Enhancing effects of various gastric carcinogens on development of pepsinogen-altered pyloric glands in rats.
To assess the possibility of establishing an in vivo, medium-term bioassay system for gastric carcinogens and promoters, a total of 220 male WKY rats were divided into two groups. Group 1 animals were treated first with a single dose of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) (160 mg/kg body wt) and starting 2 weeks later administrated one of five gastric carcinogens, a gastric promoter, one of five non-gastric carcinogens or no treatment, as a control, for 14 weeks. Saturated sodium chloride solution (1 ml) treatments were given by gastric intubation at weeks 4, 6, 8 and 10. Group 2 rats received 1 ml of DMSO instead of MNNG and were then treated in the same way as group 1. Analysis of pyloric mucosa sections for pepsinogen altered pyloric glands (PAPG) detected immunohistochemically after the animals were killed at week 16 revealed increased lesion numbers in group 1, with all gastric carcinogens and promoters examined. However, none of the five non-gastric carcinogens exerted any significant modification of PAPG development. The results strongly suggest that the experimental protocol consisting of the following four components: (i) adoption of PAPG as the end-point marker lesion; (ii) single dose of MNNG as initiator; (iii) test chemical administration for 14 weeks; and (iv) administration of saturated sodium chloride solution during the test chemical exposure, could be used effectively for the detection of gastric carcinogens as well as promoters of gastric carcinogenesis in a relatively short time period.
Tatematsu
M
M
First Department of Pathology, Nagoya City University Medical School, Japan.
Ozaki
K
K
Mutai
M
M
Shichino
Y
Y
Furihata
C
C
Ito
N
N
D000818:Animals; D015197:Carcinogenicity Tests; D004121:Dimethyl Sulfoxide; D005753:Gastric Mucosa / Q000737:chemistry / Q000187:drug effects*; D008297:Male; D008769:Methylnitronitrosoguanidine; D010435:Pepsinogens / Q000032:analysis*; D011230:Precancerous Conditions / Q000139:chemically induced* / Q000737:chemistry; D011708:Pylorus / Q000737:chemistry; D051381:Rats; D011921:Rats, Inbred WKY; D013274:Stomach Neoplasms / Q000139:chemically induced* / Q000737:chemistry; D013997:Time Factors
D010435:Pepsinogens; D008769:Methylnitronitrosoguanidine; D004121:Dimethyl Sulfoxide