Effect of chronic manganese treatment on adenosine tissue levels and adenosine A2a receptor binding in diverse regions of mouse brain

UHPLC-Q-TOF/MS based plasma metabolomics reveals the metabolic perturbations by manganese exposure in rat models

Although manganese (Mn) is an essential metal ion biological cofactor, high concentrations could potentially induce an accumulation in the brain and lead to manganism. However, there is no "gold standard" for manganism assessment due to a lack of objective biomarkers. We hypothesized that Mn-induced alterations are associated with metabolic responses to manganism. Here we use an untargeted metabolomics approach by performing ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) on control and Mn-treated rat plasma, to identify metabolic disruptions under high Mn exposure conditions. Sprague-Dawley rats had access to deionized drinking water that was either Mn-free or contained 200 mg Mn per L for 5 weeks. Mn-exposure significantly increased liver Mn concentration in comparison with the control, and also resulted in extensive necrosis and dissolved nuclei, which suggested liver damage from hepatic histopathology. Principal component analysis readily distinguished the metabolomes between the control group and the Mn-treated group. Using multivariate and univariate analysis, Mn significantly altered the concentrations of 36 metabolites (12 metabolites showed a remarkable increase in number and 24 metabolites reduced significantly in concentration) in the plasma of the Mn-treated group. Major alterations were observed for purine metabolism, amino acid metabolism and fatty acid metabolism. These data provide metabolic evidence and putative biomarkers for the Mn-induced alterations in plasma metabolism. The targets of these metabolites have the potential to improve our understanding of cell-level Mn trafficking and homeostatic mechanisms.

Changes in Brain Metallome/Metabolome Pattern due to a Single i.v. Injection of Manganese in Rats

Exposure to high concentrations of Manganese (Mn) is known to potentially induce an accumulation in the brain, leading to a Parkinson related disease, called manganism. Versatile mechanisms of Mn-induced brain injury are discussed, with inactivation of mitochondrial defense against oxidative stress being a major one. So far, studies indicate that the main Mn-species entering the brain are low molecular mass (LMM) compounds such as Mn-citrate. Applying a single low dose MnCl₂ injection in rats, we observed alterations in Mn-species pattern within the brain by analysis of aqueous brain extracts by size-exclusion chromatography—inductively coupled plasma mass spectrometry (SEC-ICP-MS). Additionally, electrospray ionization—ion cyclotron resonance-Fourier transform-mass spectrometry (ESI-ICR/FT-MS) measurement of methanolic brain extracts revealed a comprehensive analysis of changes in brain metabolisms after the single MnCl₂ injection. Major alterations were observed for amino acid, fatty acid, glutathione, glucose and purine/pyrimidine metabolism. The power of this metabolomic approach is the broad and detailed overview of affected brain metabolisms. We also correlated results from the metallomic investigations (Mn concentrations and Mn-species in brain) with the findings from metabolomics. This strategy might help to unravel the role of different Mn-species during Mn-induced alterations in brain metabolism.