Redox State of Glutathione and Cysteine in Plasma Following Acute Stroke

Ischemic stroke is a major cause of long-term disability and death, with oxidative stress contributing substantially to post-ischemic injury. Reperfusion restores oxygen supply but simultaneously increases reactive oxygen species (ROS), amplifying secondary neuronal damage. This study examined time-dependent changes in systemic thiol redox status following transient middle cerebral artery occlusion (tMCAO) in rats. Plasma concentrations of cysteine (CySH), cystine (CySS), glutathione (GSH), and glutathione disulfide (GSSG), along with corresponding CySS/CySH and GSSG/GSH ratios and redox potentials (Eh), were evaluated 24 and 48 h after occlusion. At 24 h, thiol concentrations and redox ratios showed no significant differences between sham and tMCAO groups. By 48 h, a marked oxidative shift emerged, characterized by reduced CySH, elevated GSSG, and significant increases in both CySS/CySH and GSSG/GSH ratios. Redox potentials also demonstrated substantial oxidation at this time point. These findings indicate that prolonged ischemia-reperfusion induces systemic oxidative stress, with plasma redox status serving as a sensitive indicator of reperfusion-related injury. The results underscore the plasma redox status as a potentially sensitive biomarker of reperfusion-induced oxidative injury and support the therapeutic value of targeting redox imbalance to mitigate oxidative damage following stroke.