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Methionine and arginine supply alleviate oxidative stress and inflammation in subcutaneous bovine adipose explants challenged with H2O2.

N. Ma

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06-23-2020

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Abstract:

T63
Methionine and arginine supply alleviate oxidative stress and inflammation in subcutaneous bovine adipose explants challenged with H2O2.
N. Ma*1,2, Y. Liang1, D. N. Coleman1, F. Liu1,3, Y. Li1,4, H. Ding1,4, F. F. Cardoso1, F. C. Cardoso1, X. Shen2, J. J. Loor1. 1University of Illinois Urbana, IL, 2Nanjing Agricultural University Nanjing, Jiangsu, China, 3Henan Agricultural University Zhengzhou, Henan, China, 4Anhui Agricultural University Hefei, Anhui, China.

Methionine (Met) and arginine (Arg) alter protein synthesis through the mechanistic target of rapamycin (mTOR), and regulate oxidative stress (OS) partly through their metabolism to glutathione and polyamines. We examined if enhanced supply of Met or Arg in adipose tissue (AT) explants challenged with H2O2 altered OS. Subcutaneous AT was harvested from 4 Holstein cows (parity 4 � 1.4, DIM 248 � 38 before slaughter; mean � SD). Tissue was incubated for 4 h with the following: control medium with an “ideal” profile of essential amino acids (AA) (IPAA, Lys:Met 2.9:1, Lys:Arg 2:1), IPAA plus 100 μM H2O2 (OS), H2O2 plus increased Met (OS+Met; Lys:Met 2.5:1), H2O2 plus increased Arg (OS+Arg; Lys:Arg 1:1), or H2O2 plus increased Met/Arg (OS+Met/Arg; Lys:Met 2.5:1 and Lys:Arg 1:1). The following results were protein expression measured by Western Blot. Preplanned orthogonal contrasts were IPAA vs. OS, OS vs. the average of OS+Met, OS+Arg, and OS+Met/Arg, OS+Met vs. OS+Met/Arg and OS+Arg vs. OS+Met/Arg. The MIXED procedure of SAS 9.4 was used (SAS Institute Inc., Cary, NC). Challenge with OS lowered (P < 0.01) ratio of phosphorylated (p)-mTOR to total mTOR, but greater supply of Met and Arg reversed this effect. Compared with Arg, supply of Met/Arg during OS challenge led to greater (P < 0.01) p-mTOR/mTOR. In spite of lower (P < 0.01) abundance of kelch-like ECH-associated protein 1 (KEAP1) with Met and Arg compared with OS, there was no effect (P = 0.25) of the AA on nuclear factor erythroid 2-related factor 2 (NRF2). Compared with Met or Arg alone, abundance of the proinflammatory transcription factor NF-κB p65 was lower when both AA were supplied together during OS challenge. Abundance of hydroxycarboxylic acid receptor 2 (HCAR2), known to elicit anti-inflammatory effects in non-ruminant AT, was lower with OS challenge, but supply of AA did not (P = 0.19) alleviate this effect. Overall, data suggest that enhanced supply of Met and Arg could alleviate adipose tissue oxidative stress and inflammation induced by OS. The relevance of these results in vivo merit further study.

Keywords: amino acid, oxidative stress, inflammation.