Skeletal muscle Nr4a1 hypomethylation and gene induction reduce insulin sensitivity in sedentary maternal high-fat offspring

Maternal high-fat consumption has negative effects on the offspring’s obesity/diabetes susceptibility and we hypothesize that epigenetic modifications in the skeletal muscle are partly responsible for this phenotype. To detect genes affected by maternal nutrition, offspring of low-fat (LF) and high-fat (HF) diet fed dams (C57BL/6 mice) received LF diet upon weaning and were sacrificed at an age of 6 or 25 weeks. M. quadriceps gene expression was investigated by microarray analysis revealing upregulation of the nuclear receptor Nr4a1 by maternal HF feeding. This was accompanied by promoter hypomethylation of CpG‑1408 which correlated with higher Nr4a1 gene expression at both ages. Offspring voluntary exercise training normalized Nr4a1 methylation/expression and ameliorated the negative effects of maternal HF feeding on insulin sensitivity. Overall, Nr4a1 expression correlated with higher insulin levels during oral glucose tolerance test and could, therefore, be involved in the programming offspring’s diabetes susceptibility. Starting three days prior to mating, female C57BL/6J mice (8 weeks old) received either a semisynthetic low-fat (LF; 10% energy from fat, 23% energy from protein, 67% energy from carbohydrates) or HF diet (40% energy from fat, 23% energy from protein, 37% energy from carbohydrates) diet during pregnancy and lactation (mLFD and mHFD, resp.). For mating, two females were introduced to one male for two weeks and subsequently individually caged. The litter size was adjusted to 5–7 pups, with no more than four siblings finally present in one group. Mice were kept in a light- and temperature-controlled facility at 22°C with a 12 h light-12 h dark cycle. After weaning, mLF and mHF male offspring were single caged and received LF until the end of the study at 6 weeks of age. All mice were sacrificed after 2 h of fasting using isoflurane and cervical dislocation.