Hypoxia promotes tau hyperphosphorylation with associated neuropathology in vascular dysfunction

Area of Science:

• Neuroscience
• Vascular Biology
• Pathology

Background:

• Hypertension is a leading cause of microvascular brain injury, contributing to cognitive impairment and dementia.
• Chronic hypoxia is implicated in neurodegenerative processes, but its role in hypertension-related cognitive decline requires further elucidation.

Purpose of the Study:

• To investigate the effects of chronic hypoxia on tau phosphorylation and neuronal cell death in a rat model of accelerated hypertension.
• To correlate findings in the rat model with human patients suffering from vascular dementia.

Main Methods:

• Utilized an accelerated spontaneously hypertensive stroke-prone rat model fed a high-salt, low-protein diet.
• Employed electron paramagnetic resonance oximetry for in vivo oxygen measurements and MRI for brain structural analysis.
• Assessed neuroglobin levels, oxidative stress markers (NADPH oxidase), phosphorylated tau (p-Tau), interleukin-1β, and neurodegeneration.

Main Results:

• Hypertensive rats exhibited compromised gray and white matter integrity, reduced cerebral blood flow, and lower cortical oxygen levels.
• Decreased neuroglobin, increased free radicals, elevated p-Tau, active interleukin-1β, and neurodegeneration were observed in hypertensive rats.
• Human patients with subcortical ischemic vascular disease showed brain atrophy consistent with the rat model.

Conclusions:

• Hypertension-induced vascular dysfunction is associated with tau hyperphosphorylation and cell death in a rat model.
• Findings correlate with brain atrophy observed in human patients with vascular dementia.
• The study provides insights into the mechanisms linking hypertension, hypoxia, and neurodegeneration in vascular cognitive impairment.