Physiology and Endocrinology 1

摘要

During the peripartum period, dairy cows diagnosed with hyperketonemiaexperience both an increase in circulating FA, and a changein circulating FA profile, compared with non-hyperketonemic cows.Supplementation of dietary lipids can also result in subtle shifts in thecirculating FA profile. As FA are known regulators of hepatic genes,these shifts could differentially influence gene expression. The objectivewas to determine the expression of gluconeogenic and oxidativegenes in primary hepatocytes when exposed to an in vivo relevant FAprofile and that profile enriched with additional C16:0, C18:0, or C18:1.Primary hepatocytes were isolated from 4 Holstein bull calves (<7 d)and cultured for 24 h. Treatments applied to cells for 24 h were no FA(1% BSA); 0.75 mM FA cocktail (3% C14:0, 27% C16:0, 23% C18:0,31% C18:1, 8% C18:2, and 8% C18:3; to mimic the serum FA profileof dairy cattle at calving); 0.90 mM FA cocktail; 0.75 mM FA cocktail+ 0.15 mM C16:0; 0.75 mM FA cocktail + 0.15 mM C18:0; and 0.75 FAcocktail mM + 0.15 mM C18:1. After harvest in TRIzol, samples werestored at −80°C until RNA extraction, purification, reverse transcription,and quantitative real time PCR. Expression of genes of interest(carnitine palmitoyltransferase 1A, pyruvate carboxylase, cytosolicand mitochondrial phosphoenolpyruvate carboxykinase [PEPCKc andPEPCKm], and glucose-6-phosphatase) was calculated relative to thegeometric mean of 2 reference genes chosen by geNorm (ribosomalprotein L32 and GAPDH). Data were analyzed using Proc Mixed (SAS9.4) with the fixed effect of treatment and calf in the random statement.The addition of FA compared with no FA increased the expression ofcarnitine palmitoyl transferase 1A (2.22 vs. 3.96 ± 1.59 arbitrary units[AU]; P = 0.05) and PEPCKc (0.51 vs. 1.03 ± 0.28 AU; P = 0.03).Enrichment with individual FA did not affect the expression of the genestested when compared with the 0.90 mM FA cocktail treatment (P ≥0.40). These results suggest additional shifts in circulating FA profilewithin a biological range have minimal additional effects on hepaticgluconeogenic and oxidative gene expression.