title: Functional characterization of rat plasma membrane monoamine transporter in the blood-brain and blood-cerebrospinal fluid barriers.
abstract: This study investigated the expression and functional roles of rat plasma membrane monoamine transporter (rPMAT) in the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier by using in vitro brain barrier model cells (TR-BBB13 and TR-CSFB3 cells) and multiple in vivo experimental techniques. Quantitative reverse transcription-polymerase chain reaction analysis showed relatively high expression of rPMAT mRNA in TR-BBB13 and TR-CSFB3 cells. 1-Methyl-4-phenylpyridinium (MPP(+) ) was transported into rPMAT-expressing cells in a sodium-independent manner. [(3) H]MPP(+) was taken up concentration dependently by TR-BBB13 and TR-CSFB3 cells with K(m) values similar to that of rPMAT-expressing cells. [(3) H]MPP(+) transports into these cells were markedly inhibited by serotonin, dopamine, and cationic drugs. rPMAT small interfering RNA (siRNA) significantly suppressed the [(3) H]MPP(+) uptake by TR-BBB13 cells. Intracerebrally injected [(3) H]MPP(+) was eliminated from the brain parenchymal region, whereas brain [(3) H]MPP(+) uptake did not increase with time during in situ brain perfusion, suggesting that the brain-to-blood transport across the BBB predominates over the blood-to-brain transport. Brain microdialysis studies revealed that the elimination across the BBB was significantly decreased by coperfusion of unlabelled MPP(+) , serotonin, or dopamine. [(3) H]MPP(+) was also eliminated from the CSF. These findings suggest that PMAT in brain barriers functions as the brain-to-blood transporter to regulate brain concentrations of organic cations including monoamines and cationic neurotoxins.
authors.affiliation: Department of Drug Disposition and Pharmacokinetics, School of Pharmaceutical Sciences, Teikyo University, Sagamihara, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Okura
authors.forename: Sayaka
authors.initials: S
authors.lastname: Kato
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Takano
authors.forename: Takenori
authors.initials: T
authors.lastname: Sato
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamashita
authors.forename: Riyo
authors.initials: R
authors.lastname: Morimoto
authors.forename: Sumio
authors.initials: S
authors.lastname: Ohtsuki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Terasaki
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Deguchi
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000008:administration & dosage / Q000493:pharmacokinetics; D000818:Animals; D001483:Base Sequence; D015306:Biogenic Monoamines / Q000378:metabolism*; D001812:Blood-Brain Barrier; D015153:Blotting, Western; D016466:CHO Cells; D002460:Cell Line; D002555:Cerebrospinal Fluid; D006224:Cricetinae; D003412:Cricetulus; D017931:DNA Primers; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015306:Biogenic Monoamines; D017931:DNA Primers; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D015655:1-Methyl-4-phenylpyridinium