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Butler-Struben HM, Kentner AC, Trainor BC. What's wrong with my experiment?: The impact of hidden variables on neuropsychopharmacology research. Neuropsychopharmacology 2022; 47:1285-1291. [PMID: 35338255 PMCID: PMC9117327 DOI: 10.1038/s41386-022-01309-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/22/2022] [Accepted: 03/10/2022] [Indexed: 12/24/2022]
Abstract
The field of neuropsychopharmacology relies on behavioral assays to quantify behavioral processes related to mental illness and substance use disorders. Although these assays have been highly informative, sometimes laboratories have unpublished datasets from experiments that "didn't work". Often this is because expected outcomes were not observed in positive or negative control groups. While this can be due to experimenter error, an important alternative is that under-appreciated environmental factors can have a major impact on results. "Hidden variables" such as circadian cycles, husbandry, and social environments are often omitted in methods sections, even though there is a strong body of literature documenting their impact on physiological and behavioral outcomes. Applying this knowledge in a more critical manner could provide behavioral neuroscientists with tools to develop better testing methods, improve the external validity of behavioral techniques, and make better comparisons of experimental data across institutions. Here we review the potential impact of "hidden variables" that are commonly overlooked such as light-dark cycles, transport stress, cage ventilation, and social housing structure. While some of these conditions may not be under direct control of investigators, it does not diminish the potential impact of these variables on experimental results. We provide recommendations to investigators on which variables to report in publications and how to address "hidden variables" that impact their experimental results.
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Affiliation(s)
| | - Amanda C Kentner
- School of Arts & Sciences, Massachusetts College of Pharmacy and Health Sciences, Boston, MA, 02115, USA
| | - Brian C Trainor
- Animal Behavior Graduate Group, University of California, Davis, CA, 95616, USA.
- Department of Psychology, University of California, Davis, CA, 95616, USA.
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Tsuda MC, Mahdi S, Namchuk A, Wu TJ, Lucki I. Vendor differences in anxiety-like behaviors in female and male Sprague Dawley rats. Physiol Behav 2020; 227:113131. [PMID: 32791181 DOI: 10.1016/j.physbeh.2020.113131] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/22/2020] [Accepted: 08/07/2020] [Indexed: 01/25/2023]
Abstract
Although Sprague Dawley outbred rats are commonly used in behavioral, physiological, and pharmacological studies, dramatic differences in responses may emerge from rats obtained from different suppliers even when sex, age, and environmental conditions are maintained constant. In the present study, we compared behavioral responses on three tests related to anxiety of Sprague Dawley female and male rats obtained from three different vendors in the United States: Charles River, Envigo, and Taconic. All rats were tested in the open field, light-dark box, and elevated zero maze. We found reduced time spent in the center area of the open field and decreased light compartment duration in the light-dark box test in female and male rats from Taconic compared to Charles River and Envigo rats, suggesting anxiety-like behaviors differ between the three vendors. No vendor differences were found on performance in the elevated zero maze. Furthermore, the contribution of stress hormones to vendor differences was examined by measuring serum corticosterone levels in rats 30 min after exposure to the elevated zero maze. There were no vendor differences in corticosterone levels, suggesting that endogenous levels of stress hormones most likely did not contribute to vendor differences in anxiety-like behaviors. Collectively, these findings highlight the importance of vendor selection of the Sprague Dawley stock for research involving behavioral tests related to anxiety.
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Affiliation(s)
- Mumeko C Tsuda
- Rat Behavior Core, Uniformed Services University, Bethesda, MD, USA.
| | - Sumayyah Mahdi
- Department of Obstetrics and Gynecology, Uniformed Services University, Bethesda, MD, USA
| | - Amanda Namchuk
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University, Bethesda, MD, USA
| | - T John Wu
- Rat Behavior Core, Uniformed Services University, Bethesda, MD, USA; Department of Obstetrics and Gynecology, Uniformed Services University, Bethesda, MD, USA
| | - Irwin Lucki
- Rat Behavior Core, Uniformed Services University, Bethesda, MD, USA; Department of Pharmacology and Molecular Therapeutics, Uniformed Services University, Bethesda, MD, USA
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Åhlgren J, Voikar V. Housing mice in the individually ventilated or open cages-Does it matter for behavioral phenotype? GENES, BRAIN, AND BEHAVIOR 2019; 18:e12564. [PMID: 30848040 PMCID: PMC6849734 DOI: 10.1111/gbb.12564] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/05/2019] [Accepted: 03/05/2019] [Indexed: 12/26/2022]
Abstract
Individually ventilated caging (IVC) systems for rodents are increasingly common in laboratory animal facilities. However, the impact of such substantial change in housing conditions on animal physiology and behavior is still debated. Most importantly, there arise the questions regarding reproducibility and comparison of previous or new phenotypes between the IVC and open cages. The present study was set up for detailed and systematic comparison of behavioral phenotypes in male and female mice of three widely used inbred strains (C57BL/6JRccHsd, DBA/2JRccHsd, 129S2/SvHSd) after being kept in two housing environments (IVC and open cages) for 6 weeks (since 4 weeks of age) before behavioral testing. The tests addressed exploratory, anxiety-like and stress-related behavior (light-dark box, open field, forced swim test, stress-induced hyperthermia), social approach and species-specific behavior (nest building, marble burying). In all tests, large and expected strain differences were found. Somewhat surprisingly, the most striking effect of environment was found for basal body temperature and weight loss after one night of single housing in respective cages. In addition, the performance in light-dark box and open field was affected by environment. Several parameters in different tests showed significant interaction between housing and genetic background. In summary, the IVC housing did not invalidate the well-known differences between the mouse strains which have been established by previous studies. However, within the strains the results can be influenced by sex and housing system depending on the behavioral tasks applied. The bottom-line is that the environmental conditions should be described explicitly in all publications.
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Affiliation(s)
- Johanna Åhlgren
- Laboratory Animal Center, Helsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
| | - Vootele Voikar
- Neuroscience Center, Helsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
- Laboratory Animal Center, Helsinki Institute of Life ScienceUniversity of HelsinkiHelsinkiFinland
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Burden N, Kendrick J, Knight L, McGregor V, Murphy H, Punler M, van Wijk H. Maximizing the success of bile duct cannulation studies in rats: recommendations for best practice. Lab Anim 2017; 51:457-464. [PMID: 28948900 PMCID: PMC5621694 DOI: 10.1177/0023677217698001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Bile duct cannulation (BDC) studies are usually carried out in the rat to support the absorption, distribution, metabolism and excretion profiling of novel agrochemicals and pharmaceuticals. The different aspects of these studies (e.g. surgical preparation, dosing and collection of bile) can be intricate and/or technically complex. The animals are often kept singly housed for the duration of the studies following surgical implantation of the cannulas. The generation of insufficient data to meet the study objectives, for example due to failure in cannula patency, can result in the need to repeat these studies. A working group of contract research organizations that routinely carry out BDC studies was brought together by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) to share their experiences, and to establish the key factors necessary to ensure routinely high success rates. Through these discussions the group has identified opportunities for best practice across various aspects of the studies. The aim of these recommendations is to support all staff involved in conducting BDC studies to maximize the amount of useful data generated using the fewest animals possible, while ensuring the highest possible standards of animal welfare.
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Affiliation(s)
| | - John Kendrick
- 2 Covance Laboratories Ltd, Harrogate, North Yorkshire, UK
| | | | - Victoria McGregor
- 4 Charles River Laboratories Edinburgh Ltd, Tranent, East Lothian, UK
| | | | - Malcolm Punler
- 4 Charles River Laboratories Edinburgh Ltd, Tranent, East Lothian, UK
| | - Hans van Wijk
- 2 Covance Laboratories Ltd, Harrogate, North Yorkshire, UK
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Segerström L, Roman E. Response: Commentary: Supplier-dependent differences in intermittent voluntary alcohol intake and response to naltrexone in Wistar rats. Front Neurosci 2016; 10:442. [PMID: 27746715 PMCID: PMC5042965 DOI: 10.3389/fnins.2016.00442] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 09/12/2016] [Indexed: 11/16/2022] Open
Affiliation(s)
- Lova Segerström
- Research Group Neuropharmacology, Addiction and Behavior, Department of Pharmaceutical Biosciences, Uppsala University Uppsala, Sweden
| | - Erika Roman
- Research Group Neuropharmacology, Addiction and Behavior, Department of Pharmaceutical Biosciences, Uppsala University Uppsala, Sweden
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Kalueff AV. Commentary: Supplier-dependent differences in intermittent voluntary alcohol intake and response to naltrexone in Wistar rats. Front Neurosci 2016; 10:82. [PMID: 27013944 PMCID: PMC4779880 DOI: 10.3389/fnins.2016.00082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 02/18/2016] [Indexed: 12/04/2022] Open
Affiliation(s)
- Allan V Kalueff
- Research Institute for Marine Drugs and Nutrition, College of Food Science and Technology, Guangdong Ocean UniversityZhanjiang, China; Institute of Translational Biomedicine, St. Petersburg State UniversitySt. Petersburg, Russia; Institutes of Chemical Technology and Natural Sciences, Ural Federal UniversityEkaterinburg, Russia; Neuroscience and Pharmacology Lab, ZENEREI InstituteSlidell, LA, USA
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Abstract
The longstanding concept of risk-benefit analysis is an established and familiar practice among animal research programs. It is generally preferred by researchers and statisticians and this term is used throughout the Guide for the Care and Use of Laboratory Animals. However, the term 'harm-benefit analysis' has recently come into use, particularly in the accreditation process for animal research programs. The Association for Assessment and Accreditation of Laboratory Animal Care has incorporated a new interpretation of the eighth edition of the Guide for the Care and Use of Laboratory Animals into their assessment and evaluation process, whereby they may require institutions to conduct a 'harm-benefit analysis'. However, whereas 'risk-benefit analysis' is specifically described in the Guide for the Care and Use of Laboratory Animals, harm-benefit analysis is not mentioned at all. The source of this harm-benefit language appears to be Article 38 of the European Directive 2010/63/EU. Here, the authors present a case for retaining the current language of risk-benefit analyses and not specifically introducing the language of harm-benefit analyses into ethical considerations of animal research activities, including protocol review procedures of Institutional Animal Care and Use Committees.
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Arts JWM, Oosterhuis NR, Kramer K, Ohl F. Effects of Transfer from Breeding to Research Facility on the Welfare of Rats. Animals (Basel) 2014; 4:712-28. [PMID: 26479008 PMCID: PMC4494421 DOI: 10.3390/ani4040712] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 11/18/2014] [Accepted: 11/19/2014] [Indexed: 11/16/2022] Open
Abstract
Simple Summary This study measured effects of transfer on body temperature, stress hormone levels, body weight, behavior and water and food intake in rats. Environmental temperature strongly affected body temperature of rats and needs to be controlled. Male rats need to habituate for at least one week, females for two weeks after transfer. Abstract Transfer from the breeding facility to a research facility is a stressful event for laboratory animals. Heat stress has been reported to constitute one of the major concerns during transport of animals. This study measured ambient and body temperature, corticosterone and glucose levels, body weight, behavior and water and food intake before, during and after transfer in Wistar rats. Decreased body weight, water and food intake were observed on the day of transfer in rats. Environmental temperature strongly affected body temperature of rats and needs to be controlled. Male rats need to habituate for at least one week, females for two weeks after transfer.
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Affiliation(s)
- Johanna W M Arts
- Department of Animals in Science & Society, Division of Animal Welfare & Laboratory Animal Science, Veterinary Faculty, Utrecht University, Utrecht, 3584 CM, The Netherlands.
- Harlan Laboratories B.V., P.O. Box 553, Venray, 5800 AN, The Netherlands.
| | - Nynke R Oosterhuis
- Department of Animals in Science & Society, Division of Animal Welfare & Laboratory Animal Science, Veterinary Faculty, Utrecht University, Utrecht, 3584 CM, The Netherlands.
- Department of Human and Animal Physiology, P.O. Box 338, Wageningen University and Research Centre, Wageningen, 6700 AH, The Netherlands.
| | - Klaas Kramer
- Department of Animals in Science & Society, Division of Animal Welfare & Laboratory Animal Science, Veterinary Faculty, Utrecht University, Utrecht, 3584 CM, The Netherlands.
- Department of Occupational Health, Safety and Environment, Free University, Amsterdam, 1081 HV, The Netherlands.
| | - Frauke Ohl
- Department of Animals in Science & Society, Division of Animal Welfare & Laboratory Animal Science, Veterinary Faculty, Utrecht University, Utrecht, 3584 CM, The Netherlands.
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