title: Long-Term Provision of Environmental Resources Alters Behavior but not Physiology or Neuroanatomy of Male and Female BALB/c and C57BL/6 Mice.
abstract: Few studies have evaluated the long-term effects of providing environmental resources to mice. This consideration is important given that mice are often maintained in vivaria for months. We evaluated the effects of providing simple cage resources (wood wool, cotton nesting material, a plastic tunnel, and oat cereal) compared with standard housing (solid-bottom cage with hardwood chips) to group-housed adult male and female C57BL/6 and BALB/c mice (n = 20/sex/strain/group) over 6 mo to determine whether these resources had a lasting effect on animal physiology, anatomy, and behavior. Body weights increased in all groups over time but were proportionately higher in male and female BALB/c mice housed in resource-supplemented environments. Throughout the study, adding environmental resources had no effect on hematology and lymphocyte subsets, fecal corticoid metabolite levels, response to LPS injection, or dendritic spine length or density. Strain- or sex×environmentspecific changes occurred in dark-light activity and thermal nociceptive responses. Dominant agonistic behaviors, abnormal conspecific sexual behaviors, and social nonagonistic behaviors demonstrated sex and strain×environment interactions such that fewer maladaptive social behaviors were noted in mice that were provided with environmental resources. This association was particularly evident in male mice of both strains in resource-supplemented environments. A small but significant increase in brain weight:body weight ratios occurred in mice in resource-supplemented environments. Under the conditions evaluated here, consistent use of simple environmental resources had a positive long-term effect on the behavioral wellbeing of male and female BALB/c and C57BL/6 mice yet minimally affected other aspects of murine physiology and neuroanatomy.
authors.affiliation: Department of Psychology, University of Guelph, Guelph, Canada; Department of Neuroscience, Scripps Research Institute, San Diego, California, USA.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Clipperton-Allen
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, Canada.
authors.forename: Joelle C
authors.initials: JC
authors.lastname: Ingrao
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Ruggiero
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, Canada; Nutriza Agroindustrial de Alimentos S.A., Goias, Brazil.
authors.forename: Lucas
authors.initials: L
authors.lastname: Batista
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, Canada.
authors.forename: Jelena
authors.initials: J
authors.lastname: Ovari
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, Canada.
authors.forename: Jutta
authors.initials: J
authors.lastname: Hammermueller
authors.affiliation: Department of Biomedical Sciences, University of Guelph, Guelph, Canada; Department of Biology, Mount Royal University, Calgary, Alberta, Canada.
authors.forename: John N
authors.initials: JN
authors.lastname: Armstrong
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, Canada.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Bienzle
authors.affiliation: Department of Psychology, University of Guelph, Guelph, Canada.
authors.forename: Elena
authors.initials: E
authors.lastname: Choleris
authors.affiliation: Department of Pathobiology, University of Guelph, Guelph, Canada. pvturner@uoguelph.ca.
authors.forename: Patricia V
authors.initials: PV
authors.lastname: Turner
mesh_terms: D000827:Animal Welfare; D000818:Animals; D001512:Bedding and Linens / Q000662:veterinary; D001522:Behavior, Animal; D001835:Body Weight; D049229:Dendritic Spines / Q000378:metabolism; D005260:Female; D006799:Housing, Animal; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C / Q000033:anatomy & histology / Q000502:physiology*; D008810:Mice, Inbred C57BL / Q000033:anatomy & histology / Q000502:physiology*