title: Environmental enrichment alters dentate granule cell morphology in oldest-old rat.
abstract: The hippocampus of aged rats shows marked age-related morphological changes that could cause memory deficits. Experimental evidence has established that environmental enrichment attenuates memory deficits in aged rats. We therefore studied whether environmental enrichment produces morphological changes on the dentate granule cells of aged rats. Fifteen male Sprague-Dawley rats, 24 months of age, were randomly distributed in two groups that were housed under standard (n = 7) or enriched (n = 8) environmental conditions for 26 days. Quantitative data of dendritic morphology from dentate gyrus granule cells were obtained on Golgi-Cox stained sections. Environmental enrichment significantly increased the complexity and size of dendritic tree (total number of segments increased by 61% and length by 116%), and spine density (88% increase). There were large interindividual differences within the enriched group, indicating differential individual responses to environmental stimulation. Previous studies in young animals have shown changes produced by environmental enrichment in the morphology of dentate gyrus granule cells. The results of the present study show that environmental enrichment can also produce changes in dentate granule cell morphology in the senescent brain. In conclusion, the hippocampus retains its neuroplastic capacity during aging, and enriched environmental housing conditions can attenuate age-related dendritic regression and synaptic loss, thus preserving memory functions.
authors.affiliation: Department for Neurobiology, Caring Science and Society, Division of Clinical Geriatrics, Karolinska Institutet Science Park, Novum Research Park, Stockholm, Sweden.|Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Šalata, Zagreb, Croatia.
authors.forename: Sanja
authors.initials: S
authors.lastname: Darmopil
authors.affiliation: Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Šalata, Zagreb, Croatia.|Department of Anatomy, School of Medicine, University of Zagreb, Šalata, Zagreb, Croatia.
authors.forename: Zdravko
authors.initials: Z
authors.lastname: Petanjek
authors.affiliation: Department for Neurobiology, Caring Science and Society, Division of Clinical Geriatrics, Karolinska Institutet Science Park, Novum Research Park, Stockholm, Sweden.|School of Social Sciences, Växjö University, Växjö, Sweden.
authors.forename: Abdul H
authors.initials: AH
authors.lastname: Mohammed
authors.affiliation: Department for Neurobiology, Caring Science and Society, Division of Clinical Geriatrics, Karolinska Institutet Science Park, Novum Research Park, Stockholm, Sweden.|Wyeth Pharmaceutical, Global Medical Team - Neuroscience, Maidenhead, London, UK.
authors.forename: Nenad
authors.initials: N
authors.lastname: Bogdanović
mesh_terms: D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D018891:Dentate Gyrus / Q000166:cytology*; D008297:Male; D009474:Neurons / Q000166:cytology; D051381:Rats; D017207:Rats, Sprague-Dawley