Chronic Stress Effects on Adrenocortical Responsiveness in Young and Aged Rats

Abstract

The effect of chronic stress on adrenocorticalfunction was tested in young and aged male and female rats. The rats were subjected twice a day to 2 h restraint stress for 20 days. Adrenocortical responsiveness to stressors was decreased during the treatment in all groups. Responsiveness to ACTH injection was greater than stress responsiveness in all groups. The decrease in stress responsiveness was greater in the young than in the aged groups. The data suggest that elevated corticosterone concentrations from chronic stress adrenocortical activation result in incomplete feedback inhibition of the adrenocortical control mechanism. The increased inhibition in the young groups supports the concept of decreased adrenocortical control system sensitivity in the aged animal.

Serum corticosterone concentrations in reproductively mature and inhibited deermice (Peromyscus maniculatus bairdii)

“…A similar finding was noted for the males from Population Blood corticosterone levels have been shown to be significantly elevated during acute and chronic stress of rats and some other laboratory animals (Friedman & Ader, 1968;Ganjam, Campbell & Murphy, 1972;Zimmerman, Smyrl & Critchlow, 1972;Cook, Kendall, Greer & Kramer, 1973;Dallman & Jones, 1973;Riegle, 1974;Barlow, Morrison & Sullivan, 1975), and an increase in plasma ACTH precedes the corticosterone elevation (Cook et al, 1973 (Terman, 1973b).…”

Impact of Aging on Steroid Hormone Biosynthesis and Secretion

“…However, both old female and male rats secreted significantly less corticosterone in response to either ACTH treatment or ether stress compared to respective young (control) animals.  The work of Riegle and Hess [456] and Riegel [457] suggest that the ability of aged (22-32-mo) male and female rats (Long-Evans) to a negative feedback inhibition of the hypothalamic-pituitary axis is significantly impaired as compared to young (4-6-mo) adult animals.  Meaney et al, [458,459] reported elevated corticosterone levels in 16-and 24-mo old male Long-Evans rats as compared to young (3-mo) and adult (8-mo) rats.…”

<b>Alterações em adrenais de cães relacionadas à morte súbita ou agônica:</b> análise morfométrica, histopatológica, imunoistoquímica e correlação com os níveis de adrenalina e noradrenalina na medula adrenal

“…As adrenais estão intrinsicamente relacionadas à resposta do organismo ao estresse, sendo parte dos eixos hipotálamo-hipófise-adrenal (HPA) e simpaticoadrenomedular (SAM) (RIEGLE, 1973;AXELROD;REISINE, 1984).…”

“…Embora as três zonas do córtex possam ser ativadas pelo estímulo do hormônio adrenocroticotrófico (ACTH), a zona fasciculada é a que apresenta maior resposta, principalmente em casos de estresse prolongado, resultando no aumento da produção e da liberação de cortisol (RIEGLE, 1973;AXELROD;REISINE, 1984;WHITWORTH et al, 2003;QUAN et al, 2014). Há numerosos estudos em relação ao eixo HPA e à resposta do organismo frente a estímulos estressores variados, de naturezas diversas e por períodos variáveis, como jejum, som, frio, calor, imobilização, presença de doenças crônicas, dentre outros.…”

“…Há numerosos estudos em relação ao eixo HPA e à resposta do organismo frente a estímulos estressores variados, de naturezas diversas e por períodos variáveis, como jejum, som, frio, calor, imobilização, presença de doenças crônicas, dentre outros. Tais estudos, realizados em humanos ou em diversos modelos animais, apresentam resultados envolvendo alterações morfológicas ou funcionais nas glândulas adrenais em resposta aos agentes estressores estudados (RIEGLE, 1973;KUHAJDA;HUTCHINS, 1979;SWAIN, 2000;KOKO et al, 2004;ULRICH-LAI et al, 2006;POLITO et al, 2010;PETROVIC-KOSANOVIC et al, 2012).…”