Roles of P-glycoprotein and multidrug resistance protein in transporting para-aminosalicylic acid and its N-acetylated metabolite in mice brain
Abstract
Lan HONG1, 2, Cong XU1, Stefanie O'NEAL2, Hui-chang BI3, Min HUANG3, Wei ZHENG2, *, Su ZENG1, *
1College of Pharmaceutical Sciences, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Zhejiang University, Hangzhou 310058, China; 2School of Health Sciences, Purdue University, West Lafayette, Indiana, USA; 3Institute of Clinical Pharmacology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
Aim: Para-aminosalicylic acid (PAS) is effective in the treatment of manganism-induced neurotoxicity (manganism). In this study we investigated the roles of P-glycoprotein (MDR1a) and multidrug resistance protein (MRP) in transporting PAS and its N-acetylated metabolite AcPAS through blood-brain barrier.
Methods: MDR1a-null or wild-type mice were intravenously injected with PAS (200 mg/kg). Thirty minutes after the injection, blood samples and brains were collected, and the concentrations of PAS and AcPAS in brain capillaries and parenchyma were measured using HPLC. Both MDCK-MDR1 and MDCK-MRP1 cells that overexpressed P-gp and MRP1, respectively, were used in two-chamber Transwell transport studies in vitro.
Results: After injection of PAS, the brain concentration of PAS was substantially higher in MDR1a-null mice than in wild-type mice, but the brain concentration of AcPAS had no significant difference between MDR1a-null mice and wild-type mice. Concomitant injection of PAS with the MRP-specific inhibitor MK-571 (50 mg/kg) further increased the brain concentration of PAS in MDR1a-null mice, and increased the brain concentration of AcPAS in both MDR1a-null mice and wild-type mice. Two-chamber Transwell studies with MDCK-MDR1 cells demonstrated that PAS was not only a substrate but also a competitive inhibitor of P-gp, while AcPAS was not a substrate of P-gp. Two-chamber Transwell studies with the MDCK-MRP1 cells showed that MRP1 had the ability to transport both PAS and AcPAS across the BBB.
Conclusion: P-gp plays a major role in the efflux of PAS from brain parenchyma into blood in mice, while MRP1 is involved in both PAS and AcPAS transport in the brain.
Keywords: para-aminosalicylic acid; manganism; chelating agent; blood-brain barrier; MK-571; P-glycoprotein; multidrug resistance protein; MDCK-MDR1 cells; MDCK-MRP1 cells
This work was supported by the US National Institute of Health/National Institute of Environmental Health Grant RO1 ES008146 (Wei ZHENG), the US Department of Defense Contract USAMRMC W81XWH-05-1-0239 (Wei ZHENG), and the National Major Projects from the Ministry of Science and Technology of China (2012ZX09506001-004) (Su ZENG).
* To whom correspondence should be addressed.
E-mail zengsu@zju.edu.cn (Su ZENG); wzheng@purdue.edu (Wei ZHENG)
Received 2014-06-21 Accepted 2014-09-02
Keywords:
1College of Pharmaceutical Sciences, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Zhejiang University, Hangzhou 310058, China; 2School of Health Sciences, Purdue University, West Lafayette, Indiana, USA; 3Institute of Clinical Pharmacology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
Aim: Para-aminosalicylic acid (PAS) is effective in the treatment of manganism-induced neurotoxicity (manganism). In this study we investigated the roles of P-glycoprotein (MDR1a) and multidrug resistance protein (MRP) in transporting PAS and its N-acetylated metabolite AcPAS through blood-brain barrier.
Methods: MDR1a-null or wild-type mice were intravenously injected with PAS (200 mg/kg). Thirty minutes after the injection, blood samples and brains were collected, and the concentrations of PAS and AcPAS in brain capillaries and parenchyma were measured using HPLC. Both MDCK-MDR1 and MDCK-MRP1 cells that overexpressed P-gp and MRP1, respectively, were used in two-chamber Transwell transport studies in vitro.
Results: After injection of PAS, the brain concentration of PAS was substantially higher in MDR1a-null mice than in wild-type mice, but the brain concentration of AcPAS had no significant difference between MDR1a-null mice and wild-type mice. Concomitant injection of PAS with the MRP-specific inhibitor MK-571 (50 mg/kg) further increased the brain concentration of PAS in MDR1a-null mice, and increased the brain concentration of AcPAS in both MDR1a-null mice and wild-type mice. Two-chamber Transwell studies with MDCK-MDR1 cells demonstrated that PAS was not only a substrate but also a competitive inhibitor of P-gp, while AcPAS was not a substrate of P-gp. Two-chamber Transwell studies with the MDCK-MRP1 cells showed that MRP1 had the ability to transport both PAS and AcPAS across the BBB.
Conclusion: P-gp plays a major role in the efflux of PAS from brain parenchyma into blood in mice, while MRP1 is involved in both PAS and AcPAS transport in the brain.
Keywords: para-aminosalicylic acid; manganism; chelating agent; blood-brain barrier; MK-571; P-glycoprotein; multidrug resistance protein; MDCK-MDR1 cells; MDCK-MRP1 cells
This work was supported by the US National Institute of Health/National Institute of Environmental Health Grant RO1 ES008146 (Wei ZHENG), the US Department of Defense Contract USAMRMC W81XWH-05-1-0239 (Wei ZHENG), and the National Major Projects from the Ministry of Science and Technology of China (2012ZX09506001-004) (Su ZENG).
* To whom correspondence should be addressed.
E-mail zengsu@zju.edu.cn (Su ZENG); wzheng@purdue.edu (Wei ZHENG)
Received 2014-06-21 Accepted 2014-09-02