Enhancement of dimethylnitrosamine-induced glutathione S-transferase P-positive hepatic foci by Clonorchis sinensis infestation in F344 rats.

The modifying potential of Clonorchis sinensis (CS) infestation on dimethylnitrosamine (DMN)-induced hepatocarcinogenesis was studied in male F344 rats. The metacercariae of CS were infected, 60 to each animal, by a single intragastric intubation at various times, before, during or after an 8-week period of DMN (25 ppm in drinking water) treatment. Controls were treated with DMN alone or infected with CS without carcinogen. Animals killed at the end of the 40-week experimental period showed a significant enhancing effect of CS on GST-P+ foci induction when CS was infected 4 weeks before DMN treatment, although no such influence was evident with CS infection during or following DMN exposure. The present findings suggest that CS might facilitate the proliferation of DMN-induced preneoplastic lesions of liver in rats.