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Effects of lipopolysaccharide on the expression of plasma membrane monoamine transporter (PMAT) at the blood–brain barrier and its implications to the transport of neurotoxins
Author(s) -
Wu KuoChen,
Lu YaHsuan,
Peng YiHsuan,
Hsu LihChing,
Lin ChunJung
Publication year - 2015
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/jnc.13363
Subject(s) - blood–brain barrier , organic cation transport proteins , lipopolysaccharide , monoamine neurotransmitter , chemistry , solute carrier family , blot , transporter , striatum , microbiology and biotechnology , pharmacology , dopamine transporter , medicine , endocrinology , central nervous system , biology , biochemistry , dopamine , gene , receptor , serotonin
Plasma membrane monoamine transporter (PMAT) is a polyspecific organic cation transporter that is highly expressed in the central nervous system. This study aimed to investigate the effect of lipopolysaccharide on PMAT expression at the blood–brain barrier and the interaction between PMAT and neurotoxins. As a result, PMAT mRNA was identified in brain microvessels (BMVs), brain microvascular endothelial cells (BMECs), astrocytes, and pericytes isolated from C57BL/6 mice and/or Wistar rats using RT‐qPCR. The immunofluorescence staining confirmed the expression of PMAT protein in BMVs and striatum of C57BL/6 mice. Western blotting demonstrated its localization at the luminal and abluminal sides of BMECs. In C57BL/6 mice, PMAT protein was significantly increased in BMVs 24 h after an intraperitoneal injection of 3 mg/kg lipopolysaccharide. Lipopolysaccharide treatment also significantly increased PMAT expression in cerebral cortex and the striatum in a time‐dependent manner, as well as the brain‐to‐plasma ratio of 1‐benzyl‐1,2,3,4‐tetrahydroisoquinoline (1‐benzyl‐TIQ). In isolated cells, lipopolysaccharide treatment significantly increased PMAT mRNA in brain astrocytes and the BMECs co‐cultured with astrocytes. In addition to 1‐methyl‐4‐phenylpyridinium, the kinetic study indicated that both 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine and 1‐benzyl‐TIQ are substrates of human PMAT. These findings suggest that inflammation can change PMAT expression at the blood–brain barrier, which may affect PMAT‐mediated transport of neurotoxins.We demonstrated the expression of plasma membrane monoamine transporter (PMAT; mRNA or protein) at several subunits of the blood–brain barrier. Lipopolysaccharide treatment can significantly increase the expression of PMAT in vivo (in brain microvessels, cerebral cortex, and the striatum of C57BL/6 mice) and in vitro (in brain astrocytes and brain microvascular endothelial cells co‐cultured with astrocytes). Lipopolysaccharide treatment also increased the brain‐to‐plasma ratio of 1‐benzyl‐1,2,3,4‐tetrahydroisoquinoline (1‐benzyl‐TIQ) in mice, where 1‐benzyl‐TIQ competitively inhibited 1‐methyl‐4‐phenylpyridinium (MPP + ) uptake in MDCK‐human PMAT (hPMAT) cells and its uptake in MDCK‐hPMAT is concentration dependent.