Stress-induced alternations of CuZn- and Mn- superoxide dismutase activity in rat liver

Superoxide dismutases (SODs) represent the first line of antioxidant defense and any alternation in their function might be potentially damaging. Therefore, changes of the CuZnSOD activity in cytosolic and nuclear fractions and MnSOD activity in mitochondrial fraction in liver of male rats exposed to 2h of either immobilization (IM) or cold (4°) as acute stressors, 21 day of social isolation (IS) as chronic stress, or their combination (acute+chronic stress), were investigated. Serum corticosterone (CORT) level was monitored as a stress marker. Acute stress IM with elevated CORT level led to increased CuZnSOD activity in nuclear fraction. Chronic isolation, where CORT was close to control value did not change the CuZnSOD activity neither in nuclei nor cytosol fraction, while combined stress IS+Cold led to increased cytosolic CuZnSOD activity. MnSOD activity in mitochondrial fraction was decreased in all treated groups. Data indicate that unchanged or increased cytosolic or nuclear CuZnSOD activity after different stressors mediate liver restoration of homeostasis, while decrease of mitochondrial MnSOD activity may results in cellular injury and inefficient ROS defense