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Oxidative Medicine and Cellular Longevity
Volume 2017 (2017), Article ID 3064016, 15 pages
https://doi.org/10.1155/2017/3064016
Research Article

Increased Mitochondrial Mass and Cytosolic Redox Imbalance in Hippocampal Astrocytes of a Mouse Model of Rett Syndrome: Subcellular Changes Revealed by Ratiometric Imaging of JC-1 and roGFP1 Fluorescence

1Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Georg-August-Universität Göttingen, Universitätsmedizin Göttingen, Göttingen, Germany
2Zentrum Physiologie und Pathophysiologie, Institut für Neuro- und Sinnesphysiologie, Humboldtallee, 23 Göttingen, Germany

Correspondence should be addressed to Michael Müller; ed.gdwg@7elleumm

Received 15 March 2017; Revised 16 June 2017; Accepted 27 June 2017; Published 13 August 2017

Academic Editor: Icksoo Lee

Copyright © 2017 Dörthe F. Bebensee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Rett syndrome (RTT) is a neurodevelopmental disorder with mutations in the MECP2 gene. Mostly girls are affected, and an apparently normal development is followed by cognitive impairment, motor dysfunction, epilepsy, and irregular breathing. Various indications suggest mitochondrial dysfunction. In Rett mice, brain ATP levels are reduced, mitochondria are leaking protons, and respiratory complexes are dysregulated. Furthermore, we found in MeCP2-deficient mouse (Mecp2−/y) hippocampus an intensified mitochondrial metabolism and ROS generation. We now used emission ratiometric 2-photon imaging to assess mitochondrial morphology, mass, and membrane potential (ΔΨm) in Mecp2−/y hippocampal astrocytes. Cultured astrocytes were labeled with the ΔΨm marker JC-1, and semiautomated analyses yielded the number of mitochondria per cell, their morphology, and ΔΨm. Mecp2−/y astrocytes contained more mitochondria than wild-type (WT) cells and were more oxidized. Mitochondrial size, ΔΨm, and vulnerability to pharmacological challenge did not differ. The antioxidant Trolox opposed the oxidative burden and decreased the mitochondrial mass, thereby dampening the differences among WT and Mecp2−/y astrocytes; mitochondrial size and ΔΨm were not markedly affected. In conclusion, mitochondrial alterations and redox imbalance in RTT also involve astrocytes. Mitochondria are more numerous in Mecp2−/y than in WT astrocytes. As this genotypic difference is abolished by Trolox, it seems linked to the oxidative stress in RTT.