Urinary bladder effects of levodopa in hamsters.

Levodopa (3,4-dihydroxyphenyl-L-alanine) was fed at 1.0% of the diet to 60 male weanling Syrian golden hamsters for 48 weeks, followed by control diet for an additional 38 weeks. The incidence of tumors were: three of 60 hamsters with forestomach squamous cell papillomas, one of 60 with leiomyosarcoma of the skin, and one of 60 with cortical adrenal adenoma. Two of 30 control animals developed adrenal adenomas. Hyperplasia of the urinary bladder epithelium occurred in 33 of the treated group, and hyperplasia was not found in the bladders of the control group.