石川 浩章

Fructose consumption is rising globally, but maternal high fructose intake might adversely affect offspring. Our previous report demonstrated that excess maternal fructose intake impairs hippocampal function in offspring, indicating that the hippocampi of offspring are highly sensitive to maternal fructose. Here, we examined the effect of maternal high fructose on mitochondrial physiology and uncoupling protein (UCP) expression. Rat dams received a 20% fructose solution during gestation and lactation. Immediately after weaning, offspring hippocampi were isolated. Maternal high fructose consumption attenuated the mitochondrial O2 consumption rate and stimulated lipid hydroperoxide production in the hippocampi of offspring. Reduced Ucp5 and mitochondrial transcription factor A (Tfam) mRNA levels were also observed after maternal exposure to fructose. We assessed the promoter regions of both genes and found that this treatment enhanced DNA methylation levels. In addition, luciferase assays showed that this DNA methylation could reduce the transcription of both genes. Chromatin immunoprecipitation analysis demonstrated that specificity protein 1 binding to the Ucp5 promoter regions was reduced by DNA methylation. In addition, Ucp5 knockdown induced the up-regulation of reactive oxygen species levels in a rat brain glioma cell line, whereas reduced O2 consumption was observed with Tfam knockdown. Maternal high fructose intake thus induces reduced O2 oxygen consumption and increases oxidative stress in offspring, at least partly through epigenetic mechanisms involving Ucp5 and Tfam.-Yamada, H., Munetsuna, E., Yamazaki, M., Mizuno, G., Sadamoto, N., Ando, Y., Fujii, R., Shiogama, K., Ishikawa, H., Suzuki, K., Shimono, Y., Ohashi, K., Hashimoto, S. Maternal fructose-induced oxidative stress occurs viaTfam and Ucp5 epigenetic regulation in offspring hippocampi.

Global fructose consumption is on the rise; however, maternal high-fructose intake may have adverse effects on offspring. We previously demonstrated that excessive fructose intake by rat dams altered steroidogenic gene transcription in the hippocampus of offspring. Herein, we examined how maternal high-fructose intake influences the regulation of adrenal glucocorticoid levels in offspring. Rat dams received 20% fructose solution during gestation and lactation. After weaning, the offspring were provided normal water. Maternal high-fructose intake did not alter mRNA expression levels of adrenal corticosterone-synthesizing and corticosterone-inactivating proteins or the circulating adrenocorticotropic hormone levels of offspring at postnatal day (PD) 21; however, it increased circulating corticosterone levels and decreased mRNA and protein levels of adrenal 5α-reductase type 1 and 11β-hydroxysteroid dehydrogenase type 2 in offspring at PD160. Furthermore, maternal high-fructose intake enhanced DNA methylation of the adrenal 5α-reductase 1 promoter region in PD160 offspring. Thus, maternal high-fructose intake was found to affect adrenal steroid hormone clearance in adult offspring - at least in part - through epigenetic mechanisms.