Comparative genetics of host response to N-methyl 1-N'-nitro-N-nitrosoguanidine. I. A lack of tumor production in the glandular stomach of Swiss mouse.
The present study investigated the effects of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) drink and 3 maintenance diets on both the survival and the glandular stomach morphology in a total of 480 Swiss/ICR mice. The MNNG conditioning was practised in one half of the mice for the first 8 months. The maintenance of mice on the standard (MF) diet, the rice-rich (R) diet or the rice- and salt-rich (RS) diet was continued for 12 months. The results obtained are as follows: 1) Many mice in the MNNG-conditioned groups experienced fatal bleeding into the small intestine before the termination of the feeding experiment. There was no sign of tumor formation in their digestive canals. The bleeding deaths took place more often in the MF- and RS- diet groups than in the R-diet groups, and started to appear earlier in males than in females within the MF-diet groups. 2) The tendency to gastric atophy, as assessed in terms of the wet weight of mouse glandular stomach as well as the quantitation of histological changes of the same organ in the one-year survivors, progressed in the order of the MF-diet groups, the R-diet groups and the RS-diet groups. 3) The effect of MNNG drink on the mouse glandular stomach morphology was bidirectional: it increased the incidence of advanced atrophy (and/or decreased the incidence of advanced hyperplasia) in the MF- and R-diet groups, and rather reduced the atrophy-oriented effect of the diet on stomach morphology in the RS-diet groups. 4) The above-mentioned effects of 3 maintenance diets and MNNG drink were more prominent in males than in females. 5) No neoplastic change was detected in the glandular stomachs of the one-year survivors with and without MNNG conditioning. 6) Evidence was presented to indicate that MNNG behaved as a quasi-antiandrogen in inducing the morphological changes of mouse glandular stomach.
Kodama
M
M
Kodama Research Institute of Preventine Medicine, Nagoya, Japan.
Kodama
T
T
Fukami
H
H
Ogiu
T
T
Kodama
M
M
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003213:Conditioning, Psychological; D005260:Female; D005753:Gastric Mucosa / Q000187:drug effects / Q000473:pathology; D008297:Male; D008769:Methylnitronitrosoguanidine / Q000633:toxicity*; D051379:Mice; D008813:Mice, Inbred ICR; D013045:Species Specificity; D013274:Stomach Neoplasms / Q000139:chemically induced*
D008769:Methylnitronitrosoguanidine