Differential neuroendocrine responses to chronic variable stress in adult Long Evans rats exposed to handling-maternal separation as neonates.
Psychoneuroendocrinology
; 30(6): 520-33, 2005 Jul.
Article
em En
| MEDLINE
| ID: mdl-15808921
ABSTRACT
Burgeoning evidence supports a preeminent role for early- and late-life stressors in the development of physio- and psychopathology. Handling-maternal separation (HMS) in neonatal Long Evans hooded rats leads to stable phenotypes ranging from resilient to vulnerable to later stressor exposure. Handling with 180 min of maternal separation yields a phenotype of stress hyper-responsiveness associated with facilitation of regional CRF neurocircuits and glucocorticoid resistance. This study assessed whether or not prolonged HMS (180 min/day, HMS180) on post-natal days 2-14 sensitizes the adult limbic hypothalamo-pituitary-adrenal (LHPA) axis to chronic variable stress (CS) compared to brief HMS (15 min/day, HMS15). We examined regional mRNA densities of corticotropin-releasing factor (CRF), its receptor CRF1, glucocorticoid receptor (GR), and mineralocorticoid receptor (MR); regional CRF1 and CRF2alpha binding, and pituitary-adrenal responses to an acute air-puff startle (APS) stressor in four groups HMS15, nonstressed; HMS15, stressed; HMS180, nonstressed; HMS180, stressed. As expected we observed exaggerated pituitary-adrenal responses to APS, increased regional CRF mRNA density, decreased regional CRF1 binding, and decreased cortical GR mRNA density in nonstressed HMS180 vs. HMS15 animals. However, in contrast to our hypothesis, CS decreased pituitary-adrenal reactivity and central amygdala CRF mRNA density in HMS180 rats, while increasing cortical GR mRNA density and CRF1 binding. CS had no effect on the pituitary-adrenal response to APS in HMS15 rats, despite tripling hypothalamic paraventricular CRF mRNA density. The data suggest that many effects of prolonged HMS are reversible in adulthood by CS, while the neuroendocrine adaptations imbued by brief HMS are sufficiently stable to restrain pituitary-adrenal stress responses even following CS.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Estresse Psicológico
/
Hormônio Liberador da Corticotropina
/
Receptores de Glucocorticoides
/
Receptores de Hormônio Liberador da Corticotropina
/
Sistema Hipotálamo-Hipofisário
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Psychoneuroendocrinology
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Estados Unidos