Acute and/or chronic stress models modulate CuZnSOD and MnSOD protein expression in rat liver

Abstract

Cellular protection against oxidative stress is afforded by the enzyme superoxide dismutase (SOD). In this study, the protein levels of copper-zinc SOD (CuZnSOD) in the cytosolic and nuclear fraction, manganese SOD (MnSOD) in the mitochondrial, and cytosolic fraction and cytochrome c (cyt c) in the liver of male rats exposed to 2 h of acute immobilization (IM) or Cold stress, 21 days chronic isolation or their combinations (chronic/acute stress) were examined. The serum corticosterone (CORT) level was measured, as an indicator of stress stimuli. Both acute stressors with elevated CORT levels caused a decrease of mitochondrial MnSOD, while acute IM resulted in redistribution of the CuZnSOD protein level between the cytosolic and nuclear fraction. Chronic isolation, during which the CORT level was close to control value, resulted in an increase of cytosolic CuZnSOD, whereas a decrease of MnSOD in mitochondrial and its corresponding increase in cytosol fraction was found. In both combined stress regimes, an increase of the CuZnSOD and MnSOD levels in the cytosolic fraction was recorded whereby increase of the CORT level was observed only in the chronic isolation followed by acute IM. The data indicate that acute and/or chronic stress models have different degrees of influence on serum CORT and SOD subcellular protein levels. Increased cytosolic CuZnSOD protein level under chronic isolation suggests that state of oxidative stress may also exist under CORT level similar to the basal value. The presence of MnSOD and cyt c in the cytosolic fraction could serve as useful parameters for mitochondrial dysfunction.

Molecular mechanisms of regulation of antioxidant enzymes in the brain and liver of acutely and/or chronically stressed rats

“…However, the effects of social isolation stress on CORT level in adult rats are not consistent among studies: increased CORT level has been reported [40], whereas other groups reported no changes [41, 42] or reduced CORT level [43]. In our study, chronically stressed animals showed unchanged serum CORT level, relative to control, as well as decreased mitochondrial MnSOD, which was in accordance with its protein expression [22], suggesting that its detoxifying capacity was compromised by the oxidative stress [35]. Decrease of mitochondrial MnSOD activity is in positive correlation with CORT level (Fig.…”

“…The high CuZn-SOD activity may suggest increased superoxide anion levels, which was in accordance with its increased nuclear protein expression [22], indicating protective effect of CuZnSOD on DNA and other nuclear macromolecules. Concerning MnSOD activity in mitochondrial fraction, decreased activity in cold group compared to the control group was detected, which was followed by decreased protein expression in mitochondrial fraction [22]. This could have been expected since exposure to the low temperatures elevate metabolic rate in active tissues [33] and might modulate the redox balance by activating ROS signaling [34].…”

“…respiratory chain) might have an influence on lower MnSOD activity, enabling MnSOD inactivation by generated H 2 O 2 [35]. This shows that MnSOD is not only the first line of antioxidative defense [22, 36, 37], but also the main target for generated ROS as well.After rats' exposure to 21 days of social IS stress, when serum CORT returned to the basal level, CuZnSOD activities in cytosolic and nuclear fractions were unchanged when compared to the control group. Since the unchanged CuZnSOD activity did not correspond to increased protein expression under the same chronic IS stress [22], this could indicate the lack of effective CuZnSOD response.…”

“…This shows that MnSOD is not only the first line of antioxidative defense [22, 36, 37], but also the main target for generated ROS as well.…”

Stress oxidativo e alterações enzimáticas induzidas por nanotubos de carbono de paredes múltiplas (MWCNTs) funcionalizados com polietileno glicol no tecido hepático de camundongos

“…A isoforma Cu-Zn-SOD é expressa em peroxissomos e no espaço entre membranas mitocondriais internas e externas e também no núcleo. Na verdade, foi demonstrado anteriormente que as condições e intensidade do agente agressor podem resultar em uma redistribuição da isoforma de Cu-Zn-SOD do citossol para o núcleo (FILIPOVIĆ et al, 2010).…”