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Khalil A, Barras A, Boukherroub R, Tseng CL, Devos D, Burnouf T, Neuhaus W, Szunerits S. Enhancing paracellular and transcellular permeability using nanotechnological approaches for the treatment of brain and retinal diseases. NANOSCALE HORIZONS 2023; 9:14-43. [PMID: 37853828 DOI: 10.1039/d3nh00306j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Paracellular permeability across epithelial and endothelial cells is, in large part, regulated by apical intercellular junctions also referred to as tight junctions (TJs). These junctions contribute to the spatial definition of different tissue compartments within organisms, separating them from the outside world as well as from inner compartments, with their primary physiological role of maintaining tissue homeostasis. TJs restrict the free, passive diffusion of ions and hydrophilic small molecules through paracellular clefts and are important for appropriate cell polarization and transporter protein localisation, supporting the controlled transcellular diffusion of smaller and larger hydrophilic as well as hydrophobic substances. This traditional diffusion barrier concept of TJs has been challenged lately, owing to a better understanding of the components that are associated with TJs. It is now well-established that mutations in TJ proteins are associated with a range of human diseases and that a change in the membrane fluidity of neighbouring cells can open possibilities for therapeutics to cross intercellular junctions. Nanotechnological approaches, exploiting ultrasound or hyperosmotic agents and permeation enhancers, are the paradigm for achieving enhanced paracellular diffusion. The other widely used transport route of drugs is via transcellular transport, allowing the passage of a variety of pro-drugs and nanoparticle-encapsulated drugs via different mechanisms based on receptors and others. For a long time, there was an expectation that lipidic nanocarriers and polymeric nanostructures could revolutionize the field for the delivery of RNA and protein-based therapeutics across different biological barriers equipped with TJs (e.g., blood-brain barrier (BBB), retina-blood barrier (RBB), corneal TJs, etc.). However, only a limited increase in therapeutic efficiency has been reported for most systems until now. The purpose of this review is to explore the reasons behind the current failures and to examine the emergence of synthetic and cell-derived nanomaterials and nanotechnological approaches as potential game-changers in enhancing drug delivery to target locations both at and across TJs using innovative concepts. Specifically, we will focus on recent advancements in various nanotechnological strategies enabling the bypassing or temporally opening of TJs to the brain and to the retina, and discuss their advantages and limitations.
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Affiliation(s)
- Asmaa Khalil
- Univ. Lille, CNRS, Univ. Polytechnique Hauts-de-France, UMR 8520 - IEMN, F-59000 Lille, France.
| | - Alexandre Barras
- Univ. Lille, CNRS, Univ. Polytechnique Hauts-de-France, UMR 8520 - IEMN, F-59000 Lille, France.
| | - Rabah Boukherroub
- Univ. Lille, CNRS, Univ. Polytechnique Hauts-de-France, UMR 8520 - IEMN, F-59000 Lille, France.
| | - Ching-Li Tseng
- Taipei Medical University, Graduate Institute of Biomedical Materials and Tissue Engineering (GIBMTE), New Taipei City 235603, Taiwan
- Taipei Medical University, International PhD Program in Biomedical Engineering (IPBME), New Taipei City 235603, Taiwan
| | - David Devos
- University Lille, CHU-Lille, Inserm, U1172, Lille Neuroscience & Cognition, LICEND, Lille, France
| | - Thierry Burnouf
- Taipei Medical University, Graduate Institute of Biomedical Materials and Tissue Engineering (GIBMTE), New Taipei City 235603, Taiwan
- Taipei Medical University, International PhD Program in Biomedical Engineering (IPBME), New Taipei City 235603, Taiwan
| | - Winfried Neuhaus
- AIT - Austrian Institute of Technology GmbH, Center Health and Bioresources, Competence Unit Molecular Diagnostics, 1210 Vienna, Austria
- Laboratory for Life Sciences and Technology (LiST), Faculty of Medicine and Dentistry, Danube Private University, 3500 Krems, Austria
| | - Sabine Szunerits
- Univ. Lille, CNRS, Univ. Polytechnique Hauts-de-France, UMR 8520 - IEMN, F-59000 Lille, France.
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2
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Roy PK, Rajesh Y, Mandal M. Therapeutic targeting of membrane-associated proteins in central nervous system tumors. Exp Cell Res 2021; 406:112760. [PMID: 34339674 DOI: 10.1016/j.yexcr.2021.112760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/28/2021] [Accepted: 07/28/2021] [Indexed: 12/09/2022]
Abstract
The activity of the most complex system, the central nervous system (CNS) is profoundly regulated by a huge number of membrane-associated proteins (MAP). A minor change stimulates immense chemical changes and the elicited response is organized by MAP, which acts as a receptor of that chemical or channel enabling the flow of ions. Slight changes in the activity or expression of these MAPs lead to severe consequences such as cognitive disorders, memory loss, or cancer. CNS tumors are heterogeneous in nature and hard-to-treat due to random mutations in MAPs; like as overexpression of EGFRvIII/TGFβR/VEGFR, change in adhesion molecules α5β3 integrin/SEMA3A, imbalance in ion channel proteins, etc. Extensive research is under process for developing new therapeutic approaches using these proteins such as targeted cytotoxic radiotherapy, drug-delivery, and prodrug activation, blocking of receptors like GluA1, developing viral vector against cell surface receptor. The combinatorial approach of these strategies along with the conventional one might be more potential. Henceforth, our review focuses on in-depth analysis regarding MAPs aiming for a better understanding for developing an efficient therapeutic approach for targeting CNS tumors.
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Affiliation(s)
- Pritam Kumar Roy
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, India
| | - Yetirajam Rajesh
- Department of Human and Molecular Genetics, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Mahitosh Mandal
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, India.
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3
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Kaya M, Ahishali B. Basic physiology of the blood-brain barrier in health and disease: a brief overview. Tissue Barriers 2021; 9:1840913. [PMID: 33190576 PMCID: PMC7849738 DOI: 10.1080/21688370.2020.1840913] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 10/18/2020] [Accepted: 10/19/2020] [Indexed: 12/18/2022] Open
Abstract
The blood-brain barrier (BBB), a dynamic interface between blood and brain constituted mainly by endothelial cells of brain microvessels, robustly restricts the entry of potentially harmful blood-sourced substances and cells into the brain, however, many therapeutically active agents concurrently cannot gain access into the brain at effective doses in the presence of an intact barrier. On the other hand, breakdown of BBB integrity may involve in the pathogenesis of various neurodegenerative diseases. Besides, certain diseases/disorders such as Alzheimer's disease, hypertension, and epilepsy are associated with varying degrees of BBB disruption. In this review, we aim to highlight the current knowledge on the cellular and molecular composition of the BBB with special emphasis on the major transport pathways across the barrier type endothelial cells. We further provide a discussion on the innovative brain drug delivery strategies in which the obstacle formed by BBB interferes with effective pharmacological treatment of neurodegenerative diseases/disorders.
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Affiliation(s)
- Mehmet Kaya
- Koç University School of Medicine Department of Physiology, Koç University Research Center for Translational Medicine, Istanbul, Turkey
| | - Bulent Ahishali
- Koç University School of Medicine Department of Histology and Embryology, Koç University Research Center for Translational Medicine, Istanbul, Turkey
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4
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Himmerich H, Szegedi A, Klawe C, Anghelescu I, Müller MJ. Distigmine bromide induced acute psychotic disorder in a patient with multiple sclerosis. Eur Psychiatry 2020; 18:318-9. [PMID: 14611928 DOI: 10.1016/j.eurpsy.2002.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AbstractA female patient with multiple sclerosis (MS) suffered from an acute psychotic disorder after taking distigmine bromide for detrusor dysfunction. She showed a dramatic relief of her symptoms after the medication, distigmine bromide, was stopped. Distigmine is not supposed to penetrate the blood-brain barrier (BBB). However, in MS patients a leakage of the BBB could be hypothesized.
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Affiliation(s)
- Hubertus Himmerich
- Max Planck Institute of Psychiatry, Kraepelinstrasse 2-10, 80804 Munich, Germany.
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5
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Sarma A, Das MK. Nose to brain delivery of antiretroviral drugs in the treatment of neuroAIDS. MOLECULAR BIOMEDICINE 2020; 1:15. [PMID: 34765998 PMCID: PMC7725542 DOI: 10.1186/s43556-020-00019-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 11/17/2020] [Indexed: 12/20/2022] Open
Abstract
NeuroAIDS (Neuro Acquired Immunodeficiency Syndrome) or HIV (Human Immunodeficiency Virus) associated neuronal abnormality is continuing to be a significant health issue among AIDS patients even under the treatment of combined antiretroviral therapy (cART). Injury and damage to neurons of the brain are the prime causes of neuroAIDS, which happens due to the ingress of HIV by direct permeation across the blood-brain barrier (BBB) or else via peripherally infected macrophage into the central nervous system (CNS). The BBB performs as a stringent barricade for the delivery of therapeutics drugs. The intranasal route of drug administration exhibits as a non-invasive technique to bypass the BBB for the delivery of antiretroviral drugs and other active pharmaceutical ingredients inside the brain and CNS. This method is fruitful for the drugs that are unable to invade the BBB to show its action in the CNS and thus erase the demand of systemic delivery and thereby shrink systemic side effects. Drug delivery from the nose to the brain/CNS takes very less time through both olfactory and trigeminal nerves. Intranasal delivery does not require the involvement of any receptor as it occurs by an extracellular route. Nose to brain delivery also involves nasal associated lymphatic tissues (NALT) and deep cervical lymph nodes. However, very little research has been done to explore the utility of nose to brain delivery of antiretroviral drugs in the treatment of neuroAIDS. This review focuses on the potential of nasal route for the effective delivery of antiretroviral nanoformulations directly from nose to the brain.
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Affiliation(s)
- Anupam Sarma
- Drug Delivery Research Laboratory, Department of Pharmaceutical Sciences, Dibrugarh University, Dibrugarh, Assam 786004 India.,Pratiksha Institute of Pharmaceutical Sciences, Guwahati, Assam 781026 India
| | - Malay K Das
- Drug Delivery Research Laboratory, Department of Pharmaceutical Sciences, Dibrugarh University, Dibrugarh, Assam 786004 India
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6
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Drug Delivery in an Orthotopic Tumor Stem Cell-Based Model of Human Glioblastoma. Methods Mol Biol 2018. [PMID: 30324525 DOI: 10.1007/978-1-4939-8805-1_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Grade IV gliomas, also known as glioblastoma multiforme (GBM), are incurable, lethal brain tumors, whose average life expectancy is around 15 months. There is a desperate need for a better understanding of the basic biology of these tumors, in order to devise novel, more specific and effective therapeutics. The handling of GBM represents a daunting challenge to clinicians, also considering the few therapeutic options available, none of which can significantly alter the inevitable lethal outcome of these tumors. Hence, the development of effective therapies would greatly benefit from the availability of in vivo GBM models that can reliably mimic the characteristics of malignant cells and the features of the human disease. Candidate new drugs have to be tested in these in vivo models by adopting settings concerning direct intra-brain delivery in order to define their overall therapeutic efficacy under clinical-like conditions. Here, we describe local intracranial delivery of drugs by osmotic mini-pumps.
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7
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Falanga A, Iachetta G, Lombardi L, Perillo E, Lombardi A, Morelli G, Valiante S, Galdiero S. Enhanced uptake of gH625 by blood brain barrier compared to liver in vivo: characterization of the mechanism by an in vitro model and implications for delivery. Sci Rep 2018; 8:13836. [PMID: 30218088 PMCID: PMC6138628 DOI: 10.1038/s41598-018-32095-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 08/07/2018] [Indexed: 12/14/2022] Open
Abstract
We have investigated the crossing of the blood brain barrier (BBB) by the peptide gH625 and compared to the uptake by liver in vivo. We clearly observed that in vivo administration of gH625 allows the crossing of the BBB, although part of the peptide is sequestered by the liver. Furthermore, we used a combination of biophysical techniques to gain insight into the mechanism of interaction with model membranes mimicking the BBB and the liver. We observed a stronger interaction for membranes mimicking the BBB where gH625 clearly undergoes a change in secondary structure, indicating the key role of the structural change in the uptake mechanism. We report model studies on liposomes which can be exploited for the optimization of delivery tools.
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Affiliation(s)
- Annarita Falanga
- Department of Pharmacy, Via Mezzocannone 16, 80134, Napoli, Italy.,CiRPEB- University of Naples "Federico II", Via Mezzocannone 16, 80134, Napoli, Italy
| | - Giuseppina Iachetta
- Department of Biology, University of Naples "Federico II", Via Mezzocannone 8, 80134, Napoli, Italy
| | - Lucia Lombardi
- Department of Pharmacy, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Emiliana Perillo
- Department of Pharmacy, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Assunta Lombardi
- Department of Biology, University of Naples "Federico II", Via Mezzocannone 8, 80134, Napoli, Italy
| | - Giancarlo Morelli
- Department of Pharmacy, Via Mezzocannone 16, 80134, Napoli, Italy.,CiRPEB- University of Naples "Federico II", Via Mezzocannone 16, 80134, Napoli, Italy
| | - Salvatore Valiante
- Department of Biology, University of Naples "Federico II", Via Mezzocannone 8, 80134, Napoli, Italy.,National Institute of Biostructures and Biosystems (INBB), V. le Medaglie d'Oro, 00136, Rome, Italy
| | - Stefania Galdiero
- Department of Pharmacy, Via Mezzocannone 16, 80134, Napoli, Italy. .,CiRPEB- University of Naples "Federico II", Via Mezzocannone 16, 80134, Napoli, Italy.
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8
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Huang L, Shang E, Fan W, Li X, Li B, He S, Fu Y, Zhang Y, Li Y, Fang W. S-oxiracetam protect against ischemic stroke via alleviating blood brain barrier dysfunction in rats. Eur J Pharm Sci 2017; 109:40-47. [DOI: 10.1016/j.ejps.2017.07.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/20/2017] [Accepted: 07/21/2017] [Indexed: 12/14/2022]
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9
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Zhang Z, Uchida Y, Hirano S, Ando D, Kubo Y, Auriola S, Akanuma SI, Hosoya KI, Urtti A, Terasaki T, Tachikawa M. Inner Blood–Retinal Barrier Dominantly Expresses Breast Cancer Resistance Protein: Comparative Quantitative Targeted Absolute Proteomics Study of CNS Barriers in Pig. Mol Pharm 2017; 14:3729-3738. [DOI: 10.1021/acs.molpharmaceut.7b00493] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Zhengyu Zhang
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Yasuo Uchida
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Satoshi Hirano
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Daisuke Ando
- Department
of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama,
Sugitani, Toyama 930-0194, Japan
| | - Yoshiyuki Kubo
- Department
of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama,
Sugitani, Toyama 930-0194, Japan
| | - Seppo Auriola
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
- School
of Pharmacy, University of Eastern Finland, Kuopio FI-70211, Finland
| | - Shin-ichi Akanuma
- Department
of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama,
Sugitani, Toyama 930-0194, Japan
| | - Ken-ichi Hosoya
- Department
of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama,
Sugitani, Toyama 930-0194, Japan
| | - Arto Urtti
- School
of Pharmacy, University of Eastern Finland, Kuopio FI-70211, Finland
- Faculty
of Pharmacy, University of Helsinki, Helsinki 00014, Finland
| | - Tetsuya Terasaki
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Masanori Tachikawa
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
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10
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Kaur M, Badhan RKS. Phytochemical mediated-modulation of the expression and transporter function of breast cancer resistance protein at the blood-brain barrier: An in-vitro study. Brain Res 2016; 1654:9-23. [PMID: 27771282 DOI: 10.1016/j.brainres.2016.10.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/10/2016] [Accepted: 10/18/2016] [Indexed: 01/29/2023]
Abstract
Clinical translation of BCRP inhibitors have failed due to neurotoxicity and novel approaches are required to identify suitable modulators of BCRP to enhance CNS drug delivery. In this study we examine 18 compounds, primarily phytochemicals, as potential novel modulators of AhR-mediated regulation of BCRP expression and function in immortalised and primary porcine brain microvascular endothelial cells as a mechanism to enhance CNS drug delivery. The majority of modulators possessed a cellular viability IC50 >100µm in both cell systems. BCRP activity, when exposed to modulators for 1h, was diminished for most modulators through significant increases in H33342 accumulation at <10µm with 2,6,4-trimethoflavone increasing H33342 intracellular accumulation by 3.7-6.6 fold over 1-100µm. Western blotting and qPCR identified two inducers of BCRP (quercetin and naringin) and two down-regulators (17-β-estradiol and curcumin) with associated changes in BCRP efflux transport function further confirmed in both cell lines. siRNA downregulation of AhR resulted in a 1.75±0.08 fold change in BCRP expression, confirming the role of AhR in the regulation of BCRP. These findings establish the regulatory role AhR of in controlling BCRP expression at the BBB and confirm quercetin, naringin, 17-β-estradiol, and curcumin as novel inducers and down-regulators of BCRP gene, protein expression and functional transporter activity and hence potential novel target sites and candidates for enhancing CNS drug delivery.
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Affiliation(s)
- Manjit Kaur
- Aston University, Aston Research Centre for Healthy Ageing, School of Life and Health Sciences, Birmingham B4 7ET, UK
| | - Raj K S Badhan
- Aston University, Aston Research Centre for Healthy Ageing, School of Life and Health Sciences, Birmingham B4 7ET, UK.
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11
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Kyle S, Saha S. Nanotechnology for the detection and therapy of stroke. Adv Healthc Mater 2014; 3:1703-20. [PMID: 24692428 DOI: 10.1002/adhm.201400009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Indexed: 01/06/2023]
Abstract
Over the years, nanotechnology has greatly developed, moving from careful design strategies and synthesis of novel nanostructures to producing them for specific medical and biological applications. The use of nanotechnology in diagnostics, drug delivery, and tissue engineering holds great promise for the treatment of stroke in the future. Nanoparticles are employed to monitor grafted cells upon implantation, or to enhance the imagery of the tissue, which is coupled with a noninvasive imaging modality such as magnetic resonance imaging, computed axial tomography or positron emission tomography scan. Contrast imaging agents used can range from iron oxide, perfluorocarbon, cerium oxide or platinum nanoparticles to quantum dots. The use of nanomaterial scaffolds for neuroregeneration is another area of nanomedicine, which involves the creation of an extracellular matrix mimic that not only serves as a structural support but promotes neuronal growth, inhibits glial differentiation, and controls hemostasis. Promisingly, carbon nanotubes can act as scaffolds for stem cell therapy and functionalizing these scaffolds may enhance their therapeutic potential for treatment of stroke. This Progress Report highlights the recent developments in nanotechnology for the detection and therapy of stroke. Recent advances in the use of nanomaterials as tissue engineering scaffolds for neuroregeneration will also be discussed.
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Affiliation(s)
- Stuart Kyle
- School of Medicine; University of Leeds; Leeds LS2 9JT UK
| | - Sikha Saha
- Division of Cardiovascular and Diabetes Research; Leeds Institute of Genetics; Health and Therapeutics; University of Leeds; Leeds LS2 9JT UK
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12
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Magnetic-resonance imaging for kinetic analysis of permeability changes during focused ultrasound-induced blood-brain barrier opening and brain drug delivery. J Control Release 2014; 192:1-9. [PMID: 24969355 DOI: 10.1016/j.jconrel.2014.06.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/08/2014] [Accepted: 06/15/2014] [Indexed: 11/22/2022]
Abstract
Focused ultrasound (FUS) with the presence of microbubbles has been shown to induce transient and local opening of the blood-brain barrier (BBB) for the delivery of therapeutic molecules which normally cannot penetrate into the brain. The success of FUS brain-drug delivery relies on its integration with in-vivo imaging to monitor kinetic change of therapeutic molecules into the brain. In this study, we developed a dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) technique for kinetic analysis of delivered molecules during FUS-BBB opening. Three kinetic parameters (Ktrans, Ve, Kep) were characterized dynamically to describe BBB-permeability at two FUS exposure conditions (0.4 or 0.8MPa) over 24h. Ktrans, defined as the influx volume transfer constant from plasma to EES, and Ve, the EES volume fraction, were both found to be pressure-dependent. Ktrans and Ve showed a peak increase of 0.0086-0.0131min(-1) (for 0.4-0.8MPa pressure), and 0.0431-0.0692, respectively, immediately after FUS exposure. Both parameters subsequently decreased exponentially as a function of time, with estimated half-lives of decay of 2.89-5.3 and 2.2-4.93h, respectively. The kinetics of Kep, defined as the efflux rate constant from the extracellular extravascular space (EES) to the plasma, were complementary to Ktrans, with an initial decrease from 0.2010 to 0.1901min(-1) followed by a significantly longer recovery time (half-life of 17.39-99.92h). Our observations strongly supported the existence of imbalanced and mismatched kinetics of influx (Ktrans) and efflux (Kep) between the plasma and EES, indicating the existence of directional permeability during FUS-BBB opening. We further showed that kinetic change determined by DCE-MRI correlated well with the concentration of Evans Blue (EB)-albumin (coefficient of 0.74-0.89). These findings suggest that MRI kinetic monitoring may serve as an alternative method for in-vivo monitoring of pharmacokinetics and pharmacodynamics (PK/PD) change of therapeutic agents during drug delivery to the brain, and provide useful information for future optimization of FUS-BBB opening.
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Saghir SA, Marty MS, Zablotny CL, Passage JK, Perala AW, Neal BH, Hammond L, Bus JS. Life-stage-, sex-, and dose-dependent dietary toxicokinetics and relationship to toxicity of 2,4-dichlorophenoxyacetic acid (2,4-D) in rats: implications for toxicity test dose selection, design, and interpretation. Toxicol Sci 2013; 136:294-307. [PMID: 24105888 PMCID: PMC3858196 DOI: 10.1093/toxsci/kft212] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 08/12/2013] [Indexed: 11/14/2022] Open
Abstract
Life-stage-dependent toxicity and dose-dependent toxicokinetics (TK) were evaluated in Sprague Dawley rats following dietary exposure to 2,4-dichlorophenoxyacetic acid (2,4-D). 2,4-D renal clearance is impacted by dose-dependent saturation of the renal organic anion transporter; thus, this study focused on identifying inflection points of onset of dietary nonlinear TK to inform dose selection decisions for toxicity studies. Male and female rats were fed 2,4-D-fortified diets at doses to 1600 ppm for 4-weeks premating, <2 weeks during mating, and to test day (TD) 71 to parental (P1) males and to P1 females through gestation/lactation to TD 96. F1 offspring were exposed via milk with continuing diet exposure until postnatal day (PND) 35. As assessed by plasma area under the curve for the time-course plasma concentration, nonlinear TK was observed ≥ 1200 ppm (63 mg/kg/day) for P1 males and between 200 and 400 ppm (14-27 mg/kg/day) for P1 females. Dam milk and pup plasma levels were higher on lactation day (LD) 14 than LD 4. Relative to P1 adults, 2,4-D levels were higher in dams during late gestation/lactation and postweaning pups (PND 21-35) and coincided with elevated intake of diet/kg body weight. Using conventional maximum tolerated dose (MTD) criteria based on body weight changes for dose selection would have resulted in excessive top doses approximately 2-fold higher than those identified incorporating critical TK data. These data indicate that demonstration of nonlinear TK, if present at dose levels substantially above real-world human exposures, is a key dose selection consideration for improving the human relevance of toxicity studies compared with studies employing conventional MTD dose selection strategies.
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Affiliation(s)
- Shakil A. Saghir
- *Intrinsik Environmental Sciences Inc., Mississauga, Ontario, Canada L5T 0A3, and Aga Khan University, Karachi, Pakistan 74800
| | | | | | | | | | | | - Larry Hammond
- §Industry Task Force II on 2,4-D Research Data, Washington, District of Columbia 20006
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Effects of Hepatic Ischemia-Reperfusion Injury on the P-Glycoprotein Activity at the Liver Canalicular Membrane and Blood–Brain Barrier Determined by In Vivo Administration of Rhodamine 123 in Rats. Pharm Res 2013; 31:861-73. [DOI: 10.1007/s11095-013-1208-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 09/12/2013] [Indexed: 01/09/2023]
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15
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Gunaydin H, Weiss MM, Sun Y. De novo prediction of p-glycoprotein-mediated efflux liability for druglike compounds. ACS Med Chem Lett 2013; 4:108-12. [PMID: 24900570 DOI: 10.1021/ml300314h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 11/06/2012] [Indexed: 01/16/2023] Open
Abstract
P-glycoprotein (Pgp) is capable of recognizing and transporting a wide range of chemically diverse compounds in vivo. Overcoming Pgp-mediated efflux can represent a significant challenge when penetration into the central nervous system is required or within the context of developing anticancer therapies. While numerous in silico models have been developed to predict Pgp-mediated efflux, these models rely on training sets and are best suited to make interpolations. Therefore, it is desirable to develop ab initio models that can be used to predict efflux liabilities. Herein, we present a de novo method that can be used to predict Pgp-mediated efflux potential for druglike compounds. A model, which correlates the computed solvation free energy differences obtained in water and chloroform with Pgp-mediated efflux (in logarithmic scale), was successful in predicting Pgp efflux ratios for a wide range of chemically diverse compounds with a R(2) and root-mean-square error of 0.65 and 0.29, respectively.
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Affiliation(s)
| | | | - Yaxiong Sun
- Department
of Molecular Structure, Amgen Inc., One
Amgen Center Drive, Thousand Oaks, California 91320, United States
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Wong HL, Wu XY, Bendayan R. Nanotechnological advances for the delivery of CNS therapeutics. Adv Drug Deliv Rev 2012; 64:686-700. [PMID: 22100125 DOI: 10.1016/j.addr.2011.10.007] [Citation(s) in RCA: 341] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 10/27/2011] [Indexed: 12/18/2022]
Abstract
Effective non-invasive treatment of neurological diseases is often limited by the poor access of therapeutic agents into the central nervous system (CNS). The majority of drugs and biotechnological agents do not readily permeate into brain parenchyma due to the presence of two anatomical and biochemical dynamic barriers: the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB). Therefore, one of the most significant challenges facing CNS drug development is the availability of effective brain targeting technology. Recent advances in nanotechnology have provided promising solutions to this challenge. Several nanocarriers ranging from the more established systems, e.g. polymeric nanoparticles, solid lipid nanoparticles, liposomes, micelles to the newer systems, e.g. dendrimers, nanogels, nanoemulsions and nanosuspensions have been studied for the delivery of CNS therapeutics. Many of these nanomedicines can be effectively transported across various in vitro and in vivo BBB models by endocytosis and/or transcytosis, and demonstrated early preclinical success for the management of CNS conditions such as brain tumors, HIV encephalopathy, Alzheimer's disease and acute ischemic stroke. Future development of CNS nanomedicines need to focus on increasing their drug-trafficking performance and specificity for brain tissue using novel targeting moieties, improving their BBB permeability and reducing their neurotoxicity.
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Geyer J, Janko C. Treatment of MDR1 mutant dogs with macrocyclic lactones. Curr Pharm Biotechnol 2012; 13:969-86. [PMID: 22039792 PMCID: PMC3419875 DOI: 10.2174/138920112800399301] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 11/06/2010] [Indexed: 01/03/2023]
Abstract
P-glycoprotein, encoded by the multidrug resistance gene MDR1, is an ATP-driven drug efflux pump which is highly expressed at the blood-brain barrier of vertebrates. Drug efflux of macrocyclic lactones by P-glycoprotein is highly relevant for the therapeutic safety of macrocyclic lactones, as thereby GABA-gated chloride channels, which are confined to the central nervous system in vertebrates, are protected from high drug concentrations that otherwise would induce neurological toxicity. A 4-bp deletion mutation exists in the MDR1 gene of many dog breeds such as the Collie and the Australian Shepherd, which results in the expression of a non-functional P-glycoprotein and is associated with multiple drug sensitivity. Accordingly, dogs with homozygous MDR1 mutation are in general prone to neurotoxicity by macrocyclic lactones due to their increased brain penetration. Nevertheless, treatment of these dogs with macrocyclic lactones does not inevitably result in neurological symptoms, since, the safety of treatment highly depends on the treatment indication, dosage, route of application, and the individual compound used as outlined in this review. Whereas all available macrocyclic lactones can safely be administered to MDR1 mutant dogs at doses usually used for heartworm prevention, these dogs will experience neurological toxicity following a high dose regimen which is common for mange treatment in dogs. Here, we review and discuss the neurotoxicological potential of different macrocyclic lactones as well as their treatment options in MDR1 mutant dogs.
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Affiliation(s)
- Joachim Geyer
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University of Giessen, Frankfurter Str. 107, 35392 Giessen, Germany.
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Attenello F, Raza SM, Dimeco F, Olivi A. Chemotherapy for brain tumors with polymer drug delivery. HANDBOOK OF CLINICAL NEUROLOGY 2012; 104:339-53. [PMID: 22230452 DOI: 10.1016/b978-0-444-52138-5.00022-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Frank Attenello
- Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, MD, USA
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Abstract
The blood-brain barrier (BBB) physically and metabolically functions as a neurovascular interface between the brain parenchyma and the systemic circulation, and regulates the permeability of several endogenous substrates and xenobiotics in and out of the central nervous system. Several membrane-associated transport proteins, such as P-glycoprotein (P-gp), multidrug resistance-associated proteins, breast cancer resistance protein, and organic anion transporting polypeptides, have been characterized at the BBB and identified to play a major role in regulating the brain bioavailability of several pharmacological agents. This chapter reviews several well-established techniques for the study of the molecular expression, cellular localization, and functional activity of transport proteins in primary and immortalized cell culture systems of the BBB. In particular, we describe the molecular characterization of P-gp/MDR1 at the transcript level using semiquantitative polymerase chain reaction (PCR), at the protein level using immunoblotting, and at the cellular level using immunofluorescence. In addition, the uptake/efflux and transepithelial flux studies, which characterize P-gp transport activity, are described.
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Michalke B, Nischwitz V. Review on metal speciation analysis in cerebrospinal fluid—current methods and results: A review. Anal Chim Acta 2010; 682:23-36. [DOI: 10.1016/j.aca.2010.09.054] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 08/16/2010] [Accepted: 09/30/2010] [Indexed: 11/30/2022]
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Lee KR, Maeng HJ, Chae JB, Chong S, Kim DD, Shim CK, Chung SJ. Lack of a primary physicochemical determinant in the direct transport of drugs to the brain after nasal administration in rats: potential involvement of transporters in the pathway. Drug Metab Pharmacokinet 2010; 25:430-41. [PMID: 20924140 DOI: 10.2133/dmpk.dmpk-10-rg-049] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The objectives of this study were to evaluate the relative contribution of the direct pathway in overall brain transport for 17 model drugs with different physicochemical properties after nasal administrations and to identify factors that govern the fraction of the dose transported to the brain via the direct pathway (F(a, direct)). When the model drugs were nasally administered to rats, 5 of the 17 model drugs were delivered to a significant extent to the brain via the direct pathway. Multiple linear regression analyses showed that the correlation between various physicochemical properties and F(a, direct) was not statistically significant, indicative of a lack of primary physicochemical determinants in the direct transport pathway. Transporters such as rOAT3 and rOCT2 were expressed at significant levels in rat olfactory epithelia, and uptakes of standard substrates were significantly decreased in HEK293 cells expressing rOAT3 and rOCT2 in the presence of the five model drugs that were delivered to appreciable extents to the brain via the direct pathway. Therefore, these observations indicate that carrier-mediated transport may play a role in the brain delivery of drugs from the nose via the direct transport pathway.
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Affiliation(s)
- Kyeong-Ryoon Lee
- College of Pharmacy, Seoul National University, Gwanak 599, Gwanak-ro, Gwanak-gu, Seoul 151-742, South Korea
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22
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Gundacker C, Gencik M, Hengstschläger M. The relevance of the individual genetic background for the toxicokinetics of two significant neurodevelopmental toxicants: mercury and lead. Mutat Res 2010; 705:130-140. [PMID: 20601101 DOI: 10.1016/j.mrrev.2010.06.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 06/07/2010] [Accepted: 06/10/2010] [Indexed: 11/25/2022]
Abstract
The heavy metals mercury and lead are well-known and significant developmental neurotoxicants. This review summarizes the genetic factors that modify their toxicokinetics. Understanding toxicokinetics (uptake, biotransformation, distribution, and elimination processes) is a key precondition to understanding the individual health risks associated with exposure. We selected candidate susceptibility genes when evidence was available for (1) genes/proteins playing a significant role in mercury and lead toxicokinetics, (2) gene expression/protein activity being induced by these metals, and (3) mercury and lead toxicokinetics being affected by gene knockout/knockdown or (4) by functional gene polymorphisms. The genetic background is far better known for mercury than for lead toxicokinetics. Involved are genes encoding L-type amino acid transporters, organic anion transporters, glutathione (GSH)-related enzymes, metallothioneins, and transporters of the ABC family. Certain gene variants can influence mercury toxicokinetics, potentially explaining part of the variable susceptibility to mercury toxicity. Delta-aminolevulinic acid dehydratase (ALAD), vitamin D receptor (VDR) and hemochromatosis (HFE) gene variants are the only well-established susceptibility markers of lead toxicity in humans. Many gaps remain in our knowledge about the functional genomics of this issue. This calls for studies to detect functional gene polymorphisms related to mercury- and lead-associated disease phenotypes, to demonstrate the impact of functional polymorphisms and gene knockout/knockdown in relation to toxicity, to confirm the in vivo relevance of genetic variation, and to examine gene-gene interactions on the respective toxicokinetics. Another crucial aspect is knowledge on the maternal-fetal genetic background, which modulates fetal exposure to these neurotoxicants. To completely define the genetically susceptible risk groups, research is also needed on the genes/proteins involved in the toxicodynamics, i.e., in the mechanisms causing adverse effects in the brain. Studies relating the toxicogenetics to neurodevelopmental disorders are lacking (mercury) or very scarce (lead). Thus, the extent of variability in susceptibility to heavy metal-associated neurological outcomes is poorly characterized.
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Affiliation(s)
- Claudia Gundacker
- Institute of Medical Genetics, Medical University of Vienna, Währinger Strasse 10, A-1090 Vienna, Austria.
| | - Martin Gencik
- Praxis fur Humangenetik, Brünnlbadgasse 15, A-1090 Vienna, Austria
| | - Markus Hengstschläger
- Institute of Medical Genetics, Medical University of Vienna, Währinger Strasse 10, A-1090 Vienna, Austria
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Abstract
The blood-brain barrier (BBB) is a dynamic physical and biological barrier between blood circulation and the central nervous system (CNS). This unique feature of the BBB lies in the structure of the neurovascular unit and its cerebral micro-vascular endothelial cells. The BBB restricts the passage of blood-borne drugs, neurotoxic substances and peripheral immune cells from entering the brain, while selectively facilitating the transport of nutrients across the BBB into the brain. Thus, the integrity and proper function of the BBB is crucial to homeostasis and physiological function of the CNS. A number of transport and carrier systems are expressed and polarized on the luminal or abluminal surface of the BBB to realize these discrete functions. Among these systems, ABC transporters play a critical role in keeping drugs and neurotoxic substances from entering the brain and in transporting toxic metabolites out of the brain. A number of studies have demonstrated that ABCB1 and ABCG2 are critical to drug efflux at the BBB and that ABCC1 is essential for the blood-cerebral spinal fluid (CSF) barrier. The presence of these efflux ABC transporters also creates a major obstacle for drug delivery into the brain. We have comprehensively reviewed the literature on ABC transporters and drug efflux at the BBB. Understanding the molecular mechanisms of these transporters is important in the development of new drugs and new strategies for drug delivery into the brain.
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Affiliation(s)
- Shanshan Shen
- Neurobiology Program, Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada K1A 0R6
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Sunkara G, Ayalasomayajula SP, DeRuiter J, Kompella UB. Probenecid treatment enhances retinal and brain delivery of N-4-benzoylaminophenylsulfonylglycine: an anionic aldose reductase inhibitor. Brain Res Bull 2009; 81:327-32. [PMID: 19761819 DOI: 10.1016/j.brainresbull.2009.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2009] [Revised: 09/02/2009] [Accepted: 09/03/2009] [Indexed: 01/21/2023]
Abstract
Anion efflux transporters are expected to minimize target tissue delivery of N-[4-(benzoylaminophenyl)sulfonyl]glycine (BAPSG), a novel carboxylic acid aldose reductase inhibitor, which exists as a monocarboxylate anion at physiological conditions. Therefore, the objective of this study was to determine whether BAPSG delivery to various eye tissues including the retina and the brain can be enhanced by probenecid, a competitive inhibitor of anion transporters. To determine the influence of probenecid on eye and brain distribution of BAPSG, probenecid was administered intraperitoneally (120 mg/kg body weight; i.p.) 20 min prior to BAPSG (50 mg/kg; i.p.) administration. Drug disposition in various eye tissues including the retina and the brain was determined at 15 min, 1, 2 and 4h after BAPSG dose in male Sprauge-Dawley rats. To determine whether probenecid alters plasma clearance of BAPSG, influence of probenecid (120 mg/kg; i.p.) on the plasma pharmacokinetics of intravenously administered BAPSG (15 mg/kg) was studied as well. Finally, the effect of probenecid co-administration on the ocular tissue distribution of BAPSG was assessed in rabbits following topical (eye drop) administration. Following pretreatment with probenecid in the rat study, retinal delivery at 1h was increased by about 11-fold (2580 ng/g vs. 244 ng/g; p<0.05). Further, following probenecid pretreatment, significant BAPSG levels were detectable in the brain (45 + or - 20 ng/g) at 1h, unlike controls where the drug was not detectable. Plasma concentrations, plasma elimination half-life, and total body clearance of intravenously administered BAPSG were not altered by i.p. probenecid pretreatment. In the topical dosing study, a significant decline in BAPSG delivery was observed in the iris-ciliary body but no significant changes were observed in other tissues of the anterior segment of the eye including tears. Thus, inhibition of anion transporters is a useful approach to elevate retinal and brain delivery of BAPSG.
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DiNunzio JC, Williams RO. CNS disorders--current treatment options and the prospects for advanced therapies. Drug Dev Ind Pharm 2009; 34:1141-67. [PMID: 18720140 DOI: 10.1080/03639040802020536] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The development of new pharmaceutical products has successfully addressed a multitude of disease states; however, new product development for treating disorders of the central nervous system (CNS) has lagged behind other therapeutic areas. This is due to several factors including the complexity of the diseases and the lack of technologies for delivery through the blood-brain barrier (BBB). This article examines the current state of six major CNS disease states: depression, epilepsy, multiple sclerosis (MS), neurodegenerative diseases (specifically Alzheimer's disease [AD]), neuropathic pain, and schizophrenia. Discussion topics include analysis of the biological mechanisms underlying each disease, currently approved products, and available animal models for development of new therapeutic agents. Analysis of currently approved therapies shows that all products depend on the molecular properties of the drug or prodrug to penetrate the BBB. Novel technologies, capable of enhancing BBB permeation, are also discussed relative to improving CNS therapies for these disease states.
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Affiliation(s)
- James C DiNunzio
- Division of Pharmaceutics, The University of Texas at Austin, Austin, TX 78712, USA.
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p21-Activated kinase mediates rapid estradiol-negative feedback actions in the reproductive axis. Proc Natl Acad Sci U S A 2009; 106:7221-6. [PMID: 19359483 DOI: 10.1073/pnas.0812597106] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Nonclassical estrogen receptor alpha (ERalpha) signaling can mediate E(2) negative feedback actions in the reproductive axis; however, downstream pathways conveying these effects remain unclear. These studies tested the hypothesis that p21-activated kinase 1 (PAK1), a serine/threonine kinase rapidly activated by E(2) in nonneural cells, functions as a downstream node for E(2) signaling pathways in cells of the preoptic area, and it may thereby mediate E(2) negative feedback effects. Treatment of ovariectomized (OVX) rats with estradiol benzoate (EB) caused rapid and transient induction of phosphorylated PAK1 immunoreactivity in the medial preoptic nucleus (MPN) but not the arcuate nucleus. To determine whether rapid induction of PAK phosphorylation by E(2) is mediated by nonclassical [estrogen response element (ERE)-independent] ERalpha signaling, we used female ERalpha null (ERalpha(-/-)) mice possessing an ER knock-in mutation (E207A/G208A; AA), in which the mutant ERalpha is incapable of binding DNA and can signal only through membrane-initiated or ERE-independent genotropic pathways (ERalpha(-/AA) mice). After 1-h EB treatment, the number of pPAK1-immunoreactive cells in the MPN was increased in both wild-type (ERalpha(+/+)) and ERalpha(-/AA) mice but was unchanged in ERalpha(-/-) mice. Serum luteinizing hormone (LH) was likewise suppressed within 1 h after EB treatment in ERalpha(+/+) and ERalpha(-/AA) but not ERalpha(-/ -) mice. In OVX rats, 5-min intracerebroventricular infusion of a PAK inhibitor peptide but not control peptide blocked rapid EB suppression of LH secretion. Taken together, our findings implicate PAK1 activation subsequent to nonclassical ERalpha signaling as an important component of the negative feedback actions of E(2) in the brain.
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Clarke G, O'Mahony SM, Cryan JF, Dinan TG. Verapamil in treatment resistant depression: a role for the P-glycoprotein transporter? Hum Psychopharmacol 2009; 24:217-23. [PMID: 19212940 DOI: 10.1002/hup.1008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Verapamil is a calcium channel blocker that also inhibits the P-glycoprotein (Pgp) membrane transporter. We have found that administration of verapamil with a recognised antidepressant improves clinical outcome in previously treatment resistant cases despite the fact that verapamil does not possess inherent antidepressant activity. In this study we examined the hypothesis that the antidepressant-like effects of verapamil are mediated through its blockade of the Pgp transporter in the blood brain barrier (BBB). METHODS Following pre-treatment with verapamil (20 mg/kg) or a saline solution male Sprague Dawley rats were injected with imipramine (15 mg/kg). Two hours later, the animals were sacrificed, trunk blood collected and brain regions dissected out. High performance liquid chromatography (HPLC) was used to quantitate antidepressant drug concentrations in all samples. RESULTS Verapamil pre-treatment significantly elevated imipramine concentrations in all brain regions studied. The effect was most pronounced in the brainstem and frontal cortex where we observed in excess of a doubling in the brain region: serum ratios. CONCLUSION Our results verify inhibition of Pgp as a potential mechanism of action for verapamil during treatment resistant depression. The implications of these findings are discussed in the context of novel treatment strategies in depression.
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Affiliation(s)
- Gerard Clarke
- Department of Psychiatry, Biosciences Institute, University College Cork, Cork, Ireland.
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28
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In vitro–in vivo correlation in p-glycoprotein mediated transport in intestinal absorption. Eur J Pharm Sci 2009; 36:200-11. [DOI: 10.1016/j.ejps.2008.11.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 11/07/2008] [Accepted: 11/10/2008] [Indexed: 01/11/2023]
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Nischwitz V, Berthele A, Michalke B. Speciation analysis of selected metals and determination of their total contents in paired serum and cerebrospinal fluid samples: An approach to investigate the permeability of the human blood-cerebrospinal fluid-barrier. Anal Chim Acta 2008; 627:258-69. [DOI: 10.1016/j.aca.2008.08.018] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 08/19/2008] [Accepted: 08/20/2008] [Indexed: 11/25/2022]
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Kalvass JC, Maurer TS, Pollack GM. Use of Plasma and Brain Unbound Fractions to Assess the Extent of Brain Distribution of 34 Drugs: Comparison of Unbound Concentration Ratios to in Vivo P-Glycoprotein Efflux Ratios. Drug Metab Dispos 2007; 35:660-6. [PMID: 17237155 DOI: 10.1124/dmd.106.012294] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The P-glycoprotein (P-gp)-deficient mouse model is used to assess the influence of P-gp-mediated efflux on the central nervous system (CNS) distribution of drugs. The steady-state unbound plasma/unbound brain concentration ratio ([plasma],(u)/[brain],(u)) is an alternative method for assessing CNS distribution of drugs independent of the mechanism(s) involved. The objective of this study was to compare the degree of CNS distributional impairment determined from the in vivo P-gp efflux ratio with that determined from the [plasma],(u)/[brain],(u) ratio. CNS distribution of 34 drugs, including opioids, triptans, protease inhibitors, antihistamines, and other clinically relevant drugs with either poor CNS distribution or blood-brain barrier efflux, was studied. Plasma and brain unbound fractions were determined by equilibrium dialysis. K(p,brain) and the P-gp efflux ratio were obtained from the literature or determined experimentally. The P-gp efflux ratio and the [plasma],(u)/[brain],(u) ratio were in concurrence (<3-fold difference) for 21 of the 34 drugs. However, the [plasma],(u)/[brain],(u) ratio exceeded the P-gp efflux ratio substantially (>4-fold) for 10 of the 34 drugs, suggesting that other, non-P-gp-mediated mechanism(s) may limit the CNS distribution of these drugs. The P-gp efflux ratio exceeded the [plasma],(u)/[brain],(u) ratio by more than 3-fold for three drugs, suggesting the presence of active uptake mechanism(s). These observations indicate that when mechanisms other than P-gp affect CNS distribution (non-P-gp-mediated efflux, poor passive permeability, cerebrospinal fluid bulk flow, metabolism, or active uptake), the P-gp efflux ratio may underestimate or overestimate CNS distributional impairment. The [plasma],(u)/[brain],(u) ratio provides a simple mechanism-independent alternative for assessing the CNS distribution of drugs.
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Affiliation(s)
- J Cory Kalvass
- C.B. 7360, University of North Carolina, Chapel Hill, NC 27599-7360, USA.
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Kalvass JC, Pollack GM. Kinetic considerations for the quantitative assessment of efflux activity and inhibition: implications for understanding and predicting the effects of efflux inhibition. Pharm Res 2006; 24:265-76. [PMID: 17191095 DOI: 10.1007/s11095-006-9135-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2005] [Accepted: 07/21/2006] [Indexed: 12/19/2022]
Abstract
PURPOSE Unexpected and complex experimental observations related to efflux transport have been reported in the literature. This work was conducted to develop relationships for efflux activity (PS(efflux)) as a function of commonly studied kinetic parameters [permeability-surface area product (PS), efflux ratio (ER), degree of efflux inhibition (phi(i)), 50% inhibitory concentration (IC(50)), and Michaelis-Menten constant (K(m))]. METHODS A three-compartment model (apical, cellular, and basolateral) was used to derive flux equations relating the initial rate of flux and steady-state mass transfer in the presence or absence of active efflux. Various definitions of efflux ratio (ER) were examined in terms of permeability-surface area products. The efflux activity (PS(efflux)) was expressed in terms of ER and PS. The relationships between PS(efflux) and PS, ER, phi(i), IC(50), and K(m) were solved mathematically. Simulations and examples from the literature were used to illustrate the resulting mathematical relationships. RESULTS The relationships derived according to a three-compartment model differed fundamentally from commonly accepted approaches for determining PS(efflux), phi(i), IC(50) and K(m). Based on the model assumptions and mathematical derivations, currently used mathematical relationships erroneously imply that efflux activity is proportional to change in PS (i.e., flux or P(app)) and thus underestimate PS(efflux) and phi(i,) and overestimate IC(50) and K(m). CONCLUSIONS An understanding of the relationship between efflux inhibition and kinetic parameters is critical for appropriate data interpretation, standardization in calculating and expressing the influence of efflux transport, and predicting the clinical significance of efflux inhibition.
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Affiliation(s)
- J Cory Kalvass
- Division of Drug Delivery and Disposition, School of Pharmacy, Kerr Hall C.B.# 7360 University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, USA
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Abstract
Drug transporters are membrane proteins present in various tissues such as the lymphocytes, intestine, liver, kidney, testis, placenta, and central nervous system. These transporters play a significant role in drug absorption and distribution to organic systems, particularly if the organs are protected by blood-organ barriers, such as the blood-brain barrier or the maternal-fetal barrier. In contrast to neurotransmitters and receptor-coupled transporters or other modes of interneuronal transmission, drug transporters are not directly involved in specific neuronal functions, but provide global protection to the central nervous system. The lack of capillary fenestration, the low pinocytic activity, and the tight junctions between brain capillary and choroid plexus endothelial cells represent further gatekeepers limiting the entrance of endogenous and exogenous compounds into the central nervous system. Drug transport is a result of the concerted action of efflux and influx pumps (transporters) located both in the basolateral and apical membranes of brain capillary and choroid plexus endothelial cells. By regulating efflux and influx of endogenous or exogenous substances, the blood-brain barrier and, to a lesser extent, the blood-cerebrospinal barrier in the ventricles, represents the main interface between the central nervous system and the blood, ie, the rest of the body. As drug distribution to organs is dependent on the affinity of a substrate for a specific transport system, membrane transporter proteins are increasingly recognized as a key determinant of drug disposition. Many drug transporters are members of the adenosine triphosphate (ATP)-binding cassette (ABC) transporter superfamily or the solute-linked carrier (SLC) class. The multidrug resistance protein MDR1 (ABCB1), also called P-glycoprotein, the multidrug resistance-associated proteins MRP1 (ABCC1) and MRP2 (ABCC2), and the breast cancer-resistance protein BCRP (ABCG2) are ATP-dependent efflux transporters expressed in the blood-brain barrier. They belong to the superfamily of ABC transporters, which export drugs from the intracellular to the extracellular milieu. Members of the SLC class of solute carriers include, for example, organic ion transporting peptides, organic cation transporters, and organic ion transporters. They are ATP-independent polypeptides principally expressed at the basolateral membrane of brain capillary and choroid plexus endothelial cells that also mediate drug transport through central nervous system barriers.
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Affiliation(s)
- François Girardin
- Unit of Clinical Psychopharmacology, Geneva University Hospitals, Chênes-Bourg, Geneva, Switzerland.
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Kis B, Isse T, Snipes JA, Chen L, Yamashita H, Ueta Y, Busija DW. Effects of LPS stimulation on the expression of prostaglandin carriers in the cells of the blood-brain and blood-cerebrospinal fluid barriers. J Appl Physiol (1985) 2006; 100:1392-9. [PMID: 16322371 DOI: 10.1152/japplphysiol.01259.2005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Prostaglandins produced in cerebral endothelial cells (CECs) are the final signal transduction mediators from the periphery to the brain during fever response. However, prostaglandins are organic anions at physiological pH, and they enter cells poorly using simple diffusion. Several transporters have been described that specifically transport prostaglandins across cell membranes. We examined the expression of the two principal prostaglandin carriers, prostaglandin transporter (PGT), and multidrug resistance-associated protein 4 (MRP4) in cells of the blood-brain barrier and in choroid epithelial cells in vitro as well as in vivo in rat brain in control conditions and after lipopolysaccharide (LPS) challenge. We detected PGT in primary cultures of rat CECs, astrocytes, pericytes, and choroid epithelial cells. LPS stimulation had no effect on the expression level of PGT in these cells; however, after LPS stimulation the polarized, dominantly luminal, expression pattern of PGT significantly changed. MRP4 is also expressed in CECs, and its level was not influenced by LPS treatment. In rat brain, PGT was highly expressed in the supraoptic and paraventricular nuclei of the hypothalamus, in the ependymal cell layer of the third ventricle, and in the choroid plexus. LPS treatment increased the expression of PGT in the supraoptic and paraventricular nuclei. Our results suggest that PGT and MRP4 likely play a role in transporting prostaglandins through the blood-brain and blood-cerebrospinal fluid barriers and may be involved in the maintenance of prostaglandin homeostasis in the brain and in the initiation of fever response.
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Affiliation(s)
- Bela Kis
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
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Constable PA, Lawrenson JG, Dolman DEM, Arden GB, Abbott NJ. P-Glycoprotein expression in human retinal pigment epithelium cell lines. Exp Eye Res 2006; 83:24-30. [PMID: 16530756 DOI: 10.1016/j.exer.2005.10.029] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 10/14/2005] [Accepted: 10/21/2005] [Indexed: 12/28/2022]
Abstract
P-Glycoprotein (P-gp), an active efflux transporter encoded by the MDR1 gene, has recently been identified in the human and pig retinal pigment epithelium (RPE) in situ. Efflux pumps such as P-gp are major barriers to drug delivery in several tissues. We wished to establish whether human RPE cell lines express P-gp under the culture conditions recommended for each cell line so as to determine their suitability as in vitro models for predicting drug transport across the outer blood-retinal barrier. Three human RPE cell lines, ARPE19, D407 and h1RPE were investigated. Reverse transcriptase-polymerase chain reaction (RT-PCR) was carried out to determine the expression of MDR1 mRNA. Immunocytochemistry using the P-gp-specific antibody C219 was undertaken to investigate the presence of P-gp protein in each cell type. Uptake of rhodamine 123, a P-gp substrate, in the presence or absence of pre-treatment with a P-gp inhibitor, verapamil, was measured in each cell line to determine functional expression of P-gp. For all experiments, MDCK cells stably transfected with the human MDR1 gene (MDCK-MDR1) were used as a positive control. ARPE19 cells were consistently negative for P-gp as assessed by RT-PCR and immunocytochemistry. By contrast, RT-PCR of D407 and h1RPE samples yielded weak bands corresponding to MDR1; P-gp protein expression, as demonstrated by C219 immunoreactivity, was also present. Rhodamine uptake after treatment with verapamil was significantly greater in D407 and MDCK-MDR1, indicating functional expression of P-gp in these two cell lines. No evidence of functional P-gp was found in ARPE19 and h1RPE. In conclusion, D407 and h1RPE cells express P-gp, though functional activity was demonstrable only in D407 cells. ARPE19 cells do not express P-gp. Of these human RPE cells lines D407 could be considered as a suitable model for in vitro drug transport studies, particularly those involving P-gp substrates, without modification of their usual culture conditions.
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Affiliation(s)
- Paul A Constable
- Department of Optometry and Visual Science, Henry Wellcome Laboratories for Vision Sciences, Applied Vision Research Centre, City University, Northampton Square, London EC1V OHB, UK.
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Kubota H, Ishihara H, Langmann T, Schmitz G, Stieger B, Wieser HG, Yonekawa Y, Frei K. Distribution and functional activity of P-glycoprotein and multidrug resistance-associated proteins in human brain microvascular endothelial cells in hippocampal sclerosis. Epilepsy Res 2006; 68:213-28. [PMID: 16361082 DOI: 10.1016/j.eplepsyres.2005.11.011] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 11/04/2005] [Accepted: 11/08/2005] [Indexed: 10/25/2022]
Abstract
Multidrug resistance protein, also referred as P-glycoprotein (P-gp, MDR1; ABCB1) and multidrug resistance-associated protein (MRP) 1 (ABCC1) and 2 (ABCC2) are, thus far, candidates to cause antiepileptic drug (AED) resistance epilepsy. In this study, we investigated P-gp, MRP1 and MRP2 expression, localization and functional activity on cryosections and isolated human brain-derived microvascular endothelial cells (HBMEC) from epileptic patients (HBMEC-EPI) with hippocampal sclerosis (HS), as compared with HBMEC isolated from normal brain cortex (HBMEC-CTR). We examined the expression and distribution of three transporters, P-gp, MRP1 and MRP2 on two major parts of the resected tissue, the hippocampus and the parahippocampal gyrus (Gph). P-gp showed diffuse expression not only in endothelium but also by parenchymal cells in both the hippocampus and the Gph. MRP1 labeling was observed in parenchymal cells in the Gph. By contrast, MRP2 was mainly found in endothelium of the hippocampus. P-gp and MRP1 expression in the Gph was relatively high in the patient with long-term seizure history. Quantitative RT-PCR analysis of HBMEC revealed that MDR1, MRP1 as well as MRP5 (ABCC5) and MRP6 (ABCC6) were overexpressed in HBMEC-EPI at the mRNA level. HBMEC from both normal and epilepsy groups displayed protein expression of P-gp, whereas MRP1 and MRP2 were seen only in HBMEC-EPI. Accordingly, it is of particular interest that MRP functional activities were observed in HBMEC-EPI, but not in HBMEC-CTR. Our results suggest that complex MDR expression changes not only in the hippocampus but in the Gph may play a role in AED pharmacoresistance in intractable epilepsy patients with mesial temporal lobe epilepsy (MTLE) by altering the permeability of AEDs across the blood-brain barrier (BBB).
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Adolescent
- Adult
- Cell Line, Tumor
- Cells, Cultured
- Child
- Drug Resistance, Multiple/physiology
- Endothelial Cells/metabolism
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- Epilepsy, Temporal Lobe/metabolism
- Epilepsy, Temporal Lobe/surgery
- Female
- Hippocampus/metabolism
- Humans
- Immunohistochemistry
- Male
- Middle Aged
- Multidrug Resistance-Associated Protein 2
- Multidrug Resistance-Associated Proteins/metabolism
- RNA, Messenger
- Sclerosis
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Affiliation(s)
- Hisashi Kubota
- Department of Neurosurgery, University Hospital Zurich, Frauenklinikstr. 10, CH-8091 Zurich, Switzerland
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Deguchi T, Isozaki K, Yousuke K, Terasaki T, Otagiri M. Involvement of organic anion transporters in the efflux of uremic toxins across the blood-brain barrier. J Neurochem 2006; 96:1051-9. [PMID: 16445853 DOI: 10.1111/j.1471-4159.2005.03550.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Renal failure causes multiple physiological changes involving CNS dysfunction. In cases of uremia, there is close correlation between plasma levels of uremic toxins [e.g. 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), hippurate (HA) and indoleacetate (IA)] and the degree of uremic encephalopathy, suggesting that uremic toxins are involved in uremic encephalopathy. In order to evaluate the relevance of uremic toxins to CNS dysfunction, we investigated directional transport of uremic toxins across the blood-brain barrier (BBB) using in vivo integration plot analysis and the brain efflux index method. We observed saturable efflux transport of [(3)H]CMPF, [(14)C]HA and [(3)H]IA, which was inhibited by probenecid. For all uremic toxins evaluated, apparent efflux clearance across the BBB was greater than apparent influx clearance, suggesting that these toxins are predominantly transported from the brain to blood across the BBB. Saturable efflux transport of [(3)H]CMPF, [(14)C]HA and [(3)H]IA was completely inhibited by benzylpenicillin, which is a substrate of rat organic anion transporter 3 (rOat3). Taurocholate and digoxin, which are common substrates of rat organic anion transporting polypeptide (rOatp), partially inhibited the efflux of [(3)H]CMPF. Transport experiments using a Xenopus laevis oocyte expression system revealed that CMPF, HA and IA are substrates of rOat3, and that CMPF (but not HA or IA) is a substrate of rOap2. These results suggest that rOat3 mediates brain-to-blood transport of uremic toxins, and that rOatp2 is involved in efflux of CMPF. Thus, conditions typical of uremia can cause inhibition of brain-to-blood transport involving rOat3 and/or rOatp2, leading to accumulation of endogenous metabolites and drugs in the brain.
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Affiliation(s)
- Tsuneo Deguchi
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
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37
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Kis B, Chen L, Ueta Y, Busija DW. Autocrine peptide mediators of cerebral endothelial cells and their role in the regulation of blood-brain barrier. Peptides 2006; 27:211-22. [PMID: 16137789 DOI: 10.1016/j.peptides.2005.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 07/21/2005] [Accepted: 07/21/2005] [Indexed: 01/08/2023]
Abstract
A unique feature of cerebral endothelial cells (CECs) is the formation of the blood-brain barrier (BBB), which contributes to the stability of the brain microenvironment. CECs are capable of producing several substances mediating endothelium-dependent vasorelaxation or vasoconstriction, regulating BBB permeability, and participating in the regulation of cell-cell interactions during inflammatory and immunological processes. The chemical nature of these mediators produced by CECs ranges from gaseous anorganic molecules (e.g. nitric oxide) through lipid mediators (e.g. prostaglandins) to peptides. Peptide mediators are a large and diverse family of bioactive molecules which can elicit multiple effects on cerebral endothelial functions. In this review, we summarize current knowledge of peptide mediators produced by CECs, such as adrenomedullin, angiotensin, endothelin and several others and their role in the regulation of BBB functions.
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Affiliation(s)
- Bela Kis
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Medical Center Blvd., Winston-Salem, NC 27157, USA.
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Deli MA, Abrahám CS, Kataoka Y, Niwa M. Permeability studies on in vitro blood-brain barrier models: physiology, pathology, and pharmacology. Cell Mol Neurobiol 2005; 25:59-127. [PMID: 15962509 DOI: 10.1007/s10571-004-1377-8] [Citation(s) in RCA: 466] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
(1) The specifically regulated restrictive permeability barrier to cells and molecules is the most important feature of the blood-brain barrier (BBB). The aim of this review was to summarize permeability data obtained on in vitro BBB models by measurement of transendothelial electrical resistance and by calculation of permeability coefficients for paracellular or transendothelial tracers. (2) Results from primary cultures of cerebral microvascular endothelial cells or immortalized cell lines from bovine, human, porcine, and rodent origin are presented. Effects of coculture with astroglia, neurons, mesenchymal cells, blood cells, and conditioned media, as well as physiological influence of serum components, hormones, growth factors, lipids, and lipoproteins on the barrier function are discussed. (3) BBB permeability results gained on in vitro models of pathological conditions including hypoxia and reoxygenation, neurodegenerative diseases, or bacterial and viral infections have been reviewed. Effects of cytokines, vasoactive mediators, and other pathogenic factors on barrier integrity are also detailed. (4) Pharmacological treatments modulating intracellular cyclic nucleotide or calcium levels, and activity of protein kinases, protein tyrosine phosphatases, phospholipases, cyclooxygenases, or lipoxygenases able to change BBB integrity are outlined. Barrier regulation by drugs involved in the metabolism of nitric oxide and reactive oxygen species, as well as influence of miscellaneous treatments are also listed and evaluated. (5) Though recent advances resulted in development of improved in vitro BBB model systems to investigate disease modeling, drug screening, and testing vectors targeting the brain, there is a need for checking validity of permeability models and cautious interpretation of data.
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Affiliation(s)
- Máiria A Deli
- Laboratory of Molecular Neurobiology, Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári körút 62, H-6726 Szeged, Hungary.
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Leslie EM, Deeley RG, Cole SPC. Multidrug resistance proteins: role of P-glycoprotein, MRP1, MRP2, and BCRP (ABCG2) in tissue defense. Toxicol Appl Pharmacol 2005; 204:216-37. [PMID: 15845415 DOI: 10.1016/j.taap.2004.10.012] [Citation(s) in RCA: 1001] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Accepted: 10/20/2004] [Indexed: 12/21/2022]
Abstract
In tumor cell lines, multidrug resistance is often associated with an ATP-dependent decrease in cellular drug accumulation which is attributed to the overexpression of certain ATP-binding cassette (ABC) transporter proteins. ABC proteins that confer drug resistance include (but are not limited to) P-glycoprotein (gene symbol ABCB1), the multidrug resistance protein 1 (MRP1, gene symbol ABCC1), MRP2 (gene symbol ABCC2), and the breast cancer resistance protein (BCRP, gene symbol ABCG2). In addition to their role in drug resistance, there is substantial evidence that these efflux pumps have overlapping functions in tissue defense. Collectively, these proteins are capable of transporting a vast and chemically diverse array of toxicants including bulky lipophilic cationic, anionic, and neutrally charged drugs and toxins as well as conjugated organic anions that encompass dietary and environmental carcinogens, pesticides, metals, metalloids, and lipid peroxidation products. P-glycoprotein, MRP1, MRP2, and BCRP/ABCG2 are expressed in tissues important for absorption (e.g., lung and gut) and metabolism and elimination (liver and kidney). In addition, these transporters have an important role in maintaining the barrier function of sanctuary site tissues (e.g., blood-brain barrier, blood-cerebral spinal fluid barrier, blood-testis barrier and the maternal-fetal barrier or placenta). Thus, these ABC transporters are increasingly recognized for their ability to modulate the absorption, distribution, metabolism, excretion, and toxicity of xenobiotics. In this review, the role of these four ABC transporter proteins in protecting tissues from a variety of toxicants is discussed. Species variations in substrate specificity and tissue distribution of these transporters are also addressed since these properties have implications for in vivo models of toxicity used for drug discovery and development.
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Affiliation(s)
- Elaine M Leslie
- Division of Drug Delivery and Disposition, School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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40
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Raza SM, Pradilla G, Legnani FG, Thai QA, Olivi A, Weingart JD, Brem H. Local delivery of antineoplastic agents by controlled-release polymers for the treatment of malignant brain tumours. Expert Opin Biol Ther 2005; 5:477-94. [PMID: 15934827 DOI: 10.1517/14712598.5.4.477] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Recent advances in the treatment of malignant brain tumours have focused on the development of targeted local delivery of therapeutic agents, which combine various antineoplastic strategies that include cytotoxic, anti-angiogenic and immunomodulatory mechanisms, among others. The introduction of local delivery devices for sustained administration of antineoplastic agents represents a new opportunity to effectively treat these malignancies by facilitating the intracranial administration of safe and clinically efficacious doses for prolonged periods of time in a controlled fashion. This technology circumvents the need for high systemic doses with potentially harmful toxicities, bypasses the blood-brain barrier and can be tailored to deliver new agents with complex pharmacological properties. Based on local delivery strategies, new delivery systems, including convection-enhanced delivery and microchips, have been developed. As a result, recent advances in tumour biology have been adopted as potentially translatable treatments and are undergoing preclinical and clinical evaluation at present. These novel approaches could improve the prognosis of patients with these tumours.
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Affiliation(s)
- Shaan M Raza
- Department of Neurological Surgery, The Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Meyer 7-113, Baltimore, MD 21287, USA
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Strazielle N, Ghersi-Egea JF. Factors affecting delivery of antiviral drugs to the brain. Rev Med Virol 2005; 15:105-33. [PMID: 15546130 DOI: 10.1002/rmv.454] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Although the CNS is in part protected from peripheral insults by the blood-brain barrier and the blood-cerebrospinal fluid barrier, a number of human viruses gain access to the brain, replicate within this organ, or sustain latent infection. The efficacy of antiviral drugs towards the cerebral viral load is often limited as both blood-brain interfaces impede their cerebral distribution. For polar compounds, the major factor restricting their entry lies in the tight junctions that occlude the paracellular pathway across these barriers. For compounds with more favourable lipid solubility properties, CNS penetration will be function of a number of physicochemical factors that include the degree of lipophilicity, size and ability to bind to protein or red blood cells, as well as other factors inherent to the vascular and choroidal systems, such as the local cerebral blood flow and the surface area available for exchange. In addition, influx and efflux transport systems, or metabolic processes active in both capillary endothelial cells and choroid plexus epithelial cells, can greatly change the bioavailability of a drug in one or several compartments of the CNS. The relative importance of these various factors with respect to the CNS delivery of the different classes of antiviral drugs is illustrated and discussed.
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Bagger MA, Bechgaard E. The potential of nasal application for delivery to the central brain-a microdialysis study of fluorescein in rats. Eur J Pharm Sci 2004; 21:235-42. [PMID: 14757495 DOI: 10.1016/j.ejps.2003.10.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous animal studies have shown that various types of nasally administered drugs and model substances can access the central nervous system (CNS) via direct transport across the olfactory epithelium, and thereby circumventing the blood-brain barrier (BBB). These compounds, however, have mainly been identified in the cerebrospinal fluid and the olfactory bulbs which are usually not pharmacologically relevant targets. The aim of the present study was to evaluate the potential of targeting the central brain by olfactory absorption by use of sodium fluorescein as a hydrophilic model substance with limited permeability across the blood-brain barrier. Microdialysis probes were implanted in blood and in right and left side of the brain (striatum) in rats. The pharmacokinetics of sodium fluorescein was studied from 0 to 180min following intravenous and unilateral nasal administration without occlusion of the oesophagus. Pharmacokinetic modelling showed a significantly higher absorption rate and lower T(max) in the ipsilateral striatum (0.097min(-1) and 41min) compared with the contralateral side (0.056min(-1) and 54min). The rate of elimination in brain was significantly lower after nasal administration (0.004min(-1)) compared with intravenous administration (0.012min(-1)). However, the brain to plasma area under the curve ratios of model substance were low (2-3%) and not significantly different between right and left side of the brain, regardless of the route of administration. The results obtained by microdialysis were supported by findings in whole brain homogenates where concentrations of fluorescein were approximately 40% higher in the right striatum compared with the left side initially after nasal administration to the right nostril of rats. Despite some indications of olfactory transport to the central rat brain it was concluded that the drug targeting potential of sodium fluorescein and most likely other hydrophilic compounds is limited.
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Affiliation(s)
- Morten Aavad Bagger
- Department of Pharmaceutics, The Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100, Copenhagen, Denmark.
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Hoffmann U, Kroemer HK. The ABC Transporters MDR1 and MRP2: Multiple Functions in Disposition of Xenobiotics and Drug Resistance. Drug Metab Rev 2004; 36:669-701. [PMID: 15554242 DOI: 10.1081/dmr-200033473] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
ATP-binding cassette (ABC) transporters comprise one of the largest membrane bound protein families. They are involved in transport of numerous compounds. These proteins transport substrates against a concentration gradient with ATP hydrolysis as a driving force across the membrane. Mammalian ABC proteins have important physiological, pharmacological and toxicological functions including the transport of lipids, bile salts, drugs, toxic and environmental agents. The efflux pumps serve both as natural defense mechanisms and influence the bioavailability and disposition of drugs. In general terms, the transporters remove xenobiotics from the cellular environment. For example, in cancer cells, over expression of these molecules may confer to multidrug resistance against cytostatic drugs. In addition, based on diverse structural characteristics and a broad substrate specifity, ABC transport proteins alter the intracellular concentration of a variety of therapeutically used compounds and toxicologically relevant agents. We review the function of the human multidrug resistance protein MDR1, (P-glycoprotein, ABCB1) and the multidrug resistance protein MRP2 (ABCC2). We focus on four topics namely 1) structure and physiological functions of these transporters, 2) substrates e.g., drugs, xenotoxins, and environmental toxicants including their conjugates, 3) drug-drug interactions, and the role of chemosensitizers which may be able to reverse drug resistance, and 4) pharmacologically and toxicologically relevant genetic polymorphisms in transport proteins and their clinical implications.
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Affiliation(s)
- Ulrich Hoffmann
- Department of Pharmacology, Peter Holtz Research Center of Pharmacology and Experimental Therapeutics, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
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44
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Kikuchi R, Kusuhara H, Abe T, Endou H, Sugiyama Y. Involvement of Multiple Transporters in the Efflux of 3-Hydroxy-3-methylglutaryl-CoA Reductase Inhibitors across the Blood-Brain Barrier. J Pharmacol Exp Ther 2004; 311:1147-53. [PMID: 15292460 DOI: 10.1124/jpet.104.071621] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Statins, 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors, are frequently used for the treatment of hypercholesterolemia. The present study aimed to examine the involvement of organic anion transporters in the efflux transport of pravastatin and pitavastatin across the blood-brain barrier (BBB). Transport studies using cDNA-transfected cells revealed that these statins are substrates of multispecific organic anion transporters expressed at the BBB (rOat3:Slc22a8 and rOatp2:Slco1a4). The efflux of these statins across the BBB was characterized using the brain efflux index method. The efflux clearance of pitavastatin across the BBB, obtained from the elimination rate constant and the distribution volume in the brain, was greater than that of pravastatin (364 versus 59 microl/min/g brain). The efflux of pravastatin and pitavastatin was saturable (apparent Km values: 18 and 5 muM, respectively) and inhibited by probenecid but unaffected by tetraethylammonium. Furthermore, an inhibitor of the efflux pathway for hydrophilic organic anions across the BBB (p-aminohippurate), and inhibitors of the efflux pathway for amphipathic organic anions (taurocholate and digoxin) inhibited the efflux of both statins. The degree of inhibition by p-aminohippurate was similar and partial for the efflux of pravastatin and pitavastatin. Taurocholate and digoxin completely inhibited the efflux of pitavastatin, whereas their effect was partial for the efflux of pravastatin. The results of the present study suggest the involvement of multiple transporters, including rOat3 and rOatp2, in the efflux transport of pravastatin and pitavastatin across the BBB, each making a different contribution.
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Affiliation(s)
- Ryota Kikuchi
- Department of Molecular Pharmacokinetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Crowe A, Wong P. Potential roles of P-gp and calcium channels in loperamide and diphenoxylate transport. Toxicol Appl Pharmacol 2003; 193:127-37. [PMID: 14613723 DOI: 10.1016/s0041-008x(03)00372-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study examined the accumulation and transport of two related systemic opioids used as antidiarrhoeal drugs and compared their rates of transport with known P-glycoprotein (P-gp) substrates used in our in vitro environment. Cellular uptake and efflux and transcellular transport were all determined using Caco-2 cells after exposure to loperamide or diphenoxylate, with or without a range of efflux inhibitors. Bidirectional transport studies of 5 microM loperamide showed efflux to be fivefold higher than influx (42 x 10(-6) compared to 8 x 10(-6) cm/s); however, this decreased to twofold at 10 microM and was abolished using 100 microM loperamide. An uptake pathway was also discovered when P-gp was inhibited which, in the presence of Ca(2+) channel blockers, was amplified, providing a potential mechanism for central nervous system effects to be increased upon blockage of L-type calcium channels, quite separate from any P-gp inhibition. Diphenoxylate transport, however, showed little sign of P-gp-mediated efflux. Diphenoxylate accumulated readily within cells, yet transport through cells was very low. Additionally, efflux inhibitors had little impact on transport or accumulation, suggesting that diphenoxylate was not a substrate for an efflux mechanism.
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Affiliation(s)
- Andrew Crowe
- School of Pharmacy, Curtin University of Technology, GPO Box U1987, Perth, Western Australia, 6845, Australia.
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46
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de Boer AG, van der Sandt ICJ, Gaillard PJ. The role of drug transporters at the blood-brain barrier. Annu Rev Pharmacol Toxicol 2003; 43:629-56. [PMID: 12415123 DOI: 10.1146/annurev.pharmtox.43.100901.140204] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The blood-brain barrier (BBB) is a dynamic interface between the blood and the brain. It eliminates (toxic) substances from the endothelial compartment and supplies the brain with nutrients and other (endogenous) compounds. It can be considered as an organ protecting the brain and regulating its homeostasis. Until now, many transport systems have been discovered that play an important role in maintaining BBB integrity and brain homeostasis. In this review, we focus on the role of carrier- and receptor-mediated transport systems (CMT, RMT) at the BBB. These include CMT systems, such as P-glycoprotein, multidrug-resistance proteins 1-7, nucleoside transporters, organic anion transporters, and large amino-acid transporters; RMT systems, such as the transferrin-1 and -2 receptors; and the scavenger receptors SB-AI and SB-BI.
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Affiliation(s)
- A G de Boer
- Blood-Brain Barrier Research Group, Division of Pharmacology, Leiden/Amsterdam Center for Drug Research, University of Leiden, The Netherlands.
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47
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Abstract
The drug efflux transporter P-glycoprotein (P-gp) is known to confer multidrug resistance in cancer chemotherapy. The P-gp is highly expressed in many types of tumor cells, as well as many normal tissues, including the apical surface of intestinal epithelial cells, and the luminal surface of capillary endothelial cells in the brain. Because of its expression and localization, it has been suggested that P-gp plays an important role in cancer chemotherapy, intestinal absorption, and brain uptake. This review addresses the significance of the role of P-gp in cancer chemotherapy, drug absorption, and brain uptake. Based on the clinical and animal studies with P-gp modulators, it has become apparent that the role of P-gp in multidrug resistance is far less important compared to other biological factors. Although P-gp is highly expressed in both intestinal epithelial cells and endothelial cells of brain capillaries and functions as an efflux transporter in both organs, the magnitude of P-gp's impact on intestinal absorption and brain uptake of drugs is quantitatively very different. From animal and clinical studies, it is evident that P-gp plays a very important role in CNS penetration of drugs, whereas the effect of P-gp on drug absorption is not as important as generally believed.
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Affiliation(s)
- Jiunn H Lin
- Department of Drug Metabolism, Merck Research Laboratories, West Point, Pennsylvania, USA.
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48
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Kikuchi R, Kusuhara H, Sugiyama D, Sugiyama Y. Contribution of organic anion transporter 3 (Slc22a8) to the elimination of p-aminohippuric acid and benzylpenicillin across the blood-brain barrier. J Pharmacol Exp Ther 2003; 306:51-8. [PMID: 12684544 DOI: 10.1124/jpet.103.049197] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of rat organic anion transporter 3 (rOat3; Slc22a8) in the efflux transport at the blood-brain barrier (BBB) was characterized. The expression of rOat1, rOat2, and rOat3 in the brain capillary endothelial cells (BCEC) was examined using reverse transcription-polymerase chain reaction analysis, which showed that there was no expression of rOat1 or rOat2, but moderate expression of rOat3. The expression of rOat3 in the BCEC was further confirmed by Western blotting. Immunohistochemical staining showed that rOat3 is located on the abluminal and, possibly, luminal membrane of the BCEC. The contribution of rOat3 to the efflux of para-aminohippuric acid (PAH) and benzylpenicillin (PCG), substrates of rOat3, from the cerebrum into the blood circulation across the BBB was evaluated using the Brain Efflux Index method. PAH and PCG were eliminated from the cerebrum with rate constants of 0.039 and 0.043 min-1, respectively, and the elimination was saturated at high substrate concentrations. Taking account of the dilution in the brain, the Km values for the elimination of PAH and PCG were estimated to be 168 and 29 micro M, respectively. The efflux of PAH and PCG across the BBB was inhibited in a dose-dependent manner by unlabeled PCG and PAH, respectively. The Ki value of PAH for the efflux of PCG was 106 micro M and that of PCG for the efflux of PAH was 58 micro M. These values were comparable with their Km values, suggesting that they share the same efflux mechanism at the BBB. Furthermore, cimetidine and pravastatin, which are also substrates and inhibitors of rOat3, significantly inhibited the efflux of PAH and PCG from the cerebrum. These results suggest that rOat3 is responsible for the elimination of PAH and PCG from the brain across the BBB.
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Affiliation(s)
- Ryota Kikuchi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
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Kusuhara H, He Z, Nagata Y, Nozaki Y, Ito T, Masuda H, Meier PJ, Abe T, Sugiyama Y. Expression and functional involvement of organic anion transporting polypeptide subtype 3 (Slc21a7) in rat choroid plexus. Pharm Res 2003; 20:720-7. [PMID: 12751626 DOI: 10.1023/a:1023473216759] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE It has been shown that transport(s) are involved in the uptake of estradiol 17beta glucuronide (E217betaG) by the choroid plexus (CP). The purpose of this study is to compare the substrate specificity of the transporter in the CP with those of rat organic anion transporting polypeptide 1 (rOatp1) and rOatp3. METHODS The expression of rOatp1 and rOatp3 in rat CP was confirmed by RT-PCR and Western blot analyses. The substrate specificity of rOatp1 and rOatp3 was compared using cDNA-transfected LLC-PK1 cells. The uptake of E217betaG by rat isolated CP was determined by centrifugal filtration technique. RESULTS PCR analyses demonstrated that the mRNA expression of rOatp3 was abundant in the CP, whereas that of rOatp1 was low. Immunohistochemical staining revealed that rOatp3 is expressed on the apical membrane of the CP. Kinetic parameters (Km and Ki values) of rOatp3 were similar to those for rOatp1. The results of mutual inhibition study suggest that E217betaG and taurocholate share the same mechanism in the CP. Corticosterone, estrone-3-sulfate and indomethacin are moderate inhibitors, but no effects by digoxin, p-aminohippurate, benzylpenicillin and cimetidine were observed. CONCLUSIONS rOatp3 is most possible candidate transporter involved in the uptake of organic anions on the brush border membrane of the choroid epithelial cells.
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Affiliation(s)
- Hiroyuki Kusuhara
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Kis B, Abrahám CS, Deli MA, Kobayashi H, Niwa M, Yamashita H, Busija DW, Ueta Y. Adrenomedullin, an autocrine mediator of blood-brain barrier function. Hypertens Res 2003; 26 Suppl:S61-70. [PMID: 12630813 DOI: 10.1291/hypres.26.s61] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Since the discovery that adrenomedullin gene expression is 20- to 40-fold higher in endothelial cells than even in the adrenal medulla, this peptide has been regarded as an important secretory product of the vascular endothelium, together with nitric oxide, eicosanoids, endothelin-1, and other vasoactive metabolites. Cerebral endothelial cells secrete an exceptionally large amount of adrenomedullin, and the adrenomedullin concentration is about 50% higher in the cerebral circulation than in the peripheral vasculature. The adrenomedullin production of cerebral endothelial cells is induced by astrocyte-derived factors. Adrenomedullin causes vasodilation in the cerebral circulation, may participate in the maintenance of the resting cerebral blood flow, and may be protective against ischemic brain injury. Recent data from our laboratory indicate that adrenomedullin, as an endothelium-derived autocrine/paracrine hormone, plays an important role in the regulation of specific blood-brain barrier properties. Adrenomedullin is suggested to be one of the physiological links between astrocyte-derived factors, cyclic adenosine 3'5'-monophosphate (cAMP), and the induction and maintenance of the blood-brain barrier. Moreover, the role of adrenomedullin in the differentiation and proliferation of endothelial cells and in angiogenesis suggests a more complex function for adrenomedullin in the cerebral circulation and in the development of the blood-brain barrier.
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Affiliation(s)
- Béla Kis
- Department of Physiology and Pharmacology, Wake Forest University, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
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