title: Down-regulation of hippocampal BDNF and Arc associated with improvement in aversive spatial memory performance in socially isolated rats.
abstract: Rats deprived of social contact with other rats at a young age experience a form of prolonged stress that leads to long-lasting changes in behavioral profile. Such isolation is thought to be anxiogenic for these normally gregarious animals, and the abnormal reactivity of isolated rats to environmental stimuli is thought to be a product of prolonged stress. We now show that isolation of rats at weaning reduced immobility time in the forced swim test, decreased sucrose intake and preference, and down-regulated both brain-derived neurotrophic factor (BDNF) and activity-regulated cytoskeletal associated protein (Arc) in the hippocampus. In the Morris water maze, isolated rats showed a reduced latency to reach the hidden platform during training, indicative of an improved learning performance, compared with group-housed rats. The cumulative search error during place training trials indicated a reliable difference between isolated and group-housed rats on days 4 and 5. The probe trial revealed a significant decrease of the average proximity to the target location in the isolated rats suggesting an improvement in spatial memory. Isolated rats also showed an increase in the plasma level of corticosterone on the 5th day of training and increased expression of BDNF and Arc in the hippocampus on both days 1 and 5. These results show that social isolation from weaning in rats results in development of depressive-like behavior but has a positive effect on spatial learning, supporting the existence of a facilitating effect of stress on cognitive function.
authors.affiliation: C.N.R., Institute of Neuroscience, Cagliari 09100, Italy.
authors.forename: Maria Giuseppina
authors.initials: MG
authors.lastname: Pisu
authors.forename: Riccardo
authors.initials: R
authors.lastname: Dore
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Mostallino
authors.forename: Manila
authors.initials: M
authors.lastname: Loi
authors.forename: Francesca
authors.initials: F
authors.lastname: Pibiri
authors.forename: Roberta
authors.initials: R
authors.lastname: Mameli
authors.forename: Roberto
authors.initials: R
authors.lastname: Cadeddu
authors.forename: Pietro Paolo
authors.initials: PP
authors.lastname: Secci
authors.forename: Mariangela
authors.initials: M
authors.lastname: Serra
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D003345:Corticosterone / Q000097:blood; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology*; D005518:Food Preferences / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008568:Memory / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology; D012934:Social Isolation; D013028:Space Perception / Q000502:physiology*; D013395:Sucrose / Q000378:metabolism; D013550:Swimming / Q000523:psychology; D013997:Time Factors; D014316:Tritium / Q000097:blood
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; C092069:activity regulated cytoskeletal-associated protein; D014316:Tritium; D013395:Sucrose; D003345:Corticosterone