PSV-2 - Maternal nutrient restriction and re-alimentation influences liver and muscle tissue development and gene expression

To determine the effects of maternal nutrient restriction and re-alimentation on fetal liver and muscle development, 48 pregnant ewes with singletons, were fed a control diet [100% National Research Council (NRC) requirements (CON)] starting at the beginning of gestation. On day 50 of gestation, ewes (n = 7) were euthanized and fetal liver and skeletal muscle samples were collected. The remaining animals were fed either CON or 60% NRC requirements (RES), a subset were euthanized at day 90 of gestation (n = 7/treatment), and fetal samples obtained. Remaining ewes were maintained on the current diet (CON-CON, n = 6; RES-RES, n = 7) or switched to alternative diet (CON-RES, RES-CON; n = 7/treatment). On day 130 of gestation, remaining ewes were euthanized, and fetal samples collected. Fetal liver was analyzed for general tissue morphology, and fetal skeletal muscles were analyzed for lipid accumulation. mRNA expression of growth and metabolic factors were quantified in liver and muscle tissues. Hepatocellular vacuolation was increased in RES-CON and RES-RES compared with CON-CON and CON-RES (P < 0.01). In semitendinosus and triceps brachii, intramyocellular lipid content increased 19% and 15%, respectively, in RES-CON and RES-RES compared with CON-CON and CON-RES (P£0.02) and in longissimus dorsi, lipid content was decreased 7% in CON-RES and RES-RES compared with CON-CON and RES-CON (P=0.01). In liver, insulin-like growth factor binding protein-1, glycogen synthase 2, and pyruvate dehydrogenase kinase 1 expression increased 1.92-fold, 1.45-fold, and 1.47-fold, respectively (P£0.03) in CON-RES and RES-RES compared with RES-CON and CON-CON. In LD, IGF1-R expression increased 3.19-fold in CON-RES and RES-RES compared with RES-CON and CON-CON (P = 0.05). These results demonstrate that maternal nutrient restriction followed by re-alimentation restores liver and muscle gene expression of growth and metabolic factors while negatively impacting liver composition and muscle lipid content potentially leading to altered tissue function and metabolism later in life. Supported by USDA-AFRI grants 2016-67016-24884 and 2017-67016-26568.