TABLE 1.
The Brain-to-Blood Efflux Transport Systems at the Blood-Brain Barrier
| Type | Substrates | Transporters | Localization |
|---|---|---|---|
| Neurotransmitters | GABA | GAT2/BGT-1 | ND |
| Serotonin | SERT | A, L | |
| Norepinephrine, dopamine | NET | A | |
| Neurotransmitter metabolite | Homovanillic acid | OAT3 | A |
| Excitatory amino acids | l-Glutamic acid, l-aspartic acid | ASCT2, EAATs | A |
| Neuromodulators | DHEAS, E1S, E217βG | oatp2 | A, L |
| Glycine, l-alanine, l-proline | ATA2 | ND | |
| Uremic toxin | Indoxyl sulfate | OAT3 | A |
| Xenobiotics | Vincristine, cyclosporine | MDR1/ABCB1 | L |
| Estradiol glucuronide | MRP1/ABCC1 | L | |
| Prazosin, mitoxantron | ABCG2 | L | |
| 6-Mercaptopurine | OAT3 | A | |
| BQ-123 | oatp2 | A, L | |
| Azidothymidine, dideoxyinosine | Unknown | ||
| Valproic acid | Unknown | ||
| Macromolecules | Ig | Fc receptor | |
| Apo-tranferrine | Tf receptor | ||
| β-Amyloid peptide | LRP-1, MDR1 |
EAATs = excitatory amino acid transporters; E217βG = estradiol-d-17β-glucuronide; Tf receptor = transferrin receptor; A = abluminal localization; L = luminal localization; ND = not determined.