Protection by oral phenylalanine against gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats

H Iishi,H Taniguchi,S Okuda,M Baba,M Tatsuta

doi:10.1038/bjc.1990.255

H Iishi, H Taniguchi + Show 3 more

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https://doi.org/10.1038/bjc.1990.255

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Abstract

The effect of oral administration of L-phenylalanine on the incidence and histology of gastric adenocarcinomas induced by N-methyl-N'-nitro-N-nitrosoguanidine was investigated in inbred Wistar rats. Oral administration of 6% phenylalanine after 25 weeks of treatment with the carcinogen significantly reduced the incidence and number of adenocarcinomas of the glandular stomach at experimental week 52. Oral administration of high dose phenylalanine significantly increased the basal serum gastrin level and significantly decreased the norepinephrine concentration in the antral portion of the gastric wall, as well as the labelling indices of antral mucosa. These findings indicate that orally administered phenylalanine inhibits the development of gastric cancers.

Highlights

Young male Wistar rats (n = 60), aged about 6 weeks, were purchased from SLC, Japan (Shizuoka, Japan)
The incidence and number of gastric cancers per rat were significantly lower in group 2 (MNNG + phenylalanine)
We previously found that prolonged administration of tetragastrin in depot form after MNNG treatment significantly reduced the incidence of gastric cancer and the labelling index of the antral mucosa

Summary

Methods

Young male Wistar rats (n = 60), aged about 6 weeks, were purchased from SLC, Japan (Shizuoka, Japan). The rats were housed in suspended wire-bottomed metal cages in animal quarters with controlled temperature (21-22°C), humidity (30-50%), and light (12-h cycle), and had free access to chow pellets (Oriental Yeast, Tokyo, Japan). The animals were given drinking water containing MNNG (50 fg ml-'; Aldrich Chemical, Milwaukee, WI) for 25 weeks. The MNNG was dissolved in deionised water at a concentration of 2 mg ml' and was kept in a cool, dark place. The stock solution was diluted to 50 pg ml-' with tap water just before use. Forty ml of MNNG solution (less than a given rat consumes in 48 h) was given to each rat from bottles covered with aluminium foil to prevent denaturation

Results

Discussion

Conclusion