title: Organic anion transporter 3 mediates the efflux transport of an amphipathic organic anion, dehydroepiandrosterone sulfate, across the blood-brain barrier in mice.
abstract: The present study investigated the efflux transport systems of organic anions across the blood-brain barrier (BBB) using dehydroepiandrosterone sulfate (DHEAS) as a probe. The elimination of DHEAS from the brain after microinjection into the cerebral cortex was characterized in wild-type mice and mice with deficiency of well characterized organic anion transporters, organic anion-transporting polypeptide 1a4 (Oatp1a4)/Slco1a4 and organic anion transporter 3 (Oat3)/Slc22a8, at the BBB. The saturable efflux of DHEAS from the brain was completely inhibited by probenecid, benzylpenicillin, and estrone-3-sulfate and moderately inhibited by taurocholate and p-aminohippurate (50-57%). Uptake of DHEAS and estrone-3-sulfate was greater in murine Oat3 cRNA-injected oocytes than that in water-injected oocytes. Efflux of these compounds from the brain was significantly delayed in Oat3(-/-) mice compared with that in wild-type mice, indicating that indeed Oat3 is functionally important in vivo. Furthermore, probenecid and taurocholate inhibited DHEAS efflux completely in Oat3(-/-) mice. Contrary to the past report in rats that suggested involvement of Oatp1a4, specific uptake of DHEAS and estrone-3-sulfate by murine Oatp1a4 was not detected in vitro, and efflux of both compounds from the brain was not altered in Oatp1a4(-/-) mice. There was no significant difference in the uptake of DHEAS by brain slices prepared from wild-type, Oatp1a4(-/-), and Oat3(-/-) mice. Taken together, these results suggest that Oat3 plays a significant role in the efflux of steroid conjugates across the BBB in mice and that the BBB also expresses other unknown organic anion transporters for the efflux of DHEAS. Transport mechanisms of organic anions at the BBB are far more diverse than they were assumed to be.
authors.affiliation: Laboratory of Molecular Pharmacokinetics, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Miyajima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kusuhara
authors.forename: Miki
authors.initials: M
authors.lastname: Fujishima
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Adachi
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sugiyama
mesh_terms: D000818:Animals; D000838:Anions / Q000378:metabolism; D001692:Biological Transport; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate / Q000737:chemistry / Q000493:pharmacokinetics*; D004970:Estrone / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008845:Microinjections; D009865:Oocytes / Q000378:metabolism; D029362:Organic Anion Transporters, Sodium-Independent / Q000378:metabolism*; D027701:Organic Cation Transport Proteins / Q000378:metabolism*; D011339:Probenecid / Q000378:metabolism / Q000494:pharmacology; D018075:RNA, Complementary; D013656:Taurocholic Acid / Q000378:metabolism / Q000494:pharmacology; D014982:Xenopus laevis
chemical_list: D000838:Anions; C464433:Oatp2 protein, mouse; D029362:Organic Anion Transporters, Sodium-Independent; D027701:Organic Cation Transport Proteins; D018075:RNA, Complementary; C114338:organic anion transport protein 3; D004970:Estrone; D019314:Dehydroepiandrosterone Sulfate; D013656:Taurocholic Acid; D011339:Probenecid; C017296:estrone sulfate