Selenium pretreatment attenuates ROS production and maintains mitochondrial membrane potential. ROS production was attenuated by selenium pretreatment following glutamate (A) or hypoxic exposure (B). ROS production was measured in the form of superoxide anion (which is one component of total ROS) using Dihydroethidium (DHE), after 24 h of glutamate or 10 h of hypoxia exposure in HT22 cell pretreated with selenium. C. Selenium pretreatment prevented the fall in mitochondrial membrane potential following hypoxic exposure. The results were expressed as relative DHE or TMRM intensity % of control set at 100% and represented as means ± SD. *P < 0.05, **P < 0.01 & ***P < 0.001 vs. control, and #P < 0.05 & ###p < 0.001 vs. respective group. Se = selenium, Cont = control, Hypo = hypoxia and Glu = glutamate.