KEY ENZYMES AND NUCLEAR RECEPTORS OF HEPATIC LIPID METABOLISM IN DAIRY CATTLE DURING THE TRANSITION PERIOD

ANGELI, EMMANUEL; TRIONFINI, VALENTINA; GAREIS, NATALIA C; MARELLI, BELKIS; HEIN, GUSTAVO J; ORTEGA, HUGO H

Mar del Plata

Congreso; LIX Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica.; 2016

The transition period (TP) is the most critical in the lactation of a dairy cow, characterized by a negative energy balance leading to an important lipid mobilization, with increases in the systemic non-esterified fatty acids (NEFA) and beta-hydroxybutyric (BHB) concentrations. While carnitine palmitoyltransferase-1 (CPT1), acyl-Coa oxidase-1 (ACOX1) and the nuclear receptor PPAR-alpha promotes fatty acids oxidation in several tissues, including the liver, diacylglycerol acyltransferase-1 (DGAT1) is involved in triacylglycerol biosynthesis. The aim of this study was to evaluate some pathways of hepatic lipid metabolism during the TP. Blood samples and liver biopsies from cows (n = 10) were taken at 28 and 14 days prepartum, and also at 4, 14, 28 and 60 days postpartum. Systemic NEFA, BHB, glucose and insulin concentrations were measured. Besides, the liver expressions of fatty acids oxidation (CPT1, ACOX1) and re-esterification (DGAT1) enzymes, and nuclear receptor PPAR-alpha were evaluated by Real Time-PCR and western blot. There were no significant changes (p > 0.05) in glycemia and insulinemia. Differences in the BHB and NEFA concentrations were observed at different sampling days, being significant at 4, 14 and 30 days postpartum (p < 0.05). The expressions of CPT1 and PPAR-alpha were higher in the postpartum period (p < 0.05), with an opposite behavior respect the expression of DGAT1. No differences in the mRNA expression of ACOX1 were observed (p > 0.05). These results show significant changes in hepatic lipid metabolism of dairy cows during the TP. These knowledge could represent a useful tool to understand the metabolic behavior in animals with different milk production and to optimize the health of dairy cattle during this period.