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Landers K, Richard K. Traversing barriers - How thyroid hormones pass placental, blood-brain and blood-cerebrospinal fluid barriers. Mol Cell Endocrinol 2017; 458:22-28. [PMID: 28153799 DOI: 10.1016/j.mce.2017.01.041] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/19/2017] [Accepted: 01/24/2017] [Indexed: 11/21/2022]
Abstract
Thyroid hormone is essential for normal human fetal growth and brain development. As the fetal thyroid does not secrete thyroid hormones until about 18 weeks gestation, early fetal brain development depends on passage of maternal hormone across the placenta into the fetal circulation. To reach the fetal brain, maternally derived and endogenously produced thyroid hormone has to cross the blood-brain and blood-cerebrospinal fluid barriers. In this review we will discuss the complex biological barriers (involving membrane transporters, enzymes and distributor proteins) that must be overcome to ensure that the developing human brain has adequate exposure to thyroid hormone.
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Affiliation(s)
- Kelly Landers
- Conjoint Endocrine Laboratory, Chemical Pathology, Pathology Queensland, Queensland Health, Herston, Qld 4029, Australia
| | - Kerry Richard
- Conjoint Endocrine Laboratory, Chemical Pathology, Pathology Queensland, Queensland Health, Herston, Qld 4029, Australia; School of Medicine, University of Queensland, Herston, Qld 4029, Australia; School of Biomedical Sciences, Queensland University of Technology, Brisbane, Qld 4000, Australia.
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Chen R, Chen CP, Preston JE. Effects of transthyretin on thyroxine and β-amyloid removal from cerebrospinal fluid in mice. Clin Exp Pharmacol Physiol 2017; 43:844-50. [PMID: 27220110 DOI: 10.1111/1440-1681.12598] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 05/14/2016] [Accepted: 05/20/2016] [Indexed: 11/28/2022]
Abstract
Transthyretin (TTR) is a binding protein for the thyroid hormone thyroxine (T4 ), retinol and β-amyloid peptide. TTR aids the transfer of T4 from the blood to the cerebrospinal fluid (CSF), but also prevents T4 loss from the blood-CSF barrier. It is, however, unclear whether TTR affects the clearance of β-amyloid from the CSF. This study aimed to investigate roles of TTR in β-amyloid and T4 efflux from the CSF. Eight-week-old 129sv male mice were anaesthetized and their lateral ventricles were cannulated. Mice were infused with artificial CSF containing (125) I-T4 /(3) H-mannitol, or (125) I-Aβ40/(3) H-inulin, in the presence or absence of TTR. Mice were decapitated at 2, 4, 8, 16, 24 minutes after injection. The whole brain was then removed and divided into different regions. The radioactivities in the brain were determined by liquid scintillation counting. At baseline, the net uptake of (125) I-T4 into the brain was significantly higher than that of (125) I-Aβ40, and the half time for efflux was shorter ((125) I-T4 , 5.16; (3) H-mannitol, 7.44; (125) I-Aβ40, 8.34; (3) H-inulin, 10.78 minutes). The presence of TTR increased the half time for efflux of (125) I-T4 efflux, and caused a noticeable increase in the uptake of (125) I-T4 and (125) I-Aβ40 in the choroid plexus, whilst uptakes of (3) H-mannitol and (3) H-inulin remained similar to control experiments. This study indicates that thyroxine and amyloid peptide effuse from the CSF using different transporters. TTR binds to thyroxine and amyloid peptide to prevent the loss of thyroxine from the brain and redistribute amyloid peptide to the choroid plexus.
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Affiliation(s)
- Ruoli Chen
- Institute of Pharmaceutical Science, King's College London, London, UK.,Institute of Science and Technology of Medicine, School of Pharmacy, Keele University, Staffordshire, UK
| | - Carl P Chen
- Institute of Pharmaceutical Science, King's College London, London, UK.,Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital at Linkou, College of Medicine, Chang Gung University, Taoyuan County, Taiwan, China
| | - Jane E Preston
- Institute of Pharmaceutical Science, King's College London, London, UK
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Zibara K, Zein NE, Sabra M, Hneino M, Harati H, Mohamed W, Kobeissy FH, Kassem N. Thyroxine (T 4) Transfer from Blood to Cerebrospinal Fluid in Sheep Isolated Perfused Choroid Plexus: Role of Multidrug Resistance-Associated Proteins and Organic Anion Transporting Polypeptides. Front Neurol 2017; 8:214. [PMID: 28588548 PMCID: PMC5440555 DOI: 10.3389/fneur.2017.00214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/02/2017] [Indexed: 11/21/2022] Open
Abstract
Thyroxine (T4) enters the brain either directly across the blood–brain barrier (BBB) or indirectly via the choroid plexus (CP), which forms the blood–cerebrospinal fluid barrier (B-CSF-B). In this study, using isolated perfused CP of the sheep by single-circulation paired tracer and steady-state techniques, T4 transport mechanisms from blood into lateral ventricle CP has been characterized as the first step in the transfer across the B-CSF-B. After removal of sheep brain, the CPs were perfused with 125I-T4 and 14C-mannitol. Unlabeled T4 was applied during single tracer technique to assess the mode of maximum uptake (Umax) and the net uptake (Unet) on the blood side of the CP. On the other hand, in order to characterize T4 protein transporters, steady-state extraction of 125I-T4 was measured in presence of different inhibitors such as probenecid, verapamil, BCH, or indomethacin. Increasing the concentration of unlabeled-T4 resulted in a significant reduction in Umax%, which was reflected by a complete inhibition of T4 uptake into CP. In fact, the obtained Unet% decreased as the concentration of unlabeled-T4 increased. The addition of probenecid caused a significant inhibition of T4 transport, in comparison to control, reflecting the presence of a carrier mediated process at the basolateral side of the CP and the involvement of multidrug resistance-associated proteins (MRPs: MRP1 and MRP4) and organic anion transporting polypeptides (Oatp1, Oatp2, and Oatp14). Moreover, verapamil, the P-glycoprotein (P-gp) substrate, resulted in ~34% decrease in the net extraction of T4, indicating that MDR1 contributes to T4 entry into CSF. Finally, inhibition in the net extraction of T4 caused by BCH or indomethacin suggests, respectively, a role for amino acid “L” system and MRP1/Oatp1 in mediating T4 transfer. The presence of a carrier-mediated transport mechanism for cellular uptake on the basolateral membrane of the CP, mainly P-gp and Oatp2, would account for the efficient T4 transport from blood to CSF. The current study highlights a carrier-mediated transport mechanism for T4 movement from blood to brain at the basolateral side of B-CSF-B/CP, as an alternative route to BBB.
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Affiliation(s)
- Kazem Zibara
- ER045, PRASE, Lebanese University, Beirut, Lebanon.,Faculty of Sciences, Biology Department, Lebanese University, Beirut, Lebanon
| | - Nabil El Zein
- ER045, PRASE, Lebanese University, Beirut, Lebanon.,Faculty of Sciences, Biology Department, Lebanese University, Beirut, Lebanon
| | - Mirna Sabra
- ER045, PRASE, Lebanese University, Beirut, Lebanon.,Neuroscience Research Centre, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Mohammad Hneino
- ER045, PRASE, Lebanese University, Beirut, Lebanon.,Faculty of Public Health, Medical Laboratory Department, Lebanese University, Beirut, Lebanon
| | - Hayat Harati
- Neuroscience Research Centre, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Wael Mohamed
- Basic Medical Science Department, Kulliyyah of Medicine, International Islamic University Malaysia, Kuantan, Pahang, Malaysia.,Neuroscience Unit, Menoufia Medical School, Cairo, Egypt
| | - Firas H Kobeissy
- Department of Biochemistry and Molecular Genetics, American University of Beirut, Beirut, Lebanon
| | - Nouhad Kassem
- ER045, PRASE, Lebanese University, Beirut, Lebanon.,Neuroscience Research Centre, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
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