Chronic Stress Alters Oxidative Stress Pathways and Accelerates Alzheimer’s Disease Progression in 3xTg-AD Mice

Alzheimer’s disease (AD) affects an estimated 6.2 million Americans and is a chronic neurodegenerative disorder characterized by the accumulation of β-amyloid (Aβ) plaques and neurofibrillary tau () tangles, leading to progressive cognitive decline. Chronic stress is linked to vascular contributions to cognitive impairment and dementia (VCID) through sustained HPA axis activation, neuroinflammation, oxidative stress, cerebrovascular dysfunction, and hippocampal atrophy. Chronic stress may also accelerate β-amyloid and tau pathology, highlighting its role as a modifiable risk factor for cognitive decline associated with AD. Previous research from our lab demonstrated that chronic stress induces cerebrovascular dysfunction and cognitive decline in C57BL/6 mice. However, the effects of chronic stress on the progression of AD pathology and the mechanisms underlying this relationship remain unclear. This study aims to elucidate how chronic stress-induced oxidative stress contributes to the acceleration of early-onset AD. Male and female WT and 3xTg-AD mice underwent 8 weeks of unpredictable chronic mild stress (UCMS) starting at 4 months for 5 days/week and 7 hrs/day. Mice were euthanized at 6 and 9 months to assess the impact of age on AD progression and randomized into control and UCMS groups. Mice were euthanized and brain and liver lysates were analyzed for protein expression (western blot), xanthine oxidoreductase activity (HPLC), and Aβ (1-40/42) levels (ELISA). Total RNA was extracted from brain tissues with the RNeasy Lipid Tissue Mini Kit, converted to cDNA through reverse transcription, and analyzed via real-time PCR. Fold-changes in gene expression were calculated by normalizing the expression levels of the test (UCMS) samples against control samples. Gene expression was examined in 6-month-old WT and 3xTg brains to assess the impact of oxidative stress on AD-reated pathways using RT 2 Profiler Arrays. Out of 84 genes analyzed, significant expression changes were observed across genotypes and stress conditions. In 3xTg-AD mice exposed to UCMS, oxidative stress-responsive genes such as Als2, Apoe, Nox1, Nox4, Nos2, Cat, Ccl5, Ctsb, Gpx1–7, Hmox1, Prdx1, Prdx2, Tpo, and Txnrd2 were upregulated. Additionally, genes associated with AD pathology, including those involved in amyloid-beta formation and metabolism—A2m, Ache, Apbb1, Apbb2, Adam9, Apba1, Apba3, App, Bace1, Bdnf, Ctsb, Psen1, and Psen2—showed increased expression. XOR expression and activity were significantly upregulated in 3xTg UCMS mice at 6 months. AB(1-40) expression was significantly upregulated at both 6 and 9 months in the 3xTg UCMS mice as compared to the controls. These findings suggest that with exposure to chronic stress, oxidative stress and ROS-mediated damage impair the antioxidant defense system in AD, potentially accelerating disease progression. Further gene expression analysis in 9-month-old mice is needed to understand the progressive impact of stress on early-onset AD. NIH,NINDS BINP R01 NS117754, Stroke and Alzheimer's Disease Related Dementias (ADRD) T32 WVU This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.