Biochemical and ultra-structural reactions to parenteral nutrition with two different fat emulsions in rats

Abstract

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.

Expression of islet inducible nitric oxide synthase and inhibition of glucose-stimulated insulin release after long-term lipid infusion in the rat is counteracted by PACAP27

“…Long-term lipid infusion in rats is considered a good model for investigating the effect of increased plasma levels of lipids on ␤-cell function and insulin secretion (8,31,34,36,39). We (36) have previously shown that lipid-infused animals are characterized by hyperlipidemia (FFA, triglycerides, and cholesterol), but at the same time they display normoglycemia, and there is no significant difference in blood glucose levels in these rats compared with freely-fed control rats.…”

“…Hence, FFA acutely stimulates insulin secretion from isolated pancreatic islets (9), whereas long-term incubation (24 h) of islets in the presence of FFAs negatively modulates ␤-cell function and results in a markedly decreased glucose-stimulated release of insulin (51). Indeed, it has been known for a long time that chronic elevation of plasma FFA impairs the insulin-secreting response to glucose in both humans and animals (8,31,32,34,36,45,51), and this hyperlipidemia has been suggested to be closely linked to type 2 diabetes (24). We have previously reported that nutrient-stimulated insulin secretion was markedly disrupted after lipid infusion in rats (8, 31, 34 -36, 39) and that this insulin secretory defect could be reversed by agents stimulating cyclic AMP production (34,35,39).…”

“…pancreatic islets; insulin secretion; isoforms of nitric oxide synthase; pituitary adenylate cyclase-activating polypeptide 27 THE SOLUTION USED for total parenteral nutrition (TPN) contains a high amount of lipids, which results in increased plasma levels of free fatty acid (FFA), triglycerides, and cholesterol (8,31,34,36). FFA has complex effects on pancreatic ␤-cells and insulin secretion (8,9,25,31,32,34,36,45,51). Hence, FFA acutely stimulates insulin secretion from isolated pancreatic islets (9), whereas long-term incubation (24 h) of islets in the presence of FFAs negatively modulates ␤-cell function and results in a markedly decreased glucose-stimulated release of insulin (51).…”

“…FFA has complex effects on pancreatic ␤-cells and insulin secretion (8,9,25,31,32,34,36,45,51). Hence, FFA acutely stimulates insulin secretion from isolated pancreatic islets (9), whereas long-term incubation (24 h) of islets in the presence of FFAs negatively modulates ␤-cell function and results in a markedly decreased glucose-stimulated release of insulin (51).…”

Effects of Lipid-Supplemented Total Parenteral Nutrition on Fatty Liver Disease in a Premature Neonatal Piglet Model

“…Excess carbohydrate enhances lipogenic activity [15] and during TPN in dogs, uptake of glucose in the liver is increased [16] . Studies on a rat model of TPN have demonstrated a reduction in fat deposition in the liver by adding lipid to the TPN regime to reduce the supply of carbohydrate derived calories [17] ; supplying lipid emulsions of differing composition also results in different degrees of lipid deposition in the liver of humans and rats [11,18,19] . The role a lipid emulsion may play in the causation or prevention of fatty liver remains unclear.…”