title: Behavioral and neuroendocrine consequences of juvenile stress combined with adult immobilization in male rats.
abstract: Exposure to stress during childhood and adolescence increases vulnerability to developing several psychopathologies in adulthood and alters the activity of the hypothalamic-pituitary-adrenal (HPA) axis, the prototypical stress system. Rodent models of juvenile stress appear to support this hypothesis because juvenile stress can result in reduced activity/exploration and enhanced anxiety, although results are not always consistent. Moreover, an in-depth characterization of changes in the HPA axis is lacking. In the present study, the long-lasting effects of juvenile stress on adult behavior and HPA function were evaluated in male rats. The juvenile stress consisted of a combination of stressors (cat odor, forced swim and footshock) during postnatal days 23-28. Juvenile stress reduced the maximum amplitude of the adrenocorticotropic hormone (ACTH) levels (reduced peak at lights off), without affecting the circadian corticosterone rhythm, but other aspects of the HPA function (negative glucocorticoid feedback, responsiveness to further stressors and brain gene expression of corticotrophin-releasing hormone and corticosteroid receptors) remained unaltered. The behavioral effects of juvenile stress itself at adulthood were modest (decreased activity in the circular corridor) with no evidence of enhanced anxiety. Imposition of an acute severe stressor (immobilization on boards, IMO) did not increase anxiety in control animals, as evaluated one week later in the elevated-plus maze (EPM), but it potentiated the acoustic startle response (ASR). However, acute IMO did enhance anxiety in the EPM, in juvenile stressed rats, thereby suggesting that juvenile stress sensitizes rats to the effects of additional stressors.
authors.affiliation: Institut de Neurociències, Universitat Autònoma de Barcelona, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Fuentes
authors.affiliation: Animal Physiology Unit (School of Biosciences), Universitat Autònoma de Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Carrasco
authors.affiliation: Institut de Neurociències, Universitat Autònoma de Barcelona, Spain; Animal Physiology Unit (School of Biosciences), Universitat Autònoma de Barcelona, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Armario
authors.affiliation: Institut de Neurociències, Universitat Autònoma de Barcelona, Spain; Psychobiology Unit (School of Psychology), Universitat Autònoma de Barcelona, Spain. Electronic address: roser.nadal@uab.es.
authors.forename: Roser
authors.initials: R
authors.lastname: Nadal
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000818:Animals; D001007:Anxiety / Q000378:metabolism / Q000503:physiopathology / Q000523:psychology; D001522:Behavior, Animal / Q000502:physiology*; D002415:Cats; D003345:Corticosterone / Q000378:metabolism; D005938:Glucocorticoids / Q000378:metabolism; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism / Q000502:physiology; D008297:Male; D009490:Neurosecretory Systems / Q000378:metabolism / Q000503:physiopathology*; D010913:Pituitary-Adrenal System / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013216:Reflex, Startle; D012149:Restraint, Physical; D012741:Sexual Maturation / Q000502:physiology; D013315:Stress, Psychological / Q000378:metabolism / Q000503:physiopathology* / Q000523:psychology*
chemical_list: D005938:Glucocorticoids; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone
keywords: Anxiety; HPA axis; PTSD models; Prepubertal stress; Vulnerability