Mass spectrometric analysis of rat cerebrospinal fluid proteins following exposure to the neurotoxicant carbonyl sulfide

Abstract

RATIONALE Using a proteomic-based approach we have investigated possible altered expression of a range of cerebral spinal fluid (CSF) proteins following exposure to the neurotoxicant carbonyl sulfide (COS). CSF is ideal for the investigation of markers of brain injury or disease since it is secreted from several central nervous system structures and changes in the CSF composition may reflect brain insult and many pathological processes. METHODS Animals were placed in exposure chambers and were exposed to 0 ppm or 500 ppm carbonyl sulfide for one, two or three days, six hours per day. After the last inhalation exposure, 50-70 μL CSF sample was obtained by lumbar puncture. CSF samples were analyzed by ESI/MS on either a Q-TOF Premier or an Agilent 6340 ion trap and by MALDI/MS on a 4800 MALDI–TOF/TOF Analyzer. RESULTS The dynamic range of abundance of the identified proteins spanned over more than three orders of magnitude. The four most abundant proteins identified (albumin, cystatin C, serotransferrin, transthyretin) are major proteins that are present in both CSF and blood at high levels but the fifth most abundant protein identified (prostaglandin H2D isomerase) is the second most abundant protein in human CSF and is secreted and synthesized in rat central nervous system. No significant differences were observed between carbonyl sulfide treated CSF samples and the control CSF samples because of blood contamination. CONCLUSIONS Quantitative MS protein analyses of rat CSF is limited by the low sample volumes that can practicably be obtained from rats and the low protein concentrations in rat CSF. Results of this work suggest a clear need of CSF collection that would minimize blood contamination.