The impact of environmental enrichment in laboratory rats—Behavioural and neurochemical aspects
Abstract
The provision of environmental enrichment (EE) for laboratory rats is recommended in European guidelines governing laboratory animal welfare. It is believed the EE implementation can improve animals' well-being and EE has been used to demonstrate learning and plasticity of the brain in response to the environment. This review suggests that the definition and duration of EE varies considerably across laboratories. Notwithstanding this, some EE protocols have revealed profound effects on brain neurochemistry and resulting behaviour, suggesting that EE can have the potential to significantly modify these parameters in rats. For this review, a literature search was conducted using PubMed and the search terms "Environmental Enrichment" and "rats". From the results of this search the most important variables for consideration in the implementation of EE are identified and summarised, and include cage size and housing density; rat age, sex and strain; duration of EE; the EE protocol and enrichment items employed; and the use of appropriate controls. The effects of EE in a number of behavioural tests and its effects on neurotransmitters, neurotrophic factors, stress hormones and neurogenesis and proliferation are outlined. The findings summarised in the present review show the range of EE protocols employed and their effects in tests of activity, learning and affect, as well neurochemical effects which mediate enhanced plasticity in the brain. EE, as is provided in many laboratories,…
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Environmental enrichment has been shown to decrease anxiety and increase learning and memory.
“In general, environmental enrichment has been shown to decrease anxiety and increase learning and memory (van Praag et al., 2000; Simpson and Kelly, 2011).”
From Effects of Maternal Deprivation and Complex Housing on Rat Social Behavior in Adolescence and Adulthood (2018) · cites this paper as Simpson and Kelly, 2011
Rats living in complex housing show a decreased HPA-axis response to a variety of stressors.
“but also show a decreased HPA-axis response to a variety of stressors (reviewed in Simpson and Kelly, 2011).”
From Effects of Maternal Deprivation and Complex Housing on Rat Social Behavior in Adolescence and Adulthood (2018) · cites this paper as Simpson and Kelly, 2011
Rat ultrasonic vocalizations can be categorized into two main groups: positive/"happy" 50 kHz USVs and negative/"distress" 22 kHz USVs.
“USVs in rats can be categorized into 2 main groups: positive/“happy” 50 kHz USVs and negative/“distress” 22 kHz USVs.7-9,24,33,38,39,41”
From Ultrasonic Vocalization Analysis as a Novel Metric to Assess Cage Enrichment in Rats (2022) · cites this paper as [7]
Commonly, environmental enrichment studies assess animal behavior outside the home cage, without assessment in the home environment.
“Commonly, environmental enrichment studies assess the behavior of animals in paradigms outside of the home cage,43 without assessment of the animals in the home environment.”
From Ultrasonic Vocalization Analysis as a Novel Metric to Assess Cage Enrichment in Rats (2022) · cites this paper as [43]
Evidence suggests that frequency-modulated calls, particularly those with a trill component, are indicative of positive affect.
“While the field of 50 kHz call classification is relatively novel, evidence suggests that frequency-modulated calls, particularly those with a trill component, are indicative of positive affect.7,11”
From Ultrasonic Vocalization Analysis as a Novel Metric to Assess Cage Enrichment in Rats (2022) · cites this paper as [7]
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“Housing conditions can have a significant influence on rodent behavior and have been used to induce stress or anxiety and to alter cognitive development (van Praag et al., 2000; Nithianantharajah and Hannan, 2006; Burrows et al., 2011; Simpson and Kelly, 2011).”
BackgroundUltrasonic Vocalization Analysis as a Novel Metric to Assess Cage Enrichment in Rats
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- Authors
- Simpson, J., & Kelly, J. P.
- Affiliations
- Ollscoil na Gaillimhe – University of Galway (IE)
- Corresponding author
- Simpson, Joy
- ORCID
- Kelly, John P.
- Venue
- Behavioural Brain Research
- Publisher
- Elsevier BV
- Published
- 2011-09
- Volume
- 222
- Issue
- 1
- Pages
- 246-264
- ISSN
- 0166-4328 (ISSN-L)
- OpenAlex
- W2003041124
- Cited by
- 480
- References
- 11
- Citations by year
- 2026: 18 · 2025: 37 · 2024: 30 · 2023: 31 · 2022: 28 · 2021: 26 · 2020: 32 · 2019: 28 · 2018: 46 · 2017: 46 · 2016: 23 · 2015: 43 · 2014: 38 · 2013: 28 · 2012: 20
- FWCI
- 5.49
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Behavioural Brain Research (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Veterinary › Small Animals › Animal Behavior and Welfare Studies
- Life Sciences › Neuroscience › Developmental Neuroscience › Neurogenesis and neuroplasticity mechanisms
- Life Sciences › Neuroscience › Cognitive Neuroscience › Memory and Neural Mechanisms
- Keywords
- environmental enrichment, laboratory rats, animal welfare, cage size, housing density, neurochemistry, neurotransmitters, neurotrophic factors, stress hormones, neurogenesis, neuroplasticity, learning, affect, behavioural tests
- MeSH terms
- Animals, Animals, Laboratory, Behavior, Animal, Brain Chemistry, Environment, Exploratory Behavior, Female, Male, Sex Factors, Swimming, Maze Learning, Recognition, Psychology, Rats
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