LIPID DEPOSITION IN KUPFFER CELLS AFTER PARENTERAL FAT NUTRITION IN RATS - A BIOCHEMICAL AND ULTRASTRUCTURAL-STUDY

Objective: To study fat metabolism and evaluate lipid deposition in he patocytes and Kupffer cells during parenteral nutrition (PN) with or w ithout fat. Design: 20 male Sprague-Dawley rats, divided into four gro ups, were investigated. Rats fed orally were used as a reference group and compared to three groups of rats receiving PN either without fat or with 33% of non-protein energy as fat or with 66% of non-protein en ergy as fat. The PN regimens were equicaloric and administered continu ously via a jugular catheter for 7 days. Interventions: After suffocat ion, blood was collected for determination of serum lipids. Epididymal fat and heart were collected for analysis of lipoprotein lipase activ ities, and pieces of liver were saved for analyses of liver triglyceri de concentration and hepatic lipase activity. Light and electron micro scopy were used for examination of lipid deposition in Kupffer cells. Results: Directly after termination of parenteral feeding, the serum l evels of triglycerides were similar in all PN groups, while the levels of non-high-density lipoprotein (HDL) cholesterol and non-HDL phospho lipids were significantly increased in parallel with increased doses o f fat. Lipid-free PN resulted in significantly less liver steatosis th an high-fat PN. Lipid PN also resulted in downregulated hepatic lipase activity, signs of lipid accumulation in Kupffer cells and hepatocyte s and an increased number of phagosomes in Kupffer cells. Conclusion: Fat vacuoles were found in Kupffer cells after lipid PN, although seru m levels of triglycerides were not elevated and lipoprotein lipase act ivities were not depressed. The cells were distended by fat vacuoles a fter administration of PN solutions with a high fat concentration. Mor phological signs of increased Kupffer cell activity were also found, s uggesting that intravenous fat emulsions may activate macrophages.