Effect of gastric mucus on the uptake of the carcinogen MNNG by gastric mucosal DNA.
In prostaglandin E2 (PGE2)-, pirenzepine-, and indomethacin-administered rats, the incorporation of N-[methyl-3H]-N'-nitro-N-nitrosoguanidine ([methyl-3H]MNNG) into gastric mucosal DNA was measured quantitatively by liquid scintillation counting after intragastric instillation of [methyl-3H]MNNG. The amount of incorporation was 25.4 +/- 5.9 pmol/mg DNA in control rats, 11.7 +/- 3.8 pmol/mg DNA in PGE2-administered rats, 6.2 +/- 5.6 pmol/mg DNA in pirenzepine-administered rats, and 42.9 +/- 14.4 pmol/mg DNA in indomethacin-administered rats. PGE2 and pirenzepine significantly decreased the incorporation as compared with the control group. In contrast, indomethacin increased the incorporation. In addition, gastric mucosa of these drug-treated rats was studied histochemically. PGE2 and pirenzepine increased secretion of gastric mucus whereas indomethacin decreased it. It is possible that gastric mucus has a protective effect not only against ulcerogenic agents but also against carcinogens. It is considered that gastric mucus plays an important role in the defense mechanism against carcinogenesis.
First Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan.
A
A
Torii
H
H
Kameda
T
T
Kawamura
N
N
Onizawa
H
H
Nozawa
M
M
Ariizumi
K
K
Egawa
K
K
Kondoh
D000818:Animals; D004247:DNA / Q000378:metabolism*; D015232:Dinoprostone / Q000494:pharmacology; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008769:Methylnitronitrosoguanidine / Q000493:pharmacokinetics*; D009093:Mucus / Q000187:drug effects / Q000502:physiology*; D010890:Pirenzepine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000517:prevention & control
D008769:Methylnitronitrosoguanidine; D010890:Pirenzepine; D004247:DNA; D015232:Dinoprostone; D007213:Indomethacin