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Bohn L, Bierbaum L, Kästner N, von Kortzfleisch VT, Kaiser S, Sachser N, Richter SH. Structural enrichment for laboratory mice: exploring the effects of novelty and complexity. Front Vet Sci 2023; 10:1207332. [PMID: 37841462 PMCID: PMC10570735 DOI: 10.3389/fvets.2023.1207332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/14/2023] [Indexed: 10/17/2023] Open
Abstract
Providing structural enrichment is a widespread refinement method for laboratory rodents and other animals in captivity. So far, animal welfare research has mostly focused on the effect of increased complexity either by accumulating or combining different enrichment items. However, increasing complexity is not the only possibility to refine housing conditions. Another refinement option is to increase novelty by regularly exchanging known enrichment items with new ones. In the present study, we used pair-housed non-breeding female C57BL/6J and DBA/2N mice to investigate the effect of novelty when applying structural enrichment. We used a double cage system, in which one cage served as home cage and the other as extra cage. While the home cage was furnished in the same way for all mice, in the extra cage we either provided only space with no additional enrichment items (space), a fixed set of enrichment items (complexity), or a changing set of enrichment items (novelty). Over 5 weeks, we assessed spontaneous behaviors, body weight, and extra cage usage as indicators of welfare and preference. Our main results showed that mice with access to structurally enriched extra cages (complexity and novelty) spent more time in their extra cages and complexity mice had lower latencies to enter their extra cages than mice with access to the extra cages without any structural enrichment (space). This indicates that the mice preferred the structurally enriched extra cages over the structurally non-enriched space cages. We found only one statistically significant difference between the novelty and complexity condition: during week 3, novelty mice spent more time in their extra cages than complexity mice. Although we did not detect any other significant differences between the novelty and complexity condition in the present study, more research is required to further explore the potential benefits of novelty beyond complexity.
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Affiliation(s)
- Lena Bohn
- Department of Behavioural Biology, Institute of Neuro- and Behavioural Biology, University of Münster, Münster, Germany
- Münster Graduate School of Evolution, University of Münster, Münster, Germany
| | - Louisa Bierbaum
- Department of Behavioural Biology, Institute of Neuro- and Behavioural Biology, University of Münster, Münster, Germany
- Münster Graduate School of Evolution, University of Münster, Münster, Germany
| | - Niklas Kästner
- Department of Behavioural Biology, Institute of Neuro- and Behavioural Biology, University of Münster, Münster, Germany
- Münster Graduate School of Evolution, University of Münster, Münster, Germany
| | | | - Sylvia Kaiser
- Department of Behavioural Biology, Institute of Neuro- and Behavioural Biology, University of Münster, Münster, Germany
- Münster Graduate School of Evolution, University of Münster, Münster, Germany
| | - Norbert Sachser
- Department of Behavioural Biology, Institute of Neuro- and Behavioural Biology, University of Münster, Münster, Germany
- Münster Graduate School of Evolution, University of Münster, Münster, Germany
| | - S. Helene Richter
- Department of Behavioural Biology, Institute of Neuro- and Behavioural Biology, University of Münster, Münster, Germany
- Münster Graduate School of Evolution, University of Münster, Münster, Germany
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Jaric I, Voelkl B, Clerc M, Schmid MW, Novak J, Rosso M, Rufener R, von Kortzfleisch VT, Richter SH, Buettner M, Bleich A, Amrein I, Wolfer DP, Touma C, Sunagawa S, Würbel H. The rearing environment persistently modulates mouse phenotypes from the molecular to the behavioural level. PLoS Biol 2022; 20:e3001837. [PMID: 36269766 PMCID: PMC9629646 DOI: 10.1371/journal.pbio.3001837] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 11/02/2022] [Accepted: 09/20/2022] [Indexed: 11/07/2022] Open
Abstract
The phenotype of an organism results from its genotype and the influence of the environment throughout development. Even when using animals of the same genotype, independent studies may test animals of different phenotypes, resulting in poor replicability due to genotype-by-environment interactions. Thus, genetically defined strains of mice may respond differently to experimental treatments depending on their rearing environment. However, the extent of such phenotypic plasticity and its implications for the replicability of research findings have remained unknown. Here, we examined the extent to which common environmental differences between animal facilities modulate the phenotype of genetically homogeneous (inbred) mice. We conducted a comprehensive multicentre study, whereby inbred C57BL/6J mice from a single breeding cohort were allocated to and reared in 5 different animal facilities throughout early life and adolescence, before being transported to a single test laboratory. We found persistent effects of the rearing facility on the composition and heterogeneity of the gut microbial community. These effects were paralleled by persistent differences in body weight and in the behavioural phenotype of the mice. Furthermore, we show that environmental variation among animal facilities is strong enough to influence epigenetic patterns in neurons at the level of chromatin organisation. We detected changes in chromatin organisation in the regulatory regions of genes involved in nucleosome assembly, neuronal differentiation, synaptic plasticity, and regulation of behaviour. Our findings demonstrate that common environmental differences between animal facilities may produce facility-specific phenotypes, from the molecular to the behavioural level. Furthermore, they highlight an important limitation of inferences from single-laboratory studies and thus argue that study designs should take environmental background into account to increase the robustness and replicability of findings. The phenotype of an organism results not only from its genotype but also the influence of its environment throughout development. This study shows that common environmental differences between animal facilities can induce substantial variation in the phenotype of mice, thereby highlighting an important limitation of inferences from single-laboratory studies in animal research.
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Affiliation(s)
- Ivana Jaric
- Animal Welfare Division, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- * E-mail: (IJ); (HW)
| | - Bernhard Voelkl
- Animal Welfare Division, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Melanie Clerc
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich, Zürich, Switzerland
| | | | - Janja Novak
- Animal Welfare Division, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Marianna Rosso
- Animal Welfare Division, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Reto Rufener
- Department of Oncology-Pathology, Karolinska Institutet, Solna, Sweden
| | | | - S. Helene Richter
- Department of Behavioural Biology, University of Münster, Münster, Germany
| | - Manuela Buettner
- Institute for Laboratory Animal Science and Central Animal Facility, Hannover Medical School, Hannover, Germany
| | - André Bleich
- Institute for Laboratory Animal Science and Central Animal Facility, Hannover Medical School, Hannover, Germany
| | - Irmgard Amrein
- Institute of Anatomy, Division of Functional Neuroanatomy, University of Zürich, Zürich, Switzerland; Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - David P. Wolfer
- Institute of Anatomy, Division of Functional Neuroanatomy, University of Zürich, Zürich, Switzerland; Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Chadi Touma
- Department of Behavioural Biology, Osnabrück University, Osnabrück, Germany
| | - Shinichi Sunagawa
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich, Zürich, Switzerland
| | - Hanno Würbel
- Animal Welfare Division, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- * E-mail: (IJ); (HW)
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von Kortzfleisch VT, Karp NA, Palme R, Kaiser S, Sachser N, Richter SH. Improving reproducibility in animal research by splitting the study population into several 'mini-experiments'. Sci Rep 2020; 10:16579. [PMID: 33024165 PMCID: PMC7538440 DOI: 10.1038/s41598-020-73503-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 09/11/2020] [Indexed: 01/16/2023] Open
Abstract
In light of the hotly discussed 'reproducibility crisis', a rethinking of current methodologies appears essential. Implementing multi-laboratory designs has been shown to enhance the external validity and hence the reproducibility of findings from animal research. We here aimed at proposing a new experimental strategy that transfers this logic into a single-laboratory setting. We systematically introduced heterogeneity into our study population by splitting an experiment into several 'mini-experiments' spread over different time points a few weeks apart. We hypothesised to observe improved reproducibility in such a 'mini-experiment' design in comparison to a conventionally standardised design, according to which all animals are tested at one specific point in time. By comparing both designs across independent replicates, we could indeed show that the use of such a 'mini-experiment' design improved the reproducibility and accurate detection of exemplary treatment effects (behavioural and physiological differences between four mouse strains) in about half of all investigated strain comparisons. Thus, we successfully implemented and empirically validated an easy-to-handle strategy to tackle poor reproducibility in single-laboratory studies. Since other experiments within different life science disciplines share the main characteristics with the investigation reported here, these studies are likely to also benefit from this approach.
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Affiliation(s)
- Vanessa Tabea von Kortzfleisch
- Department of Behavioural Biology, University of Münster, Badestraße 13, Münster, Germany.
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany.
| | - Natasha A Karp
- Data Sciences and Quantitative Biology, Discovery Sciences, R&D, AstraZeneca, Cambridge, UK
| | - Rupert Palme
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Badestraße 13, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Norbert Sachser
- Department of Behavioural Biology, University of Münster, Badestraße 13, Münster, Germany
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - S Helene Richter
- Department of Behavioural Biology, University of Münster, Badestraße 13, Münster, Germany.
- Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany.
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Krakenberg V, von Kortzfleisch VT, Kaiser S, Sachser N, Richter SH. Differential Effects of Serotonin Transporter Genotype on Anxiety-Like Behavior and Cognitive Judgment Bias in Mice. Front Behav Neurosci 2019; 13:263. [PMID: 31849623 PMCID: PMC6902087 DOI: 10.3389/fnbeh.2019.00263] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/19/2019] [Indexed: 02/01/2023] Open
Abstract
In humans, the short allele of a common polymorphism in the serotonin transporter (5-HTT) gene is associated with a higher risk to develop depression and anxiety disorders. Furthermore, individuals carrying this allele are characterized by negative judgment biases, as they tend to interpret ambiguous information in a more pessimistic way. 5-HTT knockout mice, lacking the 5-HTT gene either homo- or heterozygously, provide a widely used model organism for the study of symptoms related to human anxiety disorders. In the present study, we aimed to prove the anxiety-like phenotype of the 5-HTT mouse model, and to investigate whether 5-HTT genotype also causes differences in judgment bias. While our results confirm that homozygous 5-HTT knockout mice display highest levels of anxiety-like behavior, it was decreased in heterozygous mice. Against our expectations, we did not detect differences in the animals’ judgment bias. These results indicate that at least in mice the association between 5-HTT genotype and judgment bias is not straightforward and that other factors, including multiple genes as well as environmental influences, are implicated in the modulation of judgment biases. More research is needed to gain further insights into their function as potential endophenotypes for psychopathology.
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Affiliation(s)
- Viktoria Krakenberg
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Vanessa Tabea von Kortzfleisch
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Norbert Sachser
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - S Helene Richter
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
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Bodden C, von Kortzfleisch VT, Karwinkel F, Kaiser S, Sachser N, Richter SH. Heterogenising study samples across testing time improves reproducibility of behavioural data. Sci Rep 2019; 9:8247. [PMID: 31160667 PMCID: PMC6547843 DOI: 10.1038/s41598-019-44705-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 05/20/2019] [Indexed: 02/06/2023] Open
Abstract
The ongoing debate on the reproducibility crisis in the life sciences highlights the need for a rethinking of current methodologies. Since the trend towards ever more standardised experiments is at risk of causing highly idiosyncratic results, an alternative approach has been suggested to improve the robustness of findings, particularly from animal experiments. This concept, referred to as "systematic heterogenisation", postulates increased external validity and hence, improved reproducibility by introducing variation systematically into a single experiment. However, the implementation of this concept in practice requires the identification of suitable heterogenisation factors. Here we show that the time of day at which experiments are conducted has a significant impact on the reproducibility of behavioural differences between two mouse strains, C57BL/6J and DBA/2N. Specifically, we found remarkably varying strain effects on anxiety, exploration, and learning, depending on the testing time, i.e. morning, noon or afternoon. In a follow-up simulation approach, we demonstrate that the systematic inclusion of two different testing times significantly improved reproducibility between replicate experiments. Our results emphasise the potential of time as an effective and easy-to-handle heterogenisation factor for single-laboratory studies. Its systematic variation likely improves reproducibility of research findings and hence contributes to a fundamental issue of experimental design and conduct in laboratory animal science.
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Affiliation(s)
- Carina Bodden
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, VIC, Australia
| | - Vanessa Tabea von Kortzfleisch
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Fabian Karwinkel
- Department of Behavioural Biology, University of Münster, Münster, Germany
| | - Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - Norbert Sachser
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany
| | - S Helene Richter
- Department of Behavioural Biology, University of Münster, Münster, Germany. .,Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, Münster, Germany.
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