Greater glucocorticoid receptor activation in hippocampus of aged rats sensitizes microglia.
Neurobiol Aging
; 36(3): 1483-95, 2015 Mar.
Article
en En
| MEDLINE
| ID: mdl-25559333
ABSTRACT
Healthy aging individuals are more likely to suffer profound memory impairments following an immune challenge than are younger adults. These challenges produce a brain inflammatory response that is exaggerated with age. Sensitized microglia found in the normal aging brain are responsible for this amplified response, which in turn interferes with processes involved in memory formation. Here, we examine factors that may lead aging to sensitize microglia. Aged rats exhibited higher corticosterone levels in the hippocampus, but not in plasma, throughout the daytime (diurnal inactive phase). These elevated hippocampal corticosterone levels were associated with increased hippocampal 11ß-hydroxysteroid dehydrogenase type 1 protein expression, the enzyme that catalyzes glucocorticoid formation and greater hippocampal glucocorticoid receptor (GR) activation. Intracisternal administration of mifepristone, a GR antagonist, effectively reduced immune-activated proinflammatory responses, specifically from hippocampal microglia and prevented Escherichia coli-induced memory impairments in aged rats. Voluntary exercise as a therapeutic intervention significantly reduced total hippocampal GR expression. These data strongly suggest that increased GR activation in the aged hippocampus plays a critical role in sensitizing microglia.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Envejecimiento
/
Receptores de Glucocorticoides
/
Microglía
/
Hipocampo
Límite:
Animals
Idioma:
En
Revista:
Neurobiol Aging
Año:
2015
Tipo del documento:
Article