Responsiveness of the hypothalamo-pituitary-interrenal axis in an amphibian (Bufo terrestris) exposed to coal combustion wastes

To assess the responsiveness of the interrenal axis to stress, we injected toads exposed to coal combustion wastes and toads from an unpolluted refere nce site with adrenocorticotropic hormone (ACTH), as well as the vehicle al one (saline). Initial circulating levels of corticosterone in toads capture d at the polluted area were significantly higher than levels in toads from the reference site. Corticosterone levels in toads from the polluted site r emained high even after 2 weeks of laboratory acclimation and injection wit h saline. The results may suggest disruption of hepatic enzymes responsible for the metabolic clearance of steroid hormones. Injection of toads from t he polluted site with ACTH had no effect on plasma corticosterone levels, w hereas a similar treatment of toads from the reference site stimulated a ma rked increase in corticosterone. Our study provides evidence that toads exp osed to coal combustion wastes may be less efficient at responding to addit ional environmental stressors. (C) 1999 Elsevier Science Inc. All rights re served.