The effects of PCB 126 on embryotoxicity and beta-adrenoceptors in chicken (Gallus domesticus) embryos.

Abstract

Halogenated aromatic hydrocarbons such as polychlorinated biphenyls (PCBs) comprise some of the most toxic and persistent environmental pollutants associated with various developmental and reproductive effects in mammals, birds and fish. Oxidative stress can modify beta-adrenoceptor (beta-AR) function. This thesis examines the effects PCBs on beta-AR function in an avian model. Injection of 1.6 mug PCB 126/kg egg into the air cell prior to incubation increased the % mortality and the incidence of abnormalities, including liver lesions and subcutaneous edema, in day 19 chicken (Gallus domesticus ) embryos. Hepatic lipid peroxidation and EROD activity were significantly increased in PCB 126-treated embryos. These results indicate that the dose of PCB 126 used in this study induced a significant toxic response in day 19 embryos. Pharmacological characterization of chick embryo hepatic beta-ARs showed that they preferentially bind mammalian beta2-agonists and antagonists. PCB 126 significantly decreased hepatic beta-AR affinity (Kd) compared to vehicle-treated embryos. There were, however, no significant differences between control and PCB 126-treated embryos, or control and vehicle-treated embryos. This suggests there is an effect of the corn oil vehicle. (Abstract shortened by UMI.)