| 1. |
- Ekelund, Mats, et al.
(författare)
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Effects of total parenteral nutrition on lipid metabolism in rats
- 1994
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Ingår i: JPEN. - : Wiley. - 0148-6071. ; 18:6, s. 503-509
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The pathophysiologic mechanisms behind the development of liver steatosis during total parenteral nutrition (TPN) and the possible relationship to alterations of lipoprotein lipase activities in different tissues are not fully known. It is also unknown whether continuous and discontinuous administration of TPN affect lipid metabolism differently. METHODS: TPN, including 8.4 g of triglycerides per kilogram per day, was given for 10 days to two groups of male Sprague-Dawley rats that received the infusions discontinuously and continuously, respectively. Freely fed rats were used as controls. RESULTS: TPN led to hyperlipidemia and accumulation of triglycerides in the liver. High-density lipoproteins were enriched in triglycerides, whereas high-density lipoprotein cholesterol and phospholipid levels were low. The activities of hepatic lipase were markedly decreased, and lipoprotein lipase activities in adipose tissue and in cardiac muscle were both up-regulated. The increased levels of cholesterol and phospholipids in the serum of TPN animals were more pronounced after discontinuous administration. CONCLUSIONS: TPN including lipids interferes with the normal regulation of lipid metabolism. Although the mechanisms remain obscure, the elevation of lipoprotein lipase activities seems functionally important to accommodate the increased input of triglycerides during TPN. Possibly, the observed alterations in lipase activities may be attributed to a state of hypothyroidism.
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| 2. |
- Roth, Bengt, et al.
(författare)
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Biochemical and ultra-structural reactions to parenteral nutrition with two different fat emulsions in rats
- 1998
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Ingår i: Intensive Care Medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 24:7, s. 716-724
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare the effects on fat metabolism and Kupffer cell morphology by total parenteral nutrition (TPN) with two different fat emulsions. DESIGN: Thirty-two male Sprague-Dawley rats, divided into three groups, were investigated. Rats fed orally were used as a reference group, and a group of rats receiving TPN with fat emulsions containing pure long-chain triglycerides (LCT) was compared to a group of rats receiving fat emulsions containing both long-chain triglycerides and medium-chain triglycerides (MCT/LCT). The TPN regimens were equicaloric and administered continuously via a jugular catheter for 10 days. INTERVENTIONS: After suffocation, blood of the rats was collected for the determination of serum lipids. Epididymal fat and heart were collected for the analysis of lipoprotein lipase (LPL) activities, and liver specimens were saved for analyses of hepatic triglyceride concentration, as well as activities of hepatic lipase (HL) and lysosomal enzymes. Light and electron microscopy were used for examination of the Kupffer cell reaction. RESULTS: Directly after termination of parenteral feeding, the levels of serum triglycerides and high density lipoprotein (HDL) triglycerides were higher in the MCT/LCT group than in the LCT group, while no differences concerning cholesterol and phospholipid concentrations were found. No significant difference in liver steatosis was found between the two TPN groups. Comparison of the TPN groups showed that the MCT/ LCT group had significantly decreased LPL activity in adipose tissue, while the LCT group had significantly increased LPL activity in the heart. The activity of HL was low in both groups, but significantly lower in the LCT group. Lipid accumulation and an increased number of lysosomes were found in all Kupffer cell when TPN with LCTemulsions was used. Moreover, TPN induced a pronounced increase in various liver lysosomal enzyme activities, but there was no notable difference between LCT and MCT/LCT effects. CONCLUSIONS: Compared to treatment with pure LCTemulsions, treatment with MCT/LCT emulsions evoked weaker biochemical reactions in terms of lower activity of lipoprotein lipase in fat and heart together with higher serum and HDL triglyceride levels. Morphological signs of increased Kupffer cell activity such as the appearance of multiple lysosomes and fat vacuoles in the cytoplasm followed treatment with pure LCT emulsions. However, both TPN groups showed a marked increase in activities of liver lysosomal enzymes.
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| 3. |
- Roth, Bengt, et al.
(författare)
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Lipid deposition in Kupffer cells after parenteral fat nutrition in rats: a biochemical and ultrastructural study
- 1996
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Ingår i: Intensive Care Medicine. - 0342-4642. ; 22:11, s. 1224-1231
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study fat metabolism and evaluate lipid deposition in hepatocytes and Kupffer cells during parenteral nutrition (PN) with or without fat. DESIGN: 20 male Sprague-Dawley rats, divided into four groups, 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 energy as fat. The PN regimens were equicaloric and administered continuously via a jugular catheter for 7 days. INTERVENTIONS: After suffocation, blood was collected for determination of serum lipids. Epididymal fat and heart were collected for analysis of lipoprotein lipase activities, and pieces of liver were saved for analyses of liver triglyceride concentration and hepatic lipase activity. Light and electron microscopy were used for examination of lipid deposition in Kupffer cells. RESULTS: Directly after termination of parenteral feeding, the serum levels of triglycerides were similar in all PN groups, while the levels of non-high-density lipoprotein (HDL) cholesterol and non-HDL phospholipids were significantly increased in parallel with increased doses of fat. Lipid-free PN resulted in significantly less liver steatosis than high-fat PN. Lipid PN also resulted in downregulated hepatic lipase activity, signs of lipid accumulation in Kupffer cells and hepatocytes and an increased number of phagosomes in Kupffer cells. CONCLUSIONS: Fat vacuoles were found in Kupffer cells after lipid PN, although serum levels of triglycerides were not elevated and lipoprotein lipase activity were not depressed. The cells were distended by fat vacuoles after administration of PN solutions with a high fat concentration. Morphological signs of increased Kupffer cell activity were also found, suggesting that intravenous fat emulsions may activate macrophages.
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