Functional characterization of rat plasma membrane monoamine transporter in the blood-brain and blood-cerebrospinal fluid barriers

Takashi Okura, Sayaka Kato, Yusuke Takano, Takenori Sato, Atsushi Yamashita, Riyo Morimoto, Sumio Ohtsuki, Tetsuya Terasaki, Yoshiharu Deguchi

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

This study investigated the expression and functional roles of rat plasma membrane monoamine transporter (rPMAT) in the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier by using in vitro brain barrier model cells (TR-BBB13 and TR-CSFB3 cells) and multiple in vivo experimental techniques. Quantitative reverse transcription-polymerase chain reaction analysis showed relatively high expression of rPMAT mRNA in TR-BBB13 and TR-CSFB3 cells. 1-Methyl-4-phenylpyridinium (MPP+) was transported into rPMAT-expressing cells in a sodium-independent manner. [3H]MPP+ was taken up concentration dependently by TR-BBB13 and TR-CSFB3 cells with Km values similar to that of rPMAT-expressing cells. [3H]MPP+ transports into these cells were markedly inhibited by serotonin, dopamine, and cationic drugs. rPMAT small interfering RNA (siRNA) significantly suppressed the [3H]MPP+ uptake by TR-BBB13 cells. Intracerebrally injected [3H]MPP+ was eliminated from the brain parenchymal region, whereas brain [3H]MPP+ uptake did not increase with time during in situ brain perfusion, suggesting that the brain-to-blood transport across the BBB predominates over the blood-to-brain transport. Brain microdialysis studies revealed that the elimination across the BBB was significantly decreased by coperfusion of unlabelled MPP+, serotonin, or dopamine. [3H]MPP+ was also eliminated from the CSF. These findings suggest that PMAT in brain barriers functions as the brain-to-blood transporter to regulate brain concentrations of organic cations including monoamines and cationic neurotoxins.

Original languageEnglish
Pages (from-to)3924-3938
Number of pages15
JournalJournal of Pharmaceutical Sciences
Volume100
Issue number9
DOIs
Publication statusPublished - 2011 Sep

Keywords

  • 1-methyl-4-phenylpyridinium
  • Blood-brain barrier
  • Blood-cerebrospinal fluid barrier
  • CNS
  • In vitro models
  • Plasma membrane monoamine transporter
  • TR-BBB13 cells
  • TR-CSFB3 cells
  • Transporters

ASJC Scopus subject areas

  • Pharmaceutical Science

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