Induction of tumors in ACI rats given a diet containing ptaquiloside, a bracken carcinogen.

Fifteen female ACI rats initially 5 weeks old were each given a diet containing 0.027-0.08% ptaquiloside [(PT) CAS: 87625-62-5], a carcinogen in bracken, throughout the 210-day experimental period. A control group of 20 female ACI rats was given basal diet without PT. Both ileal and urinary bladder tumors developed in all rats in the experimental group. The ileal tumors were multiple and mostly developed in the distal 10 cm of the ileum. These ileal tumors were identified histologically as epithelial tumors, such as adenomas and adenocarcinomas, and also as nonepithelial malignant tumors, malignant fibrous histiocytomas. The urinary bladder tumors were transitional cell carcinomas, keratinizing squamous cell carcinomas, and sarcomas. Papillomas of the urinary bladder were found in 4 rats in the control group. These results show that, like bracken diet, PT induces tumors in both the ileum and urinary bladder.