Efflux of a suppressive neurotransmitter, GABA, across the blood-brain barrier

Atsuyuki Kakee, Hitomi Takanaga, Tetsuya Terasaki, Mikihiko Naito, Takashi Tsuruo, Yuichi Sugiyama

研究成果: Article査読

75 被引用数 (Scopus)


In this study, GABA efflux transport from brain to blood was estimated by using the brain efflux index (BEI) method. [ 3H]GABA microinjected into partietal cortex area 2 (Par2) of the rat brain was eliminated from the brain with an apparent elimination half-life of 16.9 min. The blood-brain barrier (BBB) efflux clearance of [ 3H]GABA was at least 0.153 Ml/min/g brain, which was calculated from the elimination rate constant (7.14×10 -2 min -1) and the distribution volume in the brain (2.14 Ml/g brain). Direct comparison of the apparent BBB influx clearance [ 3H]GABA (9.29 μL/min/g brain) and the apparent efflux clearance (153 μL/min/g brain) indicated that the efflux clearance was at least 16-fold greater than the influx clearance. In order to reduce the effect of metabolism in the neuronal cells following intracerebral microinjection, we determined the apparent efflux of [ 3H]GABA in the presence of nipecotic acid, a GABA transport inhibitor in parenchymal cells, using the BEI method. Under such conditions, the elimination of [ 3H]GABA across the BBB showed saturation and inhibition by probenecid in the presence of nipecotic acid. Furthermore, the uptake of [ 3H]GABA by MBEC4 cells was inhibited by GABA, taurine, β-alanine and nipecotic acid in a concentration-dependent manner. It is likely that GABA inhibits the first step in the abluminal membrane uptake by brain endothelial cells, and that probenecid selectively inhibits the luminal membrane efflux transport process from the brain capillary endothelial cells based on the in vivo and in vitro evidence. The BBB acts as the efflux pump for GABA to reduce the brain interstitial fluid concentration.

ジャーナルJournal of Neurochemistry
出版ステータスPublished - 2001

ASJC Scopus subject areas

  • 生化学
  • 細胞および分子神経科学


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