RP9 Terrestrial Ecotoxicology
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(LIM-1117-818754) Analysis of TCDD-Induced Oxidative Stress in Chicken Liver During Development.

Lim, J¹, DeWitt, J.C², Watkins III, J.B¹, Henshel, D.S¹, ¹ Indiana University, Bloomington, IN, U.S.A² US EPA NHEERL/ETD/ITB, Research Triangle Park, NC, U.S.A

ABSTRACT- 2,3,7,8-tetrachlorodibenzo-p- dioxin (TCDD) is known to induce oxidative stress during development in animals. TCDD exposure during development does not lead to direct genetic alterations, but TCDD-induced oxidative stress may play a major role as a promoter and/or an initiator of malignant tumors. Thus, exposure to TCDD is believed to increase radical oxygen species (ROS) production mainly in liver and affect major endogenous antioxidants associated with removing ROS in cellular components. This research focused on determining the activity changes of antioxidant enzymes such as glutathione peroxidase (GPx), glutathione reductase (GRx), catalase, and superoxide dismutase (SOD) in chicken liver during development. TCDD of 2 ppt, 20 ppt, and 200 ppt was injected into chicken eggs via the airsac at embryonic day zero (E0) with a no-injection control (NIC) and a vehicle control (sunflower oil) to induce oxidative stress in hatchling chicks. Liver tissue (0.3g) was homogenized and changes in activity of the antioxidant enzymes were determined to evaluate the levels of oxidative stress. Reduction of enzyme activity in GPx, GRx, catalase, and SOD was apparent; a 45∼67% decrease in GPx, a 50∼54% in GRx, a 20∼32% in catalase, a 35%∼46% in SOD. No statistically significant differences were observed between TCDD dose groups (P-values >0.05), which shows that any does-response relationship was not recognized. However, this study demonstrates that the induction of oxidative stress by embryonic TCDD exposure in ovo leads to the significant decrease of the antioxidant enzyme activity and thus is likely to contribute to the embryotoxicity of TCDD in the hatchling chicks.

Key words: TCDD, oxidative stress, antioxidant, development