(1) H NMR Metabolic Profiling of Biofluids from Rats with Gastric Mucosal Lesion and Electroacupuncture Treatment

Abstract

Gastric mucosal lesion (GML) is a common gastrointestinal disorder with multiple pathogenic mechanisms in clinical practice. In traditional Chinese medicine (TCM), electroacupuncture (EA) treatment has been proven as an effective therapy for GML, although the underlying healing mechanism is not yet clear. Here, we used proton nuclear magnetic resonance- ((1)H NMR-) based metabolomic method to investigate the metabolic perturbation induced by GML and the therapeutic effect of EA treatment on stomach meridian (SM) acupoints. Clear metabolic differences were observed between GML and control groups, and related metabolic pathways were discussed by means of online metabolic network analysis toolbox. By comparing the endogenous metabolites from GML and GML-SM groups, the disturbed pathways were partly recovered towards healthy state via EA treated on SM acupoints. Further comparison of the metabolic variations induced by EA stimulated on SM and the control gallbladder meridian (GM) acupoints showed a quite similar metabolite composition except for increased phenylacetylglycine, 3,4-dihydroxymandelate, and meta-hydroxyphenylacetate and decreased N-methylnicotinamide in urine from rats with EA treated on SM acupoints. The current study showed the potential application of metabolomics in providing further insight into the molecular mechanism of acupuncture.

Figure 1

Photomicrographs of representative sections of gastric mucosal tissues from groups of control (a), GML (b), GML-SM (c), and GML-GM (d). The tissue sections were stained with hematoxylin-eosin and observed under a 400x microscope.

Figure 2

PLS-DA models derived from NMR datasets. (a) Serum score plot (R ² X = 49.8%, R ² Y = 63.9%, Q ² = 49.4%) and (b) urine score plot (R ² X = 69.8%, R ² Y = 59.1%, Q ² = 39.8%).

Figure 3

OPLS-DA score plots (left panel) and the corresponding coefficient loading plots (middle and right panels) derived from NMR data of serum (a) and urine (b) obtained from GML-related dataset (keys: 2-HB: 2-hydroxybutyrate; 3-HB: 3-hydroxybutyrate; AA: acetoacetate; ACh: acetylcholine; Ace: acetate; Act: acetone; AD: acetamide; Ala: alanine; Ben: benzoate; Bet: betaine; Bu: butyrate; Ci: citrate; Cn: creatinine; Cr: creatine; DHM: 3,4-dihydroxymandelate; DMA: dimethylamine; DMG: N,N-dimethylglycine; EA: ethanolamine; Eth: ethanol; For: formate; GA: guanidinoacetate; GABA: gamma-aminobutyrate; Gln: glutamine; Gly: glycine; HG: homogentisate; Hip: hippurate; Ile: isoleucine; α-KG: α-ketoglutarate; Lac: lactate; m-HPA: meta-hydroxyphenylacetate; m-I: myo-inositol; MM: methylmalonate; MH: methylhistidine; MN: 1-methylnicotinamide; Mol: methanol; NAG: N-acetylglutamate; NMN: N-methylnicotinamide; p-HPA: para-hydroxyphenylacetate; PAG: phenylacetylglycine; PC: phosphocholine: Py: pyruvate; Suc: succinate; Tau: taurine; TMA: trimethylamine; Tri: trigonelline; Val: Valine; α-Glc: α-glucose; β-Glc: β-glucose).

Figure 4

Quantitative changes of serum (a) and urine (b) metabolome from the control, GML group, and GML-SM and GML-GM groups. ∗ indicates p < 0.05 statistical significance relative to control group; △ indicates p < 0.05 statistical significance relative to GML group after electroacupuncture in SM or GM acupoints of GML rats.

Figure 5

OPLS-DA score plots (left panel) and the corresponding loading plots (middle and right panels) derived from NMR data of serum obtained from two-group comparison focusing on the metabolic difference due to EA treatment.

Figure 6

OPLS-DA score plots (left panel) and the corresponding loading plots (middle and right panels) derived from NMR data of urine obtained from pairwise EA-related datasets.