Rearing environmental enrichment in two inbred strains of mice: 1. Effects on emotional reactivity.
The effects of an enriched rearing environment on two types of anxiety-like behavior (designated "trait" and "state" anxiety) and on spontaneous activity were investigated in two inbred strains of mice, BALB/c (C) and C57BL/6(B6). Subjects were socially reared from birth to 56 days of age under enriched or standard rearing conditions. The enriched environment consisted of an assembly of plastic boxes in which a various number of objects (running wheels, pieces of plastic, etc.) offered the possibility of multiple activities. The subjects were subsequently tested in three situations: a spontaneous activity recorder, an elevated plus-maze test (a model of state anxiety), and a free exploration test (a model of trait anxiety). No group differences could be found in spontaneous activity. Environmental enrichment, however, decreased the level of both types of anxiety-like behavior in the C strain. In contrast, the level of trait anxiety of the B6 mice was not modified. The results were discussed in relation to possible CNS modifications, especially in the limbic system.
Chapillon
P
P
Université de Rouen, Faculté des Sciences, Laboratoire de Neurobiologie de l'Apprentissage, Mont-Saint-Aignan, France. Pierre.Chapillon@epeire.univ-rouen.fr
Manneché
C
C
Belzung
C
C
Caston
J
J
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn / Q000235:genetics / Q000254:growth & development / Q000523:psychology; D001007:Anxiety / Q000235:genetics*; D004777:Environment; D005106:Exploratory Behavior / Q000502:physiology*; D005260:Female; D006799:Housing, Animal; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010988:Play and Playthings; D013694:Temperament / Q000502:physiology*