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Thompson Z, Fonseca IAT, Acosta W, Idarraga L, Garland T. Effects of food restriction on voluntary wheel-running behavior and body mass in selectively bred High Runner lines of mice. Physiol Behav 2024; 282:114582. [PMID: 38750805 DOI: 10.1016/j.physbeh.2024.114582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 04/28/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024]
Abstract
Food restriction can have profound effects on various aspects of behavior, physiology, and morphology. Such effects might be amplified in animals that are highly active, given that physical activity can represent a substantial fraction of the total daily energy budget. More specifically, some effects of food restriction could be associated with intrinsic, genetically based differences in the propensity or ability to perform physical activity. To address this possibility, we studied the effects of food restriction in four replicate lines of High Runner (HR) mice that have been selectively bred for high levels of voluntary wheel running. We hypothesized that HR mice would respond differently than mice from four non-selected Control (C) lines. Healthy adult females from generation 65 were housed individually with wheels and provided access to food and water ad libitum for experimental days 1-19 (Phase 1), which allowed mice to attain a plateau in daily running distances. Ad libitum food intake of each mouse was measured on days 20-22 (Phase 2). After this, each mouse experienced a 20 % food restriction for 7 days (days 24-30; Phase 3), and then a 40 % food restriction for 7 additional days (days 31-37; Phase 4). Mice were weighed on experimental days 1, 8, 9, 15, 20, and 23-37 and wheel-running activity was recorded continuously, in 1-minute bins, during the entire experiment. Repeated-measures ANOVA of daily wheel-running distance during Phases 2-4 indicated that HR mice always ran much more than C, with values being 3.29-fold higher during the ad libitum feeding trial, 3.58-fold higher with -20 % food, and 3.06-fold higher with -40 % food. Seven days of food restriction at -20 % did not significantly reduce wheel-running distance of either HR (-5.8 %, P = 0.0773) or C mice (-13.3 %, P = 0.2122). With 40 % restriction, HR mice showed a further decrease in daily wheel-running distance (P = 0.0797 vs. values at 20 % restriction), whereas C mice did not (P = 0.4068 vs. values at 20 % restriction) and recovered to levels similar to those on ad libitum food (P = 0.3634). For HR mice, daily running distances averaged 11.4 % lower at -40 % food versus baseline values (P = 0.0086), whereas for C mice no statistical difference existed (-4.8 %, P = 0.7004). Repeated-measures ANOVA of body mass during Phases 2-4 indicated a highly significant effect of food restriction (P = 0.0001), but no significant effect of linetype (P = 0.1764) and no interaction (P = 0.8524). Both HR and C mice had a significant reduction in body mass only when food rations were reduced by 40 % relative to ad libitum feeding, and even then the reductions averaged only -0.60 g for HR mice (-2.6 %) and -0.49 g (-2.0 %) for C mice. Overall, our results indicate a surprising insensitivity of body mass to food restriction in both high-activity (HR) and ordinary (C) mice, and also insensitivity of wheel running in the C lines of mice, thus calling for studies of compensatory mechanisms that allow this insensitivity.
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Affiliation(s)
- Zoe Thompson
- Neuroscience Graduate Program, University of California, Riverside, CA 92521, USA; Present Address: Department of Biology, Utah Valley University, Orem, UT, USA
| | - Ivana A T Fonseca
- Department of Physical Education, University of State of Rio Grande do Norte, Mossoró, Brazil
| | - Wendy Acosta
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA
| | - Laidy Idarraga
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA
| | - Theodore Garland
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA.
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2
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Fink LB, Mukobi A, Gruber L, Reed C, DeLibero J, Jackson S, Neill S, Walz J, Sines C, VanBeek B, Scarlata CD, Wielebnowski N. Longitudinal Analysis of Variability in Fecal Glucocorticoid Metabolite Concentrations in Three Orangutans ( Pongo pygmaeus pygmaeus and Pongo pygmaeus abelii) before, during, and after Transition from a Regular Habitat Environment to Temporary Housing in Indoor Holding Facilities. Animals (Basel) 2022; 12:ani12233303. [PMID: 36496824 PMCID: PMC9737607 DOI: 10.3390/ani12233303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 11/11/2022] [Accepted: 11/24/2022] [Indexed: 11/29/2022] Open
Abstract
Considerable research has been conducted on the effects of inter-institutional transfers, but far less consideration has been given to intra-institutional transfers and extended housing in off-habitat holding. On 15 May 2018, The Oregon Zoo's orangutans (n = 3) were moved from the Red Ape Reserve (RAR) to the Veterinary Medical Center (VMC) indoor holding areas and remained there until 22 December 2020, resulting in over two years of housing in a facility not specifically designed for orangutans. This study aimed to quantify potential changes in fecal glucocorticoid metabolites (fGM) typically associated with increased adrenal activity as a result of transfers, as well as potential differences in fGM concentrations associated with housing in the two different types of locations. We collected fecal samples from all orangutans during three time periods: the initial housing at RAR (RAR1), the time spent at VMC holding (VMC), and the return to RAR (RAR2). Samples were analyzed using enzyme-immunoassay (EIA) analyses and compared using two-way ANOVA tests with Games-Howell post-hoc evaluations. The results of our analyses showed the following: (1) significant differences in fGM concentrations based on location in two orangutans, with the highest fGM concentration occurring in fecal samples collected at the VMC; and (2) a lack of significant fGM peaks following multiple intra-institutional transfers for all three orangutans. Though requiring further corroboration through future studies, we speculated that pre-transfer behavior training and intensive, continued care by familiar animal care staff may have helped to mitigate the stress responses commonly associated with transfers and major changes in housing. Furthermore, this study highlights the individualistic nature of the stress response, as illustrated by the substantial variation in fGM concentrations across different housing regimens in the three orangutans.
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Affiliation(s)
- Laurel B. Fink
- Oregon Zoo, Portland, OR 97221, USA
- Department of Biology, Portland State University, 1719 SW 10th Avenue, SRTC rm 246, Portland, OR 97201, USA
- Correspondence:
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Yamauchi T, Kang G, Hiroi N. Heterozygosity of murine Crkl does not recapitulate behavioral dimensions of human 22q11.2 hemizygosity. GENES BRAIN AND BEHAVIOR 2020; 20:e12719. [PMID: 33269541 DOI: 10.1111/gbb.12719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/20/2020] [Accepted: 12/01/2020] [Indexed: 01/03/2023]
Abstract
Deletions in 22q11.2 human chromosome are known to be associated with psychiatric disorders, such as intellectual disability, schizophrenia, autism spectrum disorder, and anxiety disorders. This copy number variation includes a 3.0 Mb deletion and a nested proximal 1.5 Mb hemizygous deletion in the same region. Evidence indicates that the distal 22q11.2 region outside the nested 1.5 Mb deletion also might be contributory in humans. However, the precise genetic architecture within the distal region responsible for psychiatric disorders remains unclear, and this issue cannot be experimentally evaluated beyond the correlation in humans. As CRKL (CRK-like Proto-Oncogene, Adaptor Protein) is one of the genes encoded in the distal 22q11.2 segment and its homozygous deletion causes physical phenotypes of 22q11.2 hemizygous deletion, we tested the hypothesis that its murine homolog Crkl contributes to behavioral phenotypes relevant to psychiatric disorders in mice. Congenic Crkl heterozygosity reduced thigmotaxis, an anxiety-related behavior, in an inescapable open field, but had no apparent effect on social interaction, spontaneous alternation in a T-maze, anxiety-like behavior in an elevated plus maze, or motor activity in an open field. Our data indicate that the heterozygosity of murine Crkl does not recapitulate social deficits, working memory deficits, repetitive behavior traits or hyperactivity of human 22q11.2 hemizygous deletion. Moreover, while 22q11.2 hemizygous deletion is associated with high levels of phobia and anxiety in humans, our data suggest that Crkl heterozygosity rather acts as a protective factor for phobia-like behavior in an open field.
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Affiliation(s)
- Takahira Yamauchi
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Gina Kang
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Noboru Hiroi
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.,Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.,Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, Texas
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4
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Šabanović M, Liu H, Mlambo V, Aqel H, Chaudhury D. What it takes to be at the top: The interrelationship between chronic social stress and social dominance. Brain Behav 2020; 10:e01896. [PMID: 33070476 PMCID: PMC7749537 DOI: 10.1002/brb3.1896] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/11/2020] [Accepted: 09/27/2020] [Indexed: 12/20/2022] Open
Abstract
INTRODUCTION Dominance hierarchies of social animal groups are very sensitive to stress. Stress experienced prior to social interactions between conspecifics may be a determinant of their future social dynamics. Additionally, long-term occupancy of a specific hierarchical rank can have psychophysiological effects which increase vulnerability to future stressors. METHODS We aimed to delineate differential effects of stress acting before or after hierarchy formation. We studied whether exposure to the chronic social defeat stress (CSDS) paradigm before a two-week-long hierarchy formation affected the attainment of a dominant status using the social confrontation tube test (TT). These animals were singly housed for at least one week before CSDS to decrease confounding effects of prior hierarchy experience. Additionally, we investigated whether social rank predicted vulnerability to CSDS, measured by a social interaction test. RESULTS In TT, mice termed as dominant (high rank) win the majority of social confrontations, while the subordinates (low rank) lose more often. Within newly established hierarchies of stress-naïve mice, the subordinate, but not dominant, mice exhibited significantly greater avoidance of novel social targets. However, following exposure to CSDS, both lowest- and highest-ranked mice exhibited susceptibility to stress as measured by decreased interactions with a novel social target. In contrast, after CSDS, both stress-susceptible (socially avoidant) and stress-resilient (social) mice were able to attain dominant ranks in newly established hierarchies. CONCLUSION These results suggest that the response to CSDS did not determine social rank in new cohorts, but low-status mice in newly established groups exhibited lower sociability to novel social targets. Interestingly, exposure of a hierarchical social group to chronic social stress led to stress susceptibility in both high- and low-status mice as measured by social interaction.
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Affiliation(s)
- Merima Šabanović
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - He Liu
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Vongai Mlambo
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Hala Aqel
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Dipesh Chaudhury
- The Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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Effects of weaning age and housing conditions on phenotypic differences in mice. Sci Rep 2020; 10:11684. [PMID: 32669633 PMCID: PMC7363894 DOI: 10.1038/s41598-020-68549-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/26/2020] [Indexed: 01/22/2023] Open
Abstract
Poor reproducibility is considered a serious problem in laboratory animal research, with important scientific, economic, and ethical implications. One possible source of conflicting findings in laboratory animal research are environmental differences between animal facilities combined with rigorous environmental standardization within studies. Due to phenotypic plasticity, study-specific differences in environmental conditions during development can induce differences in the animals’ responsiveness to experimental treatments, thereby contributing to poor reproducibility of experimental results. Here, we studied how variation in weaning age (14–30 days) and housing conditions (single versus group housing) affects the phenotype of SWISS mice as measured by a range of behavioral and physiological outcome variables. Weaning age, housing conditions, and their interaction had little effect on the development of stereotypies, as well as on body weight, glucocorticoid metabolite concentrations, and behavior in the elevated plus-maze and open field test. These results are surprising and partly in conflict with previously published findings, especially with respect to the effects of early weaning. Our results thus question the external validity of previous findings and call for further research to identify the sources of variation between replicate studies and study designs that produce robust and reproducible experimental results.
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6
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Hohlbaum K, Frahm S, Rex A, Palme R, Thöne-Reineke C, Ullmann K. Social enrichment by separated pair housing of male C57BL/6JRj mice. Sci Rep 2020; 10:11165. [PMID: 32636413 PMCID: PMC7341880 DOI: 10.1038/s41598-020-67902-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/11/2020] [Indexed: 01/03/2023] Open
Abstract
Laboratory male mice are often housed individually due to aggressive behavior or experimental requirements, though social isolation can cause welfare issues. As a strategy to refine housing of male mice, we introduce the separated pair housing system. A perforated transparent wall divides the cage into two compartments and allows olfactory, acoustic, and visual communication between the two mice but prevents fighting and injuries. Long-term effects of separated pair housing on well-being and distress of adult male C57BL/6JRj mice were investigated and compared with both single- and group-housed mice. Behavioral analysis after eight weeks in three different housing systems revealed no differences in burrowing performance, social interaction, anxiety, and stress hormone concentrations. However, pair-housed mice built more complex nests compared to single-housed mice and the nest position suggested that pair-housed mice preferred the close proximity to their cage mates. Moreover, pair-housed mice showed less locomotor activity compared to group- and single-housed mice. Body weight was higher in group-housed mice. All in all, no unambiguous long-term beneficial effects of pair housing on the well-being were found. However, the findings emphasized that effects of the housing systems on behavioral, physical, and biochemical parameters must be considered in the design of animal experimental studies.
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Affiliation(s)
- Katharina Hohlbaum
- Institute of Animal Welfare, Animal Behavior, and Laboratory Animal Science, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Silke Frahm
- Department of Pharmacology, Charité - Universitätsmedizin, Berlin, Germany
| | - André Rex
- Department of Experimental Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Rupert Palme
- Unit of Physiology, Pathophysiology and Experimental Endocrinology, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Christa Thöne-Reineke
- Institute of Animal Welfare, Animal Behavior, and Laboratory Animal Science, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Kristina Ullmann
- Research Facilities for Experimental Medicine (FEM), Charité - Universitätsmedizin Berlin, Berlin, Germany. .,Charité 3R, Charité - Universitätsmedizin Berlin, Berlin, Germany.
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7
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Fu Y, Depue RA. A novel neurobehavioral framework of the effects of positive early postnatal experience on incentive and consummatory reward sensitivity. Neurosci Biobehav Rev 2019; 107:615-640. [DOI: 10.1016/j.neubiorev.2019.09.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 09/08/2019] [Accepted: 09/17/2019] [Indexed: 12/22/2022]
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8
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Martinez VK, Saldana-Morales F, Sun JJ, Zhu PJ, Costa-Mattioli M, Ray RS. Off-Target Effects of Clozapine-N-Oxide on the Chemosensory Reflex Are Masked by High Stress Levels. Front Physiol 2019; 10:521. [PMID: 31178741 PMCID: PMC6538678 DOI: 10.3389/fphys.2019.00521] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/11/2019] [Indexed: 12/28/2022] Open
Abstract
Respiratory chemosensory circuits are implicated in several physiological and behavioral disorders ranging from sudden infant death syndrome to panic disorder. Thus, a comprehensive map of the chemosensory network would be of significant value. To delineate chemosensory neuronal populations, we have utilized pharmacogenetic Designer Receptors Exclusively Activated by Designer Drugs (DREADD) perturbations for acute neuronal perturbations in respiratory circuit mapping. Recent studies show that the biologically inert DREADD ligand clozapine-N-oxide (CNO) is back-metabolized into the bioactive compound clozapine in rodents, emphasizing the need for CNO-only DREADD-free controls, which have been carried out in several studies. However, we show that high CNO doses used in several chemosensory circuit mapping studies nonetheless affect the chemosensory ventilatory reflexes in control mice, which is unmasked by extensive habituation. Here, unhabituated control animals showed no differences in respiratory parameters after CNO administration, whereas habituated animals receiving the commonly used dose of 10 mg/kg of CNO show a deficit in the hypercapnic (high CO2) chemosensory reflex, which is not present in 1 mg/kg CNO treated or saline control groups. Our findings indicate that even in appropriately controlled studies, additional masked CNO off-target effects may exist and underscore the importance of using minimal doses of activating ligand in combination with high levels of habituation.
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Affiliation(s)
- Vena K Martinez
- Department of Pharmacology, Baylor College of Medicine, Houston, TX, United States.,Memory Brain Research Center, Baylor College of Medicine, Houston, TX, United States
| | - Fatima Saldana-Morales
- Memory Brain Research Center, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Jenny J Sun
- Memory Brain Research Center, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Ping Jun Zhu
- Memory Brain Research Center, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Mauro Costa-Mattioli
- Memory Brain Research Center, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Russell S Ray
- Memory Brain Research Center, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States.,McNair Medical Institute, Houston, TX, United States
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9
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Goes TC, Almeida Souza TH, Marchioro M, Teixeira-Silva F. Excitotoxic lesion of the medial prefrontal cortex in Wistar rats: Effects on trait and state anxiety. Brain Res Bull 2018; 142:313-319. [PMID: 30120930 DOI: 10.1016/j.brainresbull.2018.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 07/17/2018] [Accepted: 08/13/2018] [Indexed: 01/08/2023]
Abstract
The neural substrate of anxiety response (state anxiety) to a threatening situation is well defined. However, a lot less is known about brain structures implicated in the individual's predisposition to anxiety (trait anxiety). Scientific evidences lead us to suppose that the medial prefrontal cortex (mPFC) is involved in both trait and state anxiety. Thus, the aim of this study was to investigate the involvement of mPFC in trait anxiety and to further evaluate its participation in state anxiety. Sixty six adult, Wistar, male rats were first tested in the free-exploratory paradigm (FEP) and were categorized according to their levels of trait anxiety (high, medium and low). Three to six days after this exposure, all animals were submitted to stereotaxic brain surgery. Half the animals from each anxiety category was allocated to the mPFC-lesioned group and the other half to the Sham-lesioned group. After seven to nine days, all animals were again tested in FEP. Eight to 10 days later, the animals were tested in the Hole Board test, a model of state anxiety. The mPFC lesion decreased levels of trait anxiety of highly anxious rats, whereas it reduced the state anxiety of all animals, regardless the level of trait anxiety. These data extend evidence of the participation of the mPFC in state anxiety and it demonstrate the involvement of this brain structure in trait anxiety, a personality trait supposed to be a predisposing factor for anxiety disorders.
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Affiliation(s)
- Tiago Costa Goes
- Departamento de Educação em Saúde, Universidade Federal de Sergipe, Campus Prof. Antônio Garcia Filho, 49400-000, Lagarto, SE, Brazil.
| | - Thiago Henrique Almeida Souza
- Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, Cidade Universitária "Prof. José Aloísio de Campos", 49100-000, São Cristóvão, SE, Brazil.
| | - Murilo Marchioro
- Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, Cidade Universitária "Prof. José Aloísio de Campos", 49100-000, São Cristóvão, SE, Brazil.
| | - Flavia Teixeira-Silva
- Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, Cidade Universitária "Prof. José Aloísio de Campos", 49100-000, São Cristóvão, SE, Brazil.
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10
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Holgate JY, Garcia H, Chatterjee S, Bartlett SE. Social and environmental enrichment has different effects on ethanol and sucrose consumption in mice. Brain Behav 2017; 7:e00767. [PMID: 28828224 PMCID: PMC5561324 DOI: 10.1002/brb3.767] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 05/22/2017] [Accepted: 06/12/2017] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Factors leading to the harmful consumption of substances, like alcohol and sucrose, involve a complex interaction of genes and the environment. While we cannot control the genes we inherit, we can modify our environment. Understanding the role that social and environmental experiences play in alcohol and sucrose consumption is critical for developing preventative interventions and treatments for alcohol use disorders and obesity. METHODS We used the drinking in the dark two-bottle choice (2BC) model of ethanol and sucrose consumption to compare male C57BL/6 mice housed in the IntelliCage (an automated device capable of simultaneously measuring behaviors of up to 16 mice living in an enriched social environment) with mice housed in standard isolated and social environments. RESULTS Consistent with previous publications on ethanol-naïve and -experienced mice, social and environmental enrichment reduced ethanol preference. Isolated mice had the highest ethanol preference and IntelliCage mice the least, regardless of prior ethanol experience. In mice with no prior sucrose experience, the addition of social and environmental enrichment increased sucrose preference. However, moving isolated mice to enriched conditions did not affect sucrose preference in sucrose-experienced mice. CONCLUSIONS The impact of social and environmental enrichment on ethanol consumption differs from sucrose consumption suggesting that interventions and treatments developed for alcohol use disorders may not be suitable for sucrose consumption disorders.
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Affiliation(s)
- Joan Y Holgate
- Institute of Health and Medical Innovation Translational Research Institute Queensland University of Technology Woolloongabba QLD Australia.,Ernest Gallo Clinical and Research Center University of California San Francisco CA USA
| | - Hilary Garcia
- Ernest Gallo Clinical and Research Center University of California San Francisco CA USA
| | - Susmita Chatterjee
- Ernest Gallo Clinical and Research Center University of California San Francisco CA USA
| | - Selena E Bartlett
- Institute of Health and Medical Innovation Translational Research Institute Queensland University of Technology Woolloongabba QLD Australia.,Ernest Gallo Clinical and Research Center University of California San Francisco CA USA
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11
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Effects of experimental housing conditions on recovery of laboratory mice. Lab Anim (NY) 2015; 44:65-70. [PMID: 25602397 DOI: 10.1038/laban.662] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 07/10/2014] [Indexed: 12/21/2022]
Abstract
The beneficial effects of environment and social support during disease recovery in humans are widely accepted. Because laboratory mice are social animals and are highly motivated to interact with each other and with their environment, it is very likely that environmental and social factors are also beneficial to their recovery from experimental interventions or spontaneous diseases. The beneficial effects of enriched environments have been particularly well analyzed in the field of brain disorders, but several studies suggest that positive social contact and a complex and familiar environment may also support recovery from injury, from invasive procedures such as surgery or from spontaneously occurring diseases. The author reviews relevant publications on the effects of environment and social housing on recovery from disease or surgery in laboratory mice and other rodents. She concludes that in addition to promoting animal welfare, provision of optimal experimental housing conditions might also contribute to the clinical relevance of preclinical animal models by more closely simulating the environmental and social characteristics of disease recovery in humans.
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12
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Pelloux Y, Costentin J, Duterte-Boucher D. Differential involvement of anxiety and novelty preference levels on oral ethanol consumption in rats. Psychopharmacology (Berl) 2015; 232:2711-21. [PMID: 25761842 DOI: 10.1007/s00213-015-3910-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 02/23/2015] [Indexed: 11/24/2022]
Abstract
RATIONALE Drug addiction is defined as a recurring cycle of intoxication, abstinence and relapse. The behavioural trait of novelty seeking is frequently observed in alcohol abusers. Moreover, converging evidence indicates that anxious individuals are also predisposed to alcohol abuse. OBJECTIVES We have analyzed the respective implication of those two behavioural factors on vulnerability to ethanol intake on rats in situations designed to reflect drug intoxication and relapse phases in humans. METHODS In a general population of Wistar rats, animals were tested in both the light/dark box and the novelty preference tests. Ethanol consumption was measured in a two-bottle free-choice procedure across three successive procedures. Animals were first exposed to increasing concentrations of ethanol (2, 4, 6, 8, 10, 12 % for 8 days at each concentration). Then, the concentration of the solution was diminished from 12 to 6 %. Finally, all rats were re-exposed to 6 % ethanol after 12 days of ethanol deprivation. RESULTS Novelty preference predicted the amount of ethanol consumed across all phases. In contrast, anxiety was associated with a quicker recovery of ethanol consumption after the concentration drop and a greater increase in ethanol consumption after deprivation. CONCLUSIONS Novelty seeking and anxiety are both but differentially implicated in predisposition to ethanol abuse. Whereas novelty seeking is related to the amount of ethanol consumed, anxiety is associated to higher ethanol consumption when ethanol concentration is decreased or after ethanol deprivation.
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Affiliation(s)
- Yann Pelloux
- Unité de Neuropsychopharmacologie Expérimentale, EA 4359, Institut de Recherche et d'Innovation Biomédicale (IRIB), Faculté de Médecine et de Pharmacie de Rouen, 22, Bld Gambetta, 76183, Rouen Cedex, France
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13
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Almeida-Souza TH, Goes TC, Teixeira-Silva F. Pharmacological validation of the free-exploratory paradigm in male Wistar rats: A proposed test of trait anxiety. Pharmacol Biochem Behav 2015; 135:114-20. [PMID: 26028610 DOI: 10.1016/j.pbb.2015.03.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 03/18/2015] [Accepted: 03/27/2015] [Indexed: 12/18/2022]
Abstract
The free-exploratory paradigm (FEP) has been proposed as a model of trait anxiety for both mice and rats. However, its pharmacological validation has only been carried out for the mice. Thus, the aim of the present study was to pharmacologically validate FEP for Wistar rats, by testing the effects of clinically established anxiolytic and anxiogenic drugs, in four different experiments. In all experiments, male Wistar rats were first tested in FEP to be categorized according to their levels of trait anxiety (high, medium and low). Then, only medium trait anxiety rats were selected to be tested again in FEP, two weeks later, after being pharmacologically treated, according to each experiment as follows: Experiment I: 0.5mg/kg of diazepam (DZP) or vehicle; Experiment II: 20mg/kg of pentylenetetrazole (PTZ) or vehicle; Experiment III: 5mg/kg of fluoxetine (FLX5) or vehicle: and Experiment IV: 0.5mg/kg of fluoxetine (FLX0.5) or vehicle. As a group, the results showed that PTZ and FLX5 increased levels of trait anxiety and reduced locomotor activity, whereas DZP and FLX0.5 decreased levels of trait anxiety, without impairing locomotor activity. These results demonstrate that FEP for rats is able to predict clinical anxiolytic and anxiogenic activities of different drugs, including fluoxetine, which is believed to present a dual effect on anxiety. Therefore, this paradigm can be proposed as an effective method for testing potential trait anxiety-reducing drugs, in rats.
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Affiliation(s)
- Thiago Henrique Almeida-Souza
- Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, 49100-000 São Cristóvão, SE, Brazil.
| | - Tiago Costa Goes
- Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, 49100-000 São Cristóvão, SE, Brazil.
| | - Flavia Teixeira-Silva
- Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, 49100-000 São Cristóvão, SE, Brazil.
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Harmonic and frequency modulated ultrasonic vocalizations reveal differences in conditioned and unconditioned reward processing. Behav Brain Res 2015; 287:207-14. [PMID: 25827931 DOI: 10.1016/j.bbr.2015.03.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 03/11/2015] [Accepted: 03/22/2015] [Indexed: 11/21/2022]
Abstract
Novelty and sensation seeking (NSS) and ultrasonic vocalizations (USVs) are both used as measures of individual differences in reward sensitivity in rodent models. High responders in the inescapable novelty screen have a greater response to low doses of amphetamine and acquire self-administration more rapidly, while the novelty place preference screen is positively correlated with compulsive drug seeking. These screens are uncorrelated and implicated in separate drug abuse models. 50 kHz USVs measure affective state in rats and are evoked by positive stimuli. NSS and USVs are each implicated in drug response, self-administration, and reveal differences in individual behavior, yet their relationship with each other is not understood. The present study screened rats for their response to novelty and measured USVs of all call types in response to heterospecific play to determine the relationships between these individual difference traits. Generally, we hypothesized that 50k Hz USVs would be positively correlated with the NPP screen, and that 22 kHz would be positively correlated with the IEN screen. Results indicate none of the screens were correlated indicating they are measuring different individual difference traits. However, examination of the subtypes of USVs indicated harmonic USVs and the novelty place preference were positively correlated. Harmonic 50 kHz USVs increased in response to reward associated context, suggesting animals conditioned to the heterospecific tickle arena and anticipated rewarding stimuli, while FM only increased in response to tickling. USV subtypes can be used to elucidate differences in attribution of incentive value across conditioned stimuli and receipt of rewarding stimuli. These data provide strong support that harmonic and FM USVs can be used to understand reward processing in addition to NSS.
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Kalliokoski O, Teilmann AC, Jacobsen KR, Abelson KSP, Hau J. The lonely mouse - single housing affects serotonergic signaling integrity measured by 8-OH-DPAT-induced hypothermia in male mice. PLoS One 2014; 9:e111065. [PMID: 25436462 PMCID: PMC4249803 DOI: 10.1371/journal.pone.0111065] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 09/21/2014] [Indexed: 11/18/2022] Open
Abstract
Male BALB/c mice single-housed for a period of three weeks were found to respond with a more marked hypothermia to a challenge with a selective serotonergic agonist (8-OH-DPAT) than their group-housed counterparts. This effect of single housing was verified by screening a genetically heterogeneous population of male mice on a C57BL/6 background from a breeding colony. Enhanced activity of the implicated receptor (5-HT1A) leading to an amplified hypothermic effect is strongly associated with depressive states. We therefore suggest that the 8-OH-DPAT challenge can be used to demonstrate a negative emotional state brought on by e.g. long-term single housing in male laboratory mice. The study emphasizes the importance of social housing, and demonstrates that male mice deprived of social contact respond with altered serotonergic signaling activity. Male mice not only choose social contact when given the option, as has previously been shown, but will also, when it is deprived, be negatively affected by its absence. We propose that the 8-OH-DPAT challenge constitutes a simple, but powerful, tool capable of manifesting the effect of social deprivation in laboratory mice. It potentially allows not only for an unbiased, biochemical evaluation of psychological stressors, but may also allow for determining whether the effect of these can be counteracted.
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Affiliation(s)
- Otto Kalliokoski
- Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - A. Charlotte Teilmann
- Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kirsten R. Jacobsen
- Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Klas S. P. Abelson
- Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jann Hau
- Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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The free-exploratory paradigm as a model of trait anxiety in female rats: Test–retest reliability. Neurosci Lett 2014; 580:137-41. [DOI: 10.1016/j.neulet.2014.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 07/06/2014] [Accepted: 08/04/2014] [Indexed: 11/20/2022]
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Flagel SB, Waselus M, Clinton SM, Watson SJ, Akil H. Antecedents and consequences of drug abuse in rats selectively bred for high and low response to novelty. Neuropharmacology 2014; 76 Pt B:425-36. [PMID: 23639434 PMCID: PMC3766490 DOI: 10.1016/j.neuropharm.2013.04.033] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/09/2013] [Accepted: 04/16/2013] [Indexed: 12/22/2022]
Abstract
Human genetic and epidemiological studies provide evidence that only a subset of individuals who experiment with potentially addictive drugs become addicts. What renders some individuals susceptible to addiction remains to be determined, but most would agree that there is no single trait underlying the disorder. However, there is evidence in humans that addiction liability has a genetic component, and that certain personality characteristics related to temperament (e.g. the sensation-seeking trait) are associated with individual differences in addiction liability. Consequently, we have used a selective breeding strategy based on locomotor response to a novel environment to generate two lines of rats with distinct behavioral characteristics. We have found that the resulting phenotypes differ on a number of neurobehavioral dimensions relevant to addiction. Relative to bred low-responder (bLR) rats, bred high-responder (bHR) rats exhibit increased exploratory behavior, are more impulsive, more aggressive, seek stimuli associated with rewards, and show a greater tendency to relapse. We therefore utilize this unique animal model to parse the genetic, neural and environmental factors that contribute to addiction liability. Our work shows that the glucocorticoid receptor (GR), dopaminergic molecules, and members of the fibroblast growth factor family are among the neurotransmitters and neuromodulators that play a role in both the initial susceptibility to addiction as well as the altered neural responses that follow chronic drug exposure. Moreover, our findings suggest that the hippocampus plays a major role in mediating vulnerability to addiction. It is hoped that this work will emphasize the importance of personalized treatment strategies and identify novel therapeutic targets for humans suffering from addictive disorders. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.
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Affiliation(s)
- Shelly B Flagel
- Molecular and Behavioral Neuroscience Institute, University of Michigan, 205 Zina Pitcher Place, Ann Arbor, MI 48109, USA; Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA; Neuroscience Program, University of Michigan, Ann Arbor, MI, USA; Department of Psychology, University of Michigan, Ann Arbor, MI, USA.
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Bert B, Schmidt N, Voigt J, Fink H, Rex A. Evaluation of cage leaving behaviour in rats as a free choice paradigm. J Pharmacol Toxicol Methods 2013; 68:240-249. [DOI: 10.1016/j.vascn.2013.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 12/28/2012] [Accepted: 01/02/2013] [Indexed: 10/27/2022]
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Bardo MT, Neisewander JL, Kelly TH. Individual differences and social influences on the neurobehavioral pharmacology of abused drugs. Pharmacol Rev 2013; 65:255-90. [PMID: 23343975 PMCID: PMC3565917 DOI: 10.1124/pr.111.005124] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The interaction of drugs with biologic targets is a critical area of research, particularly for the development of medications to treat substance use disorders. In addition to understanding these drug-target interactions, however, there is a need to understand more fully the psychosocial influences that moderate these interactions. The first section of this review introduces some examples from human behavioral pharmacology that illustrate the clinical importance of this research. The second section covers preclinical evidence to characterize some of the key individual differences that alter drug sensitivity and abuse vulnerability, related primarily to differences in response to novelty and impulsivity. Evidence is presented to indicate that critical neuropharmacological mechanisms associated with these individual differences involve integrated neurocircuits underlying stress, reward, and behavioral inhibitory processes. The third section covers social influences on drug abuse vulnerability, including effects experienced during infancy, adolescence, and young adulthood, such as maternal separation, housing conditions, and social interactions (defeat, play, and social rank). Some of the same neurocircuits involved in individual differences also are altered by social influences, although the precise neurochemical and cellular mechanisms involved remain to be elucidated fully. Finally, some speculation is offered about the implications of this research for the prevention and treatment of substance abuse.
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Affiliation(s)
- M T Bardo
- Department of Psychology, University of Kentucky, BBSRB Room 447, 741 S. Limestone, Lexington, KY 40536-0509, USA.
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Hansson C, Shirazi RH, Näslund J, Vogel H, Neuber C, Holm G, Anckarsäter H, Dickson SL, Eriksson E, Skibicka KP. Ghrelin influences novelty seeking behavior in rodents and men. PLoS One 2012; 7:e50409. [PMID: 23227170 PMCID: PMC3515575 DOI: 10.1371/journal.pone.0050409] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 10/19/2012] [Indexed: 12/13/2022] Open
Abstract
Recent discoveries indicate an important role for ghrelin in drug and alcohol reward and an ability of ghrelin to regulate mesolimbic dopamine activity. The role of dopamine in novelty seeking, and the association between this trait and drug and alcohol abuse, led us to hypothesize that ghrelin may influence novelty seeking behavior. To test this possibility we applied several complementary rodent models of novelty seeking behavior, i.e. inescapable novelty-induced locomotor activity (NILA), novelty-induced place preference and novel object exploration, in rats subjected to acute ghrelin receptor (growth hormone secretagogue receptor; GHSR) stimulation or blockade. Furthermore we assessed the possible association between polymorphisms in the genes encoding ghrelin and GHSR and novelty seeking behavior in humans. The rodent studies indicate an important role for ghrelin in a wide range of novelty seeking behaviors. Ghrelin-injected rats exhibited a higher preference for a novel environment and increased novel object exploration. Conversely, those with GHSR blockade drastically reduced their preference for a novel environment and displayed decreased NILA. Importantly, the mesolimbic ventral tegmental area selective GHSR blockade was sufficient to reduce the NILA response indicating that the mesolimbic GHSRs might play an important role in the observed novelty responses. Moreover, in untreated animals, a striking positive correlation between NILA and sucrose reward behavior was detected. Two GHSR single nucleotide polymorphisms (SNPs), rs2948694 and rs495225, were significantly associated with the personality trait novelty seeking, as assessed using the Temperament and Character Inventory (TCI), in human subjects. This study provides the first evidence for a role of ghrelin in novelty seeking behavior in animals and humans, and also points to an association between food reward and novelty seeking in rodents.
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Affiliation(s)
- Caroline Hansson
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
- Department of Clinical and Molecular Medicine, Institute of Medicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Rozita H. Shirazi
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Jakob Näslund
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Heike Vogel
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Corinna Neuber
- Department of Clinical and Molecular Medicine, Institute of Medicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Göran Holm
- Department of Metabolism and Cardiovascular Disease, Institute of Medicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Henrik Anckarsäter
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Suzanne L. Dickson
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Elias Eriksson
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Karolina P. Skibicka
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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Koester C, Rudolph U, Haenggi T, Papilloud A, Fritschy JM, Crestani F. Dissecting the role of diazepam-sensitive γ-aminobutyric acid type A receptors in defensive behavioral reactivity to mild threat. Pharmacol Biochem Behav 2012; 103:541-9. [PMID: 23067879 DOI: 10.1016/j.pbb.2012.10.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 10/01/2012] [Accepted: 10/06/2012] [Indexed: 12/21/2022]
Abstract
Moderate reductions in synaptic γ-aminobutyric acid(A) receptors (GABA(A)Rs) have been associated with an enhanced defensive behavioral reactivity to mild threat, sensitive to diazepam. We here tested whether a deficit in α2 subunit-containing GABAergic synapses is sufficient to cause this anxiety-related phenotype and to prevent its attenuation by the benzodiazepine. Wild type (α2+/+), heterozygous (α2+/-) and homozygous (α2-/-) knock-out littermates were tested in the free-choice exploratory (FCE) and the light/dark choice (LDC) paradigms. α2-/- mice, double mutant α1H101Rα2-/- and α3H126Rα2-/- mice, which combine a lack of α2-GABA(A)Rs with point-mutated diazepam-insensitive either α1H101R or α3H126R-GABA(A)Rs, and double point-mutated α1H101Rα2H101R and α1H101Rα3H126R mice were used to uncover the GABA(A)R subtype(s) mediating the drug effects. Data show that in the FCE, α2-/- mice exhibited more retractions (i.e. risk assessment) and longer latencies to first occurrence into the novel compartment and less transitions and time spent inside it in comparison to α2+/- and α2+/+ mice. In the LDC, α2-/- mice visited and spent less time in the lit box and stayed longer in the tunnel than the other two groups. Minor differences were found between α2+/- and α2+/+ mice in the two paradigms. Diazepam (1.5mg/kg per os) normalized retractions and latencies in the FCE in α2-/- and α3H126Rα2-/- mice, but not in α1H101Rα2-/- mice. The same drug treatment failed to attenuate behavioral aversion in both paradigms in all mutants with impaired α2-GABA(A)R function. These results reveal α2-containing GABA(A)Rs as key molecular determinants in the regulation of anxiety-related responses elicited by exposure to relative novelty and mild threat. In the absence of these receptors, diazepam through activation of α1-GABA(A)Rs remains effective in reducing risk assessment, but not behavioral aversion.
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Affiliation(s)
- Christina Koester
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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Acute and chronic ethanol differentially modify the emotional significance of a novel environment: implications for addiction. Int J Neuropsychopharmacol 2012; 15:1109-20. [PMID: 21854680 DOI: 10.1017/s1461145711001283] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Using open-field behaviour as an experimental paradigm, we demonstrated a complex interaction between the rewarding/stimulating effects and the anxiogenic/stressful effects of both novelty and acute or chronic amphetamine in mice. As a consequence of this interaction, acute amphetamine-induced hyperlocomotion was inhibited, whereas the expression of its sensitization was facilitated in a novel environment. In the present study, we aimed to investigate the interactions between exposure to a novel environment and the acute and chronic effects of ethanol (Eth), a drug of abuse known to produce anxiolytic-like behaviour in mice. Previously habituated and non-habituated male Swiss mice (3 months old) were tested in an open field after receiving an acute injection of Eth or following repeated treatment with Eth. Acute Eth administration increased locomotion with a greater magnitude in mice exposed to the apparatus for the first time, and this was thought to be related to the attenuation of the stressful effects of novelty produced by the anxiolytic-like effect of acute Eth, leading to a subsequent prevalence of its stimulant effects. However, locomotor sensitization produced by repeated Eth administration was expressed only in the previously explored environment. This result might be related to the well-known tolerance of Eth-induced anxiolytic-like behaviour following repeated treatment, which would restore the anxiogenic effect of novelty. Our data suggest that a complex and plastic interaction between the emotional and motivational properties of novelty and drugs of abuse can critically modify the behavioural expression of addiction-related mechanisms.
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Association between locomotor response to novelty and light reinforcement: sensory reinforcement as a rodent model of sensation seeking. Behav Brain Res 2012; 230:380-8. [PMID: 22586716 DOI: 10.1016/j.bbr.2012.02.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND The human personality trait of sensation seeking (SS) indicates an attraction to novel sensations and experiences, and is associated with greater likelihood of drug abuse. In rodents, locomotor activity in a novel environment (Loco) has been found to predict drug self-administration (SA), and has been hypothesized to be a translational model of human SS. Previously, we reported (Gancarz et al., 2011) that high responder (HR) animals responded more than low responder (LR) animals to produce a response contingent light onset. The primary goal of this paper was a detailed analysis of the association between Loco and light contingent responding in a large sample of rats (n = 93). METHODS Male rats were pre-exposed to dark operant test chambers for ten 30 min sessions and baseline levels of responding (snout poking) were determined. The pre-exposure phase was followed by 6 sessions during which active responding produced a visual sensory reinforcer (VSR; 5 s light onset) according to a variable interval 1 min schedule of reinforcement. After completion of the VSR phase, Loco was tested. RESULTS The activating effects (total responding) of light were associated with Loco, but the response guiding effects (proportion of active responding) of the light were not. In addition, HR rats habituated more slowly in both the VSR and Loco tests than LR rats. CONCLUSIONS These data indicate that VSR measures aspects of the rodent’s response to novel sensations and experiences that are not detected by Loco. These data provide some evidence for the use of light reinforcement as an animal model of SS.
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Murine model of repeated exposures to conspecific trained aggressors simulates features of post-traumatic stress disorder. Behav Brain Res 2012; 235:55-66. [PMID: 22824590 DOI: 10.1016/j.bbr.2012.07.022] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 07/07/2012] [Accepted: 07/12/2012] [Indexed: 12/12/2022]
Abstract
We evaluated repeated exposures of mice to a trained aggressor mouse as a model (adapted from "social stress" models of traumatic stress) for aspects of post-traumatic stress disorder (PTSD). Using a "cage-within-cage resident-intruder" protocol, subject C57BL/6J mice were exposed to aggressors for 6 h daily for 5 or 10 days. At one to three random times during each 6-h session, subjects were exposed directly to aggressor for 1 min or 10 bites, whichever came first. Behavioral, physiological, and histological changes associated with aggressor-exposure were assessed for up to 6 weeks. During aggressor exposure, subjects displayed less territorial behavior, gained weight, and increased body temperature. One day after the last aggressor exposure, inflammatory cardiac histopathologies were prevalent; after 10 days, only mild myocardial degeneration with fibrosis or fibroplasias was evident, while controls showed almost no cardiac abnormalities at any time. After 4 weeks, the medial prefrontal cortex of control mice showed increased dendritic spine density, but aggressor-exposed mice showed no increase. Behaviors affected by aggressor exposure were evaluated in a partition test wherein the subject mouse is separated from the aggressor by a fenestrated partition that permits sensory cues to pass but prevents direct physical interaction. For up to 4-6 weeks after the last aggressor exposure, subjects showed prolonged grooming, freezing, retarded locomotion and no tail rattling. PTSD and its co-morbidities are often consequent to repeated aggravated "social" assaults (e.g., combat) and manifest socially over time, suggesting the relevance of this repeated aggressor-exposure model to clinical aspects of PTSD.
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Peters S, Grunwald N, Rümmele P, Endlicher E, Lechner A, Neumann ID, Obermeier F, Reber SO. Chronic psychosocial stress increases the risk for inflammation-related colon carcinogenesis in male mice. Stress 2012; 15:403-15. [PMID: 22044139 DOI: 10.3109/10253890.2011.631232] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Patients with inflammatory bowel diseases (IBDs) have a higher risk of developing colorectal cancer (CRC) than the general population. Furthermore, chronic psychosocial stress increases the likelihood of developing IBD and multiple types of malignant neoplasms, including CRC. Here, for the first time, we investigate the effects of chronic psychosocial stress in male mice on an artificially induced CRC, by employing the chronic subordinate colony (CSC) housing paradigm in combination with the reliable azoxymethane (AOM)/dextran sodium sulfate (DSS) CRC model. Colonoscopy revealed that CSC mice showed accelerated macroscopic suspect lesions. In addition, more CSC mice developed low-grade dysplasia (LGD) and/or high-grade dysplasia (HGD) in the colonic tissue compared to the single-housed control mice (SHC). CSC mice showed an increased number of Ki67+ and a decreased number of terminal deoxynucleotidyl transferase dUTP nick end labeling epithelial cells in colonic tissue. Colonic liver receptor homolog-1 (LRH-1), cyclooxygenase II (COXII), tumor necrosis factor, forkhead box P3 (FoxP3) mRNA as well as colonic ß-catenin, COXII, and LRH-1 protein expression were also increased in CSC compared with SHC mice. Although the number of CD4+ Th cells was increased, a tendency toward a decreased colonic interferon-γ (IFN-γ) mRNA expression was observed. Furthermore, despite an increased percentage of CD3+ cells and CD3+/FoxP3+ double-positive cells within mesenteric lymph node cells of CSC mice, IFN-γ secretion from these cells was unaffected. Altogether, our results suggest that chronic psychosocial stress increases the risk for AOM/DSS-induced and, thus, inflammation-related CRC. Finally, assessment of additional time points may test whether the shift from tumor-protective Th1 cell to regulatory T-cell immunity represents a consequence of increased carcinogenesis or a causal factor involved in its development.
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Affiliation(s)
- Sebastian Peters
- Chronic Stress Group, Department of Behavioural and Molecular Neuroendocrinology, Neuroscience Centre, University of Regensburg, Regensburg, Germany
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Boleij H, van't Klooster J, Lavrijsen M, Kirchhoff S, Arndt SS, Ohl F. A test to identify judgement bias in mice. Behav Brain Res 2012; 233:45-54. [PMID: 22562041 DOI: 10.1016/j.bbr.2012.04.039] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 04/17/2012] [Accepted: 04/21/2012] [Indexed: 10/28/2022]
Abstract
Emotional states are known to affect cognitive processes. For example highly anxious individuals interpret ambiguous stimuli more negatively than low anxious people, an effect called negative judgement bias. Recently, the measurement of judgement bias has been used to try and indicate emotional states in animals. In the present experiment a potential test for judgement bias in mice was examined. Mice were trained with two distinct odour cues (vanilla or apple) predicting either a palatable or an unpalatable almond piece. Subsequently their reaction to mixtures of both odours, the ambiguous stimuli, was investigated. Mice of the BALB/cJ and 129P3/J inbred mouse strains (high initial anxiety and low initial anxiety phenotypes respectively) were tested. While BALB/cJ mice showed odour association learning and showed intermediate reactions to the ambiguous cues, 129P3/J mice did not discriminate between the cues. Additionally BALB/cJ mice that were tested under more aversive white light conditions revealed a higher latency to approach the almond piece than mice tested under less aversive red light conditions. The ambiguous stimulus however was interpreted as negative under both test conditions. Brain c-Fos expression levels (a marker for neuronal activity) differed between the BALB/c/J and 129P3/J in the lateral amygdala and the prelimbic cortex, indicating differences in ambiguous information processing between the strains. The behavioural results suggest that the present judgement bias test might be used to assess emotional states in at least BALB/c mice, however further research on both behaviour and on the involved brain mechanisms is necessary to confirm this idea.
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Affiliation(s)
- Hetty Boleij
- Department of Animals in Science and Society, Division of Animal Welfare and Laboratory Animal Science, Utrecht University, Utrecht, The Netherlands.
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Stairs DJ, Prendergast MA, Bardo MT. Environmental-induced differences in corticosterone and glucocorticoid receptor blockade of amphetamine self-administration in rats. Psychopharmacology (Berl) 2011; 218:293-301. [PMID: 21887496 PMCID: PMC3192300 DOI: 10.1007/s00213-011-2448-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 08/08/2011] [Indexed: 01/22/2023]
Abstract
RATIONALE Rats raised in isolation self-administer more amphetamine than rats raised in enrichment. OBJECTIVE This study examined whether differential rearing alters basal and amphetamine-stimulated corticosterone and whether blocking glucocorticoid receptors alters amphetamine self-administration in differentially reared rats. METHODS The rats were raised from 21 to 51 days of age in either an enriched condition (EC), social condition (SC), or isolated condition (IC). Following the repeated collection of basal blood samples, the rats were administered amphetamine (0.5 or 2.0 mg/kg, i.p.) or saline, and blood samples were collected again. In another experiment, EC and IC rats were trained to i.v. self-administer amphetamine (0.003 or 0.03 mg/kg/infusion) and then were pretreated with the glucocorticoid receptor antagonist RU-486 (5, 10, or 20 mg/kg; i.p.) or vehicle prior to the session. RESULTS Basal-free corticosterone levels were ~4 times higher in IC rats than in either EC or SC rats with the first blood collection, but not with repeated collections. IC rats showed a more rapid amphetamine-induced increase in corticosterone levels than EC and SC rats. RU-486 pretreatment decreased amphetamine self-administration dose-dependently in both EC and IC rats; however, using an amphetamine unit dose of 0.03 mg/kg/infusion, the effect of RU-486 was blunted in IC rats (maximal decrease of ~40% in IC and ~90% in EC), suggesting an environment-induced difference in the role of glucocorticoid receptors in stimulant reinforcement. CONCLUSION The increase in stimulant self-administration produced by social isolation may involve enhanced reactivity of the hypothalamo-pituitary-adrenal stress axis.
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Affiliation(s)
- Dustin J Stairs
- Department of Psychology, Creighton University, Hixson-Lied, Room 308 2500 California Plaza, Omaha, NE 68178-0321, USA.
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Hiramoto T, Kang G, Suzuki G, Satoh Y, Kucherlapati R, Watanabe Y, Hiroi N. Tbx1: identification of a 22q11.2 gene as a risk factor for autism spectrum disorder in a mouse model. Hum Mol Genet 2011; 20:4775-85. [PMID: 21908517 DOI: 10.1093/hmg/ddr404] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although twin studies indicate clear genetic bases of autism spectrum disorder (ASD), the precise mechanisms through which genetic variations causally result in ASD are poorly understood. Individuals with 3 Mb and nested 1.5 Mb hemizygosity of the chromosome 22q11.2 represent genetically identifiable cases of ASD. However, because more than 30 genes are deleted even in the minimal deletion cases of 22q11.2 deficiency, the individual 22q11.2 gene(s) responsible for ASD remain elusive. Here, we examined the impact of constitutive heterozygosity of Tbx1, a 22q11.2 gene, on the behavioral phenotypes of ASD and characterized the regional and cellular expression of its mRNA and protein in mice. Congenic Tbx1 heterozygous (HT) mice were impaired in social interaction, ultrasonic vocalization, memory-based behavioral alternation, working memory and thigmotaxis, compared with wild-type (WT) mice. These phenotypes were not due to non-specific alterations in olfactory function, exploratory behavior, motor movement or anxiety-related behavior. Tbx1 mRNA and protein were ubiquitously expressed throughout the brains of C57BL/6J mice, but protein expression was enriched in regions that postnatally retain the capacity of neurogenesis, and in fact, postnatally proliferating cells expressed Tbx1. In postnatally derived hippocampal culture cells of C57BL/6J mice, Tbx1 levels were higher during proliferation than during differentiation, and expressed in neural progenitor cells, immature and matured neurons and glial cells. Taken together, our data suggest that Tbx1 is a gene responsible for the phenotypes of 22q11.2 hemizygosity-associated ASD possibly through its role in diverse cell types, including postnatally and prenatally generated neurons.
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Affiliation(s)
- Takeshi Hiramoto
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Beerling W, Koolhaas JM, Ahnaou A, Bouwknecht JA, de Boer SF, Meerlo P, Drinkenburg WHIM. Physiological and hormonal responses to novelty exposure in rats are mainly related to ongoing behavioral activity. Physiol Behav 2011; 103:412-20. [PMID: 21406199 DOI: 10.1016/j.physbeh.2011.03.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 03/09/2011] [Accepted: 03/09/2011] [Indexed: 10/18/2022]
Abstract
Stress research has been dominated by a circular type of reasoning that occurrence of a stress response is bad. Consequently, the stimulus is often interpreted as stressful in terms of aversiveness involving uncontrollability and unpredictability, which may have maladaptive and pathological consequences. However, the hypothalamic-pituitary-adrenal (HPA) axis and sympathico-adrenomedullary (SAM) system are not only activated in response of the organism to challenges, but also prepare and support the body for behavior. Therefore, a considerable part of the physiological and hormonal responses to a certain situation can be a direct reflection of the metabolic requirements for the normal ongoing behavioral activity, rather than of the stressful nature. In order to clarify this, behavioral, physiological, hormonal and electroencephalographic (EEG) responses to novel cage exposure were studied in male Sprague-Dawley rats. Forced confrontation with a novel cage has been interpreted as a psychological and aversive stressor. However, this interpretation is simply based on the occurrence of a stress response. This study aimed at detailed analysis of the time course of the novelty-induced responses. Different parameters were measured simultaneously in freely moving rats, which allowed correlational comparisons. Hereto, radio telemetry using a small implantable transmitter combined with permanent catheters and an automated blood sampling system was used. A camera placed above the cage allowed behavioral observations. The results show that novelty exposure induced significant increases in locomotor activity, heart rate, blood pressure and plasma corticosterone together with a complete lack of sleep as compared to the undisturbed control situation. The latency to reach significance and the duration of responses varied across parameters but all had recovered within 30min after termination of novelty. The behavioral activity (locomotor activity and EEG wakefulness duration) response pattern was significantly correlated with that of heart rate, blood pressure and plasma corticosterone. Behavioral observations showed mainly explorative behavior in response to novelty. Therefore, the present results indicate that the novelty-induced physiological and hormonal responses are closely related to the ongoing, mainly explorative behavioral activity induced by novelty. An interpretation in terms of metabolic support of ongoing behavior seems to be more appropriate than the frequently used stress interpretation. The present study also emphasizes the added value of simultaneous assessment of behavioral, physiological and hormonal parameters under controlled, non-confounding conditions.
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Affiliation(s)
- W Beerling
- Department of Neuroscience, Janssen Research & Development, a division of Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340 Beerse, Belgium.
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Automation of the free-exploratory paradigm. J Neurosci Methods 2011; 197:216-20. [PMID: 21376081 DOI: 10.1016/j.jneumeth.2011.02.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 02/18/2011] [Accepted: 02/18/2011] [Indexed: 11/23/2022]
Abstract
The free-exploratory paradigm (FEP) is currently the only proposed animal model of trait anxiety, making it highly valuable to behavioural neuroscience. However, FEP has not yet been automated, so its results depend on human scoring, which can be quite imprecise. The aim of this study was, therefore, to validate an automated version of FEP, using a commercially available video-tracking system (ANY-maze(©) - Stoelting Co., USA). To achieve this, two experiments were performed. The first one evaluated the reliability of the video-based automation of FEP, and the second, assessed whether the zeolites, used as a bedding material in the first experiment to facilitate video-tracking, influenced the animals' behaviour in FEP. In experiment I, 15 drug-naive, adult, male rats were tested in FEP, while their behaviour was simultaneously evaluated by ANY-maze(©) and two human observers. Subsequently, the intraclass correlation coefficient (ICC) was calculated for the automated and manual results of the parameters "percentage of time in the novel side" (%TNS) and "total units visited" (TUV). The analysis resulted in high, significant values of ICC (%TNS: 0.9962 and TUV: 0.9453). In experiment II, 18 drug-naive, adult, male rats were allocated to two different groups: (1) tested in FEP with zeolites; and (2) tested in FEP with sawdust. The data obtained were analysed using the Student's t-test, which revealed no significant differences between the groups for the parameters %TNS and TUV. In conclusion, the data presented here show that automation of FEP, using a video-based tracking system, is not only possible, but also highly reliable.
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Belin D, Berson N, Balado E, Piazza PV, Deroche-Gamonet V. High-novelty-preference rats are predisposed to compulsive cocaine self-administration. Neuropsychopharmacology 2011; 36:569-79. [PMID: 20980989 PMCID: PMC3055686 DOI: 10.1038/npp.2010.188] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Sensation/novelty-seeking is amongst the best markers of cocaine addiction in humans. However, its implication in the vulnerability to cocaine addiction is still a matter of debate, as it is unclear whether this trait precedes or follows the development of addiction. Sensation/novelty-seeking trait has been identified in rats on the basis of either novelty-induced locomotor activity (high-responder (HR) trait) or novelty-induced place preference (high-novelty-preference trait (HNP)). HR and HNP traits have been associated with differential sensitivity to psychostimulants. However, it has recently been demonstrated that HR rats do not develop compulsive cocaine self-administration (SA) after protracted exposure to the drug, thereby suggesting that at least one dimension of sensation/novelty seeking in the rat is dissociable from the vulnerability to switch from controlled to compulsive cocaine SA. We therefore investigated whether HNP, as measured as the propensity to choose a new environment in a free choice procedure, as opposed to novelty-induced locomotor activity, predicts the vulnerability to, and the severity of, addiction-like behavior for cocaine. For this, we identified HR/LR rats and HNP/LNP rats before any exposure to cocaine. After 60 days of cocaine SA, each rat was given an addiction score based on three addiction-like behaviors (persistence of responding when the drug is signaled as not available, high breakpoint under progressive ratio schedule and resistance to punishment) that resemble the clinical features of drug addiction, namely inability to refrain from drug seeking, high motivation for the drug and compulsive drug use despite adverse consequences. We show that, as opposed to HR rats, HNP rats represent a sub-population predisposed to compulsive cocaine intake, displaying higher addiction scores than LNP rats. This study thereby provides new insights into the factors predisposing to cocaine addiction, supporting the hypothesis that addiction is sustained by two vulnerable phenotypes: a 'drug use prone' phenotype such as HR which brings an individual to develop drug use and an 'addiction prone' phenotype, such as HNP, which facilitates the shift from sustained to compulsive drug intake and addiction.
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Affiliation(s)
- David Belin
- University of Bordeaux, Bordeaux Cedex, France.
| | - Nadège Berson
- University of Bordeaux, Bordeaux Cedex, France,INSERM U862, Pathophysiology of Addiction, NeuroCentre Magendie, Bordeaux Cedex, France
| | - Eric Balado
- University of Bordeaux, Bordeaux Cedex, France,INSERM U862, Pathophysiology of Addiction, NeuroCentre Magendie, Bordeaux Cedex, France
| | - Pier Vincenzo Piazza
- University of Bordeaux, Bordeaux Cedex, France,INSERM U862, Pathophysiology of Addiction, NeuroCentre Magendie, Bordeaux Cedex, France
| | - Véronique Deroche-Gamonet
- University of Bordeaux, Bordeaux Cedex, France,INSERM U862, Pathophysiology of Addiction, NeuroCentre Magendie, Bordeaux Cedex, France
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Beckmann JS, Marusich JA, Gipson CD, Bardo MT. Novelty seeking, incentive salience and acquisition of cocaine self-administration in the rat. Behav Brain Res 2010; 216:159-65. [PMID: 20655954 DOI: 10.1016/j.bbr.2010.07.022] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 07/16/2010] [Accepted: 07/19/2010] [Indexed: 11/19/2022]
Abstract
It has been suggested that incentive salience plays a major role in drug abuse and the development of addiction. Additionally, novelty seeking has been identified as a significant risk factor for drug abuse. However, how differences in the readiness to attribute incentive salience relate to novelty seeking and drug abuse vulnerability has not been explored. The present experiments examined how individual differences in incentive salience attribution relate to novelty seeking and acquisition of cocaine self-administration in a preclinical model. Rats were first assessed in an inescapable novelty task and a novelty place preference task (measures of novelty seeking), followed by a Pavlovian conditioned approach task for food (a measure of incentive salience attribution). Rats then were trained to self-administer cocaine (0.3 or 1.0 mg/kg/infusion) using an autoshaping procedure. The results demonstrate that animals that attributed incentive salience to a food-associated cue were higher novelty seekers and acquired cocaine self-administration more quickly at the lower dose. The results suggest that novelty-seeking behavior may be a mediator of incentive salience attribution and that incentive salience magnitude may be an indicator of drug reward.
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Affiliation(s)
- Joshua S Beckmann
- University of Kentucky, Department of Psychology, 741 S. Limestone, BBSRB, Room 447, Lexington, KY 40536-0509, United States.
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Transient early-life forebrain corticotropin-releasing hormone elevation causes long-lasting anxiogenic and despair-like changes in mice. J Neurosci 2010; 30:2571-81. [PMID: 20164342 DOI: 10.1523/jneurosci.4470-09.2010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During development, early-life stress, such as abuse or trauma, induces long-lasting changes that are linked to adult anxiety and depressive behavior. It has been postulated that altered expression of corticotropin-releasing hormone (CRH) can at least partially account for the various effects of stress on behavior. In accord with this hypothesis, evidence from pharmacological and genetic studies has indicated the capacity of differing levels of CRH activity in different brain areas to produce behavioral changes. Furthermore, stress during early life or adulthood causes an increase in CRH release in a variety of neural sites. To evaluate the temporal and spatial specificity of the effect of early-life CRH exposure on adult behavior, the tetracycline-off system was used to produce mice with forebrain-restricted inducible expression of CRH. After transient elevation of CRH during development only, behavioral testing in adult mice revealed a persistent anxiogenic and despair-like phenotype. These behavioral changes were not associated with alterations in adult circadian or stress-induced corticosterone release but were associated with changes in CRH receptor type 1 expression. Furthermore, the despair-like changes were normalized with antidepressant treatment. Overall, these studies suggest that forebrain-restricted CRH signaling during development can permanently alter stress adaptation leading to increases in maladaptive behavior in adulthood.
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The contribution of the central nucleus of the amygdala to individual differences in amphetamine-induced hyperactivity. Behav Brain Res 2009; 202:11-8. [PMID: 19447275 DOI: 10.1016/j.bbr.2009.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2008] [Revised: 03/01/2009] [Accepted: 03/07/2009] [Indexed: 11/21/2022]
Abstract
Rats classified as high responders (HR) based on their response to an inescapable novel environment self-administer more amphetamine and have greater amphetamine-induced sensitization than rats classified as low responders (LR). Recent research suggests that the central nucleus of the amygdala (ACe) contributes to the elevated self-administration in HR rats. Therefore, the current study examined the role of the ACe in the expression of both amphetamine-induced sensitization and conditioned hyperactivity in HR and LR rats. Male Sprague-Dawley rats were screened for their response to inescapable novelty and classified as HR or LR rats. Rats were implanted with bilateral cannulae into the ACe and received amphetamine (1.0 mg/kg, s.c.) or saline injections immediately prior to 1-h locomotor sessions. Following five training sessions, all rats received an infusion of muscimol (0.5 microg/0.5 microl) or phosphate buffered saline (PBS) followed by a saline injection to measure conditioned hyperactivity. HR rats displayed conditioned hyperactivity, while LR rats did not, suggesting that HR and LR rats differ in the expression of conditioned hyperactivity. While ACe inactivation attenuated the expression of conditioned hyperactivity, it did not differentially affect HR and LR rats. Following additional training and a 10-day rest period, all rats were then tested for amphetamine-induced sensitization (1.0 mg/kg) following an infusion of muscimol or PBS. Inactivation of the ACe attenuated the expression of sensitization only in HR rats. These results suggest the ACe contributes to the greater amphetamine sensitization in HR rats.
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Zhu J, Reith MEA. Role of the dopamine transporter in the action of psychostimulants, nicotine, and other drugs of abuse. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2009; 7:393-409. [PMID: 19128199 DOI: 10.2174/187152708786927877] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A number of studies over the last two decades have demonstrated the critical importance of dopamine (DA) in the behavioral pharmacology and addictive properties of abused drugs. The DA transporter (DAT) is a major target for drugs of abuse in the category of psychostimulants, and for methylphenidate (MPH), a drug used for treating attention deficit hyperactivity disorder (ADHD), which can also be a psychostimulant drug of abuse. Other drugs of abuse such as nicotine, ethanol, heroin and morphine interact with the DAT in more indirect ways. Despite the different ways in which drugs of abuse can affect DAT function, one evolving theme in all cases is regulation of the DAT at the level of surface expression. DAT function is dynamically regulated by multiple intracellular and extracellular signaling pathways and several protein-protein interactions. In addition, DAT expression is regulated through the removal (internalization) and recycling of the protein from the cell surface. Furthermore, recent studies have demonstrated that individual differences in response to novel environments and psychostimulants can be predicted based on individual basal functional DAT expression. Although current knowledge of multiple factors regulating DAT activity has greatly expanded, many aspects of this regulation remain to be elucidated; these data will enable efforts to identify drugs that might be used therapeutically for drug dependence therapeutics.
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Affiliation(s)
- J Zhu
- Department of Psychology, University of South Carolina, Columbia, SC 29208, USA.
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Roy V, Chapillon P, Jeljeli M, Caston J, Belzung C. Free versus forced exposure to an elevated plus-maze: evidence for new behavioral interpretations during test and retest. Psychopharmacology (Berl) 2009; 203:131-41. [PMID: 18998112 DOI: 10.1007/s00213-008-1378-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2008] [Accepted: 10/13/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE The rodent elevated plus-maze is based on an approach/avoidance conflict between secure closed arms and aversive open arms that can be measured to assess anxiety. Despite this apparent simplicity, several discrepancies emerge from the interpretation of an animal's behavior in the maze, especially when considering the one-trial tolerance effect. OBJECTIVES AND METHODS In order to bring new elements of interpretation, we compared the behavior of rats exposed to the standard version of the test (forced exposure) to the behavior of rats that were allowed to freely explore the apparatus. We also compared the effects of testing/retesting and chlordiazepoxide in these two situations. RESULTS Our results confirm that open-arm avoidance is a natural tendency and therefore that it is not learned during initial exposure to the maze. In addition, comparison of the two situations suggests that some of the open-arm entries during a forced confrontation with the maze are better interpreted as attempts to avoid the whole situation, rather than as indications of a low level of anxiety. Finally, the one-trial tolerance effect was partially reduced in the free-exposure situation. CONCLUSIONS Our results contradict the hypothesis that there is acquisition of a phobic-like response to open arms during trial 1. Rather, they are discussed in line with the hypotheses by Rodgers and Shepherd (Psychopharmacology (Berl) 113:237-242, 1993) and Bertoglio and Carobrez (Behav Brain Res 108:197-203, 2000) concerning the acquisition of spatial information about the whole apparatus, leading on trial 2 to an unbalanced approach/avoidance conflict and to the inefficiency of anxiolytic drugs.
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Affiliation(s)
- Vincent Roy
- UPRES PSY-NCA, EA4306, Laboratoire de Psychologie et Neurosciences de la Cognition et de l'Affectivité, European Institute for Peptide Research (IFRMP 23), Université de Rouen, 76821, Mont-Saint-Aignan, Cedex, France.
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Teixeira-Silva F, Antunes FD, Santos Silva PR, Goes TC, Dantas EC, Santiago MF, de Andrade RM. The free-exploratory paradigm as a model of trait anxiety in rats: Test–retest reliability. Physiol Behav 2009; 96:729-34. [DOI: 10.1016/j.physbeh.2009.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Goes TC, Antunes FD, Teixeira-Silva F. Trait and state anxiety in animal models: Is there correlation? Neurosci Lett 2009; 450:266-9. [DOI: 10.1016/j.neulet.2008.11.037] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 11/12/2008] [Accepted: 11/16/2008] [Indexed: 11/24/2022]
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Habituation to repeated stress: get used to it. Neurobiol Learn Mem 2008; 92:215-24. [PMID: 18667167 DOI: 10.1016/j.nlm.2008.07.001] [Citation(s) in RCA: 343] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Revised: 07/01/2008] [Accepted: 07/07/2008] [Indexed: 11/23/2022]
Abstract
Habituation, as described in the landmark paper by Thompson et al. [Thompson, R. F., & Spencer, W. A. (1966). Habituation: A model phenomenon for the study of neuronal substrates of behavior. Psychological Review, 73(1), 16-43], is a form of simple, nonassociative learning in which the magnitude of the response to a specific stimulus decreases with repeated exposure to that stimulus. A variety of neuronal and behavioral responses have been shown to be subject to habituation based on the criteria presented in that paper. It has been known for several decades that the magnitude of hypothalamic-pituitary-adrenal (HPA) activation occurring in response to a stressor declines with repeated exposure to that same stressor. For some time this decline has been referred to as "habituation" in the stress neurobiology literature. However, how this usage compares to the definition proposed by Thompson and Spencer has not been systematically addressed. For this special issue, we review the stress neurobiology literature and examine the support available for considering declines in HPA response to repeated stress to be response habituation in the sense defined by Thompson and Spencer. We conclude that habituation of HPA activity meets many, but not all, important criteria for response habituation, supporting the use of this term within the context of repeated stress. However, we also propose that response habituation can, at best, only partially explain the phenomenon of HPA habituation, which also involves well-known negative feedback mechanisms, activation of broad stress-related neural circuitry and potentially more complex associative learning mechanisms.
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Cunningham RL, McGinnis MY. Prepubertal social subjugation and anabolic androgenic steroid-induced aggression in male rats. J Neuroendocrinol 2008; 20:997-1005. [PMID: 18510706 DOI: 10.1111/j.1365-2826.2008.01756.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Abused children are more prone to abuse drugs, such as anabolic androgenic steroids (AAS), as teenagers and display violence as adults. AAS use has been linked with elevated aggression. Thus, exposure to child abuse and AAS may potentiate aggression. A social subjugation paradigm was used as an animal model of childhood abuse to determine whether prior subjugation increases AAS-induced aggression in male rats. Prepubertal gonadally intact male rats were exposed to social subjugation, a novel cage experience, or remained undisturbed in their home cages. Experimental males were socially subjugated by being placed in the home cage of an adult male. At puberty, both subjugated and nonsubjugated rats were injected with either the AAS testosterone or vehicle. AAS treatment continued for 5 weeks. Aggression was measured during the last week of AAS exposure. AAS was then discontinued. Aggression was again tested 12 weeks after AAS withdrawal. Aggression was tested under three conditions: (i) physical provocation of the experimental male; (ii) provocation of the intruder male; and (iii) without provocation. Both AAS-treated males and socially subjugated males displayed significantly more aggression than did controls. Elevated aggression by subjugated males was still present 17 weeks after social subjugation. AAS males also showed increased aggression 12 weeks after AAS withdrawal. However, exposure to both social subjugation and AAS had no long-term effects on aggression. The results of the present study indicate that social subjugation may have lasting consequences on the expression of adaptive social behaviours.
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Affiliation(s)
- R L Cunningham
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Veenema AH, Reber SO, Selch S, Obermeier F, Neumann ID. Early life stress enhances the vulnerability to chronic psychosocial stress and experimental colitis in adult mice. Endocrinology 2008; 149:2727-36. [PMID: 18308845 DOI: 10.1210/en.2007-1469] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Early life stress enhances the vulnerability to both mood and chronic inflammatory disorders, suggesting a link between these stress-related disorders. To study this, we exposed male C57BL/6 mice to early life stress [maternal separation (MS), 3 h/d, d 1-14] and to adult chronic psychosocial stress [chronic subordinate colony housing (CSC)] and measured changes in neuroendocrine parameters and in the severity of a chemically induced colitis. In both unseparated and MS mice, 19 d of CSC exposure resulted in a transient decrease in body weight gain, increased anxiety-related behavior, and decreased vasopressin mRNA expression in the hypothalamic paraventricular nucleus compared with respective nonstressed mice. However, only CSC-stressed MS mice showed elevated CRH mRNA expression in the paraventricular nucleus and reduced plasma corticosterone. Subsequent treatment with dextran sulfate sodium (1%, 7 d) resulted in a more severe colonic inflammation in MS compared with unseparated mice. This was indicated by an increased histological damage score and increased TNF secretion (nonstressed MS mice), more severe body weight loss and inflammatory reduction in colon length (CSC-stressed MS mice), and increased interferon-gamma secretion (nonstressed and CSC-stressed MS mice). In conclusion, early life stress and subsequent exposure to chronic psychosocial stress in adulthood induced neuroendocrine abnormalities, which likely contributed to enhanced vulnerability to chemically induced colitis. The combined use of MS and CSC represents a potential animal model providing novel (patho)physiological insights into the complex interactions between neuroendocrine and inflammatory actions upon chronic stress exposure. These findings may further help to reveal mechanisms of hypocortisolemic disorders.
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Affiliation(s)
- Alexa H Veenema
- Department of Behavioral Neuroendocrinology, Institute of Zoology, University of Regensburg, 93053 Regensburg, Germany.
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Cain ME, Denehy ED, Bardo MT. Individual differences in amphetamine self-administration: the role of the central nucleus of the amygdala. Neuropsychopharmacology 2008; 33:1149-61. [PMID: 17568395 PMCID: PMC2742632 DOI: 10.1038/sj.npp.1301478] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Rats categorized as high responder (HR), based on their activity in an inescapable novel environment, self-administer more amphetamine than low responder (LR) rats. The current study examined if the central nucleus of the amygdala (ACe) contributes to the elevated response for amphetamine in HR rats. Male Sprague-Dawley rats were classified as HR and LR rats based on their activity in inescapable novelty and novelty place preference, and then were trained to self-administer amphetamine (0.1 mg/kg/infusion). Once stable responding was achieved, rats received microinfusions of the GABA(A) agonist muscimol (0.5 microg/0.5 microl) or phosphate-buffered saline into the ACe immediately before self-administration of amphetamine (0.1, 0.03, 0.01, or 0.001 mg/kg/infusion) or saline. An additional group of rats was trained to lever press for sucrose rather than amphetamine. Based on the inescapable novelty test, HR rats self-administered more amphetamine than LR rats at the 0.03 and 0.01 mg/kg/infusion unit doses; there were no significant individual differences in amphetamine self-administration based on the novelty place preference test. Inactivation of the ACe with muscimol decreased self-administration at the 0.03 and 0.01 mg/kg/infusion unit doses in HR rats, but had no effect on LR rats. ACe inactivation had no reliable effect on inactive lever responding and appeared to be region specific based on anatomical controls. In addition, while inactivation of the ACe decreased responding for sucrose, inactivation did not differentially affect HR and LR rats. These results suggest that the ACe contributes to the elevated rate of amphetamine self-administration in HR rats.
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Affiliation(s)
- Mary E Cain
- Department of Psychology, Kansas State University, Manhattan, KS 66506-5302, USA.
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Zhu H, Lee M, Agatsuma S, Hiroi N. Pleiotropic impact of constitutive fosB inactivation on nicotine-induced behavioral alterations and stress-related traits in mice. Hum Mol Genet 2007; 16:820-36. [PMID: 17468183 DOI: 10.1093/hmg/ddm027] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Multiple genes are thought to influence both susceptibility to nicotine dependence and its comorbid behavioral traits in humans. However, which specific genes contribute to this pleiotropic effect is poorly understood. Previous rodent studies have shown that many addictive substances and stressful stimuli increase the expression of the transcription factor FosB in limbic and associated regions and that the protein products of fosB contribute to certain behavioral effects of cocaine and morphine. However, the role of this gene in nicotine-regulated behaviors and dependence-related behavioral traits is unknown. We tested the hypothesis that a constitutive level of FosB affects nicotine-regulated behaviors and comorbid behavioral traits using constitutive fosB knockout (KO) mice. Following repeated or prolonged nicotine administration, but not a single acute administration, KO mice were impaired in conditioned place preference, oral nicotine intake and motor suppression. In wild-type mice, repeated nicotine injections, but not a single acute injection, increased the expression of FosB and its truncated variant DeltaFosB in the targets but not at the origins of the mesolimbic and nigrostriatal dopamine pathways; no detectable level of FosB/DeltaFosB was found in KO mice. In tasks designed to assess behavioral traits, KO mice exhibited more pronounced behavioral abnormalities when stress levels were high than when they were minimized. Our results suggest that the constitutive absence of fosB has a pleiotropic influence on the behavioral effects of repeated or prolonged nicotine administration and on stress-related behavioral traits in mice.
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Affiliation(s)
- Hongwen Zhu
- Laboratory of Molecular Psychobiology, Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Zhu J, Bardo MT, Bruntz RC, Stairs DJ, Dwoskin LP. Individual differences in response to novelty predict prefrontal cortex dopamine transporter function and cell surface expression. Eur J Neurosci 2007; 26:717-28. [PMID: 17651428 DOI: 10.1111/j.1460-9568.2007.05690.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Previous research has shown that individual differences in response to novelty predict self-administration and the locomotor response to psychostimulant drugs of abuse. The aim of the present study was to determine if individual differences in response to novelty based on inescapable or free-choice novelty tests predict dopamine transporter (DAT) function and trafficking as well as nicotine-induced modulation of DAT. Results show that the maximal velocity (Vmax) of [3H]dopamine uptake into prefrontal cortex (PFC) synaptosomes correlated negatively with the locomotor response to inescapable novelty. In contrast, Vmax correlated positively with novelty place preference in the free-choice novelty test. The divergent correlations between DAT and the two behavioral phenotypes suggest a differential contribution of DAT in these phenotypes, which are known not to be isomorphic. Furthermore, rats categorized as high responders to inescapable novelty had lower Vmax values, which were accompanied by less DAT expression at the cell surface in PFC compared with low responders, suggesting that inherent individual differences in DAT cellular localization may underlie the differential response to novelty. Compared with the saline control, nicotine increased Vmax and cell surface DAT immunoreactivity in PFC from high responders but not from low responders. Similarly, nicotine increased Vmax and cell surface DAT in PFC in rats classified as low in novelty place preference but not in rats classified as high in novelty place preference. Thus, despite the different behavioral phenotypes, the pharmacological effect of nicotine to increase DAT function and cell surface expression was apparent, such that rats with inherently lower DAT function show a greater sensitivity to the neurochemical effect of nicotine.
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Affiliation(s)
- Jun Zhu
- College of Pharmacy, University of Kentucky, 725 Rose Street, Lexington, KY 40536-0082, USA
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Armando I, Volpi S, Aguilera G, Saavedra JM. Angiotensin II AT1 receptor blockade prevents the hypothalamic corticotropin-releasing factor response to isolation stress. Brain Res 2007; 1142:92-9. [PMID: 17306778 PMCID: PMC2682713 DOI: 10.1016/j.brainres.2007.01.037] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 01/05/2007] [Accepted: 01/10/2007] [Indexed: 11/24/2022]
Abstract
Sustained pretreatment with angiotensin II AT(1) receptor antagonists prevents the sympathoadrenal and hormonal responses to 24 h isolation stress. To elucidate the mechanism of the anti-stress effects of AT(1) receptor antagonism, we examined the effect of subcutaneous infusion of candesartan, a non-competitive AT(1) receptor antagonist, 0.5 mg/kg/day for 14 days, to Wistar rats on the hypothalamic pituitary adrenal (HPA) axis after 24 h isolation stress. In the morning of day 15, we measured AT(1) receptors corticotropin-releasing factor (CRF) mRNA and immunoreactive CRF in the paraventricular nucleus (PVN), the pituitary adrenocorticotropin hormone (ACTH) and adrenal corticosterone content, and the urinary corticosterone excretion. In rats not treated with candesartan, 24 h isolation stress increased pituitary ACTH, adrenal corticosterone content and AT(1) receptor binding in the PVN but decreased CRF mRNA and CRF content in the PVN. This indicates enhanced CRF utilization not compensated by CRF gene transcription and effective glucocorticoid feedback inhibition in spite of the increase in AT(1) receptor expression. The effects of stress on HPA axis activation and CRF mRNA and content in the PVN were prevented by candesartan pretreatment, suggesting that activation of AT(1) receptors is required for the HPA axis response to isolation. Our results support the hypothesis that the activity of PVN AT(1) receptors is part of the mechanism necessary for development of a full stress-induced HPA axis activation. Inhibition of central AT(1) receptors limits the CRF response to stress and should be considered as a therapeutic tool to preserve homeostasis under chronic stress conditions.
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Affiliation(s)
- Ines Armando
- Section on Pharmacology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-, USA
| | - Simona Volpi
- Section on Endocrine Physiology, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-1303, USA
| | - Greti Aguilera
- Section on Endocrine Physiology, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-1303, USA
| | - Juan M. Saavedra
- Section on Pharmacology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-, USA
- To whom correspondence should be sent. Juan M. Saavedra, MD, Section on Pharmacology, DIRP, NIMH, NIH, DHHS, 10 Center Drive, Bldg. 10, Room 2D-57, Bethesda, MD 20892. Telephone: (301) 496-0160. Fax: (301) 402-0337. E-mail:
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Hughes RN. Neotic preferences in laboratory rodents: Issues, assessment and substrates. Neurosci Biobehav Rev 2007; 31:441-64. [PMID: 17198729 DOI: 10.1016/j.neubiorev.2006.11.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 10/18/2006] [Accepted: 11/09/2006] [Indexed: 11/18/2022]
Abstract
Neotic preference refers to the extent to which animals prefer stimuli of differing novelty value. Degree of novelty is determined by within- and between-trials habituation and amount of temporal (novelty) and spatial change (complexity) in stimulation which in turn will determine the amount of curiosity-based approach (neophilia) or fear-based avoidance (neophobia) of novel stimuli. Tests of genuine neotic preferences enable direct assessments of responsiveness to temporal and spatial changes and include measurements of novel versus familiar locations (such as novelty-related location preferences), responsiveness to stimulus complexity (such as object exploration) and learning for exploratory rewards (such as light-contingent bar-pressing). Effects of brain lesions and peripherally administered drugs have implicated several brain areas and neurotransmitters that subserve memory, fear and reward in neotic preferences namely the hippocampus and ACh (memory), the amygdala, GABA and 5-HT (fear), and the mesolimbic DA reward system. However, more attention should be paid to the complexity of interactions between different brain and neurotransmitter systems and improvements in methodology before conclusions should be drawn about the neurobiological basis of neotic preferences.
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Affiliation(s)
- Robert N Hughes
- Department of Psychology, University of Canterbury, Ilam Road, Private Bag 4800, Christchurch 8020, New Zealand.
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The effects of individual housing on mice and rats: a review. Anim Welf 2006. [DOI: 10.1017/s0962728600030669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
AbstractIsolating an animal refers to the situation where the animal is physically fully demarcated from conspecifics without physical, visual, olfactory and auditory contact. Animals housed in separate cages in the same room are, although deprived of physical and visual contact, still in olfactory and auditory contact, and thus not totally isolated. During the fifties and sixties several studies claimed to show physiological and behavioural differences between individually and group housed rats and mice. The so-called ‘Isolation Syndrome’ characterised by changes in corticosterone levels, metabolism, growth, and behaviour was introduced, rather as a model for psychoneurosis than through any concern for animal welfare. Today, it is often stated as common knowledge in laboratory animal science textbooks that individual housing as well as isolation of rats and mice has an effect on physiology and behaviour. It is, however, unclear whether this effect actually impairs animal welfare.The aim of this paper is to analyse studies on individual housing of mice and rats to evaluate whether there is documented proof that individual housing affects welfare, and, alternatively whether it is possible to house these animals individually without negative impact on welfare, eg by providing special housing improvements.A range of studies have shown that individual housing or isolation has effects on corticosterone, the open field behaviour, barbiturate sleeping time and the metabolism of different pharmaceuticals in the animals. However, this review of 37 studies in rats and 17 studies in mice showed divergence in test results difficult to explain, as many studies lacked basal information about the study, eg information on genetic strains and housing conditions, such as bedding, enrichment and cage sizes. Furthermore, test and control groups most frequently differed in cage sizes and stocking densities, and behavioural tests differed in ways which may very well explain the differences in results. Overall, there seemed to be an effect of individual housing, although it may be small, and it seems reasonable to assume that, through making small changes in the procedures and housing environments, the effects can be minimised or even eliminated. More well-controlled and standardised studies are needed to give more specific answers to the questions this issue poses.
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Marin MT, Cruz FC, Planeta CS. Chronic restraint or variable stresses differently affect the behavior, corticosterone secretion and body weight in rats. Physiol Behav 2006; 90:29-35. [PMID: 17023009 DOI: 10.1016/j.physbeh.2006.08.021] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Revised: 08/09/2006] [Accepted: 08/23/2006] [Indexed: 01/04/2023]
Abstract
Organisms are constantly subjected to stressful stimuli that affect numerous physiological processes and activate the hypothalamo-pituitary-adrenal (HPA) axis, increasing the release of glucocorticoids. Exposure to chronic stress is known to alter basic mechanisms of the stress response. The purpose of the present study was to compare the effect of two different stress paradigms (chronic restraint or variable stress) on behavioral and corticosterone release to a subsequent exposure to stressors. Considering that the HPA axis might respond differently when it is challenged with a novel or a familiar stressor we investigated the changes in the corticosterone levels following the exposure to two stressors: restraint (familiar stress) or forced novelty (novel stress). The changes in the behavioral response were evaluated by measuring the locomotor response to a novel environment. In addition, we examined changes in body, adrenals, and thymus weights in response to the chronic paradigms. Our results showed that exposure to chronic variable stress increased basal plasma corticosterone levels and that both, chronic restraint and variable stresses, promote higher corticosterone levels in response to a novel environment, but not to a challenge restraint stress, as compared to the control (non-stressed) group. Exposure to chronic restraint leads to increased novelty-induced locomotor activity. Furthermore, only the exposure to variable stress reduced body weights. In conclusion, the present results provide additional evidence on how chronic stress affects the organism physiology and point to the importance of the chronic paradigm and challenge stress on the behavioral and hormonal adaptations induced by chronic stress.
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Affiliation(s)
- Marcelo T Marin
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, UNESP-São Paulo State University, Rod. Araraquara-Jaú Km 1, 14801-902, Araraquara, São Paulo, Brazil
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Todorova MT, Mantis JG, Le M, Kim CY, Seyfried TN. Genetic and environmental interactions determine seizure susceptibility in epileptic EL mice. GENES BRAIN AND BEHAVIOR 2006; 5:518-27. [PMID: 17010098 DOI: 10.1111/j.1601-183x.2006.00204.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Gene identification has progressed rapidly for monogenic epilepsies, but complex gene-environmental interactions have hindered progress in gene identification for multifactorial epilepsies. We analyzed the role of environmental risk factors in the inheritance of multifactorial idiopathic generalized epilepsy in the EL mouse. Seizure susceptibility was evaluated in the EL (E) and seizure-resistant ABP/LeJ (A) parental mouse strains and in their AEF1 and AEF2 hybrid offspring using a handling-induced seizure test. The seizure test was administered in three environments (environments I, II and III) that differed with respect to the number of seizure tests administered (one test or four tests) and the age of the mice when tested (young or old). The inheritance of seizure susceptibility appeared dominant after repetitive seizure testing in young or old mice, but recessive after a single test in old mice. Heritability was high (0.67-0.77) in each environment. Significant quantitative trait loci (QTL) that were associated with environments I and III (repetitive testing) were found on chromosomes 2 and 9 and colocalized with previously mapped El2 and El4, respectively. The El2 QTL found in environment I associated only with female susceptibility. A novel QTL, El-N, for age-dependent predisposition to seizures was found on proximal chromosome 9 only in environment II. The findings indicate that environmental risk factors determine the genetic architecture of seizure susceptibility in EL mice and suggest that QTL for complex epilepsies should be defined in terms of the environment in which they are expressed.
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Affiliation(s)
- M T Todorova
- Biology Department, Boston College, Chestnut Hill, MA 02467, USA
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Agatsuma S, Lee M, Zhu H, Chen K, Shih JC, Seif I, Hiroi N. Monoamine oxidase A knockout mice exhibit impaired nicotine preference but normal responses to novel stimuli. Hum Mol Genet 2006; 15:2721-31. [PMID: 16893910 DOI: 10.1093/hmg/ddl206] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nicotine is thought to act on brain monoamine systems that normally mediate diverse motivational behaviors. How monoamine-related genes contribute to behavioral traits (e.g. responses to novel stimuli) comorbid with the susceptibility to nicotine addiction is still poorly understood. We examined the impact of constitutive monoamine oxidase A (MAOA) deficiency in mice on nicotine reward and responses to novel stimuli. Age-matched, male Maoa-knockout (KO) mice and wild-type (WT) littermates were tested for nicotine-induced conditioned place preference (CPP); voluntary oral nicotine preference/intake; spontaneous locomotor activity in a novel, inescapable open field; and novelty place preference. Nicotine preference in WT mice was reduced in Maoa-KO mice in the CPP and oral preference/intake tests. Control experiments showed that these phenotypes were not due to abnormalities in nicotine metabolism, fluid intake or response to taste. In contrast, Maoa-KO mice were normal in their behavioral response to a novel, inescapable open field and in their preference for a novel place. The observed phenotypes suggest that a constitutive deficiency of MAOA reduces the rewarding effects of nicotine without altering behavioral responses to novel stimuli in mice. Constitutive MAOA activity levels are likely to contribute to the vulnerability or resiliency to nicotine addiction by altering the rewarding effects of nicotine.
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Affiliation(s)
- Soh Agatsuma
- Laboratory of Molecular Psychobiology, Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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