Table 2. Differential metabolites in rat testis responsive to arsenic exposure.

HMDB ID	Metabolite	Measured MW (Da)	Change	Fold change (Treatment/Control)a
				1 mg/L	5 mg/L	25 mg/L
HMDB00687	L-Leucine	132.1019	↑	0.94 ± 0.08	0.99 ± 0.10	1.82 ± 0.46**
HMDB00157	Hypoxanthine	137.0456	↓	0.80 ± 0.15*	0.74 ± 0.10**	0.48 ± 0.10**
HMDB00875	Trigonelline	138.0502	↑	4.28 ± 3.15	2.67 ± 2.56	3.65 ± 2.81*
HMDB00696	L-Methionine	150.058	↑	0.91 ± 0.14	0.98 ± 0.13	1.40 ± 0.20**
HMDB00159	L-Phenylalanine	166.0859	↑	0.98 ± 0.18	1.04 ± 0.16	2.20 ± 0.83**
HMDB12247	L-2,3-Dihydrodipicolinate	170.0323	↓	0.96 ± 0.09	0.95 ± 0.06	0.88 ± 0.11*
HMDB00158	L-Tyrosine	182.0808	↑	0.91 ± 0.15	0.96 ± 0.15	1.47 ± 0.26**
HMDB12150	2-Keto-6-acetamidocaproate	188.0703	↑	1.01 ± 0.20	1.12 ± 0.14	1.29 ± 0.40**
HMDB00201	L-Acetylcarnitine	204.1052	↑	1.23 ± 0.17**	1.22 ± 0.18**	3.21 ± 1.78**
HMDB00195	Inosine	269.0874	↓	0.80 ± 0.14*	0.74 ± 0.12**	0.47 ± 0.11**
HMDB01449	Allopregnanolone	319.2627	↓	0.78 ± 0.20	0.71 ± 0.41	0.36 ± 0.28**
HMDB03128	Cortolone	367.2601	↓	0.64 ± 0.27	0.56 ± 0.25*	0.30 ± 0.21**
HMDB11487	LysoPE(0:0/20:4(5Z,8Z,11Z,14Z))	502.2921	↑	1.80 ± 0.86	1.47 ± 0.38*	1.96 ± 0.90*

^aThe change of metabolite abundance is expressed as the average ratio of treatment/control (control = 1, mean ± SD). A value >1 represents up-regulation, whereas a value <1 indicates down-regulation. ^*p < 0.05, ^**p < 0.01.