Liver changes in rats on continuous and intermittent parenteral nutrition with and without fat (Intralipid 20%)

The possible advantages of including fat in a regimen of total parenteral nutrition (TPN) have long been debated. In order to investigate the role of fat in liver function during different intravenous regimens, two groups of rats received a regimen including fat (Intralipid 20%) during 12 and 24 hours/day, respectively and two groups received a fat-free regimen, isocaloric and isonitrogenous, during the same intervals, all for a period of 10 days. A control group received for 10 days the fat-including regimen orally and libitum. The liver was investigated biochemically and morphologically. Fatty infiltration of the parenchymal liver cells, a low content of linoleic acid and a high content of palmitic and oleic acid among the liver lipids were found in the rats receiving the fat-free regimen. Fat pigments in the cells of the reticuloendothelial system of the livers and values of fatty acid among the liver lipids comparable to those found in orally-fed rats were seen in rat receiving the fat-including regimen. This study underscores the physiological importance of including intravenous fat emulsion in the TPN regimen. Our results also indicate that essential fatty acid deficiency in tissue may develop rapidly.