title: Environmental change during postnatal development alters behaviour, cognitions and neurogenesis of mice.
abstract: Four groups of male C57BL/6 mice were reared differing combinations of the two environments from 3 to 11 weeks after birth. At 12 and 13 weeks they were assessed by measures of behaviour and learning: open-field activity, auditory startle reflex and prepulse inhibition, water maze learning, and passive avoidance. Another four groups of mice reared under these varying conditions were examined for generation of neurons in hippocampus and cerebral cortex using bromodeoxyuridine (BrdU) at 12 weeks. Enriched (EE) and impoverished (PP) groups were housed in their respective environment for 8 weeks, enriched-impoverished (EP) and impoverished-enriched (PE) mice respectively were reared for 6 weeks in the first-mentioned environment and then for 2 weeks in the second. PP and EP mice showed hyperactivity, greater startle amplitude and significantly slower learning in a water maze than EE or PE animals, and also showed a memory deficit in a probe test, avoidance performance did not differ. Neural generation was greater in the EE and PE than PP and EP groups, especially in the hippocampus. These results suggest that environmental change critically affects behavioural and anatomic brain development, even if brief. In these mice, the effect of unfavourable early experience could be reversed by a later short of favourable experience.
authors.affiliation: Department of Behaviour Science, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan. iso@hyo-med.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Iso
authors.forename: Shigero
authors.initials: S
authors.lastname: Simoda
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Matsuyama
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development*; D018592:Cross-Over Studies; D004777:Environment; D005106:Exploratory Behavior / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology; D013216:Reflex, Startle / Q000502:physiology