Activity of purine catabolism enzymes during the reproductive cycle of male and female brown trout (Salmo trutta).

In order to detect predicted changes in purine catabolism during the annual reproductive cycle of brown trout, we measured the activity of xanthine dehydrogenase, urate oxidase, and allantoinase. In kidney, only xanthine dehydrogenase was detected. In female liver and kidney, the activity of these enzymes was higher in May and decreased during vitellogenesis, with urate oxidase being undetectable in this period. In male liver, a similar variation pattern was found; however, in kidney, high activities were found in both May and December. These results suggest an influence of sex hormones in trout purine catabolism, especially in females.