Stress-induced anhedonia is associated to increased Alzheimer's disease markers

Abstract

Background and purpose: stress is believed to be associated with the development of neuropsychiatric disorders, including Alzheimer's disease (AD). We have studied mechanism implicated in vulnerability to stress and the relationship with changes in AD-related markers. Key results: when using the chronic mild stress (CMS) paradigm to induce anhedonia, 40% percent of rats were resistant to the development of anhedonia (CMSR), whereas the remaining were responsive (CMSA). Only CMSA rats displayed significant increases in immobility time in the forced swimming test, cognitive deficits in the novel object recognition test and significant decreases in synaptophysin, pAkt and pERK1/2 expression in the hippocampus. Increased levels of Aβ40, β-secretase (BACE1) and Tau phosphorylation were also found only in CMSA rats. Interestingly, all these effects in CMSA rats were reverted by normalization of the HPA axis activity by pharmacological treatment with the antidepressant venlafaxine. Conclusions and implications: It is proposed that vulnerability to stress might be related to development of AD pathology and that venlafaxine might be considered as a new therapeutical approach for the treatment of AD.