Abstract
Alzheimer's disease (AD) may disturb functions of the blood-brain barrier and change the disposition of drugs to the brain. This study assessed the disease-induced changes in drug transporters in the brain capillaries of transgenic AD mice. Eighteen drug transporters and four tight junction-associated proteins were analyzed by RT-qPCR in cortex, hippocampus and cerebellum tissue samples of 12-16-month-old APdE9, Tg2576 and APP/PS1 transgenic mice and their healthy age-matched controls. In addition, microvessel fractions enriched from 1-3-month-old APdE9 mice were analyzed using RT-qPCR and Western blotting. Brain transport of methotrexate in APdE9 mice was assessed by in vivo microdialysis. The expression profiles of studied genes were similar in brain tissues of AD and control mice. Instead, in the microvessel fraction in APdE9 mice, >2-fold alterations were detected in the expressions of 11 genes but none at the protein level. In control mice strains, >5-fold changes between different brain regions were identified for Slc15a2, Slc22a3 and occludin. Methotrexate distribution into hippocampus of APdE9 mice was faster than in controls. The expression profile of mice carrying presenilin and amyloid precursor protein mutations is comparable to controls, but clear regional differences exist in the expression of drug transporters in brain.
Highlights
Alzheimer’s disease (AD) is the most common form of dementia; it is associated with accumulation of senile plaques and neurofibrillary tangles in the brain [1]
This study aimed to characterize the expression of drug transporters and tight junction-associated proteins in three mouse models of AD, the APdE9, amyloid precursor protein (APP)/PS1 and Tg2576 mice, and to investigate the regional expression differences in the brain
In the APdE9 model, the greatest difference was detected for Abcb1b gene, which had a 1.4-fold higher expression level in AD CX and HC tissues when compared to wt (Fig. 1a)
Summary
Alzheimer’s disease (AD) is the most common form of dementia; it is associated with accumulation of senile plaques and neurofibrillary tangles in the brain [1]. The extracellular senile plaques are mainly formed by aggregating amyloid-β (Aβ) peptides in the brain parenchyma, whereas hyperphosphorylated and misfolded tau proteins are the main constituent of the intraneuronal neurofibrillary tangles. A dysfunctional BBB may alter the access of AD drugs to their site of action; it may either increase the drug exposure to the brain, potentially causing unwanted effects, or decrease drug access and lead to an insufficient response. BBB dysfunction can either increase or decrease the brain distribution of other concomitant medications and possibly increase their adverse effects on the central nervous system
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