Eisen im alternden Gehirn

Ein Überschuss an Eisen im Gehirn trägt zu Alterung und Neurodegeneration in Form verschiedener Erkrankungen bei. Dieser Übersichtsartikel beschreibt die Grundlagen der zerebralen Eisenaufnahme und -speicherung, zeigt ihre Bedeutung für Alterung und Neurodegeneration auf und gibt einen Ausblick auf entsprechende Therapieoptionen.

Kernaussagen

• Eisen ist ein essenzielles Spurenelement für eine Vielzahl von Stoffwechselreaktionen des Körpers. Auch im Gehirn ist es von besonderer Bedeutung. Die Aufnahme über die Blut-Hirn-Schranke und die Verteilung und Speicherung im Gehirn sind streng reguliert, damit neurotoxische Effekte des Eisens verhindert werden.

• Im alternden Gehirn geht eine vermehrte Eisenspeicherung in Kortex und Basalganglien mit Einschränkungen der kognitiven und motorischen Fähigkeiten einher. Es wird außerdem davon ausgegangen, dass Eisen zu neurodegenerativen Erkrankungen des Alters wie Morbus Parkinson und Morbus Alzheimer beiträgt.

• Eine vermehrte Eisenablagerung findet sich beim Morbus Parkinson in der Substantia nigra, wo dopaminerge Neurone untergehen. Eisen fördert außerdem die α-Synuclein-Aggregation in Lewy-Körperchen und sorgt für die Bildung toxischer Hydroxylradikale.

• Beim Morbus Alzheimer ist Eisen an der Bildung von β-Amyloid-Plaques und Neurofibrillenbündeln beteiligt. Eine verminderte Ferroxidaseaktivität des Amyloidvorläuferproteins trägt zu erhöhter zerebraler Eisenakkumulation bei. Die Liquorferritinspiegel bei Trägern des Alzheimer-Risikoallels ApoE4 sind erhöht. Klinisch sind die Eisenspiegel in Basalganglien und Hippokampi negativ mit kognitiven Leistungen assoziiert. Gleichzeitig sind erhöhte Liquorferritinspiegel mit früherem Krankheitsbeginn assoziiert.

• Schließlich betont die pathologische zerebrale Eisenakkumulation bei allen Subformen der NBIA die Bedeutung des Eisens für neurodegenerative Erkrankungen.

Schlüsselwörter

Eisen - Altern - Gehirn - Neurodegeneration

• Literatur

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