| Research Abstract |
So far our laboratory has been carrying out the histopathological and molecular biological studies on the potentiating effect of food-related chemicals on gastric cancer by administering Sterigmatocystin(ST), sodium chloride(NaCl), iodine and nitrite to Mongolian gerbil mice infected with Helicobacter pylori(HP)(Scand J Gastroenterol. 2003 ; 38 : 360-369, Food Chem Toxicol. 2005 ; 43 : 1773-1780, W J Gastroenterol. 2006 12 : 2174-2180, Jap J Hyg. 2006 ; 61 : 248&277).
In order to further investigate the relationship between lower concentration of ST (10ppb) or nitrite (10ppm) and gastric cancer in HP-infected Mongolian gerbil mice, totally 11 experiment groups were established such as control (without HP infection or HP (-)), HP (-)+ 1000ppb ST, HP-infected, HP (+) + 10ppb ST, HP (+) + 100ppb ST, HP (+) + 1000ppb ST, HP (+)+ 750ppm nitrite, HP (+)+ 3000ppm nitrite, HP (+) + 5% NaC1, HP (+) + 10% NaCl, HP (+)+ 1000ppb ST + 10% NaCl. Each group contained 15 mice except for HP (-)+ 1000ppb
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ST group which contained 10 mice. All the exposed groups of mice were consecutively administered with chemicals which were supplemented in diet or solved in water for total 24 weeks from the age of 75 weeks. Except for the mice that died before the termination of the experiment, 147 mice at their 99 weeks old were killed and autopsy were performed. Immunostaining (p53 and PCNA) was used to investigate gastric histopathological changes. The results showed that the p53 positive rates in all HP-infected and exposed groups (22.8-49.0%) were significantly higher than those in control group (2.2%). Moreover, 5 mice in each group were histopathologically observed by using HE, PAS and Alucian Blue (pH2.5, 1.0) staining, and the results showed that other 7 groups of mice had significant active gastritis changes compared to control mice except for the mice in HP (-)+ 1000ppb ST, HP (+)+ l0ppb ST, and HP (+)+ 750 ppm nitrite groups. Contrast to control mice, the mice in 7 HP-infected and chemical-exposed groups showed significant intestinal metaplasia which was considered as histopathological change prior to gastric cancer except for HP (-)+ 1000ppb ST, HP (+)+ 10ppb ST, and HP (+) + 3000 ppm nitrite groups of mice. These results revealed that food-related chemicals have some potentiating effects on gastric cancer caused by HP infection. Our data may be useful to the prevention and control of gastric diseases caused by HP infection. Less
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