Physiologyand Pharmacologyof. the Blood-BrainBarrierContributors

N.J. Abbott, D. Barnes, D.J. Begley, A.L. BetzM.W.B. Bradbury, M.W. Brightman, D.J. Brooks, H.F. CserrP.A. Fraser, A. Gjedde, G.W. Goldstein, J. GreenwoodN.H. Greig, M.K. Gumerlock, J.J. LaterraJ.-M. Lefauconnier, P.J. Luthert, D.K. Male, E.A. NeuweltC.S. Patlak, O.E. Pratt, S.I. Rapoport, P.J. RobinsonN.R. Saunders, G.P. Schielke, Q.R. Smith

Editor

Michael W.B. Bradbury

Springer-VerlagBerlin Heidelberg New York London ParisTokyo Hong Kong Barcelona Budapest

Contents

CHAPTER 1

Ultrastructure of Brain EndotheliumM.W. BRIGHTMAN. With 5 Figures 1

A. Endothelium as a Blood-Brain Barrier 1B. Astroglia as a Blood-Brain Barrier 2C. Blood-Brain Access 6

I. Vascularization of Grafts to the Brain 61. Grafts of Peripheral Tissues 62. Similarity Between Ventricle and Anterior Chamber

of the Eye 63. CNS Versus Peripheral Tissue Grafts 9

II. Immunological Aspects of the Endothelium 9III. Circumventricular Organs 11

1. Fenestrae 122. Pits and Vesicles 123. Tubules : 13

D. Ontogeny 14E. Astrocytic Modulation of the Barrier 15F. Constituents of Barrier Cell Membranes 18References 19

CHAPTER 2Methods of StudyQ.R. SMITH 23

A. Introduction 23B. Morphologic Techniques 24

I. Organic Dye Tracers 24II. Electron Microscopy 24

III. Quantitative Morphometry 25C. In Vivo Transport Methods 25

I. Intravenous Administration/Compartmental Analysis 26II. Brain Perfusion 30

XII Contents

III. Indicator Dilution 32IV. Brain Uptake Index 33V. Other Techniques 34

D. New Dimensions 36I. Evaluation of Barrier Transport and Permeability in Humans . . 36

1. Positron Emission Tomography 362. Magnetic Resonance Imaging 37

II. Autoradiography 37III. Brain Vasculature/Perfused Capillaries 38IV. Other Barrier Sites 39

1. Choroid Plexus Epithelium 392. Blood-Nerve Barrier 403. Blood-Retinal Barrier 40

V. In Vivo Microdialysis 41VI. Single Capillary Studies 41

E. Molecular/Cellular Biology 42I. Isolated Microvessels/Endothelial Monolayers 42

II. Identification of Barrier Transporters and Enzymes 43III. Expression of Barrier Characteristics 43

F. Summary and Perspectives 44References 44

CHAPTER 3Diffusional and Osmotic Permeability to WaterP.A. FRASER. With 3 Figures 53

A. Introduction 53B. The Nature of Permeability 54C. Water Permeability of the Blood-Brain Barrier 55

I. Diffusive Permeability 56II. Osmotic Permeability 59

D. Conclusion 62References 63

CHAPTER 4

Blood-Brain Glucose TransferA. GJEDDE. With 8 Figures 65

A. Brief History 65B. Brain Endothelial Glucose Transporter 66

I. Molecular Biology 66II. Molecular Kinetics 68

III. Structural Requirements of Glucose Transport 69

Contents XIII

C. Theory of Blood-Brain Glucose Transfer 70I. Apparent Permeability and Flux 71

II. Facilitated Diffusion 741. Michaelis-Menten Equation 742. Michaelis-Menten Constants 753. Partition Volume 75

III. Multiple Membranes 761. Endothelial Membranes 772. Glial and Neuronal Cell Membranes 78

D. Evidence of Blood-Brain Glucose Transfer 79I. Methods 79

1. Operational Equations 792. Experimental Procedures 813. The Blood-Brain Barrier In Vitro 83

II. Normal Values in Awake Subjects 851. Permeability and Flux in Normoglycemia 852. Michaelis-Menten Constants 883. Non-Saturable Glucose Transfer 894. Metabolism-Flux Ratio and the Lumped Constant 90

III. Acute Changes of Glucose Transport 911. Activation and Deactivation 912. Carbon Dioxide and Spreading Depression 953. Anoxia and Ischaemia 96

IV. Chronic Changes 971. Pre- and Postnatal Development 972. Dementia 983. Hypo- and Hyperglycaemia 98

References 103

CHAPTER 5

Transport of Amino AcidsJ.-M. LEFAUCONNIER. With 3 Figures 117

A. Amino Acid Transport Systems in Animal Cells 117B. Neutral and Cationic Amino Acids 118

I. Influx 1181. Quantification of Influx 1182. Summary of the Results Obtained 120

II. Efflux 1241. Efflux in the Capillaries 1242. Passive Efflux Via the Arachnoid Villi 1273. Efflux Via the Choroid Plexus and Arachnoid Membrane. . . 127

III. Net Uptake 128C. Anionic Amino Acids 129

XIV Contents

D. Metabolism in the Endothelial Cells of Some TransportedAmino Acids 129

E. Regulation of Blood-Brain Amino Acid Transport 130I. Availability of Amino Acids: Plasma Amino Acid

Concentration 131II. Proportions and Rate of Transport of the Amino Acids

Between Blood and Brain 131III. Is Amino Acid Transport Modified by Hormones? 132IV. Can Amino Acid Transport Be Modified

by Neurotransmitters? 133F. Physiological and Pathological Modifications 134

I. Blood-Brain Amino Acid Transport During Development 1341. Technical Problems 1342. How Many Blood-Brain Transport Systems Have Been

Found in Immature Animals? 1353. Coexistence of Higher Blood-Brain Transport with a Lower

Density of Capillaries 1354. When Does the Asymmetry of Transport Between the Two

Membranes of the Endothelial Cells Appear? 136II. Effect of Drugs on Blood-Brain Transport of Amino Acids . . . . 136

III. Pathological Modifications of Amino Acid Transport 1381. Hepatic Encephalopathies 1382. Uraemia 1393. Diabetes 1394. Aminoaciduria 1405. Intoxications 1406. Depressive States 141

References 142

CHAPTER 6

Peptides and the Blood-Brain BarrierD.J. BEGLEY. With 1 Figure 151

A. Introduction: Central Actions of PeripherallyAdministered Peptides 151

B. Uptake of Peptides at the Blood-Brain Interfaces 153I. Intracarotid Bolus Injection Studies (Brain Uptake Index) . . . . 153

II. Intravenous Bolus Injection Studies 158III. Brain Perfusion Studies 164IV. Choroid Plexus Perfusion Studies 171V. Isolated Cerebral Microvessels 174

VI. Cultured Cerebral Endothelial Cells 178C. Evidence for Transport Into Brain Extracellular Fluid 181D. The Influence of Peptides on Blood-Brain Barrier Permeability

to Specific Solutes 189

Contents XV

E. General Conclusions 194References 196

CHAPTER 7

The Movement of Vitamins Into the BrainO.E. PRATT.1 With 1 Figure 205

A. Routes 205I. The Trans-Capillary Route 205

II. Other Possible Routes 205B. Mechanisms 207

I. Passive Diffusion 207II. Carrier-Mediated Transport 207

III. Binding Proteins 208IV. Covalently Bound Carriers 208

C. The Individual Vitamins 208I. Thiamine 208

II. Ascorbic Acid 211III. Pyridoxine 212IV. Folates 213V. Vitamin B,2 213

VI. Nicotinamide, Nicotinic Acid 214VII. Choline 214

VIII. Nucleosides and Purine Bases 214IX. Other B-Vitamins 215X. Lipophilic Vitamins 215

D. Clinical Implications 215E. Homeostasis 216F. Conclusions 217References 218

CHAPTER 8

Electrolyte TransportG.P. SCHIELKE and A.L. BETZ. With 3 Figures 221

A. Brain Electrolyte Homeostasis 221I. Stability of the Extracellular Potassium Concentration 221

II. Spatial Buffering of Potassium 222III. Extracellular Sodium and Chloride Concentrations 222IV. Pathologic Conditions 223

B. Blood-Brain Barrier Permeability to Electrolytes 224I. Measurements of Electrolyte Permeability 224

II. Route of Electrolyte Passage Across the BBB 2251. Passive Permeability Pathways 226

XVI Contents

2. Evidence for Active Transport Pathways 228III. Epithelial Properties of the Brain Capillary Endothelium 229IV. Mechanisms of Ion Transport Across the BBB 230

1. Luminal Entry Mechanisms 2302. Abluminal Transport Systems 233

V. Regulation of BBB Permeability to Ions 2361. Regulation by Electrolytes and Glucose 2362. Regulation by Nerves 2373. Regulation by Hormones 237

References 238

CHAPTER 9

Secretion and Bulk Flow of Interstitial FluidH.F. CSERR and C.S. PATLAK. With 4 Figures 245

A. Introduction 245B. Factors Governing Extracellular Fluid Exchanges

Within the Brain 246I. Blood-Brain Barrier 246

II. Cerebral ISF and CSF 246III. Pathways of Flow Between Brain and CSF 247

C. Bulk Flow of ISF 248I. Methods of Study 248

II. Drainage of ISF from Brain to CSF 2491. Historical Perspectives 2492. Recent Studies 250

III. Retrograde Flow of CSF Into Brain 252IV. Studies Using Horseradish Peroxidase as Tracer 253

D. Secretion of ISF by the Cerebral Endothelium: An Hypothesis 254E. Outflow of ISF to Blood and Deep Cervical Lymph 255F. Functions of ISF Flow 256

I. Clearance 256II. Brain Volume Regulation 256

III. Immune Function 258References 258

CHAPTER 10

Trace Metal Transport at the Blood-Brain BarrierM.W.B. BRADBURY. With 4 Figures 263

A. Introduction 263B. Theoretical and Experimental Approach 264C. Intravenous Administration in Intact Rat 264

Contents XVII

D. Short Vascular Perfusion of the Brain etc 266E. Solutions for Brain Perfusion etc 266F. Uptake of Various Trace Metals Into Brain

After Radiotracer Infusions 268I. Lead 270

II. Zinc 271III. Iron 273IV. Gallium 274

G. Conclusions 275References 276

CHAPTER 11

Transport of DrugsP.J. ROBINSON and S.I. RAPOPORT. With 4 Figures 279

A. Introduction 279B. Protein Binding and Drug Uptake 282

I. Kinetics of Protein Binding 283II. Measurable Quantities 284

III. Limiting Cases 2851. Restrictive Elimination 2852. Instantaneous Equilibration 2863. Dissociation-Limited Uptake 287

IV. Implications and Examples 288V. Additional Factors 289

C. Modification of the Blood-Brain Barrier 290I. Osmotic Blood-Brain Barrier Opening 290

II. Tumor Chemotherapy 294D. Conclusions 295References 297

CHAPTER 12

Clinical Assessment of Blood-Brain Barrier Permeability:Magnetic Resonance ImagingD. BARNES. With 1 Figure 301

A. Introduction 301B. Multiple Sclerosis 302C. Tumours 305D. Cerebrovascular Disease 306E. Other Cerebral Diseases 307F. Quantification of BBB Permeability 307References 309

XVIII Contents

CHAPTER 13

Clinical Assessment of the Blood-Brain Barrier:Positron Emission TomographyD.J. BROOKS. With 1 Figure 313

A. Introduction 313B. 82Rb+ Transport 314C. 68Ga-EDTA Transport 318D. Glucose Transport 319E. Albumin Diffusion and Microvascular Haematocrit 320F. Amino Acid Transport 321G. Conclusions 322References 323

CHAPTER 14

Ontogenetic Development of Brain Barrier MechanismsN.R. SAUNDERS. With 12 Figures 327

A. Introduction 327B. Barriers to Dyes and Proteins in the Developing Brain 330C. Formation of the Fundamental Blood-Brain

and Blood-CSF Barriers in the Embryonic and Fetal Brain 332D. Ultrastructure of Tight Junctions in Embryonic and Fetal Brain . . . . 333E. Cerebral Endothelial Cells In Vitro 335F. Suitable Preparations for Studies of Barrier Mechanisms

in the Developing Brain In Vivo 337G. Barrier Permeability to Lipid Insoluble Molecules

in the Fetal/Neonatal Brain 339H. CSF-Brain Barrier in the Immature Brain 341I. CSF Secretion and Pressure 345J. Electrolytes in CSF in the Developing Brain 348K. Glucose and Amino Acid Transport in the Developing Brain 351L. Proteins in CSF in the Fetus and Neonate 353M. Trace Metals and Brain-Liver Glycoproteins

in the Developing Brain :. 358N. Drugs and Barriers in the Developing Brain 360O. Conclusions 361

References 362

Contents XIX

CHAPTER 15

Comparative Physiology of the Blood-Brain BarrierN.J. ABBOTT. With 9 Figures 371

A. Introduction 371I. History of Blood-Brain Barrier Studies 371

II. Value of Comparative Studies 3721. Comparisons Between Animal Groups 3722. Selection of Convenient Experimental Preparation 3723. Preparations Offering Unique Advantages 373

B. Evolutionary Pressures Leading to Developmentof a Blood-Brain Barrier 373

I. Why Do We Need a Blood-Brain Barrier? 373II. Ionic Homeostasis and Neural Function 374

III. Isolation for Chemical Signalling 375IV. Regulation of the Periaxonal Environment 376

C. Site of the Barrier Layer 378I. Endothelial Barrier of Vertebrates 378

II. Glial Barriers in Higher Invertebrates 378III. Transitional Glial/Pericyte Barrier of Cephalopod Molluscs . . . 379IV. Apparently Anomalous Glial Blood-Brain Barrier

of Elasmobranch Fish 379V. Residual Barrier-Forming Properties of Vertebrate Glia

and Ependyma 380VI. Role of Pericytes in Barrier Function 381

D. Inductive Signals in Barrier Formation 381I. Grafting Studies: Brain Versus Non-Brain 381

II. Implanted Astrocytes 382III. Induction in Culture 383

1. Differences Between Cultured and In SituEndothelial Cells 383

2. Effects of Astrocytes on the Endothelium 3833. Effects of Endothelial Cells on Astrocytes 383

IV. Induction in Development 383V. Global Hypothesis of Induction 384

E. Comparative Approach in Developmental Studies 384I. Maturity at Birth 384

II. Blood-Brain Barrier Development and Ion Homeostasis 385III. Relation of Ontogeny and Phlyogeny 385

F. Permeability and Transport Properties of Barrier Layers 387I. The Vertebrate Endothelial Barrier 387

II. The Vertebrate Choroid Plexus 387III. The Elasmobranch Glial Barrier 388IV. The Cephalopod Glial Barrier 389V. Crustacean and Insect Glial Barriers 389

XX Contents

• VI. Comparison of Endothelial and Glial Barriers 3891. Properties Common to Barrier Layers 3892. Differences of Endothelial and Glial Barriers 389

G. Relation of Interstitial Fluid and Cerebrospinal Fluid 390I. Vertebrate Brain 390

II. Cephalopod Brain 391H. Summary and Conclusions 391

References 391

CHAPTER 16

Immunology of Brain Endothelium and the Blood-Brain BarrierD.K. MALE. With 4 Figures 397

A. Introduction 397B. Molecular Permeability 398

I. Antibodies 398II. Routes of Molecular Movement 399

C. Movement of Antigens out of the CNS 401D. Antigen Presentation by Brain Endothelial Cells 401

I. MHC Expression and Induction 402II. Stimulation of T-Cell Proliferation 404

E. Cellular Migration Across Brain Endothelium 405I. The Role of Lymphocytes 405

II. Control by Brain Endothelium 408III. Molecules Controlling Cell Migration into Brain 409

F. Summary and Synthesis 412References 412

CHAPTER 17

The Blood-Brain Barrier In Vitro and in CultureJ.J. LATERRA and G.W. GOLDSTEIN. With 6 Figures 417

A. Introduction 417B. Isolated Microvessels 418C. Transport 418

I. Glucose 421II. Amino Acids 423

III. Potassium 425D. The Blood-Brain Barrier in Cell Culture 425E. Microvessel Morphogenesis In Vitro 427F. Conclusion 432References 434

Contents XXI

CHAPTER 18

Opening of the Barrier in Cerebral PathologyP.J. LUTHERT. With 2 Figures 439

A. Introduction 439B. Demonstration of Barrier Breakdown in Pathological States 440

I. Technical Aspects 440II. Barrier Breakdown in Cerebral Tumours 440

III. Barrier Breakdown in Alzheimer's Disease 441IV. Barrier Breakdown in Other Pathological States 441

C. An Anatomical Approach to Barrier Openingin Cerebral Pathology 442

I. Luminal Factors 4421. Loss of Autoregulation 4422. Circulating Factors 443

II. Reorganisation of Angioarchitecture 4431. Angioarchitecture of Cerebral Tumours 4442. Angioarchitecture in Alzheimer's Disease 445

III. The Endothelial Cell 4451. Ultrastructural Correlates of Barrier Breakdown 445

IV. The Basement Membrane 447V. Pericytes . 448

VI. Astrocytes 4481. The Role of the Astrocyte in Barrier Maintenance 4482. Astrocyte Reactions to Cerebral Injury 448

VII. Blood-Brain Barrier Innervation 449VIII. Immune Aspects 450

IX. Parenchymal Factors 450D. Consequences of Barrier Opening 451

I. Benefits of Barrier Opening 451II. Complications of Barrier Opening 451

E. Manipulation of the Pathologically Disturbed Barrier 452F. Conclusions 452References 453

CHAPTER 19

Experimental Manipulation of the Blood-Brain and Blood-Retinal BarriersJ. GREENWOOD. With 4 Figures 459

A. Introduction 459B. Manipulation of the Blood-Brain and Blood-Retinal Barriers 461

I. Disruptive Agents of Non-Pathological Origin 4611. Hyperosmolar Solutions 4612. Bile Salts 464

XXII Contents

3. Drugs and Anaesthetics 4654. Enzymes 4685. Cations and Endothelial Cell Surface Charge 469

II. Disruptive Agents of Pathological Origin 4701. Arachidonic Acid and the Eicosanoids 4702. Histamine 4723. Bradykinin 4734. 5-Hydroxytryptamine 4745. Cytokines, Platelet Activating Factor and Complement . . . 4756. Tumour Secreted Vascular Permeability Factor 476

III. Miscellaneous Techniques 477C. Cellular Mechanisms of Increased Barrier Permeability

and Route of Leakage 478References 479

CHAPTER 20

Drug Entry Into the Brain and Its Pharmacologic ManipulationN.H. GREIG. With 18 Figures 487

A. Introduction 487B. The Presence and Function of a Blood-Brain Barrier 488

I. The Structural Barrier 488II. The Enzymatic Barrier . . 489

III. Barrier Permeability 491C. Factors Determining Time-Dependent Brain Drug Levels 493

I. Ionization. ~ 493II. Drug Binding to Plasma Proteins 494

III. Time-Dependent Plasma Concentration 495IV. Cerebral Blood Flow 498

D. Strategies for Increasing the Brain Concentration of Drugs 499I. Development of Lipophilic Analogues and Prodrugs 499

II. Carrier-Mediated Transport 510E. Summary 515References 516

CHAPTER 21

Therapeutic Opening of the Blood-Brain Barrier in ManM.K. GUMERLOCK and E.A. NEUWELT. With 2 Figures 525

A. Introduction 525B. Chemotherapy for Malignant Brain Tumors 527

I. Published Clinical Series 527II. Malignant Glioma 532

Contents XXIII

III. Cerebral Lymphoma 534IV. Metastatic Tumors to the Brain 535

C. Imaging BBB Disruption 535D. Complications of BBB Disruption/Chemotherapy 536E. Tumor-Specific Monoclonal Antibody Infusion

after BBB Disruption 537F. Treatment of Fungal Brain Abscess with BBB Disruption/

Chemotherapy 538G. Conclusion 539

References 540

Subject Index 543