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Blecher AS, Oosthuizen MK. Social Isolation Does Not Alter Exploratory Behaviour, Spatial Learning and Memory in Captive Damaraland Mole-Rats ( Fukomys damarensis). Animals (Basel) 2023; 13:543. [PMID: 36766430 PMCID: PMC9913580 DOI: 10.3390/ani13030543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/28/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023] Open
Abstract
Exploratory behaviour, spatial learning and memory affect the survival of animals and appear to be dependent on the specific habitat that a species occupies. Good spatial navigation and memory are particularly important for subterranean animals, as it is energetically expensive to inhabit this niche. Damaraland mole-rats are subterranean mammals that live in colonies with organised social structures. Damaraland mole-rats have been maintained in the laboratory for many years and can be housed in groups or individually. We evaluated the effect of social isolation on the exploratory behaviour and spatial memory of single-housed and colony-housed animals and also considered potential differences in animals with different social statuses. We predicted that solitary housing would increase anxiety-like behaviour and result in higher activity and more errors when solving a maze. Exploration by colony- and single-housed mole-rats was tested in an open-field test, where all individuals explored readily. Single-housed queens and non-breeding females showed increased activity and spent more time in tunnels, which can be explained by increased anxiety. In the Y-maze, improvements in solving the maze were observed in all experimental groups, except in single-housed non-breeding females. In addition, all males showed a decrease in the number of errors in the maze. Spatial learning is thus apparent but could not be conclusively proven. It was possibly underestimated, as magnetic cues that may be used by mole-rats as stimuli for navigation were removed in the experimental setup. Overall, it appears that social isolation has a limited effect on the exploratory behaviour and spatial learning of Damaraland mole-rats.
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Affiliation(s)
- Arantxa Silvia Blecher
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Pretoria 0028, South Africa
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Pretoria 0028, South Africa
| | - Maria Kathleen Oosthuizen
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Pretoria 0028, South Africa
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Pretoria 0028, South Africa
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Age-Related Individual Behavioural Characteristics of Adult Wistar Rats. Animals (Basel) 2021; 11:ani11082282. [PMID: 34438740 PMCID: PMC8388463 DOI: 10.3390/ani11082282] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/21/2021] [Accepted: 07/31/2021] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Rats are considered adults from 2 to 5 months. During this period, they are used for experimentation in physiology and pharmacology. Adult rats, depending on their age, can be in a different physiological state, which can influence the results of experiments carried out on them. Despite this, age-related changes in adult rats have not yet been examined. Our results showed that as male and female rats progressed from 2 to 5 months of age there was a decrease in the level of motor and exploratory activities, and an increase in the level of anxiety-like behaviour. Age-related changes were dependent upon initial individual characteristics of behaviour. For example, animals that demonstrated high motor activity at 2 months become significantly less active by 5 months, and animals that showed a low level of anxiety at 2 months become more anxious by 5 months. Low-activity and high-anxiety rats did not show any significant age-related changes from 2 to 5 months of age. The results of this work should be taken into account when choosing the age of rats for conducting behavioural experiments. Abstract The aim of this work was to study age-related changes in the behaviour of adult Wistar rats using the open field (OF) and elevated plus maze (EPM) tests. Behavioural changes related to motor activity and anxiety were of particular interest. Results showed that as male and female rats progressed from 2 to 5 months of age, there was a decrease in the level of motor and exploratory activities and an increase in their level of anxiety. Age-related changes were dependent upon initial individual characteristics of behaviour. For example, animals that demonstrated high motor activity at 2 months become significantly less active by 5 months, and animals that showed a low level of anxiety at 2 months become more anxious by 5 months. Low-activity and high-anxiety rats did not show any significant age-related changes in OF and EPM tests from 2 to 5 months of age, except for a decrease in the number of rearings in the EPM. Thus, the behaviour of the same adult rat at 2 and 5 months of age is significantly different, which may lead to differences in the experimental results of physiological and pharmacological studies using adult animals of different ages.
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Olszyński KH, Polowy R, Małż M, Boguszewski PM, Filipkowski RK. Playback of Alarm and Appetitive Calls Differentially Impacts Vocal, Heart-Rate, and Motor Response in Rats. iScience 2020; 23:101577. [PMID: 33083743 PMCID: PMC7553343 DOI: 10.1016/j.isci.2020.101577] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/07/2020] [Accepted: 09/15/2020] [Indexed: 11/02/2022] Open
Abstract
Our rudimentary knowledge about rat intraspecific vocal system of information exchange is limited by experimental models of communication. Rats emit 50-kHz ultrasonic vocalizations in appetitive states and 22-kHz ones in aversive states. Both affective states influence heart rate. We propose a behavioral model employing exposure to pre-recorded playbacks in home-cage-like conditions. Fifty-kHz playbacks elicited the most vocalizations (>60 calls per minute, mostly of 50-kHz type), increased heart rate, and locomotor activity. In contrast, 22-kHz playback led to abrupt decrease in heart rate and locomotor activity. Observed effects were more pronounced in singly housed rats compared with the paired housed group; they were stronger when evoked by natural playback than by corresponding artificial tones. Finally, we also observed correlations between the number of vocalizations, heart rate levels, and locomotor activity. The correlations were especially strong in response to 50-kHz playback.
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Affiliation(s)
- Krzysztof H Olszyński
- Behavior and Metabolism Research Laboratory, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawinskiego St, 02-106 Warsaw, Poland
| | - Rafał Polowy
- Behavior and Metabolism Research Laboratory, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawinskiego St, 02-106 Warsaw, Poland
| | - Monika Małż
- Behavior and Metabolism Research Laboratory, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawinskiego St, 02-106 Warsaw, Poland
| | - Paweł M Boguszewski
- Laboratory of Animal Models, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093 Warsaw, Poland
| | - Robert K Filipkowski
- Behavior and Metabolism Research Laboratory, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawinskiego St, 02-106 Warsaw, Poland
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Walker DM, Cunningham AM, Gregory JK, Nestler EJ. Long-Term Behavioral Effects of Post-weaning Social Isolation in Males and Females. Front Behav Neurosci 2019; 13:66. [PMID: 31031604 PMCID: PMC6470390 DOI: 10.3389/fnbeh.2019.00066] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/14/2019] [Indexed: 11/13/2022] Open
Abstract
Adolescence is a developmental period associated with vast neural and behavioral changes which are accompanied by altered sensitivity to stimuli, both stressful and rewarding. Perturbations, especially stressful stimuli, during this period have been shown to alter behavior in adulthood. Social isolation rearing is one such perturbation. This review highlights the long-term behavioral consequences of adolescent social isolation rearing in rodents with a specific focus on anxiety- and addiction-related behaviors. Sex-specific effects are discussed where data are available. We then consider changes in monoaminergic neurotransmission as one possible mechanism for the behavioral effects described. This research on both normative and perturbed adolescent development is crucial to understanding and treating the increased vulnerability to psychiatric disorders seen in humans during this life stage.
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Affiliation(s)
- Deena M Walker
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Ashley M Cunningham
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Jill K Gregory
- Academic IT: Instructional Technology Group, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Eric J Nestler
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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5
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Arakawa H. Ethological approach to social isolation effects in behavioral studies of laboratory rodents. Behav Brain Res 2018; 341:98-108. [DOI: 10.1016/j.bbr.2017.12.022] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 12/15/2017] [Accepted: 12/17/2017] [Indexed: 12/31/2022]
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Dalrymple-Alford JC, Benton D. Behavioural Inhibition and the Age at Social Isolation in Rats. ACTA ACUST UNITED AC 2018. [DOI: 10.1080/14640748408402192] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Rats that were socially isolated or group-housed at weaning were re-housed at 51 days of age in either the same housing condition or the opposite housing condition until 91 days and throughout subsequent behavioural testing. Increased resistance to extinction of running in an alley and poorer Hebb-Williams maze learning were found only after social isolation between 23 and 51 days of age. In contrast, slower running to reach the water reward during alley training and lower rearing activity at the beginning of open field testing were evident only in rats that were isolated at the time of testing. As in previous studies, open field hyperactivity was found in rats isolated at weaning but slower emergence latency was found in animals isolated at the time of testing. These findings confirm that the many behavioural effects of social isolation at different ages do not reflect a unitary aetiology. The behaviour of rats isolated at weaning is suggestive of a “disinhibition syndrome” but the precise nature of this syndrome is as yet unclear.
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Affiliation(s)
| | - David Benton
- Department of Psychology, University College of Swansea, Swansea, Wales
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Dalrymple-Alford JC, Benton D. The effect of social isolation of the rat on open field activity and emergence. Behav Processes 2014; 6:283-90. [PMID: 24925818 DOI: 10.1016/0376-6357(81)90007-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/1981] [Indexed: 11/28/2022]
Abstract
It has been suggested that naive isolated rats show more "fear responses" than group-housed controls. However, in contrast to previous studies, dark conditions and low noise levels were used to evaluate the latency to emerge from a small chamber into an open field and the subsequent ambulation and rearing behaviour of isolated and group-housed rats. The prediction that these conditions would be conducive to the rapid development of hyperactivity in isolates was confirmed, but there were no significant differences in emergence latency.
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Affiliation(s)
- J C Dalrymple-Alford
- Department of Psychology, University College of Swansea, Singleton Park, Swansea SA2 8PP, West Glam. Great Britain
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8
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Locomotor activity in juvenile Norway rats as a function of amount of filial huddling at 5-9 days of age. ACTA ACUST UNITED AC 2013. [DOI: 10.3758/bf03330100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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9
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Wu R, Song Z, Tai F, Wang L, Kong L, Wang J. Post-weaning living with parents during juvenile period alters locomotor activity, social and parental behaviors in mandarin voles. Behav Processes 2013; 98:78-84. [DOI: 10.1016/j.beproc.2013.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 04/01/2013] [Accepted: 05/10/2013] [Indexed: 11/28/2022]
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Leasure JL, Decker L. Social isolation prevents exercise-induced proliferation of hippocampal progenitor cells in female rats. Hippocampus 2009; 19:907-12. [PMID: 19235230 DOI: 10.1002/hipo.20563] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Social isolation negatively affects the behavior and health of laboratory rats. Recently, it has been found that social isolation retards exercise-induced neurogenesis in the hippocampal dentate gyrus (DG) of male rats (Stranahan et al. (2006) Nat Neurosci 9:526-533). Since male and female rats react differently to housing changes and exercise opportunities, we investigated whether social isolation would also suppress the exercise-dependent increase in proliferation of dentate gyrus progenitor cells in females. Accordingly, female rats were housed either alone (isolated) or in groups (social) with (exercise) or without (sedentary) the opportunity to run in an exercise wheel. Proliferating progenitor cells were labeled with bromodeoxyuridine (BrdU). As expected, exercise increased the number of BrdU+ cells in socially housed animals. However, isolation prevented this running-induced increase. Our results expand upon previous findings by showing that the female brain is also susceptible to the suppressive effect of social isolation on exercise-induced neurogenesis.
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Affiliation(s)
- J Leigh Leasure
- Department of Psychology, University of Houston, Houston, TX 77204, USA.
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11
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Lukkes JL, Mokin MV, Scholl JL, Forster GL. Adult rats exposed to early-life social isolation exhibit increased anxiety and conditioned fear behavior, and altered hormonal stress responses. Horm Behav 2009; 55:248-56. [PMID: 19027017 DOI: 10.1016/j.yhbeh.2008.10.014] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 10/24/2008] [Accepted: 10/24/2008] [Indexed: 10/21/2022]
Abstract
Social isolation of rodents during development is thought to be a relevant model of early-life chronic stress. We investigated the effects of early-life social isolation on later adult fear and anxiety behavior, and on corticosterone stress responses, in male rats. On postnatal day 21, male rats were either housed in isolation or in groups of 3 for a 3 week period, after which, all rats were group-reared for an additional 2 weeks. After the 5-week treatment, adult rats were examined for conditioned fear, open field anxiety-like behavior, social interaction behavior and corticosterone responses to restraint stress. Isolates exhibited increased anxiety-like behaviors in a brightly-lit open field during the first 10 min of the test period compared to group-reared rats. Isolation-reared rats also showed increased fear behavior and reduced social contact in a social interaction test, and a transient increase in fear behavior to a conditioned stimulus that predicted foot-shock. Isolation-reared rats showed similar restraint-induced increases in plasma corticosterone as group-reared controls, but plasma corticosterone levels 2 h after restraint were significantly lower than pre-stress levels in isolates. Overall, this study shows that isolation restricted to an early part of development increases anxiety-like and fear behaviors in adulthood, and also results in depressed levels of plasma corticosterone following restraint stress.
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Affiliation(s)
- Jodi L Lukkes
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069-2390, USA
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Amaral OB, Vargas RS, Hansel G, Izquierdo I, Souza DO. Duration of environmental enrichment influences the magnitude and persistence of its behavioral effects on mice. Physiol Behav 2007; 93:388-94. [PMID: 17949760 DOI: 10.1016/j.physbeh.2007.09.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 07/19/2007] [Accepted: 09/19/2007] [Indexed: 11/26/2022]
Abstract
A wide range of data in the literature suggests that environmental enrichment has beneficial effects on various cognitive parameters in rodents. However, the magnitude of these effects and their persistence after the cessation of enrichment vary markedly across studies, with the use of different enrichment protocols probably playing a significant role in this variation. Using an open field habituation task as a paradigm, we investigate whether the duration and starting age of environmental enrichment affect the magnitude and persistence of its behavioral effects on male CF-1 albino mice. Our data shows that, at least in our protocol, (a) environmental enrichment, both after weaning and in early adulthood, decreases locomotion in an open field task, probably by increasing habituation; (b) a minimum enrichment period is necessary to induce this behavioral effect; (c) the effect of enrichment can persist at least partially for many months after its cessation; and (d) the degree of this persistence appears to be somewhat greater in animals exposed to longer durations of enrichment.
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Affiliation(s)
- Olavo B Amaral
- Depatmento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Brazil.
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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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Bourgeon S, Xerri C, Coq JO. Abilities in tactile discrimination of textures in adult rats exposed to enriched or impoverished environments. Behav Brain Res 2004; 153:217-31. [PMID: 15219723 DOI: 10.1016/j.bbr.2003.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2003] [Revised: 11/28/2003] [Accepted: 12/02/2003] [Indexed: 11/23/2022]
Abstract
In previous studies, we have shown that housing in enriched environment for about 3 months after weaning improved the topographic organization and decreased the size of the receptive fields (RFs) located on the glabrous skin surfaces in the forepaw maps of the primary somatosensory cortex (SI) in rats [Exp. Brain Res. 121 (1998) 191]. In contrast, housing in impoverished environment induced a degradation of the SI forepaw representation, characterized by topographic disruptions, a reduction of the cutaneous forepaw area and an enlargement of the glabrous RFs [Exp. Brain Res. 129 (1999) 518]. Based on these two studies, we postulated that these representational alterations could underlie changes in haptic perception. Therefore, the present study was aimed at determining the influence of housing conditions on the rat's abilities in tactile texture discrimination. After a 2-month exposure to enriched or impoverished environments, rats were trained to perform a discrimination task during locomotion on floorboards of different roughness. At the end of every daily behavioral session, rats were replaced in their respective housing environment. Rats had to discriminate homogeneous (low roughness) from heterogeneous floorboards (combination of two different roughness levels). To determine the maximum performance in texture discrimination, the roughness contrast of the heterogeneous texture was gradually reduced, so that homogeneous and heterogeneous floorboards became harder to differentiate. We found that the enriched rats learned the first steps of the behavioral task faster than the impoverished rats, whereas both groups exhibited similar performances in texture discrimination. An individual "predilection" for either homogeneous or heterogeneous floorboards, presumably reflecting a behavioral strategy, seemed to account for the absence of differences in haptic discrimination between groups. The sensory experience depending on the rewarded texture discrimination task seems to have a greater influence on individual texture discrimination abilities than the sensorimotor experience related to housing conditions.
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Affiliation(s)
- Stéphanie Bourgeon
- UMR 6149 Neurobiologie Intégrative et Adaptative, Université de Provence-CNRS, Marseille, France
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15
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Genaro G, Schmidek WR. The influence of handling and isolation postweaning on open field, exploratory and maternal behavior of female rats. Physiol Behav 2002; 75:681-8. [PMID: 12020733 DOI: 10.1016/s0031-9384(02)00661-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Fifty-three black-hooded female rats, raised from the 28th to the 128th day of life under four types of environmental conditions differing in social and handling factors, had their behavioral performance evaluated in eight tests involving exploration of a complex environment (EX) in two open field (OF) tests and in three pup-retrieving tests. These tests were held before, during and after the period of lactation of their first brood. Females differed from (previously studied) males in that environmental raising conditions had a much smaller influence, especially during the lactation period. Nevertheless, females raised in isolation tended to remain for longer times inside a protected den in the exploration tests and to have greater locomotion in the open field. Previous handling allowed a greater exploration during the first contact with the novel complex environment as well as greater activity in the open field. The presence of small pups drastically reduced the exploratory motivation, but the presence of pups more than 20 days old tended to increase it. Maternal behavior evaluated in the pup retrieval test and in the test of time for the female to leave the nest side of the double box system was markedly refractory to previous environmental influences.
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Affiliation(s)
- Gelson Genaro
- Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, CEP 14049-900, Ribeirão Preto, SP, Brazil.
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Beck KD, Luine VN. Sex differences in behavioral and neurochemical profiles after chronic stress: role of housing conditions. Physiol Behav 2002; 75:661-73. [PMID: 12020731 DOI: 10.1016/s0031-9384(02)00670-4] [Citation(s) in RCA: 167] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This experiment sought to identify the extent housing conditions can differentially enhance or dampen the effects chronic restraint stress has on exploration and object memory in male and female rats. Subjects were either pair- or singly housed during stress (21 days of 6-h restraint) and maintained under those conditions during poststress behavior testing (7 days). Neurochemical analysis of neural tissue was accomplished by HPLC with electrochemical detection. Interactions between stress and housing conditions were found across both sexes. Stress was associated with less activity in the center of the forced open-field in both sexes. Stress also decreased the latency for males to enter the free open-field to female levels. Object recognition was greatly impaired in double-housed males but unaffected by stress or housing in females. Object location memory was impaired in stressed males if they were singly housed, and females performed as well as control males only if they were stressed. Both sexes generally showed increased in hippocampal (CA3) norepinephrine levels in their respective stress groups. Singly housed subjects had higher CA1 serotonin levels compared to double-housed subjects, whereas in the prefrontal cortex, a general sex difference was found with females having higher levels of serotonin and dopamine metabolites. These results show that stress affects limbic neurochemistry across sex, although only males exhibit stress-dependent decrements in object memory. Housing condition also has a profound effect on neurochemistry and male performance on object recognition. Thus, housing condition is a critical variable for male models of stress that can influence the extent the stress manipulation affects behavior. The differences observed across sex are further discussed in the context of behavioral inhibition.
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Affiliation(s)
- Kevin D Beck
- Department of Psychology, Hunter College, 695 Park Avenue, New York, NY 10021, USA.
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Molina-Hernandez M, Tellez-Alcantara P, Perez-Garcia J. Isolation rearing induced fear-like behavior without affecting learning abilities of Wistar rats. Prog Neuropsychopharmacol Biol Psychiatry 2001; 25:1111-23. [PMID: 11444680 DOI: 10.1016/s0278-5846(01)00168-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Isolation-reared rats display fear-like behavior and depressive-like behavior in several behavioral tasks, suggesting that isolation rearing may model certain aspects of human psychopathologies. 2. After weaning (20 days old), male and female Wistar rats were isolation-reared during 20, 50 or 70 days. After that, they were tested in the elevated plus maze test, and in the open field test. Another group of isolation-reared rats (70 days of isolation) were tested in an auto-shaping task. 3. Isolation-reared rats displayed high levels of fear-like behavior in the elevated plus-maze test, and hyperlocomotion in the open field test. But, isolation-reared rats learned an auto-shaping task. 4. In conclusion, isolation rearing induced fear-like behavior, without affect learning abilities of rats.
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Affiliation(s)
- M Molina-Hernandez
- Laboratorio de Conducta, Instituto de Investigaciones Psicológicas, Universidad Veracruzana, Mexico.
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18
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O'Donnell JM, Grealy M. Neuroendocrine response to clonidine and 8-OH-DPAT in rats following chronic administration of desipramine or sertraline. Br J Pharmacol 1992; 105:863-8. [PMID: 1387021 PMCID: PMC1908697 DOI: 10.1111/j.1476-5381.1992.tb09069.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
1. Rats were administered either desipramine (DMI) or sertraline daily at doses 7.5 mg kg-1 or 10 mg kg-1, i.p., respectively and the effects on the functional state of hypothalamic neuroendocrine control mechanisms assessed by measurements of plasma hormones following acute drug challenge. The effects of treatment on gross behaviour and brain adrenoceptor density were also determined. 2. Both DMI and sertraline caused significant reduction in activity measured as ambulation and rearing at 14 days of treatment. 3. All animals were chronically cannulated after 14 days of treatment and tested for neuroendocrine response to acute i.v. clonidine (50 micrograms kg-1) or 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, 250 micrograms kg-1) after 21 or more days of treatment. 4. Rats treated with DMI but not sertraline showed a virtually complete suppression of the growth hormone (GH) secretion elicited by clonidine in controls, while the secretion of corticosterone was augmented. 5. Treatment with DMI but not sertraline led to a significantly greater 8-OH-DPAT-induced secretion of prolactin than in the control rats, while the plasma concentrations of corticosterone following 8-OH-DPAT were not influenced by either DMI or sertraline treatment. 6. The density (but not the affinity) of cerebral cortical binding of [3H]-dihydroalprenolol was significantly reduced by DMI treatment. 7. These results show that DMI treatment blunted the sensitivity of post-synaptic alpha 2-adrenoceptors, accompanied by complex interactions manifested as increased responsiveness of alpha 1-adrenoceptors and 5-HT1A receptors. Sertraline had no significant neurendocrine effects at a dose which significantly reduced gross activity.
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Affiliation(s)
- J M O'Donnell
- Department of Pharmacology, University College, Galway, Ireland
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19
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Gentsch C, Lichtsteiner M, Feer H. Genetic and environmental influences on reactive and spontaneous locomotor activities in rats. EXPERIENTIA 1991; 47:998-1008. [PMID: 1936209 DOI: 10.1007/bf01923335] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Paired groups of rats (derived from divergent, selective breeding or living in divergent environmental conditions) were compared with regard to locomotor activities. Intrapair differences were found to vary non-systematically, depending upon whether the rats were initially exposed to a test-environment with or without a slight environmental modification (reactive activities), or were allowed to habituate extensively to the environment (spontaneous activity). Since the behavioral patterns were found to represent distinct entities, this pointed to the necessity of differentiating clearly between spontaneous and reactive activities and indicated, once again, that both genetic and environmental influences are important in these behaviors and must be taken into account. Accepting and controlling for these variables makes it possible to use the factor of individual differences in laboratory animal behavior to advantage.
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Affiliation(s)
- C Gentsch
- Psychiatrische Universitätsklinik Basel, Switzerland
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20
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Effects of rearing condition, gender, and sexual experience on odor preferences and urine marking in Long-Evans rats. ACTA ACUST UNITED AC 1991. [DOI: 10.3758/bf03197856] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Gentsch C, Lichtsteiner M, Feer H. Competition for sucrose-pellets in triads of male Wistar rats: disinhibitory effect of individual housing in poor-performing rats. Behav Brain Res 1990; 38:19-24. [PMID: 2161240 DOI: 10.1016/0166-4328(90)90020-f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Within triads of male Wistar rats, some animals almost completely abstain from competition for palatable sucrose-pellets (so-called poor-performing rats). Individual housing temporarily helped these rats to behave more competitively. Such changes in the poor-performing rats' competition-scores are discussed in relation to previously described, isolation-induced alterations in serotonergic and noradrenergic neurotransmission.
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Affiliation(s)
- C Gentsch
- Psychiatric University Clinic Basle, Biochemical Laboratory, Switzerland
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22
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Wolffgramm J. Free choice ethanol intake of laboratory rats under different social conditions. Psychopharmacology (Berl) 1990; 101:233-9. [PMID: 2349365 DOI: 10.1007/bf02244132] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
To study the effects of different kinds of social deprivation on voluntary ethanol (ETOH) intake male Wistar rats were housed by (a) individual caging, (b) "contact" caging (partial social deprivation), and (c) group caging (four individuals per cage). In the latter condition the individuals were separated once a week from each other for 24 h. The rats simultaneously received water 5%, 10% and 20% ETOH for a period of 14 weeks. Additional control animals received water. Isolated individuals drank significantly more alcohol than group-housed or contact-caged rats. After a few days they preferred the 20% solution. Circadian measures revealed a discontinuous intake of high doses (greater than 0.5 g/kg/h) during short time periods. Contact-caged rats consumed much less ETOH, but both the preference for 20% ETOH and the circadian course of intake were similar to those occurring after isolation. ETOH intake of group-housed individuals was low. These individuals preferred the 5% solution and continuously consumed small ETOH doses. During the period of short-term isolation they drank even more ETOH than long-term isolated individuals. In contrast to the latter, the enhancement of intake decreased after some weeks. It is suggested that the differences between the housing groups not only reflect different degrees of isolation stress, but may also be explained by a contribution of different reinforcing or aversive psychotropic effects of ETOH. Reduction of isolation stress is probably most important in the situation of short term separation, whereas dose-dependent reinforcement via social stimulation or sedation may affect the drug taking behavior under the other social conditions.
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Affiliation(s)
- J Wolffgramm
- Institute for Neuropsychopharmacology, Free University, Berlin
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23
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van der Staay FJ, Kerbusch S, Raaijmakers W. Genetic correlations in validating emotionality. Behav Genet 1990; 20:51-62. [PMID: 2346469 DOI: 10.1007/bf01070740] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Sixty-six rats of seven inbred strains were observed in an open field (OF) and in a light-dark preference box (LDB). Each set of apparatus provides measures of locomotor activity and of the time spent in the "most protected" area (the corners in the OF, the dark compartment in the LDB). These measures are proposed to be indices of emotionality. In the present study, the reliability and validity of the OF and LDB measures were determined by genetic correlations. Genetic correlations (rGEN) within and between tests were used as they provide a more coherent picture of reliability and validity of the measures than product-moment correlations (rPM), since rGEN's are appropriate estimates of "true" individual scores. It appeared that the activity measure in the OF and the occupancies of the most protected parts of OF and LDB were valid indices of emotionality, while the activity measure in the LDB was not. We recommend that the occupancy measures in the OF and the LDB should be used in addition to the commonly used activity measure in the OF to assess emotionality. The results indicate that genetic correlations provide a useful tool to validate measures in animal research. The only experimental manipulation in this approach consists of using the variation between inbred strains.
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24
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Gentsch C, Lichtsteiner M, Feer H. Genetic and environmental influences on behavioral and neurochemical aspects of emotionality in rats. EXPERIENTIA 1988; 44:482-90. [PMID: 3288494 DOI: 10.1007/bf01958922] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Three pairings of rats (two derived from divergent, selective breeding and one from divergent environmental conditions) were compared with regard to behavioral and hormonal parameters. Striking differences were observed: results obtained in our own laboratory as well as those found in a review of the literature pointed to higher emotionality (e.g., increased defecation and corticosterone secretion, etc.) in Roman low-avoidance, Wistar-Kyoto and group-housed rats, as compared to their respective counterparts, Roman high-avoidance, spontaneously hypertensive, and individually housed Wistar rats. Concomitant receptor binding studies reviewed here (3H-diazepam- and 3H-imipramine-binding sites) have revealed, however, less consistent intrapair differences.
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Affiliation(s)
- C Gentsch
- Psychiatrische Universitätsklinik Basel, Biochem. Labor, Switzerland
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25
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Nest-box exploration and choice in male and female mice tested under individual and social conditions. Behav Processes 1986; 13:119-48. [DOI: 10.1016/0376-6357(86)90021-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/1986] [Indexed: 11/19/2022]
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26
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Menich SR, Baron A. Social housing of rats: life-span effects on reaction time, exploration, weight, and longevity. Exp Aging Res 1984; 10:95-100. [PMID: 6499893 DOI: 10.1080/03610738408258550] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Sprague-Dawley rats were housed throughout their lives either in group cages or singly in standard laboratory cages. Locomotor activity was observed at selected ages and, in addition, operant conditioning procedures were used with an extensively trained subset of the animals to study reaction time and fixed ratio responding. The major effect of prolonged isolation was to induce timidity and inactivity during open field and emergence tests. Responding by isolates was depressed relative to socially-housed animals at 13 and 19 months of age although the higher levels of the social animals progressively declined during tests at 19 and 25 months. By comparison, neither housing condition nor age (7 to 25 months) systematically influenced the well-practiced operant responses (response rates, postreinforcement pauses, reaction times, foreperiod responses). A serendipitous finding was that isolated animals tended to die at earlier ages, an outcome that may be related to the fact that isolates also tended to weigh more throughout the experiment.
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27
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Niesink RJ, van Ree JM. Short-term isolation increases social interactions of male rats: a parametric analysis. Physiol Behav 1982; 29:819-25. [PMID: 7156221 DOI: 10.1016/0031-9384(82)90331-6] [Citation(s) in RCA: 124] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Frequencies of social interactions were higher in pairs of short-term individually housed male Wistar rats as compared to group-housed animals. This was most pronounced when an individually housed rat and a group-housed conspecific were tested together in the morning under red light conditions. Then, in particular the behavioral elements exploration partner, anogenital investigation, crawl over/mount and social grooming were enhanced. The increases in social interactions was dependent on the duration of the period of individual housing and appeared to be maximal after 4 to 7 days of individual housing. The effect extinguished after repeated testing. The observed behavioral changes were hardly affected by habituation to the test cage and were also present in young animals. The increase in social interactions is apparently not due to a general increase in locomotor or exploratory behavior, since no differences in ambulation between individually- and group-housed animals were observed when they were tested together in the social interaction test, and locomotor activities hardly differed in an open field test procedure.
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28
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Gentsch C, Lichtsteiner M, Feer H. Behavioural comparisons between individually- and group-housed male rats: effects of novel environments and diurnal rhythm. Behav Brain Res 1982; 6:93-100. [PMID: 7126327 DOI: 10.1016/0166-4328(82)90084-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Individually-housed rats, when compared with group-housed controls, have been previously shown to be hyper-reactive when exposed to an openfield at the beginning of the dark-phase; this was not due to elevated spontaneous activity. In the present experiments locomotor and rearing activities were determined immediately after exposing animals to a novel environment, and after 6 and 24 h of habituation to the test-environment. Additionally, after 24 h of adaptation, animals' responses towards a modification of the test-environment were examined. Four parallel experiments were carried out, each starting at a different time in the light/dark cycle. Individually-housed rats were hyper-reactive in novel environments and showed a slower habituation at all time points tested. Part of behavioural parameters show clearcut day/night variations, but differences between individually- and group-housed rats do not seem to be influenced by the time of day.
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