Glutathione peroxidase & subarachnoid hemorrhage: implications for the role of oxidative stress in cerebral vasospasm Introduction It has long been suspected that reactive oxygen species (ROS) play a major role in the etiology of CV after SAH. We hypothesize that glutathione peroxidase (GSH-Px1) activity is altered between CSF from SAH patients with CV (CSF V ), compared with those without CV (CSF C ), and that the difference in total antioxidant capacity of CSF V and CSF C will be largely due to GSH-Px1. There are many ways in which oxidative stress is implicated in these disease processes (Fig. 1). Methods CSF was obtained with appropriate local IRB approval. GSH-Px1 protein levels were determined using standard SDS-PAGE and western blotting techniques, as published by us and many others 1. GSH-Px1 Activity levels were measured using a commercially available kit (Zeptometrix Corp., Franklin, MA). Oxygen Radical Absorbance capacity (ORAC) was measured using a commercially available kit (Cayman Chem. Co., Ann Arbor, MI) Results Discussion There was a significant y higher ORAC in the vasospastic CSF, which may indicate either a greater response in vasospastic patients, or that a higher ORAC baseline exists in patients likely to develop CV after SAH. This observation warrants further investigation. We observed that a significant portion of the increased ORAC is due to increased activity, but not increased amount of protein, of glutathione peroxidase, possible implication selenium moieties. Previous data from our laboratory has shown significantly increased lipid peroxidation in the CSF milieu in vasospastic patients ‘ CSF 2,3. Thus, despite increased ORAC and GSH-Px1 activity, there is still elevated oxidative damage associated with CV after SAH. Whether this elevation occurs before or after the onset of CV after SAH is as yet unclear. Conclusions Glutathione peroxidase activity, but not content, was significantly higher, associated with CV after SAH. Total oxygen radical capacity was also higher associated with CV after SAH, and yet elevated lipid peroxidation is not prevented in these patients’ CSF. Gail Pyne-Geithman, D.Phil. 1,3,4, Danielle Caudell, BA 3, Porus Prakash 3, Joseph Clark, PhD 1,3, Lori Shutter, MD 1,2,3,4,5 University of Cincinnati (UC) Neuroscience Institute 1 : Division of Neurocritical Care 2 ; Department of Neurology 3, Department of Neurosurgery 4, UC College of Medicine; Mayfield Clinic 5, Cincinnati, OH Figure 1. A concept map illustrating the multiple steps in the disease process of cerebral vasospasm after subarachnoid hemorrhage in which oxidative stress plays a known role. Figure 2. Panel A shows a representative (N=5) western blot of GSH-Px1 protein in human CSF, along with a pure protein control. Panel B is a densitometric semi- quantitation of these bands, errors are standard deviation. There was no difference between vasospastic and non-vasospastic SAH CSF with respect to protein content when probed specifically for human GSH-PX1. Figure 3. Panel A shows the increased ORAC of the vasospastic CSF compared to that from SAH patients without vasospasm. Panel B shows that GSH-Px1 activity is significantly higher in CSF V than CSF C. N=5 for each group, and errors are standard deviations. * indicates significant difference from control by ANOVA (p<0.05). References 1.Pyne-Geithman, G. J., S. G. Nair, D. N. Caudell, J. F. Clark. PKC and Rho in vascular smooth muscle: Activation by BOXes and SAH CSF. Front. Biosci : Review 2.Clark, J. F., M. Loftspring, W. L. Wurster, G. J. Pyne-Geithman Chemical and biochemical oxidations in spinal fluid after subarachnoid hemorrhage. Front. Biosci : Review 3.Pyne-Geithman, G. J., C. J. Morgan, K. R. Wagner, E. M. Dulaney, J. A. Carrozzella, D. S. Kanter, M. Zuccarello, J. F. Clark. Bilirubin production and oxidation in CSF of patients with cerebral vasospasm after subarachnoid hemorrhage. J. Cereb. Bl. Fl. Metab :