Fig. 3.

mutUNG1-expressing mice fed a ketogenic diet have upregulated mitochondrial antioxidant defenses. (A) Coronal sections of paraffin-embedded hippocampus immunolabeled for SOD2 (green) indicate induction in mitochondrial antioxidant defenses in mutUNG1-expressing mice fed a standard diet, and a further strong increase in mutUNG1-expressing mice fed a ketogenic diet (KD). The nuclear DNA encoded electron transport complex II (red, middle row) shows a similar distribution as SOD2 in all 3 conditions. In the merged frames (bottom row), yellow-orange color signifies colocalization of immunoreactivities in the same structures. Strong mitochondrial labeling of perikarya (arrowhead) in mutUNG1 mice with and without ketogenic diet but not in wild-type mice. Both red and green are brighter for mutUNG1 + KD than for only mutUNG1. Stippled rectangle indicates region of interest used for quantification of immunoreactivity (B), stippled squares indicate approximate positions of close-up pictures (C). Scale bar = 100 µm (objective lens 10 ×). (B) Quantification of SOD2 and mitochondrial complex II immunofluorescence (average per area in rectangular regions of interest as indicated in A (top). SOD2 increases in mutUNG1 mice compared to wild-type (p = 0.003) and in mutUNG1 mice fed a ketogenic diet (p < 0.0001). Complex II increases in mutUNG1 mice when fed a ketogenic diet (p = 0.001). (C) High magnification of areas equivalent to the stippled squares in A demonstrates colocalization of SOD2 and complex II in mitochondria-like structures in neuronal perikarya (dg cells, large arrowheads) as well as in the neuropil (small arrowheads). Clusters of such structures accumulate in neuronal perikarya in mutUNG1-expressing mice, particularly when on ketogenic diet (lower right frame). Scale bar = 10 µm (objective lens 63× oil immersion). Abbreviations: dg, granule cell layer; h, hilus of the dentate gyrus; lm, stratum lacunosum-moleculare of hippocampus CA1; m, stratum moleculare of dentate gyrus; o, stratum oriens; p, pyramidal cell layer; r, stratum radiatum; SOD2, superoxide dismutase 2; asterisk series marks fissura hippocampi between lm and m. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)