Time Trends of Plasma Lipids and Enzymes Synthesizing Hepatic Triacylglycerol During Postpartum Development of Fatty Liver in Dairy Cows

• Published in: Journal of dairy science 1995-10, Vol.78 (10), p.2208-2220
• Main Authors: Van Den Top, A. M, Wensing, T, Geelen, M.J.H, Wentink, G. H, Van't Klooster, A. T, Beynen, A. C
• Format: Article
• Language: English
• Subjects: Acyltransferases - metabolism; Animal productions; Animals; Biological and medical sciences; Cattle; Cattle Diseases - metabolism; Choline-Phosphate Cytidylyltransferase; Diacylglycerol O-Acyltransferase; Fatty Acids, Nonesterified - blood; Fatty Liver - metabolism; Fatty Liver - veterinary; Female; Fundamental and applied biological sciences. Psychology; Glycerol-3-Phosphate O-Acyltransferase - metabolism; Glycogen - metabolism; Lactation; Lipids - blood; Lipoproteins, HDL - blood; Lipoproteins, LDL - blood; Lipoproteins, VLDL - blood; Liver - enzymology; Liver - metabolism; Nucleotidyltransferases - metabolism; Phosphatidate Phosphatase - metabolism; Phospholipids - metabolism; Postpartum Period; Terrestrial animal productions; Triglycerides - biosynthesis; Vertebrates
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(95)76848-5

We studied development of fatty liver in high producing dairy cows with free access to feed during the dry period and thus showed the combined effects of parturition and prepartum overfeeding. Postpartum liver triacylglycerol concentrations at 1 wk postpartum, as measured in liver biopsies, had increased more than 6-fold, which was preceded or accompanied by an increase in plasma NEFA concentrations. Concentrations of hepatic phospholipid changed only slightly. The amounts of total lipids in serum, very low density lipoproteins, and high density lipoproteins significantly decreased by .5 wk after parturition, and concentrations of high density lipoproteins rose steadily. The pattern was similar for concentrations of total cholesterol and phospholipid in serum. Total lipid concentrations in low density lipoproteins were not altered after parturition. The activity of microsomal phosphatidate phosphohydrolase in the liver showed a transient increase at .5 wk after calving, but activity of microsomal glycerolphosphate acyltransferase remained relatively constant. The activities of diacylglycerol acyltransferase had increased about twice at 1 wk after calving and remained at this high level until at least 4 wk after parturition. The rise in activity of diacyglycerol acyltransferase was probably a response to the extra influx of fatty acids to channel them into triacylglycerol. Activities of microsomal cholinephosphate cytidylyltransferase initially increased after calving and then decreased slightly. Activities of hepatic choline kinase had increased after calving. This study indicates that hepatic triacylglycerol accumulates because of the increased hepatic uptake of NEFA and the simultaneous increase in activity of diacylglycerol acyltransferase.