Three species comparison—Tissues.

Comparison of the concentrations of TMA, TMAO and the TMAO/TMA ratios in the liver, heart and lungs. Abbreviations: TMA, Trimethylamine; TMAO, Trimethylamine oxide. All data are expressed as the individual values and median; Kruskal-Wallis test followed by post-hoc Dunn’s test; *P<0.05; **P<0.01; ***P<0.001.</p

Species-specific comparison of TMAO, TMA and other metabolites concentrations in plasma and urine.

Species-specific comparison of TMAO, TMA and other metabolites concentrations in plasma and urine.</p

Three species comparison–Tissues, continuation.

Comparison of the concentrations of TMA, TMAO and the TMAO/TMA ratios in the renal cortex and renal medulla. Abbreviations: TMA, Trimethylamine; TMAO, Trimethylamine oxide. All data are expressed as the individual values and median; Kruskal-Wallis test followed by post-hoc Dunn’s test; *P<0.05; **P<0.01; ***P<0.001.</p

FMO3 and FMO5 in the liver.

Western blot analysis of FMO3 (A) and FMO5 (C) protein levels from total protein extract prepared from the liver in rats, mice and guinea pigs. (B) A representative immunoblot. Immunolabeled FMO3 and beta actin loading control bands were quantified using a Molecular Imager. Relative levels of the test proteins are plotted in arbitrary units. Abbreviations: FMO, Flavin-containing monooxygenase. All data are expressed as the median, mean, Q1, Q3, MIN, MAX (n = 4–6); ANOVA followed by post-hoc Tuckey test. **P < 0.01; ***P < 0.001.</p

Species-specific comparison of TMAO, TMA, and other metabolites plasma and urine concentrations.

Species-specific comparison of TMAO, TMA, and other metabolites plasma and urine concentrations.</p

Species-specific comparison of choline and carnitine concentrations in various tissues.

Species-specific comparison of choline and carnitine concentrations in various tissues.</p

Western blotting–original images.

IntroductionIncreased plasma trimethylamine oxide (TMAO) is observed in cardiovascular and metabolic diseases, originating from the gut microbiota product, trimethylamine (TMA), via flavin-containing monooxygenases (FMOs)-dependent oxidation. Numerous studies have investigated the association between plasma TMAO and various pathologies, yet limited knowledge exists regarding tissue concentrations of TMAO, TMAO precursors, and interspecies variability.MethodsChromatography coupled with mass spectrometry was employed to evaluate tissue concentrations of TMAO and its precursors in adult male mice, rats, and guinea pigs. FMO mRNA and protein levels were assessed through PCR and Western blot, respectively.ResultsPlasma TMAO levels were similar among the studied species. However, significant differences in tissue concentrations of TMAO were observed between mice, rats, and guinea pigs. The rat renal medulla exhibited the highest TMAO concentration, while the lowest was found in the mouse liver. Mice demonstrated significantly higher plasma TMA concentrations compared to rats and guinea pigs, with the highest TMA concentration found in the mouse renal medulla and the lowest in the rat lungs. FMO5 exhibited the highest expression in mouse liver, while FMO3 was highly expressed in rats. Guinea pigs displayed low expression of FMOs in this tissue.ConclusionDespite similar plasma TMAO levels, mice, rats, and guinea pigs exhibited significant differences in tissue concentrations of TMA, TMAO, and FMO expression. These interspecies variations should be considered in the design and interpretation of experimental studies. Furthermore, these findings may suggest a diverse importance of the TMAO pathway in the physiology of the evaluated species.</div

List of antibodies used for western blot analyses.

List of antibodies used for western blot analyses.</p

Raw data.

IntroductionIncreased plasma trimethylamine oxide (TMAO) is observed in cardiovascular and metabolic diseases, originating from the gut microbiota product, trimethylamine (TMA), via flavin-containing monooxygenases (FMOs)-dependent oxidation. Numerous studies have investigated the association between plasma TMAO and various pathologies, yet limited knowledge exists regarding tissue concentrations of TMAO, TMAO precursors, and interspecies variability.MethodsChromatography coupled with mass spectrometry was employed to evaluate tissue concentrations of TMAO and its precursors in adult male mice, rats, and guinea pigs. FMO mRNA and protein levels were assessed through PCR and Western blot, respectively.ResultsPlasma TMAO levels were similar among the studied species. However, significant differences in tissue concentrations of TMAO were observed between mice, rats, and guinea pigs. The rat renal medulla exhibited the highest TMAO concentration, while the lowest was found in the mouse liver. Mice demonstrated significantly higher plasma TMA concentrations compared to rats and guinea pigs, with the highest TMA concentration found in the mouse renal medulla and the lowest in the rat lungs. FMO5 exhibited the highest expression in mouse liver, while FMO3 was highly expressed in rats. Guinea pigs displayed low expression of FMOs in this tissue.ConclusionDespite similar plasma TMAO levels, mice, rats, and guinea pigs exhibited significant differences in tissue concentrations of TMA, TMAO, and FMO expression. These interspecies variations should be considered in the design and interpretation of experimental studies. Furthermore, these findings may suggest a diverse importance of the TMAO pathway in the physiology of the evaluated species.</div

Three species comparison—Plasma.

Comparison of the concentrations of TMA, TMAO and the TMAO/TMA ratio in the plasma. Abbreviations: TMA, Trimethylamine; TMAO, Trimethylamine oxide. LOQ for TMA in plasma = 0.017 μM/l. All data are expressed as the individual values and median; Kruskal-Wallis test followed by post-hoc Dunn’s test; *P<0.05; **P<0.01.</p