Cisternino Salvatore, Rousselle Christophe, Lorico Aurelio, Rappa Germana, Scherrmann Jean-Michel
INSERM U26, Hôpital Fernand Widal, 200 Rue du Faubourg Saint-Denis, 75475 Paris cedex 10, France.
Pharm Res. 2003 Jun;20(6):904-9. doi: 10.1023/a:1023895404929.
The purpose of this work was to determine mrpl-mediated efflux across the luminal membrane of endothelial cells at the blood-brain barrier (BBB) in mice.
The transport of radiolabeled etoposide, 17beta-estradiol-D-17beta-glucuronide (E217betaG), vincristine, and doxorubicin across the BBB of mrp1(-/-) and wild-type mice was evaluated by in situ brain perfusion. Etoposide transport was also determined in P-glycoprotein-deficient mdr1a(-/-) mice perfused with both etoposide and mrpl inhibitors like probenecid or MK571. Cerebral vascular volume was determined by co-perfusion with labeled sucrose.
Sucrose perfusion indicated that the vascular space was close to normal in all the studies, indicating that the BBB remained intact. The transport of etoposide, E217betaG, vincristine, and doxorubicin into the brain was not affected by the lack of mrp1. Trans-efflux studies in mrp1-deficient mice with etoposide and E217betaG confirmed that mrpl was not involved in the efflux of these substrates across the BBB. There was also a significant P-gp-mediated efflux of etoposide in studies with P-glycoprotein-deficient mdr1a(-/-) mice. Perfusion of mdr1a(-/-) mice etoposide plus probenecid or MK571 did not affect the brain transport of etoposide.
Efflux mediated by mrp1 does not seem to occur across the luminal membrane of the endothelial cells forming the mouse BBB.
本研究旨在确定多药耐药相关蛋白1（mrpl）介导的外排作用是否存在于小鼠血脑屏障（BBB）内皮细胞的管腔膜上。
通过原位脑灌注评估放射性标记的依托泊苷、17β-雌二醇-D-17β-葡萄糖醛酸苷（E217βG）、长春新碱和阿霉素在mrp1基因敲除小鼠和野生型小鼠血脑屏障中的转运情况。还在缺乏P-糖蛋白的mdr1a基因敲除小鼠中测定依托泊苷的转运，这些小鼠同时灌注依托泊苷和mrpl抑制剂，如丙磺舒或MK571。通过与标记的蔗糖共同灌注来测定脑血管容积。
蔗糖灌注表明，在所有研究中血管空间接近正常，这表明血脑屏障保持完整。依托泊苷、E217βG、长春新碱和阿霉素向脑内的转运不受mrp1缺失的影响。对mrp1基因敲除小鼠进行依托泊苷和E217βG的跨膜外排研究证实，mrpl不参与这些底物通过血脑屏障的外排。在对缺乏P-糖蛋白的mdr1a基因敲除小鼠的研究中，依托泊苷也存在明显的P-糖蛋白介导的外排作用。对mdr1a基因敲除小鼠灌注依托泊苷加丙磺舒或MK571并不影响依托泊苷在脑内的转运。
由mrpl介导的外排在构成小鼠血脑屏障的内皮细胞管腔膜上似乎并不发生。
