Effects of water cadmium concentrations on bioaccumulation and various oxidative stress parameters in Rhamdia quelen

The effects of sublethal cadmium concentrations on oxidative stress parameters were evaluated in Rhamdia quelen. The fish were exposed to 0.44, 236, and 414 μg l⁻¹ cadmium for 7 and 14 days, followed by the same time periods for recovery. Enzymes, such as catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST), and indicators of oxidative stress, such as thiobarbituric acid-reactive species (TBARS) and protein carbonyl, were verified in fish tissues. In addition, the accumulation of cadmium was evaluated in these tissues. Our results indicate that CAT and GST levels decreased in gills after exposure periods associated with increased TBARS levels. In hepatic tissue, CAT, GST, TBARS, and protein carbonyl levels increased after 7 days of exposure, whereas SOD activity decreased after exposure for 14 days. In the kidney, TBARS levels decreased after exposure for 7 days and increased after exposure for 14 days. During the recovery periods, some variations persisted in gills, liver, and kidney. Cadmium accumulation was most significant in liver, followed by kidney and gills. These results indicate that cadmium concentrations studied invoke a stress response in silver catfish.

Antioxidant therapy attenuates oxidative stress in the blood of subjects exposed to occupational airborne contamination from coal mining extraction and incineration of hospital residues

Coal mining and incineration of solid residues of health services (SRHS) generate several contaminants that are delivered into the environment, such as heavy metals and dioxins. These xenobiotics can lead to oxidative stress overgeneration in organisms and cause different kinds of pathologies, including cancer. In the present study the concentrations of heavy metals such as lead, copper, iron, manganese and zinc in the urine, as well as several enzymatic and non-enzymatic biomarkers of oxidative stress in the blood (contents of lipoperoxidation = TBARS, protein carbonyls = PC, protein thiols = PT, α-tocopherol = AT, reduced glutathione = GSH, and the activities of glutathione S-transferase = GST, glutathione reductase = GR, glutathione peroxidase = GPx, catalase = CAT and superoxide dismutase = SOD), in the blood of six different groups (n = 20 each) of subjects exposed to airborne contamination related to coal mining as well as incineration of solid residues of health services (SRHS) after vitamin E (800 mg/day) and vitamin C (500 mg/day) supplementation during 6 months, which were compared to the situation before the antioxidant intervention (Ávila et al., Ecotoxicology 18:1150-1157, 2009; Possamai et al., Ecotoxicology 18:1158-1164, 2009). Except for the decreased manganese contents, heavy metal concentrations were elevated in all groups exposed to both sources of airborne contamination when compared to controls. TBARS and PC concentrations, which were elevated before the antioxidant intervention decreased after the antioxidant supplementation. Similarly, the contents of PC, AT and GSH, which were decreased before the antioxidant intervention, reached values near those found in controls, GPx activity was reestablished in underground miners, and SOD, CAT and GST activities were reestablished in all groups. The results showed that the oxidative stress condition detected previously to the antioxidant supplementation in both directly and indirectly subjects exposed to the airborne contamination from coal dusts and SRHS incineration, was attenuated after the antioxidant intervention.