Interactions between age, stress and insulin on cognition: implications for Alzheimer's disease.
There is much interest in understanding the mechanisms responsible for interactions among stress, aging, 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 h of daily separation from the dam during the first 3 weeks of life, was used to study the interactions between stress and aging. Young (3 months) MS rats showed an altered hypothalamic-pituitary-adrenal (HPA) axis reactivity, depressive-like behavior in the Porsolt swimming test and cognitive impairments in the Morris water maze and new object recognition test that persisted in aged (18 months) rats. Levels of insulin receptor, phosphorylated insulin receptor and markers of downstream signaling pathways (pAkt, pGSK3 beta, 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 with single MS or aged rats. It is interesting to note that there was a significant increase in the C99 : C83 ratio, A beta 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 amyloid precursor protein (APP). These results are integrated in a tentative mechanism through which aging interplay with stress to influence cognition as the basis of Alzheimer disease (AD). The present results may provide the proof-of-concept for the use of glucocorticoid-/insulin-related drugs in the treatment of AD.
Solas
Maite
M
Department of Pharmacology, School of Medicine, Center for Applied Medical Research, University of Navarra, Pamplona, Spain.
Aisa
Bárbara
B
Mugueta
María C
MC
Del Río
Joaquín
J
Tordera
Rosa M
RM
Ramírez
María J
MJ
D000375:Aging; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism; D003072:Cognition Disorders / Q000209:etiology*; D003345:Corticosterone / Q000097:blood; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D003863:Depression / Q000209:etiology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism; D007328:Insulin / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008426:Maternal Deprivation; D018782:Maze Learning / Q000502:physiology; D009043:Motor Activity / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009483:Neuropsychological Tests; D010446:Peptide Fragments / Q000378:metabolism; D010913:Pituitary-Adrenal System / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011972:Receptor, Insulin / Q000378:metabolism; D021641:Recognition, Psychology / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D018709:Statistics, Nonparametric; D013315:Stress, Psychological / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D013550:Swimming / Q000523:psychology
D016229:Amyloid beta-Peptides; D019208:Brain-Derived Neurotrophic Factor; D003598:Cytoskeletal Proteins; D007328:Insulin; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D012333:RNA, Messenger; C092069:activity regulated cytoskeletal-associated protein; C075222:amyloid beta-protein (1-42); D007334:Insulin-Like Growth Factor I; D011972:Receptor, Insulin; D003345:Corticosterone