A validated quantitative method for the assessment of neuroprotective barrier impairment in neurodegenerative disease models

The blood–brain barrier (BBB) and blood–spinal cord barrier (BSCB) are highly specialized structures that limit molecule entry from the blood and maintain homeostasis within the central nervous system (CNS). BBB and BSCB breakdown are associated with multiple neurodegenerative diseases. Given the key role of neuroprotective barrier impairment in neurodegeneration, it is important to identify an effective quantitative method to assess barrier integrity in animal models. In this study, we developed and validated a quantitative method for assessing BBB and BSCB integrity using sodium fluorescein, a compound that outperformed other fluorescent dyes. We demonstrated using this method that multiple CNS regions progressively increase in permeability in models of Huntington’s disease and amyotrophic lateral sclerosis, whereas biphasic disruption occurred in a mouse model of Alzheimer’s disease with disease progression. Collectively, we report a quantitative fluorometric marker with validated reproducible experimental methods that allows the effective assessment of BBB and BSCB integrity in animal models. This method could be useful to further the understanding of the contribution of these neuroprotective barriers to neurodegeneration processes. We demonstrate that Na‐FL is a sensitive marker to measure neuroprotective barrier integrity in an acute LPS‐induced BBB/BSCB breakdown model. We then demonstrate using this technique that multiple CNS regions progressively increase in permeability with age, and in models of Huntington’s disease and amyotrophic lateral sclerosis, while biphasic disruption (early increase, and later decrease) occurs in a model of Alzheimer’s disease. Collectively, we report a quantitative fluorometric marker with validated reproducible experimental methods, that allows the effective assessment of BBB/BSCB integrity in animal models. This method could be useful to further the understanding of the contribution of these neuroprotective barriers to neurodegeneration processes.