Protein restricted diet during gestation and/or lactation in mice affects (15)N natural isotopic abundance of organs in the offspring: Effect of diet (15)N content and growth

OBJECTIVES AND STUDY: This study aimed at measuring the effect in normal to restricted protein diets with specific (15)N natural isotopic abundance (NIA) given during gestation and/or lactation on the (15)N NIA of fur, liver and muscle in dams and their offspring from birth to adulthood. The secondary aim was to study the effect of growth on the same parameters. METHODS: Female Balb/c mice were fed normal protein diet containing 22% protein or isocaloric low protein diet containing 10% protein throughout gestation. Dam’s diets were either maintained or switched to the other diet until weaning at 30 days. All animals were fed standard chow thereafter. Offspring were sacrificed at 1, 11, 30, 60, 480 days and a group of dams at d1. Growth was modeled as an exponential function on the group followed up until 480 days. Fur, liver and muscle were sampled at sacrifice and analyzed for bulk (15)N NIA. Fixed effects and interactions between fixed effects and random elements were tested by three-way ANOVA. RESULTS: Higher (15)N NIA in the diet resulted in higher organ (15)N NIA. Switching from one diet to another changed (15)N NIA in each organ. Although dam and offspring shared the same isotopic environment during gestation, (15)N NIA at day 1 was higher in dams. Growth rate did not differ between groups after 10 days and decreased between 1 and 5 months. (15)N NIA differed between organs and was affected by growth and gestation/lactation. CONCLUSION: Dietary (15)N NIA is a major determinant of the (15)N NIA of organs. (15)N NIA depended on organ and age (i.e. growth) suggesting an effect of metabolism and/or dilution space. Post-natal normal-protein diet of lactating dams could reverse the effect of a protein-restricted diet during gestation on the offspring growth. Measuring (15)N NIA in various matrices may open a field of application particularly useful in studying the pre- and post-natal origins of health and disease.