Effects of Western Diet on Histological Characteristics of Muscle in Leptin‐Resistant Pigs

Abstract

Leptin‐resistant pigs offer a promising model for the study of non‐alcoholic fatty liver disease (NAFLD), particularly in pediatric populations. Muscle is a large and metabolically active tissue that may play an important role in the storage and metabolism of lipid during the development of NAFLD.In this study, 10‐day old piglets were fed either a control diet (CON) (n=8) or a Western diet containing high levels of fructose, saturated fat and cholesterol (HFF) (n=12) every 6 hours for 70 days. Half of the pigs in each diet group were supplemented with a blend of probiotics containing Pediococcus, Lactobacillus and Bacillus. Longissimus dorsi muscle was collected on day 70 for immunohistochemistry and triacylglyceride (TG) quantification. Tissue sections were stained for lipid content with Oil Red O and muscle cells were fiber‐typed based on myosin heavy chain isoforms.Muscle tissue from pigs fed HFF diets had higher total TG content, but a lower number of Oil Red O positive cells and a lower lipid staining intensity of these cells. HFF diet also caused a reduction in the fraction of type I (slow‐twitch) muscle fibers.In summary, this staining pattern suggests that the muscle from HFF fed animals may have an increased accumulation of lipid in extramyocellular depots rather than within muscle cells and a decreased capacity to oxidize lipids. Such shifts in muscle metabolic characteristics may contribute to the progression of metabolic disease.Support or Funding InformationThe project was funded by ARI#58873, STRIDE#35466, and the William and Linda Frost Fund.