Serum lipids and fatty acids composition of tissues in rats on total parenteral nutrition (TPN)

The modulating effect of energy and exogenous triglyceride supply on serum lipids and fatty acid composition of liver, tibialis anterior muscle, subcutaneous and peri-epididymal fat was assessed in rats using Total Parenteral Nutrition (TPN). Nutrients were infused continuously for 10 days through a central vein catheter. Four levels of fat were tested: No fat, Low fat (6% non-protein calories), Medium fat (30%) and High fat (60%), at 2 energy levels (270 kcal and 350 kcal/kg X day). An isonitrogenous supply was given to all groups as 0.9 g N/kg X day. At the highest level of fat intake (20.4 g/kg) at the high energy level triglycerides, cholesterol and phospholipids of serum were elevated. Biochemical signs of essential fatty acid (EFA) deficiency were observed as rising levels of eicosatrienoic acid and lowered concentrations of linoleic and arachidonic acid, mostly in the liver and the muscle in the No fat groups. EFA levels were reduced significantly in the No fat and Low fat groups and more pronounced at the high energy level. In conclusion, our study suggests that when energy intake is increased the EFA status becomes more critical. It seems evident that more EFA is required in absolute values when hypercaloric diets are given.