Fate and mode of action of zearalenone.

Oral administration of zearalenone to ovariectomized mice induced increases in the uterine weight, RNA, protein and DNA. In vitro incubation of the uterine tissues isolated form zearalenone-pretreated mice resulted in a temporal acceleration in the uterine permeability to sugar, nucleoside and amino acid. 3H-zearalenone orally administrated to female rats was excreted mostly via feces. Chemical analysis revealed the metabolite-I from the feces, and the metabolite-II and 2 glucuronides from the urine. The toxin was distributed into the adipose tissue, ovary, uterus and others. The 9.000 g-supernatant fraction from the livers of mice, rats, guinea-pigs, rabbits and human biotransformed the mycotoxin into the metabolite-I in the presence of NADH or NADPH. This biotransforming activity localized in the cytosol was neither inhibited by SKF nor induced by phenobarbital. The metabolite-I, which still possess the estrogenic activity to mice, is presumed to be a hydroxylated zearalenone.