Potentiation of aflatoxin B1-induced hepatocarcinogenesis in the rat by pretreatment with buthionine sulfoximine.

Abstract A single i.p. dose of aflatoxin B 1 (AFB 1 ) (1.0 and 2.0 mg/kg body wt)-induced hepatocarcinogenesis with phenobarbital as a promoter has been examined in young male Fischer rats. Immunohistochemical method has been employed to detect AFB 1 -induced glutathione S-transferase placental form (GST-P)-positive hepatic foci observed from 3 week and 10 week to 40–48 week periods. With 2.0 mg AFB 1 dosing, the number, area and volume occupied by GST-P-positive hepatic foci increased significantly and progressively from 3 week, 10 week and 48 week periods. In long term studies (40–48 weeks), 1.0 mg and 2.0 mg AFB 1 dose levels yielded linear response in area and volume occupied by AFB 1 -induced hepatic foci. Pretreatment of rats with l -buthionine sulfoximine (BSO), a GSH depleter, at a dose of 4 mmol/kg body wt 4 and 2 h before 1.0 or 2.0 mg AFB 1 treatment enhanced the number, area and volume of GST-P-positive hepatic foci, increases being the largest at shorter time periods (3 and 10 weeks) compared to longer time periods (40 and 48 weeks). This report appears to be the first example of an enhanced chemical induced hepatocarcinogenesis in a long term study in any experimental animals species by a GSH depleting agent.