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アカタラセミアマウスにおけるN-diethyl- nitrosamine により肝腫瘍発生の増強：汪　達紘，武田和久，船守有香，吉良尚平（岡山大・医・公衛）

Enhanced hepatocarcinogenesis in acatalasemic mice treated with N-diethylnitrosamine: Da-Hong WANG, Kazuhisa TAKETA, Yuka FUNAMORI, Shohei KIRA (Dept. of Public Health, Okayama Univ. Med. Sch.)

N-diethylnitrosamine (DEN)-induced hepatocellular carcinogenesis was compared between acatalasemic (C3H/AnLC_s^bC_s^b) and normal (C3H/AnLC_s^aCsa) mice. A total of 31 normal and 38 acatalasemic male mice, at an average age of 9 weeks, received a single intraperitoneal injection of of DEN (75mg/kg body wt) weekly for 6 weeks. All animals that survived until the end of week 31 (25th week after the last injection) developed liver tumors. Grossly extrahepatic metastases were not detected. Liver tumors were varing from one to multiple in number and from 1 to 15 mm in diameter.
The numbers as well as the size of liver tumors per liver were significantly greater (p < 0.05) in acatalasemic mice (mean±SD: 3.8±2.0 in numbers per liver; 9.6±7.4 in mm diameter per liver ) than in normal mice (1.8 ±1.1 in number per liver, 2.8 ±1.9 in mm diameter per liver). Histological examination of the tumor tissues revealed the development of well-differentiated hepatocellular carcinomas. The catalase activity in liver of acatalasemic mice was one-thirds that of normal mice (p< 0.01) before DEN treatment. We suggest that H₂O₂ or・OH formed from H₂O₂ is likely to be involved in DEN-induced hepatocarcinogenesis and catalase plays a critical role in the prevention of hepatocarcinogenesis.