Decreased liver triglyceride content in adult rats exposed to protein restriction during gestation and lactation: role of hepatic triglyceride utilization

摘要

We have previously demonstrated that protein restriction throughout gestation and lactation reduced liver triglyceride content in adult rat offspring. The mechanism(s) mediating the decrease in liver triglyceride content are not understood. The objective of the current study was to use a new group of pregnant animals and their offspring and determine the contribution of increased triglyceride utilization via the hepatic fatty acid oxidation and triglyceride secretory pathways to the reduction in liver triglyceride content. Pregnant Sprague-Dawley rats received either a control or a low protein diet throughout pregnancy and lactation. Pups were weaned onto laboratory chow on day 28 and sacrificed on day 65. Liver triglyceride content was reduced in male, but not female, low protein offspring both in the fed and fasted states. The reduction was accompanied by a trend towards higher liver carnitine palmitoyltransferase-1a activity suggesting increased fatty acid transport into the mitochondrial matrix. However, medium chain acyl CoA dehydrogenase activity within the mitochondrial matrix, expression of nuclear peroxisome proliferator activated receptor-α, and plasma levels of β-hydroxybutyrate were similar between low protein and control offspring indicating a lack of change in fatty acid oxidation. Hepatic triglyceride secretion, assessed by blocking peripheral triglyceride utilization and measuring serum triglyceride accumulation rate, and the activity of microsomal transfer protein were similar between low protein and control offspring. Since enhanced triglyceride utilization is not a significant contributor, the decrease in liver triglyceride content in male low protein offspring is likely due to alterations in liver fatty acid transport or triglyceride biosynthesis.