Alzheimer's Disease Phenotype or Inflammatory Insult Does Not Alter Function of L-Type Amino Acid Transporter 1 in Mouse Blood-Brain Barrier and Primary Astrocytes.

Purpose: The study aim was to evaluate the effect of Alzheimer's disease (AD) and inflammatory insult on the function of L-type amino acid transporter 1 (Lat1) at the mouse blood-brain barrier (BBB) as well as Lat1 function and expression in mouse primary astrocytes.
Methods: The Lat1 function and expression was determined in wildtype astrocytes with and without lipopolysaccharide (LPS)-induced inflammation and in LPS treated AD APP/PS1 transgenic astrocytes. The function of Lat1 at the BBB was evaluated in wildtype mice with and without LPS-induced neuroinflammation and APP/PS1 transgenic mice by in situ brain perfusion.
Results: There were 2.1 and 1.6 -fold decreases in Lat1 mRNA and protein expression in LPS-treated wildtype astrocytes compared to vehicle-treated astrocytes. In contrast, Lat1 mRNA and protein expression were increased by 1.7 and 1.2 -fold (not statistically significant) in the transgenic cells. A similar trend was observed in the cell uptake of [ ¹⁴ C]-L-leucine. There were no statistically significant differences in [ ¹⁴ C]-L-leucine BBB permeation between the groups.
Conclusions: The results showed that neither LPS-induced inflammation or the presence of APP/PS1 mutations alters Lat1 function at the mouse BBB as well as Lat1 protein expression and function in mouse primary astrocytes.