Maternal high-protein and low-protein diets perturb hypothalamus and liver transcriptome and metabolic homeostasis in adult mouse offspring

Early life nutritional imbalances are risk factors for metabolic dysfunctions in adulthood, but the effects of perinatal exposure to high versus low protein diets are poorly understood. We exposed C57BL/6 offspring to a high protein/low carbohydrate (HP/LC) or low protein/high carbohydrate (LP/HC) diet during gestation and lactation, and measured metabolic phenotypes between birth and ten months of age in male offspring. Perinatal HP/LC and LP/HC exposures resulted in a decreased ability to clear glucose in the offspring, with reduced baseline insulin and glucose levels in the LP/HC group and a reduced insulin response post-glucose challenge in the HP/LC group. The LP/HC diet group also showed reduced weight at birth and at weaning age, whereas the HP/LC offspring showed an increased weight at weaning and increased adiposity after 5 months of age. Gene expression profiling of hypothalamic and liver tissues indicated alterations of diverse molecular pathways by both diets. Specifically, hypothalamic transcriptome and pathway analyses indicate perturbations of MAPK and hedgehog signaling, processes associated with neural restructuring and transmission, and phosphate metabolism by perinatal protein imbalances. Liver transcriptome data revealed changes in purine and phosphate metabolism, hedgehog signaling, and circadian rhythm pathways. Our results support that maternal protein imbalances perturb molecular pathways in central and peripheral metabolic tissues and predispose offspring to metabolic dysfunctions. The LP/HC diet (D02041002, Research Diets Inc. New Brunswick, NJ) contains 9% protein, 4.4% fat, and 77% carbohydrates (6). The HP/LC diet (D02041001, Research Diets Inc. New Brunswick, NJ) has 23% protein, 4.4% fat and 64% carbohydrate by weight. Standard chow diet (TD 7013, Harlan Teklad. Placentia, CA), containing 18% protein, 6% fat, and 75% carbohydrate by weight, was used as the control diet. The diets were matched by total caloric content. As most dams cannibalized first litters, all the offspring were from second litters from multiple dams 10 to 12 weeks old. C57BL/6 females were mated overnight with males between 10 and 16 weeks of age. Gestational day 0 (GD0) was determined by the detection of a vaginal plug in the morning. On GD8, pregnant females were placed on a LP/HC, HP/LC, or chow diet. Pups were weaned at 28 days of age into cages of four animals per cage, separated by sex and maternal environment. In order to maintain the four animal-per-cage requirements, some cages had mice from different treatments. A total of 22, 27, and 20 male offspring from the LP/HC, HP/LC, or chow diet group, respectively, were examined. Hypothalamus and liver were dissected between 10 AM and 12 PM from male mice at 10 months of age, placed immediately into liquid nitrogen, and stored at -80oC until RNA was extracted with the RNAeasy kit (Qiagen). At 9 months GTT were done, Body Composition was measured at day 2 and monthly thereafter.