GAT2/BGT-1 as a system responsible for the transport of γ-aminobutyric acid at the mouse blood-brain barrier

Hitomi Takanaga, Sumio Ohtsuki, Ken Ichi Hosoya, Tetsuya Terasaki

Research output: Contribution to journalArticlepeer-review

111 Citations (Scopus)

Abstract

In this study, the γ-aminobutyric acid (GABA) transporter at the blood-brain barrier (BBB) was identified by reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunostaining analysis, and the transport mechanism was characterized using a conditionally immortalized mouse brain capillary endothelial cell line (TM-BBB) as an in vitro model of the BBB. γ-Aminobutyric acid transport was studied by the cellular uptake of [3H]GABA. [3H]GABA uptake by TM-BBB cells was Na+-, Cl--, and concentration-dependent. The corresponding Michaelis-Menten constant was 679 ± 80 μmol/L and the maximal uptake rate was 4,790 ± 494 pmol/(mg protein · 5 minutes). [3H]GABA uptake by TM-BBB cells was significantly inhibited by betaine, β-alanine, nipecotic acid, taurine, and quinidine, whereas probenecid, L-proline, creatine, and glycine had no effect. This type of inhibition is consistent with the predominant involvement of the GAT2/BGT-1 transporter in TM-BBB cells. RT-PCR analysis showed that GAT2/BGT-1 mRNA was expressed in TM-BBB cells, whereas Western blot analysis showed that TM-BBB cells and mouse brain capillaries express GAT2/BGT-1 protein. Moreover, confocal immunofluorescent microscopy of dual-labeled mouse brain sections demonstrated the colocalization of GAT2/BGT-1 and P-glycoprotein, a BBB-specific marker, on brain capillaries labeled with anti-GAT2/BGT-1 antibody and anti-P-glycoprotein antibody, respectively. These results are evidence that GAT2/BGT-1 is expressed at the BBB and is involved in GABA transport across the BBB.

Original languageEnglish
Pages (from-to)1232-1239
Number of pages8
JournalJournal of Cerebral Blood Flow and Metabolism
Volume21
Issue number10
DOIs
Publication statusPublished - 2001

Keywords

  • Blood-brain barrier
  • Carrier-mediated transport
  • GAT
  • GAT2/BGT-1
  • Neurotransmitter
  • γ-Aminobutyric acid

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Cardiology and Cardiovascular Medicine

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