Oxidative stress damage in the liver of fish and rats receiving an intraperitoneal injection of hexavalent chromium as evaluated by chemiluminescence.

The livers fractions of Oreochromis niloticus (Tilapia) and Wistar rats taken from treated animals to single intraperitoneal doses of hexavalent chromium (K(2)Cr(2)O(7)), were analyzed for tert butyl hydroperoxide-initiated chemiluminescence (CL), lipid peroxidation using thiobarbituric acid reactive substances (TBARS), enzymes superoxide dismutase (SOD) and catalase activities, and the quantification of cytochromes P450 and b5. The CL time course curve was significantly higher in O. niloticus treated with Cr(VI) at all times studied. The maximum CL was observed after 24h of exposure. The CL mean ratio treated/control was 4.6 and the initial velocity (V(0)) increased 7.4 times at 24h of intoxication. The TBARS levels however increased only 24h after intoxication. The CL time course curve was significantly higher in rats treated with Cr(VI) as early as 3h after intoxication. The maximum CL occurred 24h after exposure. The CL mean ratio treated/control was 2.1 and the V(0) increased 3.8 times at 24h of intoxication. On the contrary, was not observed any increase in TBARS in this study. Compared to the controls, in fish, SOD activity increased significantly only 24h after of exposure. In rats, there was a significant increase in SOD activity after 3 and 24h of intoxication. There was no catalase activity, nor cytochrome P450 and cytochrome b5 variation in both species studied. Through CL approach, it was possible to detect oxidative stress as early as 15min in fish and 3h in rats. Also a marked oxidative stress was revealed by the increased CL parameters that at 24h of intoxication was accompanied by arose SOD activity in liver of O. niloticus and Wistar rats and increased TBARS in O. niloticus. In addition, it was possible to show higher levels of oxidative stress in fish compared to the rat in spite of the dose to be four times smaller. Furthermore, CL provide a sensitive method for possible use to detect earlier biological impact in contaminated environments.