Abstract
Background: This study was undertaken to determine the effect of chemically defined structured lipids on nonspecific host defense and on histologic patterns of liver and lungs compared with a physical mixture of long-chain triglycerides and medium-chain triglycerides in a continuous low-dose endotoxin rat model. Methods: Forty male Sprague-Dawley rats, divided into four feeding groups (structured lipids, structured lipids + endotoxin, physical mixture, physical mixture + endotoxin), received total parenteral nutrition for 48 hours. During the first part of the study, 24 animals were given an injection of live Escherichia coli labeled with radioactive iron ( 59Fe) to investigate the function of the reticuloendothelial system. During the second part of the study, the liver and lungs of 16 animals were histologically examined using light and electron microscopy. Results: Despite the similar values in the control groups, the animals receiving structured lipids + endotoxin sequestered a significantly greater percentage of bacteria in the liver and spleen (p ≤ .01) and a significantly lesser percentage in the lung (p ≤ .05) compared with the animals given physical mixture + endotoxin as part of their diet. Moreover, rats in the physical mixture + endotoxin group showed a microscopically evaluated higher fatty infiltration in the liver than did the structured lipids + endotoxin group. Conclusions: The results of this study indicate that chemically defined structured lipids reduce fatty infiltration of the liver compared with a physical mixture of the same compounds in an animal model of metabolic stress. They were accompanied by a better function of the reticuloendothelial system and a lesser bacterial sequestration in the lungs. (Journal of Parenteral and Enteral Nutrition
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