Effect of Splenectomy on gastric carcinogenesis induced by continuous administration of MNNG to rats.

• Project/Area Number: 02670571
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Digestive surgery
• Research Institution: Yamanashi Medical College
• Principal Investigator: SEKIKAWA Takayoshi Yamanashi Medical College, 医学部, 講師 (10134553)
• Co-Investigator(Kenkyū-buntansha): NOGUCHI Akihiro Yamanashi Medical College, 医学部, 助手 (80208313) ; NAGAHORI Kaoru Yamanashi Medical College, 医学部, 助手 (00137035)
• Project Period (FY): 1990 – 1991
• Project Status: Completed (Fiscal Year 1991)
• Budget Amount: ¥1,400,000 (Direct Cost: ¥1,400,000); Fiscal Year 1991: ¥400,000 (Direct Cost: ¥400,000); Fiscal Year 1990: ¥1,000,000 (Direct Cost: ¥1,000,000)
• Keywords: Splenectomy / Experimental Stomach Cancer / MNNG / 実験肝癌 / 脾免疫能

Research Abstract

We examined the effect of splenectomy on the gastric carcinogenesis induced by administration of N-methyl-N'-nitro-N-nitrosoguanidine(KNNG)to rat.
Three groups of 20 male Wistar-strain rats, 6 weeds old, received MNNG in the drinking water ad libitum at concentrations of 80, 100 and 120 mug/ml, respectively, for 44 weeks. In order to study the role of splenic function on the gastric carcinogenesis, we classified 20 rats to four groups, I group, sham operation before administration of MNNG, (sham G.) (n=5), II group, splenectomy before administration of MNNG (spx G.) (n=5), III group, splenectomy after 2 months from administration of MNNG (2M spx G.) (n=5) IV group, splenectomy after 4 months from administration of MNNG (4M spx G.) (n=5).
The animals were carefully autopsied when after receiving MNNG continuously for 44 weeks.
The numbers, sizes and histological study of the tumors in the glandular stomach were examined.
In 60 rats, 31 adenocarcinomas were found. The incidences of gastric c ancer of each group were as follows, in 80, mug/ml MNNG concentration, sham G. 2/5(40%), spx G. 2/4(50%), 2M spx G. 3/5(60%)and 4M spx G. 3/4(75%) ; in 100, mug/ml MNNG concentration, 2/5, 1/5, 2/5, 3/5 ; in 120mug/ml MNNG concentration, 2/5, 1/4, 3/5, 3/5, respectively. So the incidence of gastric cancer was the highest in the splenectomyed group after 4 months. The mean sizes of the gastric carcinomas were 4.0<plus-minus>2. Omm in the sham G. (6), 11.4<plus-minus>14.4mm in the spx G. (5), 5.2<plus-minus>3.7mm in the 2M spx G. (9)and 4.9<plus-minus>2.4mm in the 4H spx G. (11). The depth of invation of the gastric carcinomas were 3 within submucosal layer(sm)and 3 beyond muscle layer(pm)in the sham G. ; 2 within sm and 3 beyond pm in the spx G., 5 within sm and 4 beyond pm in 2M spx G. and 10 within sm and I beyond pm in 4
These results suggested that splenectomy maight have the progressive effect on the gastric carcinogenesis after 4 months in the course of continuous administraion of MNNG.