title: Behavioral, cognitive and biochemical responses to different environmental conditions in male Ts65Dn mice, a model of Down syndrome.
abstract: Ts65Dn mouse is the most widely accepted model for Down syndrome. We previously showed that environmental enrichment improved spatial learning in female but deteriorated it in male Ts65Dn mice. This study analyzed the factors contributing to the disturbed cognition of male Ts65Dn mice after enriched housing, by allocating male control and Ts65Dn mice in four conditions after weaning: small (n = 2-3) and large group (n = 8-10) housing, and enriched housing in small (2-3) and large groups (8-10). Learning, aggressive behavior, anxiety-like behavior and biochemical correlates of stress were evaluated when Ts65Dn and control mice were 4-5 months old. Environmental enrichment in large mixed colonies of Ts65Dn and diploid littermates disturbed behavioral and learning skills of Ts65Dn mice in the Morris water maze. ACTH and testosterone levels were not modified in any group of mice. Ts65Dn and control mice subjected to enriched housing in large groups and Ts65Dn mice housed in large groups showed higher corticosterone levels. Aggressive behavior was evaluated by measuring the number of attacks performed in the presence of an intruder. Ts65Dn mice performed less attacks than controls in all conditions, especially after enriched housing, indicating subordination. In the plus maze, cognitive aspects (i.e. risk assessment) and motor components (open arm avoidance) of anxiety behavior were evaluated; no difference in any condition was found. It is suggested that an excess of social and/or physical stimulation in Ts65Dn mice may affect cognition by disturbing the emotional and behavioral components of the learning process.
authors.affiliation: Laboratory of Developmental Neurobiology, Department of Physiology and Pharmacology, Faculty of Medicine, University of Cantabria, Santander, Spain. martinec@unican.es
authors.forename: Carmen
authors.initials: C
authors.lastname: Martínez-Cué
authors.forename: Noemí
authors.initials: N
authors.lastname: Rueda
authors.forename: Eva
authors.initials: E
authors.lastname: García
authors.forename: Muriel T
authors.initials: MT
authors.lastname: Davisson
authors.forename: Cecilia
authors.initials: C
authors.lastname: Schmidt
authors.forename: Jesús
authors.initials: J
authors.lastname: Flórez
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000374:Aggression / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D004195:Disease Models, Animal; D004314:Down Syndrome / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D004777:Environment; D008297:Male; D018782:Maze Learning / Q000502:physiology; D051379:Mice; D008809:Mice, Inbred C3H; D008818:Mice, Neurologic Mutants; D009043:Motor Activity / Q000502:physiology; D011930:Reaction Time; D012930:Social Dominance; D013550:Swimming; D013739:Testosterone / Q000097:blood; D014314:Trisomy
chemical_list: D013739:Testosterone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone