Serum metabolomics study in a group of Parkinson's disease patients from northern India

Background: Parkinson's disease (PD) is the result of progressive degeneration of the nigrostriatal dopaminergic pathway and depletion of neurotransmitter dopamine in the striatum. Methods: We included 17 patients with PD along with 7 patients of progressive supranuclear palsy (PSP), 6 patients of multiple system atrophy (MSA) and 22 age and sex-matched healthy controls. We analyzed metabolite profiles in the serum of these patients and controls using H-1 NMR spectroscopy. Results: Isoleucine, valine, alanine, glutamine and histidine in PD, PSP and MSA were significantly (P < 0.001) higher than controls, whereas, glutamate and glucose were significantly increased in PD (P < 0.001), PSP and MSA (P < 0.05) vs. control. Citrate was increased in PD, PSP and MSA (P < 0.05) vs. control. While, acetone, lactate and formate were higher at P < 0.001, threonine is increased at P < 0.05. The 3D scattered score plot of OPLS-DA model revealed clear differentiation among the groups, R2 = 0.92 and Q2 = 0.78. Conclusion: Significant differences in various metabolite levels were found between control and disease groups. Common amino acids that are significantly higher in all groups include branched chain amino acids, which could increase neuronal excitability.