Effects of Various Concentrations of Trimethylamine‐N‐oxide on Serum and Cecal Metabolites in Female SD Rats Fed a High‐Fat Diet

Abstract

Trimethylamine‐N‐oxide (TMAO) has been shown to be a putative promoter of cardiovascular disease. Trimethylamine (TMA) precursors, such as choline and L‐carnitine, in foods can be metabolized to TMA by some gut microbiota and further converted to TMAO in liver. Recently, gut microbiota has been found to play an important role in nutrient metabolism. It can metabolize not only nutrients but also bile acids, which could affect gut liver axis and modulate metabolism. However, the effects of various concentrations of TMAO on microbial metabolites including TMA, TMAO, individual bile acids, and short chain fatty acids in rats have been little studied. The aim of this study was to evaluate effects of dietary TMAO on levels of metabolites in serum (TMA, TMAO, and bile acids) and cecum (TMA, TMAO, bile acids, and short chain fatty acids) of female SD rats fed a high‐fat (HF) diet. Sixteen female SD rats were fed HF diet (AIN‐93G diet providing 45% of energy from fat) with or without various concentrations of TMAO (0.05%, 0.15%, and 0.3%; T0.05, T0.15, and T0.3, respectively) (w/w) in autoclaved tap water for 8 weeks. Levels of TMA, TMAO, and bile acids were determined by UPLC‐Synapt G2‐Si. Short chain fatty acid profile was determined by GC‐FID. Serum TMA and TMAO levels were significantly (p<0.05) higher in the T0.3 than control group (CON), while cecal TMA level showed the opposite response. Glycocholic and tauro‐alpha‐muricholic acids were significantly (p<0.05) higher in the serum of the T0.3 than that of the CON. Taurocholic and taurodeoxycholic acids were significantly (p<0.05) the highest in the cecum of the CON. Valeric and isovaleric acids were significantly (p<0.05) higher in the cecum of the T0.05 than that of the CON.Support or Funding InformationThis research has been supported by National Research Foundation of Korea (NRF‐2017R1D1A1B03028407) funded by the Ministry of Education of Korea.