Papers of the Week

Chronic inflammation pain is a debilitating disease, and its mechanism still remains poorly understood. This study was attempt to illuminate the metabolic mechanism of chronic inflammation pain induced by Complete Freund's adjuvant (CFA) injection especially at spinal level. The chronic inflammation pain model was established by CFA administration. The behavioral testing including mechanical allodynia and thermal hyperalgesia was performed. Meanwhile, liquid chromatograph-mass spectrometer (LC-MS)-based metabolomics approach was applied to analyze potential metabolic biomarkers. The orthogonal partial least squares discrimination analysis (OPLS-DA) mode was employed for determining metabolic changes, and western blot was performed to detect the protein expression change. The results showed that twenty-seven metabolites were obviously abnormal expression and seven metabolic pathways were significantly enriched comprising of aminoacyl-tRNA biosynthesis, arginine and proline metabolism, histidine metabolism, purine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, glutathione metabolism, and phenylalanine metabolism. Meanwhile, the results showed that the expression of arginase I and NO level were elevated in CFA group than that of in Control group, while the protein of argininosuccinate synthetase and argininosuccinatelyase were not significantly different between CFA group and Control group. These findings demonstrated that metabolic changes of spinal cord may implicate in neurotransmitter release and pain conductivity following CFA administration.