DNA Hypomethylation of GR Promoters is Associated with GR Activation and BDNF/AKT/ERK1/2-Induced Hippocampal Neurogenesis in Mice Derived From Folic-Acid-Supplemented Dams

SCOPE

Glucocorticoid receptor (GR) mediates the nutritional programing of offspring performance. Maternal folic acid has been shown to regulate hippocampal neurogenesis and affect cognitive function in offspring, yet it remains unclear whether and how GR is involved in such effects.

METHODS AND RESULTS

Adult male mice derived from dams fed basal or folic-acid-supplemented diet (5 mg folic acid/kg) throughout gestation and lactation are used in this study. Maternal folic acid significantly enhances offspring learning and memory with less fear-related behavior. Concurrently, hippocampal neurogenesis is improved with upregulation of brain-derived neurotrophic factor and its downstream AKT/ERK1/2 signaling pathway. More GR immune-positive cells are observed in hippocampus of folic acid group, which are in line with higher GR protein and mRNA abundances. Differential expression of GR exon 1 transcript variants is detected, which is inversely associated with modified DNA methylation on their alternate promoters.

CONCLUSION

The results indicate that maternal folic acid supplementation promotes hippocampal neurogenesis and improves learning and memory behavior in mouse offspring. The mechanisms involve modification of DNA methylation on GR alternate promoters and GR upregulation in the hippocampus, which is associated with activation of BDNF/AKT/ERK1/2 signaling.

Nutritional Influence on Epigenetic Marks and Effect on Livestock Production

Nutrition represents one of the greatest environmental determinants of an individual’s health. While nutrient quantity and quality impart direct effects, the interaction of nutrition with genetic and epigenetic modifications is often overlooked despite being shown to influence biological variation in mammals. Dissecting complex traits, such as those that are diet or nutrition related, to determine the genetic and epigenetic contributions toward a phenotype can be a formidable process. Epigenetic modifications add another layer of complexity as they do not change the DNA sequence itself but can affect transcription and are important mediators of gene expression and ensuing phenotypic variation. Altered carbohydrate metabolism and rates of fat and protein deposition resulting from diet-induced hypo- or hyper-methylation highlight the capability of nutritional epigenetics to influence livestock commodity quality and quantity. This interaction can yield either products tailored to consumer preference, such as marbling in meat cuts, or potentially increasing productivity and yield both in terms of carcass yield and/or offspring performance. Understanding how these and other desirable phenotypes result from epigenetic mechanisms will facilitate their inducible potential in livestock systems. Here, we discuss the establishment of the epigenome, examples of nutritional mediated alterations of epigenetics and epigenetic effects on livestock production.

In utero Undernutrition Programs Skeletal and Cardiac Muscle Metabolism

In utero undernutrition is associated with increased risk for insulin resistance, obesity, and cardiovascular disease during adult life. A common phenotype associated with low birth weight is reduced skeletal muscle mass. Given the central role of skeletal muscle in whole body metabolism, alterations in its mass as well as its metabolic characteristics may contribute to disease risk. This review highlights the metabolic alterations in cardiac and skeletal muscle associated with in utero undernutrition and low birth weight. These tissues have high metabolic demands and are known to be sites of major metabolic dysfunction in obesity, type 2 diabetes, and cardiovascular disease. Recent research demonstrates that mitochondrial energetics are decreased in skeletal and cardiac muscles of adult offspring from undernourished mothers. These effects apparently lead to the development of a thrifty phenotype, which may represent overall a compensatory mechanism programmed in utero to handle times of limited nutrient availability. However, in an environment characterized by food abundance, the effects are maladaptive and increase adulthood risks of metabolic disease.