title: Periodic maternal separation decreases hippocampal neurogenesis without affecting basal corticosterone during the stress hyporesponsive period, but alters HPA axis and coping behavior in adulthood.
abstract: Although not directly evaluated, the early rise of glucocorticoid (GC) levels, as occur after exposure to adverse early life experience, are assumed to affect hippocampal ontogeny by altering the hippocampus negative feedback on adult HPA axis. To test whether hippocampal ontogeny is affected by early exposure to stress we estimated the survival of recently formed hippocampal granule cells in rat pups subjected to periodic maternal separation (180 min/day; MS180) from postnatal days (PND) 1 to 14. Accordingly, MS180 pups injected with bromodeoxyuridine (BrdU, 50 mg/kg, ip) at PND 5 showed decreased density of doublecortin (DCX) positive BrdU-labeled cells at PND 15. MS180 and AFR pups showed similar corticosterone (CORT) basal levels between PND 3 and 12, whereas adult MS180 rats presented with higher CORT levels than AFR adults. Nonetheless, both AFR and MS180 pups and adults showed similar transient increments of CORT levels in response to stress. In addition, MS180 had no effect on the adult anxiety-like behavior evaluated in the elevated plus maze, but evoked a passive coping strategy in the forced swimming test. The data show that the decrease in hippocampal neurogenesis is an early onset phenomenon, and suggests that adverse experiences alter hippocampal ontogeny without chronic elevation of GC levels.
authors.affiliation: División de Neurociencias, Centro de Investigación Biomédica de Michoacán - Instituto Mexicano del Seguro Social, Morelia 58341, Michoacán, Mexico.
authors.forename: Naima
authors.initials: N
authors.lastname: Lajud
authors.forename: Angélica
authors.initials: A
authors.lastname: Roque
authors.forename: Marco
authors.initials: M
authors.lastname: Cajero
authors.forename: Gabriel
authors.initials: G
authors.lastname: Gutiérrez-Ospina
authors.forename: Luz
authors.initials: L
authors.lastname: Torner
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight; D003345:Corticosterone / Q000097:blood*; D003423:Critical Period, Psychological; D000089662:Doublecortin Protein; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008426:Maternal Deprivation; D018782:Maze Learning / Q000502:physiology; D057054:Molecular Imaging / Q000379:methods / Q000523:psychology; D055495:Neurogenesis / Q000502:physiology*; D010913:Pituitary-Adrenal System / Q000378:metabolism / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological / Q000097:blood / Q000378:metabolism / Q000503:physiopathology*; D013997:Time Factors
chemical_list: C000714848:Dcx protein, rat; D000089662:Doublecortin Protein; D003345:Corticosterone