processes that contribute to drug abuse, such as sensitization of the dopamine system. Dams were injected with IV nicotine (0.05 mg/kg/injection) or saline, 3×/day on gestational days 8-21. Testing was conducted when offspring reached adulthood (around postnatal day 90). Following 3 once daily habituation sessions the animals received a saline injection and baseline locomotor activity was measured. PN and prenatal saline (PS)-exposed offspring then received 10 once daily injections of METH (0.3 mg/kg) to induce locomotor sensitization. The animals received a METH injection (0.3 mg/kg) to assess the expression of sensitization following a 14-day period of no injections. A day later, all animals were injected with saline and conditioned hyperactivity was assessed. Brain tissue was harvested 24 h later. PN animals habituated more slowly to the activity chambers compared to PS controls. PN rats treated with METH showed significant enhancement of locomotor behavior compared to PS rats following acute and repeated injections; however, PN did not produce differential initiation or expression of behavioral sensitization. METH produced conditioned hyperactivity, and PN rats exhibited a greater conditioned response of hyperactivity relative to controls. PN and METH exposure produced changes in BDNF protein levels in all three regions, and complex interactions were observed between these two factors. Logistic regression revealed that BDNF protein levels, throughout the mesocorticolimbic system, significantly predicted the difference in the conditioned hyperactive response of the animals: both correlations were significant, but the predicted relationship between BDNF and context-elicited activity was stronger in the PN (r = 0.67) compared to the PS rats (r = 0.42). These findings indicate that low-dose PN exposure produces long-term changes in activity and enhanced sensitivity to the locomotor effects of METH. The enhanced METH-induced contextual conditioning shown by the PN animals suggests that offspring of in utero tobacco smoke exposure have greater susceptibility to learn about drug-related conditional stimuli, such as the context. The PN-induced alterations in mesocorticolimbic BDNF protein lend further support for the hypothesis that maternal smoking during pregnancy produces alterations in neuronal plasticity that contribute to drug abuse vulnerability. The current findings demonstrate that these changes are persistent into adulthood.
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Affiliation(s)
- Ryan T Lacy
- Behavioral Neuroscience Program, Department of Psychology, University of South Carolina, Columbia, S.C., USA
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507
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Kyzar EJ, Floreani C, Teppen TL, Pandey SC. Adolescent Alcohol Exposure: Burden of Epigenetic Reprogramming, Synaptic Remodeling, and Adult Psychopathology. Front Neurosci 2016; 10:222. [PMID: 27303256 PMCID: PMC4885838 DOI: 10.3389/fnins.2016.00222] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/06/2016] [Indexed: 12/22/2022] Open
Abstract
Adolescence represents a crucial phase of synaptic maturation characterized by molecular changes in the developing brain that shape normal behavioral patterns. Epigenetic mechanisms play an important role in these neuromaturation processes. Perturbations of normal epigenetic programming during adolescence by ethanol can disrupt these molecular events, leading to synaptic remodeling and abnormal adult behaviors. Repeated exposure to binge levels of alcohol increases the risk for alcohol use disorder (AUD) and comorbid psychopathology including anxiety in adulthood. Recent studies in the field clearly suggest that adolescent alcohol exposure causes widespread and persistent changes in epigenetic, neurotrophic, and neuroimmune pathways in the brain. These changes are manifested by altered synaptic remodeling and neurogenesis in key brain regions leading to adult psychopathology such as anxiety and alcoholism. This review details the molecular mechanisms underlying adolescent alcohol exposure-induced changes in synaptic plasticity and the development of alcohol addiction-related phenotypes in adulthood.
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Affiliation(s)
- Evan J Kyzar
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at ChicagoChicago, IL, USA; Jesse Brown Veterans Affairs Medical CenterChicago, IL, USA
| | - Christina Floreani
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at ChicagoChicago, IL, USA; Jesse Brown Veterans Affairs Medical CenterChicago, IL, USA
| | - Tara L Teppen
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at ChicagoChicago, IL, USA; Jesse Brown Veterans Affairs Medical CenterChicago, IL, USA
| | - Subhash C Pandey
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at ChicagoChicago, IL, USA; Jesse Brown Veterans Affairs Medical CenterChicago, IL, USA; Anatomy and Cell Biology, University of Illinois at ChicagoChicago, IL, USA
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508
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Butler TR, Karkhanis AN, Jones SR, Weiner JL. Adolescent Social Isolation as a Model of Heightened Vulnerability to Comorbid Alcoholism and Anxiety Disorders. Alcohol Clin Exp Res 2016; 40:1202-14. [PMID: 27154240 DOI: 10.1111/acer.13075] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 03/24/2016] [Indexed: 01/01/2023]
Abstract
Individuals diagnosed with anxiety-related illnesses are at increased risk of developing alcoholism, exhibit a telescoped progression of this disease and fare worse in recovery, relative to alcoholics that do not suffer from a comorbid anxiety disorder. Similarly, preclinical evidence supports the notion that stress and anxiety represent major risk factors for the development of alcohol use disorder (AUD). Despite the importance of understanding the link between anxiety and alcoholism, much remains unknown about the neurobiological substrates underlying this relationship. One stumbling block has been the lack of animal models that reliably reproduce the spectrum of behaviors associated with increased vulnerability to these diseases. Here, we review the literature that has examined the behavioral and neurobiological outcomes of a simple rodent adolescent social isolation procedure and discuss its validity as a model of vulnerability to comorbid anxiety disorders and alcoholism. Recent studies have provided strong evidence that adolescent social isolation of male rats leads to the expression of a variety of behaviors linked with increased vulnerability to anxiety and/or AUD, including deficits in sensory gating and fear extinction, and increases in anxiety measures and ethanol drinking. Neurobiological studies are beginning to identify mesolimbic adaptations that may contribute to the behavioral phenotype engendered by this model. Some of these changes include increased excitability of ventral tegmental area dopamine neurons and pyramidal cells in the basolateral amygdala and significant alterations in baseline and stimulated catecholamine signaling. A growing body of evidence suggests that adolescent social isolation may represent a reliable rodent model of heightened vulnerability to anxiety disorders and alcoholism in male rats. These studies provide initial support for the face, construct, and predictive validity of this model and highlight its utility in identifying neurobiological adaptations associated with increased risk of developing these disorders.
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Affiliation(s)
- Tracy R Butler
- Department of Psychology , University of Dayton, Dayton, Ohio
| | - Anushree N Karkhanis
- Department of Physiology and Pharmacology , Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Sara R Jones
- Department of Physiology and Pharmacology , Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Jeffrey L Weiner
- Department of Physiology and Pharmacology , Wake Forest School of Medicine, Winston Salem, North Carolina
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509
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Guizzetti M, Davies DL, Egli M, Finn DA, Molina P, Regunathan S, Robinson DL, Sohrabji F. Sex and the Lab: An Alcohol-Focused Commentary on the NIH Initiative to Balance Sex in Cell and Animal Studies. Alcohol Clin Exp Res 2016; 40:1182-91. [PMID: 27154003 DOI: 10.1111/acer.13072] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 03/21/2016] [Indexed: 11/28/2022]
Abstract
In May 2014, Dr. Francis Collins, the director of U.S. National Institutes of Health (NIH), and Dr. Janine Clayton, the director of the U.S. National Institutes of Health Office of Research on Women's Health, published a commentary in the journal Nature announcing new policies to ensure that preclinical research funded by the NIH considers both males and females. While these policies are still developing, they have already generated great interest by the scientific community and triggered both criticism and applause. This review provides a description and interpretation of the NIH guidelines, and it traces the history that led to their implementation. As expected, this NIH initiative generated some anxiety in the scientific community. The use of female animals in the investigation of basic mechanisms is perceived to increase variability in the results, and the use of both sexes has been claimed to slow the pace of scientific discoveries and to increase the cost at a time characterized by declining research support. This review discusses issues related to the study of sex as a biological variable (SABV) in alcohol studies and provides examples of how researchers have successfully addressed some of them. A practical strategy is provided to include both sexes in biomedical research while maintaining control of the research direction. The inclusion of sex as an important biological variable in experimental design, analysis, and reporting of preclinical alcohol research is likely to lead to a better understanding of alcohol pharmacology and the development of alcohol use disorder, may promote drug discovery for new pharmacotherapies by increasing scientific rigor, and may provide clinical benefit to women's health. This review aims to promote the understanding of the NIH's SABV guidelines and to provide alcohol researchers with a theoretical and practical framework for working with both sexes in preclinical research.
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Affiliation(s)
- Marina Guizzetti
- Department of Behavioral Neuroscience, Oregon Health & Science University, VA Portland Health Care System, Portland, Oregon
| | - Daryl L Davies
- Department of Clinical Pharmacy, University of Southern California, Los Angeles, California
| | - Mark Egli
- Division of Neuroscience and Behavior, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
| | - Deborah A Finn
- Department of Behavioral Neuroscience, Oregon Health & Science University, VA Portland Health Care System, Portland, Oregon
| | - Patricia Molina
- Department of Physiology and Alcohol and Drug Abuse Center of Excellence , Louisiana State University, New Orleans, Louisiana
| | - Soundar Regunathan
- Division of Neuroscience and Behavior, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
| | - Donita L Robinson
- Bowles Center for Alcohol Studies and Department of Psychiatry , University of North Carolina, Chapel Hill, North Carolina
| | - Farida Sohrabji
- Department of Neuroscience and Experimental Therapeutics , Texas A&M, Bryan, Texas
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510
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Fattore L, Melis M. Editorial: Exploring Gender and Sex Differences in Behavioral Dyscontrol: From Drug Addiction to Impulse Control Disorders. Front Psychiatry 2016; 7:19. [PMID: 26941657 PMCID: PMC4762070 DOI: 10.3389/fpsyt.2016.00019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 02/08/2016] [Indexed: 01/04/2023] Open
Affiliation(s)
- Liana Fattore
- CNR Neuroscience Institute, National Research Council , Cagliari , Italy
| | - Miriam Melis
- Department of Biomedical Sciences, University of Cagliari , Cagliari , Italy
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