Retinoic acid reduces kidney injury by regulating oxidative stress, NRF-2, and apoptosis in hyperoxic mice.

Nuclear factor-erythroid-2-related factor-2 (NRF-2) is a cellular resistance protein to oxidants. We investigated the effect of exogenous all-trans retinoic acid (ATRA) on the antioxidant system and NRF-2 in mice kidneys under hyperoxia-induced oxidative stress. Mice were divided into four groups. Daily, two groups were given either peanut-oil/dimethyl sulfoxide (PoDMSO) mixture or 50 mg/kg ATRA. Oxidative stress was induced by hyperoxia in the remaining groups. They were treated with PoDMSO or ATRA as described above, following hyperoxia (100% oxygen) for 72 h. NRF-2 and active-caspase-3 levels, lipid peroxidation (LPO), activities of antioxidant enzymes, xanthine oxidase (XO), paraoxonase1 (PON1), lactate dehydrogenase (LDH), tissue factor (TF), and prolidase were assayed in kidneys. Hyperoxia causes kidney damage induced by oxidative stress and apoptosis. Increased LPO, LDH, TF, and XO activities and decreased PON1 and prolidase activities contributed to kidney damage in hyperoxic mice. After hyperoxia, increases in the activities of antioxidant enzymes and NRF-2 level could not prevent this damage. ATRA attenuated damage via its oxidative stress-lowering effect. The decreased LDH and TF activities increased PON1 and prolidase activities, and normalized antioxidant statuses are indicators of the positive effects of ATRA. We recommend that ATRA can be used as a renoprotective agent against oxidative stress induced-kidney damage.

Effects of swimming activity and feed restriction on antioxidant and digestive enzymes in juvenile rainbow trout: Implications for nutritional and exercise strategies in aquaculture.

BACKGROUND: In this study, we investigated the effects of swimming activity and feed restriction on digestion and antioxidant enzyme activities in juvenile rainbow trout (average body weight of 26.54 ± 0.36 g). METHODS: The stomach, liver and kidney tissues were obtained from four distinct groups: the static water group (fish were kept in static water and fed to satiation), the feeding restricted group (fish were kept in static water with a 25% feed restriction), the swimming exercised group (fish were forced to swimming at a flow rate of 1 Body Length per second (BL/s)) and the swimming exercised-feed restricted group (subjected to swimming exercise at a 1 BL/s flow rate along with a 25% feed restriction). We determined the levels of glutathione, lipid peroxidation and the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and lactate dehydrogenase, as well as the presence of reactive oxygen species in the tissues obtained from the fish. Additionally, the activities of pepsin, protease, lipase and arginase in these tissues were measured. RESULTS: Swimming activity and feed restriction showed different effects on the enzyme activities of the fish in the experimental groups. CONCLUSION: It can be concluded that proper nutrition and exercise positively influence the antioxidant system and enzyme activities in fish, reducing the formation of free radicals. This situation is likely to contribute to the fish's development.