Impact of maternal high fat diet on hypothalamic transcriptome in neonatal Sprague Dawley rats

Maternal consumption of a high fat diet during early development has been shown to impact the formation of hypothalamic neurocircuitry, thereby contributing to imbalances in appetite and energy homeostasis and increasing the risk of obesity in subsequent generations. Early in postnatal life, the neuronal projections responsible for energy homeostasis develop in response to appetite-related peptides such as leptin. To date, no study characterises the genome-wide transcriptional changes that occur in response to exposure to high fat diet during this critical window. We explored the effects of maternal high fat diet consumption on hypothalamic gene expression in Sprague Dawley rat offspring at postnatal day 10. RNA-sequencing enabled discovery of differentially expressed genes between offspring of dams fed a high fat diet and offspring of control diet fed dams. Female high fat diet offspring displayed altered expression of 86 genes (adjusted P-value<0.05), including genes coding for proteins of the extra cellular matrix, particularly Collagen 1a1 (Col1a1), Col1a2, Col3a1, and the imprinted Insulin-like growth factor 2 (Igf2) gene. Male high fat diet offspring showed significant changes in collagen genes (Col1a1 and Col3a1) and significant upregulation of two genes involved in regulation of dopamine availability in the brain, tyrosine hydroxylase (Th) and dopamine reuptake transporter Slc6a3 (also known as Dat1). Transcriptional changes were accompanied by increased body weight, body fat and body length in the high fat diet offspring, as well as altered blood glucose and plasma leptin. Transcriptional changes identified in the hypothalamus of offspring of high fat diet mothers could alter neuronal projection formation during early development leading to abnormalities in the neuronal circuitry controlling appetite in later life, hence priming offspring to the development of obesity

Programming the genome in embryonic and somatic stem cells

In opposition to terminally differentiated cells, stem cells can self-renew and give rise to multiple cell types. Embryonic stem cells retain the ability of the inner cell mass of blastocysts to differentiate into all cell types of the body and have acquired in culture unlimited self-renewal capacity. Somatic stem cells are found in many adult tissues, have an extensive but finite lifespan and can differentiate into a more restricted array of cell types. A growing body of evidence indicates that multi-lineage differentiation ability of stem cells can be defined by the potential for expression of lineage-specification genes. Gene expression, or as emphasized here, potential for gene expression, is largely controlled by epigenetic modifications of DNA and chromatin on genomic regulatory and coding regions. These modifications modulate chromatin organization not only on specific genes but also at the level of the whole nucleus; they can also affect timing of DNA replication. This review highlights how mechanisms by which genes are poised for transcription in undifferentiated stem cells are being uncovered through primarily the mapping of DNA methylation, histone modifications and transcription factor binding throughout the genome. The combinatorial association of epigenetic marks on developmentally regulated and lineage-specifying genes in undifferentiated cells seems to define a pluripotent state

Understanding the Role of Maternal Diet on Kidney Development; an Opportunity to Improve Cardiovascular and Renal Health for Future Generations

The leading causes of mortality and morbidity worldwide are cardiovascular disease (high blood pressure, high cholesterol and renal disease), cancer and diabetes. It is increasingly obvious that the development of these diseases encompasses complex interactions between adult lifestyle and genetic predisposition. Maternal malnutrition can influence the fetal and early life environment and pose a risk factor for the future development of adult diseases, most likely due to impaired organogenesis in the developing offspring. This then predisposes these offspring to cardiovascular disease and renal dysfunction in adulthood. Studies in experimental animals have further illustrated the significant impact maternal diet has on offspring health. Many studies report changes in kidney structure (a reduction in the number of nephrons in the kidney) in offspring of protein-deprived dams. Although the early studies suggested that increased blood pressure was also present in offspring of protein-restricted dams, this is not a universal finding and requires clarification. Importantly, to date, the literature offers little to no understanding of when in development these changes in kidney development occur, nor are the cellular and molecular mechanisms that drive these changes well characterised. Moreover, the mechanisms linking maternal nutrition and a suboptimal renal phenotype in offspring are yet to be discerned—one potential mechanism involves epigenetics. This review will focus on recent information on potential mechanisms by which maternal nutrition   (focusing on malnutrition due to protein restriction, micronutrient restriction and excessive fat intake) influences kidney development and thereby function in later life

Study set up.

<p>Female <i>Sprague Dawley</i> rats received either control diet (CON) or high fat diet (HFD) throughout the study until postnatal day 10 (PN10) when offspring and dams were killed humanely and endpoint data collected.</p

Top molecular and cellular functions identified by Ingenuity pathway analyses (IPA).

<p>Top molecular and cellular functions identified by Ingenuity pathway analyses (IPA).</p

RNA-sequencing data.

<p>(A) Venn diagram illustrating differentially expressed genes in male and female offspring with stringent Adj. P-value<0.05. (B) Representation of selected differentially expressed genes in female offspring. All genes indicated have Adj.P-value <0.05. (C) Representation of selected differentially expressed genes in male offspring. All genes have P-value<0.01 or *Adj.p-value<0.05. CON-O (n = 6), HFD-O (n = 6) for both sexes. BioVenn, [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189492#pone.0189492.ref031" target="_blank">31</a>], an online web application was used to generate Venn diagrams.</p

Offspring phenotype.

<p>HFD offspring are significantly heavier at (A) PN1, (B) PN5 and (C) PN10. (D) HFD offspring are significantly longer compared with CON offspring. (E) HFD offspring display increased percentage of fat mass (relative to lean mass). (F) Total water was unchanged. (G) HFD offspring have increased blood glucose at PN10 compared to CON offspring. (H) HFD offspring have increased plasma leptin at PN10 compared to CON offspring. Maternal high fat diet offspring (HFD-O) = filled bars, maternal CON offspring (CON-O) = unfilled bars. P values from 2-way mixed model ANOVA analyses. Data represent mean± SEM. CON-O (n = 6), HFD-O (n = 11) except for blood glucose and plasma leptin CON-O (n = 6) and HFD-O (n = 6). M = male, F = female.</p

Maternal phenotype and metabolic data.

<p>(A) Illustration of maternal bodyweight changes (as percentage of weight gain to start weight) over the course of the study in HFD (filled symbol) and CON fed (unfilled symbols) females. Time points presented had CON n = 4–6 and HFD n = 8–11. (B) HFD significantly increases body weight (bodyweight change as a percentage of start weight) during the three weeks of diet, but not during pregnancy or lactation. (C) HFD does not alter fat or lean mass in HFD dams. (D) HFD dams have significantly higher average daily energy intake (MJ) during the three week diet and pregnancy but not lactation. (E) Both groups have similar water consumption. (F) Maternal blood glucose at start of diet, after 3 weeks of diet and at lactation (PN10 time point). HFD female rats have significantly lower blood glucose at lactation. (G) HFD dams have elevated plasma leptin concentrations compared with CON dams (n = 5 CON, n = 6 HFD). (H) No difference was observed in milk leptin concentrations between the group (n = 6 CON, n = 6 HFD). HFD = filled bars, CON = unfilled bars. P values are from 1-way ANOVA. Data indicate mean ± SEM. CON n = 12, HFD n = 14 for 3 week diet, CON n = 6, HFD n = 10–11 for pregnancy and lactation unless otherwise noted.</p