{"id":11699,"date":"2026-10-29T12:51:41","date_gmt":"2026-10-29T12:51:41","guid":{"rendered":"https:\/\/nonsensia.pl\/?p=11699"},"modified":"2026-10-21T07:56:53","modified_gmt":"2026-10-21T07:56:53","slug":"levodopa-blood-brain-barrier-lat1-transport","status":"publish","type":"post","link":"https:\/\/nonsensia.pl\/fr\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/","title":{"rendered":"La l\u00e9vodopa et la barri\u00e8re h\u00e9mato-enc\u00e9phalique\u00a0: une mol\u00e9cule con\u00e7ue autour d\u2019un probl\u00e8me de transport"},"content":{"rendered":"

Voici un chiffre qui contredit le r\u00e9cit habituel des manuels. PubChem attribue \u00e0 la L-DOPA un XLogP3 calcul\u00e9 de −2,7 et une surface polaire topologique de 104 Å2<\/sup>. Pour la dopamine, les m\u00eames calculs donnent −1,0 et 66,5 Å2<\/sup>. Selon ces deux descripteurs, la dopamine est le compos\u00e9 le moins<\/em> polaire des deux.<\/p>\n

Pourtant, la dopamine administr\u00e9e dans la circulation sanguine n\u2019atteint pas le cerveau, alors que son pr\u00e9curseur biosynth\u00e9tique imm\u00e9diat y parvient. Si le m\u00e9canisme \u00e9tait une diffusion passive \u00e0 travers une membrane lipidique, ce r\u00e9sultat serait invers\u00e9. Comprendre la l\u00e9vodopa et la barri\u00e8re h\u00e9mato-enc\u00e9phalique suppose d\u2019abandonner enti\u00e8rement le sch\u00e9ma de la diffusion.<\/p>\n

Le probl\u00e8me de la l\u00e9vodopa face \u00e0 la barri\u00e8re h\u00e9mato-enc\u00e9phalique\u00a0: un poste de contr\u00f4le, non un mur<\/h2>\n

Les cellules endoth\u00e9liales des capillaires c\u00e9r\u00e9braux sont scell\u00e9es par des jonctions serr\u00e9es, de sorte qu\u2019une mol\u00e9cule pr\u00e9sente dans le plasma ne peut pas se glisser entre elles. Ce qu\u2019elle peut faire, c\u2019est emprunter l\u2019une des prot\u00e9ines de transport que ces cellules exposent, et le transporteur qui compte ici est LAT1, le transporteur des acides amin\u00e9s neutres \u00e0 grande cha\u00eene lat\u00e9rale, g\u00e8ne SLC7A5<\/em>.<\/p>\n

LAT1 n\u2019agit pas seul. Comme l\u2019exposent Singh et Ecker dans une revue de 2018 publi\u00e9e dans International Journal of Molecular Sciences<\/em>, il forme un h\u00e9t\u00e9rodim\u00e8re avec la glycoprot\u00e9ine 4F2hc (\u00e9galement appel\u00e9e CD98, g\u00e8ne SLC3A2<\/em>), les deux sous-unit\u00e9s \u00e9tant r\u00e9unies par un pont disulfure conserv\u00e9. 4F2hc agit comme une chaperonne qui am\u00e8ne le complexe \u00e0 la membrane. L\u2019ensemble est ind\u00e9pendant du sodium et du pH et fonctionne comme un antiport obligatoire\u00a0: pour chaque acide amin\u00e9 neutre \u00e0 grande cha\u00eene lat\u00e9rale qu\u2019il fait entrer, un acide amin\u00e9 intracellulaire sort.<\/p>\n

En 2019, Yan et ses coll\u00e8gues ont publi\u00e9 une structure du complexe humain LAT1–4F2hc dans Nature<\/em>, transformant un mod\u00e8le de transport d\u00e9duit de la cin\u00e9tique en un objet dot\u00e9 de coordonn\u00e9es.<\/p>\n

La liste de crit\u00e8res de substrat \u00e0 laquelle la dopamine ne r\u00e9pond pas<\/h2>\n

LAT1 reconna\u00eet une forme, et non un coefficient de partage. Singh et Ecker \u00e9num\u00e8rent quatre exigences structurales pour un ligand\u00a0: un groupe carboxyle Cα libre non substitu\u00e9, un groupe amino primaire Cα non substitu\u00e9, un hydrog\u00e8ne ou un m\u00e9thyle en Cα, et une cha\u00eene lat\u00e9rale neutre, hydrophobe et volumineuse. Le transport est st\u00e9r\u00e9osp\u00e9cifique et privil\u00e9gie les formes L.<\/p>\n

Confrontez ces quatre conditions aux deux mol\u00e9cules et le paradoxe se dissipe.<\/p>\n\n\n\n\n\n\n\n\n\n\n
Propri\u00e9t\u00e9<\/th>\nLevodopa<\/th>\nDopamine<\/th>\n<\/tr>\n<\/thead>\n
PubChem CID<\/td>\n6047<\/td>\n681<\/td>\n<\/tr>\n
Formule<\/td>\nC9<\/sub>H11<\/sub>NO4<\/sub><\/td>\nC8<\/sub>H11<\/sub>NO2<\/sub><\/td>\n<\/tr>\n
Masse mol\u00e9culaire<\/td>\n197,19<\/td>\n153,18<\/td>\n<\/tr>\n
XLogP3<\/td>\n−2,7<\/td>\n−1.0<\/td>\n<\/tr>\n
TPSA<\/td>\n104 Å2<\/sup><\/td>\n66.5 Å2<\/sup><\/td>\n<\/tr>\n
Carboxyle α libre<\/td>\noui<\/td>\naucun<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

La dopamine est le 4-(2-amino\u00e9thyl)benz\u00e8ne-1,2-diol. C\u2019est la l\u00e9vodopa moins un groupe carboxyle. Ce COOH manquant n\u2019est pas une diff\u00e9rence mineure de polarit\u00e9 — c\u2019est la poign\u00e9e de reconnaissance qu\u2019exige LAT1. Retirez-le et la mol\u00e9cule cesse d\u2019\u00eatre un acide amin\u00e9 pour devenir une amine qu\u2019aucun transporteur d\u2019acides amin\u00e9s n\u2019acceptera.<\/p>\n

La l\u00e9vodopa, formellement l\u2019acide (2S)-2-amino-3-(3,4-dihydroxyph\u00e9nyl)propano\u00efque, conserve le squelette intact d\u2019α-acide amin\u00e9, assorti d\u2019une cha\u00eene lat\u00e9rale cat\u00e9chol volumineuse. Aux yeux de LAT1, elle ressemble \u00e0 la tyrosine ou \u00e0 la ph\u00e9nylalanine portant un hydroxyle suppl\u00e9mentaire.<\/p>\n

La d\u00e9monstration au niveau de la barri\u00e8re elle-m\u00eame<\/h2>\n

L\u2019exp\u00e9rience directe a \u00e9t\u00e9 publi\u00e9e dans Brain Research<\/em> en 2000 par Kageyama et ses collaborateurs de l\u2019universit\u00e9 de Kyoto. Travaillant sur des cellules endoth\u00e9liales de capillaires c\u00e9r\u00e9braux de souris comme mod\u00e8le in vitro de barri\u00e8re h\u00e9mato-enc\u00e9phalique, ils ont montr\u00e9 que 4F2hc et LAT1 y sont tous deux exprim\u00e9s et forment des h\u00e9t\u00e9rodim\u00e8res, et que la captation de L-DOPA par ces cellules d\u00e9pend du temps, est sensible \u00e0 la temp\u00e9rature et ind\u00e9pendante du sodium — la signature d\u2019un transport facilit\u00e9 plut\u00f4t que d\u2019une diffusion.<\/p>\n

Les donn\u00e9es de comp\u00e9tition ont tranch\u00e9 l\u2019identification. Les acides amin\u00e9s neutres \u00e0 cha\u00eene lat\u00e9rale volumineuse inhibaient fortement la captation de L-DOPA\u00a0; les acides amin\u00e9s acides et basiques ne l\u2019affectaient quasiment pas. L\u2019immunohistochimie a localis\u00e9 LAT1 principalement dans les microvaisseaux du syst\u00e8me nerveux central. Les auteurs ont conclu que le complexe 4F2hc\/LAT1 participe au transport de la L-DOPA \u00e0 travers la barri\u00e8re.<\/p>\n

Cette comp\u00e9tition n\u2019est pas un artefact de laboratoire. Les acides amin\u00e9s neutres \u00e0 grande cha\u00eene lat\u00e9rale d\u2019origine alimentaire empruntent le m\u00eame transporteur\u00a0: celui qui achemine la l\u00e9vodopa est donc celui que la leucine, l\u2019isoleucine, la valine, la ph\u00e9nylalanine et la tyrosine occupent d\u00e9j\u00e0. Singh et Ecker rel\u00e8vent la m\u00eame inhibition comp\u00e9titive comme caract\u00e9ristique g\u00e9n\u00e9rale de la pharmacologie de LAT1, et elle s\u2019applique tout autant \u00e0 la gabapentine, au melphalan et aux hormones thyro\u00efdiennes, que la revue cite tous comme substrats de LAT1.<\/p>\n

Le second probl\u00e8me\u00a0: la mol\u00e9cule n\u2019y parvient jamais<\/h2>\n

R\u00e9soudre la reconnaissance ne r\u00e9sout pas l\u2019acheminement. La d\u00e9carboxylase des acides L-amin\u00e9s aromatiques, l\u2019enzyme qui convertit la l\u00e9vodopa en dopamine dans les neurones, est \u00e9galement abondante en dehors du syst\u00e8me nerveux central. La l\u00e9vodopa pr\u00e9sente dans la circulation est donc d\u00e9carboxyl\u00e9e en p\u00e9riph\u00e9rie, et la cat\u00e9chol-O<\/em>-m\u00e9thyltransf\u00e9rase en d\u00e9tourne une part suppl\u00e9mentaire vers la 3-O<\/em>-methyldopa.<\/p>\n

L\u2019ampleur de la perte est frappante. Une analyse de pharmacovigilance de 2025 publi\u00e9e dans Frontiers in Pharmacology<\/em> indique que, sans intervention, environ 1 % seulement de la l\u00e9vodopa administr\u00e9e par voie orale atteint les neurones dopaminergiques. Quatre-vingt-dix-neuf pour cent de la mol\u00e9cule sont consomm\u00e9s avant m\u00eame de rencontrer un transporteur LAT1 au niveau de la barri\u00e8re — et la dopamine form\u00e9e en p\u00e9riph\u00e9rie ne peut pas la suivre, pr\u00e9cis\u00e9ment pour la raison structurale expos\u00e9e plus haut.<\/p>\n

La solution a consist\u00e9 \u00e0 coadministrer un inhibiteur de la d\u00e9carboxylase. Le m\u00eame article rapporte que l\u2019association \u00e0 la carbidopa ou au bens\u00e9razide multiplie par environ dix la disponibilit\u00e9 c\u00e9r\u00e9brale et porte la demi-vie p\u00e9riph\u00e9rique de la l\u00e9vodopa \u00e0 environ 90 minutes, ce qui r\u00e9duit en retour les effets p\u00e9riph\u00e9riques tels que les naus\u00e9es et l\u2019hypotension.<\/p>\n

La structure de la carbidopa est elle-m\u00eame instructive. PubChem la d\u00e9crit comme l\u2019acide (2S)-3-(3,4-dihydroxyph\u00e9nyl)-2-hydrazinyl-2-m\u00e9thylpropano\u00efque, CID 34359, C10<\/sub>H14<\/sub>N2<\/sub>O4<\/sub>. C\u2019est la l\u00e9vodopa assortie de deux modifications d\u00e9lib\u00e9r\u00e9es\u00a0: un groupe m\u00e9thyle en Cα et, surtout, le groupe amino primaire α remplac\u00e9 par une hydrazine. C\u2019est l\u2019hydrazine qui pi\u00e8ge le cofacteur pyridoxal-phosphate de l\u2019enzyme. Cela signifie aussi que la mol\u00e9cule ne satisfait plus l\u2019exigence d\u2019un groupe amino primaire Cα non substitu\u00e9 figurant dans la liste des crit\u00e8res de substrat de LAT1 — ce qui est coh\u00e9rent avec un inhibiteur destin\u00e9 \u00e0 n\u2019agir qu\u2019en p\u00e9riph\u00e9rie.<\/p>\n

Pourquoi l\u2019histoire a pris une d\u00e9cennie<\/h2>\n

La perc\u00e9e clinique est habituellement dat\u00e9e de 1967, lorsque Cotzias, Van Woert et Schiffer ont publi\u00e9 Acides amin\u00e9s aromatiques et modification du parkinsonisme<\/em> dans la configuration New England Journal of Medicine<\/em>, volume 276, pages 374–379. Les tentatives ant\u00e9rieures avaient donn\u00e9 des r\u00e9sultats inconstants, et l\u2019arithm\u00e9tique du transport et du m\u00e9tabolisme expos\u00e9e ci-dessus explique en grande partie cette inconstance\u00a0: un compos\u00e9 qui perd 99 % de lui-m\u00eame avant d\u2019atteindre son site d\u2019action a une marge th\u00e9rapeutique impitoyable.<\/p>\n

Pour les laboratoires qui \u00e9tudient aujourd\u2019hui cette chimie, l\u2019identit\u00e9 et la puret\u00e9 du mat\u00e9riau importent autant que la biologie. Le cat\u00e9chol est sensible \u00e0 l\u2019air et le st\u00e9r\u00e9ocentre est tout l\u2019enjeu\u00a0: les travaux sont donc normalement rapport\u00e9s \u00e0 un \u00e9talon de r\u00e9f\u00e9rence analytique<\/a> accompagn\u00e9 d\u2019un certificat d\u2019analyse plut\u00f4t qu\u2019\u00e0 la teneur nominale indiqu\u00e9e sur l\u2019\u00e9tiquette.<\/p>\n

Questions fr\u00e9quentes<\/h2>\n

Pourquoi la l\u00e9vodopa franchit-elle la barri\u00e8re h\u00e9mato-enc\u00e9phalique alors que la dopamine n\u2019y parvient pas\u00a0?<\/h3>\n

Non parce que la l\u00e9vodopa serait moins polaire — les descripteurs calcul\u00e9s de PubChem la rendent plus hydrophile que la dopamine. La l\u00e9vodopa franchit la barri\u00e8re parce qu\u2019elle conserve un squelette intact d\u2019α-acide amin\u00e9, reconnu par le transporteur LAT1\/4F2hc des cellules endoth\u00e9liales des capillaires c\u00e9r\u00e9braux. La dopamine est d\u00e9pourvue du groupe carboxyle α libre qu\u2019exige ce transporteur, de sorte qu\u2019aucun transporteur ne l\u2019accepte.<\/p>\n

Qu\u2019est-ce que LAT1\u00a0?<\/h3>\n

LAT1 est le transporteur 1 des acides amin\u00e9s neutres \u00e0 grande cha\u00eene lat\u00e9rale, cod\u00e9 par SLC7A5<\/em>. Il s\u2019associe \u00e0 la glycoprot\u00e9ine 4F2hc (CD98, SLC3A2<\/em>) par un pont disulfure et fonctionne comme un antiport obligatoire ind\u00e9pendant du sodium, \u00e9changeant des acides amin\u00e9s neutres \u00e0 grande cha\u00eene lat\u00e9rale extracellulaires contre des acides amin\u00e9s intracellulaires. Il est fortement exprim\u00e9 dans les microvaisseaux du syst\u00e8me nerveux central et transporte la L-DOPA, la gabapentine, le melphalan et les hormones thyro\u00efdiennes.<\/p>\n

Pourquoi la l\u00e9vodopa est-elle administr\u00e9e avec de la carbidopa ou du bens\u00e9razide\u00a0?<\/h3>\n

La d\u00e9carboxylase des acides L-amin\u00e9s aromatiques convertit la l\u00e9vodopa en dopamine dans tout l\u2019organisme, et non seulement dans le cerveau. Les analyses publi\u00e9es estiment \u00e0 environ 1 % la fraction de l\u00e9vodopa administr\u00e9e par voie orale qui atteint les neurones dopaminergiques en l\u2019absence d\u2019inhibiteur. L\u2019ajout d\u2019un inhibiteur de la d\u00e9carboxylase \u00e0 action p\u00e9riph\u00e9rique multiplie par environ dix la disponibilit\u00e9 c\u00e9r\u00e9brale et porte la demi-vie p\u00e9riph\u00e9rique \u00e0 environ 90 minutes.<\/p>\n

Les acides amin\u00e9s alimentaires entrent-ils en comp\u00e9tition avec la l\u00e9vodopa pour le transport\u00a0?<\/h3>\n

Oui. LAT1 transporte la leucine, l\u2019isoleucine, la valine, la ph\u00e9nylalanine et la tyrosine, et Kageyama et ses coll\u00e8gues ont montr\u00e9 que les acides amin\u00e9s neutres \u00e0 cha\u00eene lat\u00e9rale volumineuse inhibent fortement la captation de L-DOPA par les cellules endoth\u00e9liales des capillaires c\u00e9r\u00e9braux, alors que les acides amin\u00e9s acides et basiques ne l\u2019inhibent pas. La comp\u00e9tition pour un transporteur partag\u00e9 est une caract\u00e9ristique intrins\u00e8que de cette voie d\u2019acheminement.<\/p>\n

R\u00e9f\u00e9rences<\/h2>\n
    \n
  1. PubChem CID 6047, l\u00e9vodopa — propri\u00e9t\u00e9s calcul\u00e9es<\/a><\/li>\n
  2. PubChem CID 681, dopamine — propri\u00e9t\u00e9s calcul\u00e9es<\/a><\/li>\n
  3. PubChem CID 34359, carbidopa — propri\u00e9t\u00e9s calcul\u00e9es<\/a><\/li>\n
  4. Kageyama T, et al. The 4F2hc\/LAT1 complex transports L-DOPA across the blood-brain barrier. Brain Res. 2000;879:115–121<\/a><\/li>\n
  5. Singh N, Ecker GF. Insights into the structure, function, and ligand discovery of the large neutral amino acid transporter 1, LAT1. Int J Mol Sci. 2018;19(5):1278<\/a><\/li>\n
  6. Yan R, Zhao X, Lei J, Zhou Q. Structure of the human LAT1–4F2hc heteromeric amino acid transporter complex. Nature 2019;568:127–130<\/a><\/li>\n
  7. Qiu H, Liu C, Wang Z. Levodopa-induced motor complications associated with benserazide and carbidopa in Parkinson’s disease. Front Pharmacol. 2025;16:1529932<\/a><\/li>\n
  8. Cotzias GC, Van Woert MH, Schiffer LM. Aromatic Amino Acids and Modification of Parkinsonism. N Engl J Med. 1967;276(7):374–379<\/a><\/li>\n<\/ol>\n
    \n

    R\u00e9serv\u00e9 \u00e0 la recherche.<\/strong> Nonsensia fournit des \u00e9talons de r\u00e9f\u00e9rence analytiques destin\u00e9s au laboratoire et \u00e0 la recherche. Cet article est publi\u00e9 \u00e0 des fins scientifiques et p\u00e9dagogiques. Il ne constitue pas un avis m\u00e9dical, il ne d\u00e9crit aucune utilisation chez l\u2019\u00eatre humain et rien de son contenu ne doit \u00eatre interpr\u00e9t\u00e9 comme une recommandation d\u2019administrer une quelconque substance \u00e0 une personne ou \u00e0 un animal.<\/p>","protected":false},"excerpt":{"rendered":"

    PubChem attribue \u00e0 la l\u00e9vodopa un XLogP3 calcul\u00e9 de -2,7 et \u00e0 la dopamine de -1,0\u00a0: l\u2019explication classique selon laquelle la dopamine serait simplement trop polaire pour franchir la barri\u00e8re ne peut donc pas \u00eatre exacte. La v\u00e9ritable r\u00e9ponse est un transporteur dot\u00e9 d\u2019une liste de crit\u00e8res structuraux stricts.<\/p>","protected":false},"author":517,"featured_media":11779,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[384],"tags":[],"class_list":["post-11699","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-chemistry-discovery"],"yoast_head":"\nLevodopa and the Blood-Brain Barrier: LAT1 Explained<\/title>\n<meta name=\"description\" content=\"Levodopa is more hydrophilic than dopamine, yet only levodopa reaches the brain. The reason is LAT1 recognition, not passive diffusion.\" \/>\n<meta name=\"robots\" content=\"noindex, follow\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Levodopa and the Blood-Brain Barrier: LAT1 Explained\" \/>\n<meta property=\"og:description\" content=\"Levodopa is more hydrophilic than dopamine, yet only levodopa reaches the brain. The reason is LAT1 recognition, not passive diffusion.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/nonsensia.pl\/fr\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/\" \/>\n<meta property=\"og:site_name\" content=\"Nonsensia\" \/>\n<meta property=\"article:published_time\" content=\"2026-10-29T12:51:41+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/nonsensia.pl\/wp-content\/uploads\/2026\/09\/nonsensia-chemistry-discovery.png\" \/>\n\t<meta property=\"og:image:width\" content=\"1200\" \/>\n\t<meta property=\"og:image:height\" content=\"630\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"author\" content=\"Thomas Reyner\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Thomas Reyner\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"7 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/\"},\"author\":{\"name\":\"Thomas Reyner\",\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/#\\\/schema\\\/person\\\/97c0a8a75ea8c654fd606679bb6d01fb\"},\"headline\":\"Levodopa and the Blood-Brain Barrier: A Molecule Designed Around a Transport Problem\",\"datePublished\":\"2026-10-29T12:51:41+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/\"},\"wordCount\":1446,\"publisher\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/#organization\"},\"image\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/nonsensia.pl\\\/wp-content\\\/uploads\\\/2026\\\/09\\\/nonsensia-chemistry-discovery.png\",\"articleSection\":[\"Chemistry & Discovery\"],\"inLanguage\":\"fr-FR\",\"copyrightYear\":\"2026\",\"copyrightHolder\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/fr\\\/#organization\"}},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/\",\"url\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/\",\"name\":\"Levodopa and the Blood-Brain Barrier: LAT1 Explained\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/nonsensia.pl\\\/wp-content\\\/uploads\\\/2026\\\/09\\\/nonsensia-chemistry-discovery.png\",\"datePublished\":\"2026-10-29T12:51:41+00:00\",\"description\":\"Levodopa is more hydrophilic than dopamine, yet only levodopa reaches the brain. The reason is LAT1 recognition, not passive diffusion.\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#breadcrumb\"},\"inLanguage\":\"fr-FR\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#primaryimage\",\"url\":\"https:\\\/\\\/nonsensia.pl\\\/wp-content\\\/uploads\\\/2026\\\/09\\\/nonsensia-chemistry-discovery.png\",\"contentUrl\":\"https:\\\/\\\/nonsensia.pl\\\/wp-content\\\/uploads\\\/2026\\\/09\\\/nonsensia-chemistry-discovery.png\",\"width\":1200,\"height\":630,\"caption\":\"Chemistry & Discovery \u2014 analytical reference standards, Nonsensia\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/nonsensia.pl\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Levodopa and the Blood-Brain Barrier: A Molecule Designed Around a Transport Problem\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/#website\",\"url\":\"https:\\\/\\\/nonsensia.pl\\\/\",\"name\":\"Nonsensia\",\"description\":\"NON-SENSIA...? We bring sense!\",\"publisher\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/nonsensia.pl\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"fr-FR\"},{\"@type\":[\"Organization\",\"Place\"],\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/#organization\",\"name\":\"Nonsensia\",\"url\":\"https:\\\/\\\/nonsensia.pl\\\/\",\"logo\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#local-main-organization-logo\"},\"image\":{\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#local-main-organization-logo\"},\"telephone\":[],\"openingHoursSpecification\":[{\"@type\":\"OpeningHoursSpecification\",\"dayOfWeek\":[\"Monday\",\"Tuesday\",\"Wednesday\",\"Thursday\",\"Friday\",\"Saturday\",\"Sunday\"],\"opens\":\"09:00\",\"closes\":\"17:00\"}],\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"ul. Marsza\u0142kowska 80\",\"postalCode\":\"00-517\",\"addressLocality\":\"Warszawa\",\"addressCountry\":\"PL\"},\"email\":\"lab@nonsensia.pl\"},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/#\\\/schema\\\/person\\\/97c0a8a75ea8c654fd606679bb6d01fb\",\"name\":\"Thomas Reyner\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/17721409ed81a1e4666b08b23530653af17971df2e2cde4fad397c4da1e60ba7?s=96&d=mm&r=g\",\"url\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/17721409ed81a1e4666b08b23530653af17971df2e2cde4fad397c4da1e60ba7?s=96&d=mm&r=g\",\"contentUrl\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/17721409ed81a1e4666b08b23530653af17971df2e2cde4fad397c4da1e60ba7?s=96&d=mm&r=g\",\"caption\":\"Thomas Reyner\"},\"description\":\"Writes on spectroscopy, structural elucidation and laboratory instrumentation for Nonsensia.\",\"url\":\"https:\\\/\\\/nonsensia.pl\\\/fr\\\/author\\\/treyner\\\/\"},{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\\\/\\\/nonsensia.pl\\\/2026\\\/10\\\/29\\\/levodopa-blood-brain-barrier-lat1-transport\\\/#local-main-organization-logo\",\"url\":\"https:\\\/\\\/nonsensia.pl\\\/wp-content\\\/uploads\\\/2024\\\/12\\\/cropped-Nonsensia_Logo-8.png\",\"contentUrl\":\"https:\\\/\\\/nonsensia.pl\\\/wp-content\\\/uploads\\\/2024\\\/12\\\/cropped-Nonsensia_Logo-8.png\",\"width\":512,\"height\":512,\"caption\":\"Nonsensia\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Levodopa and the Blood-Brain Barrier: LAT1 Explained","description":"Levodopa is more hydrophilic than dopamine, yet only levodopa reaches the brain. The reason is LAT1 recognition, not passive diffusion.","robots":{"index":"noindex","follow":"follow"},"og_locale":"fr_FR","og_type":"article","og_title":"Levodopa and the Blood-Brain Barrier: LAT1 Explained","og_description":"Levodopa is more hydrophilic than dopamine, yet only levodopa reaches the brain. The reason is LAT1 recognition, not passive diffusion.","og_url":"https:\/\/nonsensia.pl\/fr\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/","og_site_name":"Nonsensia","article_published_time":"2026-10-29T12:51:41+00:00","og_image":[{"width":1200,"height":630,"url":"https:\/\/nonsensia.pl\/wp-content\/uploads\/2026\/09\/nonsensia-chemistry-discovery.png","type":"image\/png"}],"author":"Thomas Reyner","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Thomas Reyner","Est. reading time":"7 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#article","isPartOf":{"@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/"},"author":{"name":"Thomas Reyner","@id":"https:\/\/nonsensia.pl\/#\/schema\/person\/97c0a8a75ea8c654fd606679bb6d01fb"},"headline":"Levodopa and the Blood-Brain Barrier: A Molecule Designed Around a Transport Problem","datePublished":"2026-10-29T12:51:41+00:00","mainEntityOfPage":{"@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/"},"wordCount":1446,"publisher":{"@id":"https:\/\/nonsensia.pl\/#organization"},"image":{"@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#primaryimage"},"thumbnailUrl":"https:\/\/nonsensia.pl\/wp-content\/uploads\/2026\/09\/nonsensia-chemistry-discovery.png","articleSection":["Chemistry & Discovery"],"inLanguage":"fr-FR","copyrightYear":"2026","copyrightHolder":{"@id":"https:\/\/nonsensia.pl\/fr\/#organization"}},{"@type":"WebPage","@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/","url":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/","name":"Levodopa and the Blood-Brain Barrier: LAT1 Explained","isPartOf":{"@id":"https:\/\/nonsensia.pl\/#website"},"primaryImageOfPage":{"@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#primaryimage"},"image":{"@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#primaryimage"},"thumbnailUrl":"https:\/\/nonsensia.pl\/wp-content\/uploads\/2026\/09\/nonsensia-chemistry-discovery.png","datePublished":"2026-10-29T12:51:41+00:00","description":"Levodopa is more hydrophilic than dopamine, yet only levodopa reaches the brain. The reason is LAT1 recognition, not passive diffusion.","breadcrumb":{"@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#breadcrumb"},"inLanguage":"fr-FR","potentialAction":[{"@type":"ReadAction","target":["https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/"]}]},{"@type":"ImageObject","inLanguage":"fr-FR","@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#primaryimage","url":"https:\/\/nonsensia.pl\/wp-content\/uploads\/2026\/09\/nonsensia-chemistry-discovery.png","contentUrl":"https:\/\/nonsensia.pl\/wp-content\/uploads\/2026\/09\/nonsensia-chemistry-discovery.png","width":1200,"height":630,"caption":"Chemistry & Discovery \u2014 analytical reference standards, Nonsensia"},{"@type":"BreadcrumbList","@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/nonsensia.pl\/"},{"@type":"ListItem","position":2,"name":"Levodopa and the Blood-Brain Barrier: A Molecule Designed Around a Transport Problem"}]},{"@type":"WebSite","@id":"https:\/\/nonsensia.pl\/#website","url":"https:\/\/nonsensia.pl\/","name":"Nonsensia","description":"NON-SENSIA...? We bring sense!","publisher":{"@id":"https:\/\/nonsensia.pl\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/nonsensia.pl\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"fr-FR"},{"@type":["Organization","Place"],"@id":"https:\/\/nonsensia.pl\/#organization","name":"Nonsensia","url":"https:\/\/nonsensia.pl\/","logo":{"@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#local-main-organization-logo"},"image":{"@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#local-main-organization-logo"},"telephone":[],"openingHoursSpecification":[{"@type":"OpeningHoursSpecification","dayOfWeek":["Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"],"opens":"09:00","closes":"17:00"}],"address":{"@type":"PostalAddress","streetAddress":"ul. Marsza\u0142kowska 80","postalCode":"00-517","addressLocality":"Warszawa","addressCountry":"PL"},"email":"lab@nonsensia.pl"},{"@type":"Person","@id":"https:\/\/nonsensia.pl\/#\/schema\/person\/97c0a8a75ea8c654fd606679bb6d01fb","name":"Thomas Reyner","image":{"@type":"ImageObject","inLanguage":"fr-FR","@id":"https:\/\/secure.gravatar.com\/avatar\/17721409ed81a1e4666b08b23530653af17971df2e2cde4fad397c4da1e60ba7?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/17721409ed81a1e4666b08b23530653af17971df2e2cde4fad397c4da1e60ba7?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/17721409ed81a1e4666b08b23530653af17971df2e2cde4fad397c4da1e60ba7?s=96&d=mm&r=g","caption":"Thomas Reyner"},"description":"\u00c9crit sur la spectroscopie, l'\u00e9lucidation structurale et l'instrumentation de laboratoire pour Nonsensia.","url":"https:\/\/nonsensia.pl\/fr\/author\/treyner\/"},{"@type":"ImageObject","inLanguage":"fr-FR","@id":"https:\/\/nonsensia.pl\/2026\/10\/29\/levodopa-blood-brain-barrier-lat1-transport\/#local-main-organization-logo","url":"https:\/\/nonsensia.pl\/wp-content\/uploads\/2024\/12\/cropped-Nonsensia_Logo-8.png","contentUrl":"https:\/\/nonsensia.pl\/wp-content\/uploads\/2024\/12\/cropped-Nonsensia_Logo-8.png","width":512,"height":512,"caption":"Nonsensia"}]}},"_links":{"self":[{"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/posts\/11699","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/users\/517"}],"replies":[{"embeddable":true,"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/comments?post=11699"}],"version-history":[{"count":3,"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/posts\/11699\/revisions"}],"predecessor-version":[{"id":12008,"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/posts\/11699\/revisions\/12008"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/media\/11779"}],"wp:attachment":[{"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/media?parent=11699"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/categories?post=11699"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nonsensia.pl\/fr\/wp-json\/wp\/v2\/tags?post=11699"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}