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Low expression of sirtuin 1 in the dairy cows with mild fatty liver alters hepatic lipid metabolism.

Y. Li

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06-22-2020

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Abstract:

M40
Low expression of sirtuin 1 in the dairy cows with mild fatty liver alters hepatic lipid metabolism.
Y. Li*1, H. Ding1, S. Feng1, J. Li1, X. Wang1, J. Wu1, Y. Liang2, J. J. Loor2. 1Anhui Agricultural University Hefei, Anhui, China, 2University of Illinois at Urbana-Champaign Urbana, IL.

This study aimed to investigate the effect of hepatic steatosis on mRNA and protein abundance of the sirtuin 1 (SIRT1), along with the target mRNA and protein expressions and activities of related to lipid metabolism in liver tissue. Lactating Holstein multiparous cows (days postpartum 70 � 12) of the same breed, age and having similar milk production characteristics and body condition scores were selected from a commercial dairy farm. Control cows (n = 6, parity 3.0 � 2.0, milk production 28 � 7 kg/d) and mild fatty liver cows (n = 6, parity 2.3 � 1.5, milk production 20 � 6 kg/d) were retrospectively selected based on liver triglycerides (TG) content (% wet liver)(control = 0.45, fatty liver = 7.65, 5—10 was considered as mild fatty liver) . Dairy cows were slaughtered for collecting liver tissue samples and processed as part of the normal work of a commercial abattoir. One-way ANOVA (with Dunnett's post hoc test) and a 2-tailed Student's t-test were performed by Statistical Package for the Social Science (SPSS) 17.0. Compared with the control group, fatty liver cows had greater concentrations of cholesterol and TG along with the typically vacuolated appearance and greater lipid droplets in the liver. Furthermore, fatty liver cows had greater mRNA and protein abundance related to hepatic lipid synthesis (SREBP-1c, ACSL, ACC and FAS) and lipid transport (L-FABP, ApoE, LDLR and MTTP) (P < 0.05). However, they had lower mRNA and protein abundance associated with fatty acid β-oxidation (SIRT1, PGC-1α, PPARα, RXRα, ACO, CPT1, CPT2 and LCAD) (P < 0.05). Besides, mRNA abundance and enzyme activity of Cu/Zn SOD, CAT, GSH-Px and Mn-SOD decreased and mRNA and protein abundance of Nrf1 and TFAM decreased (P < 0.05). Lower enzyme activities of SIRT1, PGC-1α, Cu/Zn SOD, CAT, GSH-Px and Mn-SOD (P < 0.05) and concentration of GSH (P < 0.05) were observed in fatty liver cows. Overall, data suggest that low SIRT1 expression associated with hepatic steatosis promotes hepatic fatty acid synthesis and inhibits fatty acid β-oxidation. Hence, SIRT1 might be a novel therapeutic target for coping with fatty liver in dairy cows.

Keywords: dairy cow, SIRT1, fatty liver.