Fig. 7.

A ketogenic diet accelerates changes in the glutamate receptor distribution at excitatory synapses. (A–C) Micrographs illustrating representative excitatory synapses in the stratum radiatum of the CA1 region are shown for (A) wild-type (B) mutUNG1-expressing mice fed a standard diet, and (C) mutUNG1-expressing mice fed a ketogenic diet. Red arrows indicate gold particles (black dots) representing labeled NR2A/B receptor subunits within the postsynaptic membranes (limited by black arrows). Scale bar = 100 nm. (D–F) Quantification of excitatory AMPA receptor subunits GluR1 (D), GluR2/3 (E), and NMDA receptor subunits NR2A/B (F) in the stratum radiatum of the hippocampus CA1 region. Gold particles within 25 nm of either side of the postsynaptic membranes were counted. The GluR1 and GluR2/3 labeling showed no statistically significant differences between the 3 groups of mice. The NR2A/B labeling showed a significant decrease between the wild-type and mutUNG1-expressing mice fed a standard diet (p = 0.03) and between the wild-type and mutUNG1-expressing mice fed a ketogenic diet (p = 0.01). The Mann–Whitney U test (#) revealed a significant reduction (p = 0.04) of NR2A/B labeling of synapses in mutUNG1-expressing mice on a ketogenic diet (n = 140 synapses) compared with a standard diet (n = 152 synapses). Data are shown as mean subunit-representing particle number per µm²± standard deviation, n = 3 mice per group; *p≤ 0.05; **p ≤ 0.01. Abbreviations: KD, ketogenic diet; m, mitochondria; s, postsynaptic spine; t, presynaptic terminal; v, synaptic vesicles. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)