Folic acid supplementation modulates offspring genes involved in energy metabolism: In vivo study

Summary: Background & aims: Nutritional epigenetics involves essential mechanisms for proper embryonic development in mammals. Changes in this stage cause various metabolic disorders. Under healthy conditions, epigenetic processes and adequate homeostasis, especially energy metabolism, are balanced. However, interruption or imbalance of metabolic homeostasis, or both, leads to several pathologies, such as insulin resistance, cardiovascular diseases, and obesity. This study investigates the methylation and expression patterns of the peroxisome proliferator-activated receptor gamma (Pparγ) and forkhead Box 1 (Foxo1) genes in rat offspring submitted to folate-deficient or folate-supplemented diet. Methods: Groups of male and female Wistar rat offspring (n=40 per group, 3 groups) were fed folate-normal (control), a folate-deficient, or a folate-supplemented diet (2.0, 0.5, or 8.0 mg of folic acid/kg of feed, respectively) for 13 weeks. The diet was the same diet the mothers had received during pregnancy and lactation. Liver, white adipose tissue (WAT), and brown adipose tissue (BAT) samples were collected. Specific commercial kits were used to extract RNA, DNA, and protein from these samples. Gene expression, DNA methylation, and protein expression were analyzed by polymerase chain reaction (PCR), Pyrosequencing, and Western Blot, respectively. Results: In liver, the Pparγ and Foxo1 genes did not differ in terms of DNA methylation; however, Pparγ gene expression was higher (P=0.03) in the folate-supplemented diet group than in the other groups. Hepatic Pparγ protein expression was higher (P=0.00) in the folate-supplemented and folate-deficient diet groups than in the control diet group. Hepatic Foxo1 protein expression was lower (P=0.01) in the folate-supplemented diet group than in the other groups. In WAT, Foxo1 methylation was lower (P=0.00) in the folate-supplemented diet group than in the control diet group; Pparγ methylation was lower (P=0.02) in the folate-deficient diet group than in the control diet group; and Foxo1 gene expression was higher (P=0.01) in the folate-supplemented diet group than in the folate-deficient diet group. In BAT, the folate-deficient and folate-supplemented diet groups had lower Pparγ gene expression (P=0.00) and protein (P=0.00) expression than the control diet group. Conclusion: Depending on offspring sex and tissue, folate-supplemented diet generally modulates genes in a beneficial way because these genes are involved in energy metabolism and may participate in some pathways related to metabolic diseases.