Different Roles of 8‐Hydroxyguanine Formation and 2‐Thiobarbituric Acid‐reacting Substance Generation in the Early Phase of Liver Carcinogenesis Induced by a Choline‐deficient, l‐Amino Acid‐defined Diet in Rats

Abstract

The present study was performed to assess the roles of hepatocellular oxidative damage to DNA and constituents other than DNA in rat liver carcinogenesis caused by a choline‐deficient, l‐amino acid‐defined (CDAA) diet by examining the effects of the antioxidant N, N′‐diphenyl‐p‐phenylenediamine (DPPD). The parameters used for cellular oxidative damage were the level of 8‐hydroxyguanine (8‐OHGua) for DNA and that of 2‐thiobarbituric acid‐reacting substance (TBARS) for constituents other than DNA. A total of 40 male Fischer 344 rats, 6 weeks old, were fed the CDAA diet for 12 weeks with or without DPPD (0.05, 0.10 or 0.20%) or butylated hydroxytoluene (BHT, 0.25%). In the livers of the rats, the numbers and sizes of glutathione S‐transferasc (EC 2.5.1.18) placental form (GSTP)‐ and/or γ‐glutamyltransferase (GGT, EC 2.3.2.2)‐positive lesions and levels of 8‐OHGua and TBARS were determined. The GSTP‐positive lesions of 0.08 mm2 or larger were all stained positively for GGT as well in cross‐sectional area, whereas the smaller lesions were generally negative for GGT. DPPD and BHT reduced the size of the GSTP‐positive lesions without affecting their total numbers. At the same time, they reduced TBARS generation without affecting 8‐OHGua formation in DNA. The present results indicate that oxidative DNA damage (represented by 8‐OHGua formation) and damage to constituents other than DNA (represented by TBARS generation) may play different roles in rat liver carcinogenesis caused by the CDAA diet; the former appears to be involved in the induction of phenotypically altered hepatocyte populations while the latter may be related to the growth of such populations.

Leptin-mediated neovascularization is a prerequisite for progression of nonalcoholic steatohepatitis in rats

“…On the contrary, and in accordance with previous reports, the final body weight of the CDAA-treated littermate rats (group 4) was lighter than that of the CSAA-treated rats (group 3). 26 Obesity was significantly more remarkable in Zucker rats than in littermate rats regardless of diet (i.e., CDAA or CSAA). Zucker rats also showed significant hyperglycemia.…”

“…The details of both diets are described elsewhere. 26 Recombinant human leptin and VEGF, and VEGF-neutralizing monoclonal antibody were purchased from R&D systems (Minneapolis, MN).…”

Immunotherapy for nonalcoholic steatohepatitis using themultiple cytokine production modulator Y-40138

“…CDAA and choline-supplemented L-amino acid-defined (CSAA) feeds were purchased from CLEA Japan Inc. (Tokyo, Japan). The details of both diets are described elsewhere [10] . The study groups were fed a CDAA diet for 8 wk to produce NASH.…”

Decreased phagocytic activity of Kupffer cells in a rat nonalcoholic steatohepatitis model

“…A cholinedeficient L-amino acid-defined (CDAA), and a cholinesupplemented L-amino acid-defined (CSAA) diet were purchased from CLEA Japan Inc. (Tokyo, Japan). The details of both diets are described elsewhere [10] . The study group was fed a CDAA diet for 8 wk in order to produce NASH.…”