Protein and gene expression of relevant enzymes and nuclear receptor of hepatic lipid metabolism in grazing dairy cattle during the transition period

Abstract

We aimed to study the protein and gene expression of some hepatic enzymes of lipid metabolism along with plasma biomarkers in grazing dairy cattle during the transition period. Blood and liver biopsies from a group of eight multiparous cows were sampled at -28, -14, +4, +14, +28 and +56 days relative to parturition. Peak concentrations of NEFA and beta-hydroxybutyric acid with high triacylglycerol content in the liver were recorded on day 4 postpartum. Consistent with blood biomarkers, the gene expression of carnitine palmitoyltransferase 1A (CPT1A) and acyl-CoA oxidase 1 (ACOX1) increased, whereas that of diacylglycerol O-acyltransferase 1 (DGAT1) decreased. Nevertheless, CPT1A protein expression did not change during all the period evaluated and ACOX1 protein expression increased on day 56 postpartum. In addition, the protein expression of peroxisome proliferator-activated receptor alpha (PPAR-alpha) increased on day 28 postpartum. On the other hand, DGAT1 protein expression decreased on day 14 postpartum. As expected, the expression of genes associated with fatty acid oxidation increased on the first days postpartum but, notably, protein expression was highest after transition. Since most infectious diseases and metabolic disorders in dairy cattle occur particularly on the first days postpartum, it is not so clear whether an increase in the oxidation capacity of the liver at that time could help to prevent disease and improve dairy production. The valuable results about protein expression of enzymes involved in liver lipid metabolism could help to better characterize the metabolism of dairy cattle during the transition period.

Keywords: Dairy cattle; Lipid metabolism; Liver; PPAR-alpha; Transition period.