Functional ultrasound imaging reveals microvascular rarefaction, decreased cerebral blood flow, and impaired neurovascular coupling in a mouse model of paclitaxel-induced chemobrain

Chemotherapy-induced cognitive impairment (CICI), often referred to as "chemobrain," significantly affects the quality of life in cancer survivors. Although traditionally attributed to neuronal toxicity, emerging evidence suggests a key role of cerebrovascular dysfunction in its pathogenesis. We hypothesized that paclitaxel (PTX, Taxol) treatment induces long-term cerebrovascular dysfunction, including microvascular rarefaction, impaired neurovascular coupling (NVC), and altered cerebral blood flow (CBF), which contribute to CICI. Using a clinically relevant PTX treatment regimen in non-tumor-bearing mice, we evaluated the long-term effects of PTX on cerebrovascular health. Ultrasound localization microscopy (ULM) and functional ultrasound imaging (fUS) were employed to assess microvascular density, CBF, and NVC. PTX treatment resulted in a significant reduction in microvascular density in the cerebral cortex and hippocampus, key regions involved in cognitive function. PTX significantly reduced blood velocity in the middle cerebral artery. Moreover, PTX impaired NVC responses, as evidenced by a diminished CBF increase in response to whisker stimulation, indicative of impaired reactive hyperemia. In conclusion, these findings demonstrate that PTX induces long-lasting cerebrovascular dysfunction, including microvascular rarefaction, impaired NVC, and altered CBF dynamics, which likely contribute to CICI. This study underscores the critical role of cerebrovascular health in cognitive function and highlights the potential of targeting cerebrovascular pathways as a therapeutic approach for mitigating chemotherapy-induced cognitive deficits.