Effect of rumen-protected choline supplementation on liver and adipose gene expression during the transition period in dairy cattle

Abstract

We previously reported that supplementation of rumen-protected choline (RPC) reduces the hepatic triacylglycerol concentration in periparturient dairy cows during early lactation. Here, we investigated the effect of RPC on the transcript levels of lipid metabolism-related genes in liver and adipose tissue biopsies, taken at wk -3, 1, 3, and 6 after calving, to elucidate the mechanisms underlying this RPC-induced reduction of hepatic lipidosis. Sixteen multiparous cows were blocked into 8 pairs and randomly allocated to either 1 of 2 treatments, with or without RPC. Treatments were applied from 3 wk before to 6 wk after calving. Both groups received a basal diet and concentrate mixture. One group received RPC supplementation, resulting in an intake of 14.4 g of choline per day, whereas controls received an isoenergetic mixture of palm oil and additional soybean meal. Liver and adipose tissue biopsies were taken at wk -3, 1, 3, and 6 to determine the mRNA abundance of 18 key genes involved in liver and adipose tissue lipid and energy metabolism. Milk samples were collected in wk 1, 2, 3, and 6 postpartum for analysis of milk fatty acid (FA) composition. The RPC-induced reduction in hepatic lipidosis could not be attributed to altered lipolysis in adipose tissue, as no treatment effect was observed on the expression of peroxisome proliferator-activated receptor γ, lipoprotein lipase, or FA synthase in adipose tissue, or on the milk FA composition. Rumen-protected choline supplementation increased the expression of FA transport protein 5 and carnitine transporter SLC22A5 in the liver, suggesting an increase in the capacity of FA uptake and intracellular transport, but no treatment effect was observed on carnitine palmitoyl transferase 1A, transporting long-chain FA into mitochondria. In the same organ, RPC appeared to promote apolipoprotein B-containing lipoprotein assembly, as shown by elevated microsomal triglyceride transfer protein expression and apolipoprotein B100 expression. Cows supplemented with RPC displayed elevated levels of glucose transporter 2 mRNA and a reduced peak in pyruvate carboxylase mRNA immediately after calving, showing that supplementation also resulted in improved carbohydrate metabolism. The results from this study suggest that RPC supplementation reduces liver triacylglycerol by improved FA processing and very-low-density lipoprotein synthesis, and RPC also benefits hepatic carbohydrate metabolism.

Non-esterified fatty acids promote expression and secretion of angiopoietin-like protein 4 in calf hepatocytes cultured in vitro

“…ANG-PTL4 has been shown to be a downstream target of PPAR [5]. In particular, studies have suggested that PPARc and PPARa act as ligand-activated nuclear transcription factors activated by NEFA and their derivatives, thereby controlling the expression of several genes, such as fatty acid transporters, fatty acid activation genes, and rate-limiting enzymes of fatty acid oxidation, involved in lipid metabolism [31]. Typically, PPARc is mainly expressed in adipose tissue and is expressed at very low levels in the liver; however, the importance of up-regulated PPARc expression in the development of fatty livers has been demonstrated in mouse models [32].…”

Effect of prepartal ad libitum feeding of grass silage on transcriptional adaptations of the liver and subcutaneous adipose tissue in dairy cows during the periparturient period

“…The absence of differences in the mRNA abundances of glucose-6-phosphatase catalytic subunit (G6PC) and solute carrier family 2 (facilitated glucose transporter), member 2 (SLC2A2) suggest that hepatic glucogenic status, particularly glucose release from the liver (Hammon et al, 2009;Goselink et al, 2013), did not differ between the treatment groups. However, it is noteworthy that no time effect was observed in the mRNA expression of these genes, as was also reported by Hammon et al (2009) and Goselink et al (2013).…”

Effects of short- and long-chain fatty acids on the expression of stearoyl-CoA desaturase and other lipogenic genes in bovine mammary epithelial cells

“…The primers selected for qPCR are presented in Supplementary Table S1. The primers to quantify bovine SCD1, ACTB, 18S RNA, peroxisome proliferator-activated receptor alpha (PPARA) and peroxisome proliferatoractivated receptor delta (PPARD) expression have been used previously (Jacobs et al, 2011;Goselink et al, 2013;Jacobs et al, 2013). PCR efficiencies for the genes were established to be at least 91%.…”

“…Tissue sampling For comparison of the expression pattern in native tissue v. that in MAC-T cells, liver, mammary gland and adipose tissue, biopsies were taken from three lactating Holstein-Friesian cows as described previously (Jacobs et al, 2011;Goselink et al, 2013). Collected tissues were stored at 2808C until RNA extraction.…”