Therapeutischer Einfluss des Radikalfängers Trolox in einem Mausmodell für das Rett-Syndrom: Bewertung oxidativer Stressmarker in zerebralem Gewebe
Therapeutic impact of the free-radical scavenger Trolox in a mouse model of Rett-syndrome: Assessment of oxidative stress marker in cerebral tissue
von Marc Albert Hüser
Datum der mündl. Prüfung:2017-05-23
Erschienen:2017-05-10
Betreuer:Prof. Dr. Michael Müller
Gutachter:Prof. Dr. Michael Müller
Gutachter:Prof. Dr. Freddy Wouters-Bunt
Dateien
Name:Marc Diss final2.5.pdf
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Zusammenfassung
Englisch
The aim of this work was to assess a variety of phenotypic and biochemical features in a mouse model of Rett-syndrome, which was treated in vivo with the free radical scavenger Trolox. Rett-syndrome is a postnatal progressive neurological developmental disorder. At present a cure is not available. It has been known for long that blood samples of Rett patients show reduced vitamin E levels. Also, unbalanced levels of reactive oxygen species (ROS) are a critical aspect of this disorder. Accordingly, the in vivo vitamin E supplementation with the antioxidant Trolox, represents a plausible therapeutic approach, which has already been successfully tested in isolated brain tissue of these mice. The analyses carried out in this thesis represent only part of a detailed preclinical testing of antioxidants for the treatment of Rett syndrome, which is currently conducted in the hosting lab. Accordingly, the overall view of all experiments carried out within the framework of this project is important. The major focus of my thesis was to establish two biochemical methods - the protein carbonylation assay and the lipid peroxidation measurements in isolated brain tissue. In addition, mitochondrial membrane potentials were monitored photometrically, the behavior of the treated mice was tested, and the morphological tissue structure was analyzed by Nissl staining. After systemic Trolox treatment, significant changes could be detected for some of tested parameters. In particular, the extent of lipid peroxidation in frontal cortex was reduced and the exploratory activity of the Mecp2-/y mice was improved. However, in part Trolox had also inverse effects on wildtype mice, suggesting an extremely sensitive redox balance and emphasizing the importance of a careful antioxidant dosing. Furthermore, clear indications for handling effects became evident in the mice which were treated for several weeks. This issue needs to be addressed in the future by optimizing study design. For example, an application of drug substances via food may be considered to rule out such unwanted handling effects. Furthermore, the exact blood-brain barrier permeation of Trolox may be a limiting factor. Therefore, a combination of vitamin E compounds for example with vitamin C could be considered, since the recovery of vitamin E is directly related to the availability of vitamin C. As a result, synergistic effects and an improved drug efficiency may be expected.
Keywords: Trolox; reactive oxygen species (ROS); antioxidant treatment; oxidative stress; mitochondrial dysfunction; oxidative tissue damage; mouse behavior; Rett-syndrome; vitamin E