Triplet Male Lambs Are More Susceptible than Twins to Dietary Soybean Oil–Induced Fatty Liver

Abstract

Litter size affects fetal development but its relation to diet-induced fatty liver later in life is unknown. This aim of this study was to test the hypothesis that litter size influences postweaning fatty liver development in response to soybean oil-supplemented diet. Weanling twin (TW) or triplet (TP) male lambs (n=16) were fed a control diet or 2% soybean oil-supplemented diet (SO) for 90 d. Liver tissue morphology, biochemical parameters, and lipid metabolic enzymes were determined. Hepatic gene expression was analyzed by RNA sequencing (n=3), followed by enrichment analysis according to Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes. Differentially expressed genes involved in lipid metabolism were further verified by quantitative reverse transcriptase-polymerase chain reaction (n=4). All data were analyzed by a 2-factor ANOVA, apart from differentially expressed genes, which were identified by the Benjamini-Hochberg approach (q value ≤0.05). SO increased liver triglyceride (by 55%) and nonesterified fatty acid (by 54%) concentrations in TPs (P≤0.05) but not in TWs (P>0.05). SO also induced a 2.3- and 2.1-fold increase in the liver steatosis score of TPs and TWs, respectively (P≤0.05). Moreover, SO reduced the activity of lipolytic enzymes including hepatic lipase and total lipase in TPs by 47% and 25%, respectively (P≤0.05). In contrast, activities of lipogenic enzymes, including malic enzyme and acetyl coenzyme A carboxylase, were significantly higher in TPs (P≤0.05). Moreover, TPs had higher expression of lipogenic genes, such as FASN (by 45%) and APOB (by 72%), and lower expression of lipolytic genes, such as PRKAA2 (by 28%) and CPT1A (by 43%), compared with TWs (P≤0.05). TPs have a gene expression profile that is more susceptible to SO-induced fatty liver than that of TWs, which indicates that insufficient maternal nutrient supply at fetal and neonatal stages may increase the risk of nonalcoholic fatty liver disease.