Session: Advances in Mass Spectrometry:

Traumatic brain injury (TBI), a growing cause for concern, has received great attention in diagnosis but remains lacking in its treatment. After initial trauma, the brain experiences an imbalance in the ratio of reactive oxygen and nitrogen species to endogenous antioxidants -which have been subjected to depletion- like glutathione (GSH), which shields cells from free radical-induced oxidative stress by transforming into its oxidized form of glutathione disulfide (GSSG).TBI is also characterized by an elevation of membrane lipid peroxidation by-products and oxidative-stress generated biomarkers such as F2a-isoprostane, malondialdehyde, 4-Hydroxynonenal, N-acetylaspartic acid, 5-Hydroxyindoleacetic acid. Apart from monitoring the biomarker levels, the reduced GSH/GSSG ratio is a good indicator of the oxidative stress in cells post-TBI. Antioxidant prodrugs like N-acetylcysteine amide (NACA) are GSH precursors and are efficient in improving the GSH level in the cell. NACA also has comparatively higher permeability through blood-brain barrier and cell membrane. Therefore, NACA was evaluated in this study as a therapeutic agent for treating TBI-induced rat models. Mild to severe TBI was induced using explosive blast placed at different distances from the rats. Some of the rats were pretreated with oral administration of the antioxidant prodrug NACA at different timelines (before and after blast). The rats were sacrificed to collect the urine, blood, and brain samples for the analysis of oxidative stress biomarkers using a UFLC-MS/MS. The UFLC-MS/MS methods yielded excellent sensitivity, linearity, recovery, and reproducibility. Additional steps including the derivatization and addition of antioxidants were employed for the stability of analytes in the collected samples. Analyte levels in urine and plasma samples were normalized using creatinine and corresponding internal standards. The GSH/GSSG ratios were also evaluated for the efficacy of NACA in treating TBI.

Catherine Johnson

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