Diffusion Connectome Analysis in a Rat Model of Hypertension

Abstract

While hypertension is recognized as a significant risk factor for cerebrovascular diseases(e.g., Alzheimer’s Disease and dementia) and cognitive decline, its impact on brain connectivity is not fully understood. A prior study investigated the effects of induced hypertension on the macrostructural and microstructural anatomy of Fischer 344 Cyp1a1-Ren2 transgenic rats using diffusion MRI (dMRI). Results showed that while hypertension resulted in end-organ damage in the heart and the kidney, the brain remained unaffected in terms of volume and microstructural characteristics. The purpose of this study is to further investigate the effects of hypertension on structural white matter connectivity in the same transgenic rat model using connectome analysis. Connectomes were generated from diffusion data collected and processed in the previous study using probabilistic tractography. Structural connectivity was quantified and compared between and within normotensive and hypertensive rats at baseline and 10 weeks across four regions of interest (left cortex, right cortex, left hippocampal CA subfields, and right hippocampal CA subfields). No significant differences were observed in structural connectivity across these four regions, further establishing the findings reported in the prior study. These findings indicate that the brain may implement intrinsic protective mechanisms to preserve structural connectivity and mitigate damage from hypertension, even in the presence of systemic end-organ damage.