Table 1 Plasma, urinary and hepatic aqueous metabolites found to be altered between RYGB- and SHAM-operated rats based on OPLS-DA models

Plasma metabolite	An OPLS-DA model of plasma CPMG spectral data (Q ² Y=0.83; R ² X=33.5%)
	Change in RYGB	Peak (ppm)	P-value	q-value
CH₃	↓	0.87	0.002	0.025
(CH₂)n	↓	1.266	0.005	0.03
CH₂CH₂CO	↓	1.562	0.006	0.03
CH₂C=C	↓	2.036	0.002	0.02
CH₂C=O	↓	2.227	0.004	0.03
CH=CH	↓	5.3	0.007	0.03
Pyruvate	↑	2.357	0.006	0.03
Lactate	↑	4.107	0.004	0.03
D-3-hydroxybutyrate	↓	1.178	0.09	0.14
Glutamine	↓	2.426	0.003	0.03
Citrate	↑	2.664	0.02	0.06
Creatine	↓	3.023	0.004	0.03
TMAO+betain	↓	3.252	0.004	0.03
Glycerol	↓	3.566	<0.001	0.01
2-deoxycytidine	↓	6.04	<0.001	0.02
Formate	↑	8.443	<0.001	0.003
Phenylalanine	↓	7.407	0.004	0.03
Acetate	↑	1.904	0.03	0.06
2-phenylpropionate*	↑	1.425	<0.001	0.005
Alanine	↑	1.471	<0.001	0.005
Lysine	↑	1.892	<0.001	0.006
3-aminoisobutyrate*	↑	1.2	0.004	0.03

Urinary metabolite	An OPLS-DA model of urinary spectral data (Q ² Y=0.93; R ² X=36.8%)
	Change in RYGB	Peak (ppm)	P-value	q-value
Succinate	↓	2.413	<0.001	<0.001
2-oxoglutarate	↓	2.448	<0.001	<0.001
Citrate	↓	2.548	<0.001	<0.001
Fumarate	↓	5.528	<0.001	<0.001
2-oxoadipate	↑	1.824	<0.001	0.002
5-aminovalerate	↑	1.645	0.05	0.06
Pimelate	↑	1.31	0.004	0.01
TMAO	↑	3.273	0.002	0.007
Taurine	↓	3.433	0.002	0.006
Creatine	↑	3.933	0.1	0.09
Creatinine	↓	4.054	<0.001	0.003
4-hydroxyphenylacetate	↑	3.454	0.001	0.004
Unknown	↑	3.523	0.002	0.006
p-cresyl glucuronide	↑	2.301	0.002	0.005
p-cresyl sulfate	↑	2.346	0.002	0.007
PAG	↑	3.757	<0.001	<0.001
Hippurate	↓	3.974	0.009	0.02
Trigonelline	↓	4.436	<0.001	<0.001
Indoxyl sulfate	↑	7.714	<0.001	0.002

Liver metabolite	An OPLS-DA model of liver aqueous extract (Q ² Y=0.81; R ² X=45.6%)
	Change in RYGB	Peak (ppm)	P-value	q-value
Lactate	↑	1.339	0.001	0.005
Alanine	↑	1.479	0.01	0.02
Glucose	↑	5.238	<0.001	0.002
Glycogen	↑	5.415	<0.001	0.002
Glycerol	↑	3.78	<0.001	0.001
Uracil	↑	5.803	0.03	0.05
Hypoxanthine	↑	8.2	0.006	0.02

Abbreviations: CPMG, Carr-Purcell-Meiboom-Gill; OPLS-DA, orthogonal-partial least squares-discriminant analysis; PAG, phenylacetylglycine; RYGB, Roux-en-Y gastric bypass; TMAO, trimethylamine-N-oxide.
R²X represents the variation in ¹H NMR spectral data explained by the OPLS-DA model. Q²Y indicates the level of significance of the metabolic differences between two classes. The P- and q-values in the table represent the significance of the metabolite changes and false discovery rate-adjusted P-values, respectively. The arrow up or arrow down represents the increased or decreased trend of metabolites in RYGB-operated rats compared with SHAM controls. *Tentative metabolite assignment.

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