Liver and kidney pathology in rainbow trout (Salmo gairdneri) exposed to dietary pyrrolizidine (Senecio) alkaloids

Abstract Duplicate groups of rainbow trout fingerlings were fed diets containing a muxture of pyrrolizidine ( Senecio ) alkaloids (PAs), at levels of 20 and 100 ppm, for 12 months. The 100-ppm diet resulted in severe growth depression and mortalities and one group receiving that diet was terminated at 6 months. The other 100-ppm group was placed on the control diet after 2 months and held until termination at 12 months. Both levels of PAs resulted in severe hepatic lesions including megalocytosis, necrosis, and fibrosis. In addition venoocclusive disease was present in centrolobular and hepatic veins. The high dose of PAs also caused significant thickening of glomerular basement membranes. Removal of the fish from the 100-ppm diet at 2 months and feeding the control diet for 10 months resulted in only slight improvement in growth, and hepatic, vascular, and renal lesions persisted through 12 months. No evidence of neoplastic change was observed, although some nodular hyperplasia was seen in the fish fed 100 ppm PAs for 2 months and control diet for 10 months. In vitro studies with trout liver microsomes showed that control trout liver was capable of producing the toxic pyrrole metabolites at a rate comparable to uninduced rat liver microsomes.