Interactions between age, stress and insulin on cognition: implications for Alzheimer´s disease
Résumé
There is much interest in understanding the mechanisms responsible for interactions among stress, ageing, memory and Alzheimer´s disease. Glucocorticoid secretion associated with early life stress may contribute to the variability of the aging process and to the development of neuro- and psychopathologies. Maternal separation (MS), a model of early life stress in which rats experience 3-hour daily separations from the dam during the first 3 weeks of life, was used to study the interactions between stress and ageing. Young (3 months) MS rats showed an altered HPA axis reactivity, depressive-like behavior in the Porsolt swimming test and cognitive impairments in the Morris water maze and novel object recognition test that persisted in aged (18 months) rats. Levels of insulin receptor, phosphorylated insulin receptor and markers of downstream signaling pathways (pAkt, pGSK3β, pTau and pERK1 levels) were significantly decreased in aged rats. There was a significant decrease in pERK2 and in the plasticity marker ARC in MS aged rats compared to single MS or aged rats. Interestingly, there was a significant increase in the C99/C83 ratio, A levels and BACE1 levels the hippocampus of MS aged rats, suggesting that in aged rats subjected to early life stress, there was an increase in the amyloidogenic processing of APP. These results are integrated in a tentative mechanism through which aging interplay with stress to influence cognition as the basis of AD. The present results may provide the proof-of-concept for the use of glucocorticoid/insulin related drugs in the treatment of Alzheimer disease.
Origine : Fichiers produits par l'(les) auteur(s)
Loading...