Chemopreventive effects of taurine on diethylnitrosamine and phenobarbital-induced hepatocarcinogenesis in male F344 rats.
Modifying effects of taurine, a naturally occurring organosulfur compound, on diethylnitrosamine (DEN) and phenobarbital (PB)-induced hepatocarcinogenesis were examined in rats. Male F344 rats, 5 weeks old, were divided into 8 groups. Rats of groups 1 through 5 were given i.p. injections of DEN (100 mg/kg body weight) once a week for 3 weeks from one week after the start of the experiment. Of them, animals of group 2 received taurine mixed in a basal diet at a concentration of 2000 ppm for the initial 4 weeks, and those of groups 3 and 5 were given the agent starting 4 weeks after the beginning of the experiment until the end (24 weeks). Rats in groups 1, 4, 7 and 8 were kept on the basal diet throughout the experiment (24 weeks). Group 6 was given taurine throughout the experiment and group 8 was treated as a vehicle control. Animals of groups 1,2, 3 and 7 received PB in drinking water at a dose of 500 ppm from one week after the end of carcinogen or vehicle treatment. Liver neoplasms were recognized only in DEN-treated groups. The incidence and average number of liver neoplasms of group 3 were significantly lower than those of group 1. The number of glutathione S-transferase placental form (GST-P)-positive foci of group 2 or 3 was significantly smaller than that of group 1 (P < 0.01 or P < 0.005). The average and unit areas of GST-P-positive foci in groups 2 and 3 were also significantly smaller than those in group 1 (P < 0.005 and P < 0.0001 and P < 0.0001, respectively). In this study, the level of ornithine decarboxylase activity in non-neoplastic liver tissue was reduced by taurine treatment in both the initiation and postinitiation phases. These results suggest that taurine could be a chemopreventive agent for liver neoplasia.
Okamoto
K
K
Department of Pathology, Gifu University School of Medicine.
Sugie
S
S
Ohnishi
M
M
Makita
H
H
Kawamori
T
T
Watanabe
T
T
Tanaka
T
T
Mori
H
H
D000818:Animals; D016588:Anticarcinogenic Agents / Q000627:therapeutic use*; D002273:Carcinogens; D004052:Diethylnitrosamine; D005982:Glutathione Transferase / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced* / Q000201:enzymology / Q000517:prevention & control*; D008297:Male; D009955:Ornithine Decarboxylase / Q000378:metabolism; D010634:Phenobarbital; D010920:Placenta / Q000201:enzymology; D051381:Rats; D011916:Rats, Inbred F344; D013654:Taurine / Q000627:therapeutic use*
D016588:Anticarcinogenic Agents; D002273:Carcinogens; D013654:Taurine; D004052:Diethylnitrosamine; D005982:Glutathione Transferase; D009955:Ornithine Decarboxylase; D010634:Phenobarbital