Estrogens normalize the hypothalamic-pituitary-adrenal axis response to stress and increase glucocorticoid receptor immunoreactivity in hippocampus of aging male rats

Aging is associated with a disturbance in the regulation of the hypothalamic-pituitary-adrenal axis (HPA) and reduced levels of glucocorticoid receptors (GR) in the hippocampus. To compensate for these effects, we have investigated whether estrogen therapy normalized the HPA response to stress and G...

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Detalles Bibliográficos
Autores principales: Ferrini, M., Piroli, G., Frontera, M., Falbo, A., Lima, A., De Nicola, A.F.
Formato: JOUR
Materias:
Adrenal steroid receptors
Adrenal steroids
Aging
Corticotropin
Gonadal steroids
Hippocampus
Stress
corticosterone
estrogen
glucocorticoid receptor
aging
Alzheimer disease
animal experiment
animal tissue
article
controlled study
corticosterone blood level
estrogen therapy
feedback system
hippocampus
hypothalamus hypophysis adrenal system
immunoreactivity
male
nonhuman
priority journal
rat
stress
subiculum
Adrenal Glands
Animals
Corticosterone
Estradiol
Ether, Ethyl
Hypothalamus
Kinetics
Male
Organ Size
Pituitary Gland
Rats
Rats, Sprague-Dawley
Receptors, Glucocorticoid
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00283835_v69_n2_p129_Ferrini
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:Aging is associated with a disturbance in the regulation of the hypothalamic-pituitary-adrenal axis (HPA) and reduced levels of glucocorticoid receptors (GR) in the hippocampus. To compensate for these effects, we have investigated whether estrogen therapy normalized the HPA response to stress and GR in hippocampus and paraventricular (PVN) nucleus. Young (3-4 months) and old (20 months) male Sprague-Dawley rats were bled by tail cut in the basal state and following ether stress. While basal and ether-stimulated levels of plasma corticosterone (CORT) were similar in the two groups, old animals presented a delayed termination of the response to ether stress. A dexamethasone inhibition test carried out in old animals, showed a failure to completely block plasma CORT after ether stimulation. Furthermore, in old rats GR-immunoreactive levels were reduced in CA1-CA2 hippocampal subfields and subiculum, while normal levels were obtained in CA3-CA4 and PVN. We observed that prolonged estrogen treatment (6 weeks) of old rats normalized the termination of the stress response, restored dexamethasone inhibition of plasma CORT, and increased GR immunoreactivity in CA1 and CA2 hippocampal subfields and subiculum. The results suggest that estrogen treatment enhanced the glucocorticoid feedback signal by increasing GR in hippocampus, and corrected the disturbances in HPA axis regulation. These animal experiments may be important to elucidate the effects of estrogenic on the hippocampal and HPA dysfunction associated with aging and Alzheimer's disease in humans.

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