Maternal low protein diet and postnatal high fat diet increases adipose imprinted gene expression

Abstract

Maternal and postnatal diet can alter Igf2 gene expression and DNA methylation. To test whether maternal low protein and postnatal high fat (HF) diet result in alteration in Igf2 expression and obesity, we fed obese‐prone Sprague‐Dawley rats 8% (LP) or 20% (NP) protein for 3 wk prior to breeding and through pregnancy and lactation. At weaning, male offspring were placed on 10% (NE) or 45% (HE) fat, thus, giving 4 groups (LP‐NE, NP‐NE, LP‐HE, NP‐HE). At 12 wk, LP‐HE rats had the greatest increase in body wt (14‐fold) and adipose tissue mass (27‐fold). LP‐HE rats also had the greatest increase in Igf2 expression (~7.5‐ fold increase) in subcutaneous adipose tissue (ScAT) while no difference was found in the visceral adipose tissue (VisAT). To determine whether DNA methylation may be involved, we measured the methylation status of the Igf2 imprinting control region but found no differences. Because mitochondria play a central role in regulating energy metabolism, we tested whether mitochondrial (mt) copy number is altered with increased calories from HF diet. Results showed that LP‐HE rats had the lowest mt copy number in ScAT (1.4 fold‐change relative NP‐NE) while no difference was found in VisAT. These data demonstrate that maternal low protein and postnatal HF diet results in greater propensity to develop obesity by increased adipose tissue mass, increased ScAT Igf2 expression, and reduced ScAT mt copy numbers.