The role of fat and calcium in the production of foci of aberrant crypts in the colon of rats fed 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine.
The modulation by dietary fat levels of intestine carcinogenesis is well documented. New developments suggest that calcium ions may also play a role. A rapid bioassay, the induction of foci of aberrant crypts in the colon, was used to explore the interaction between dietary fat and calcium. Male F344 rats 6 weeks of age were placed on diets containing 5 or 20% corn oil, and 0.04 or 0.32% calcium ion, as calcium lactate. Each dietary group was fed 400 ppm 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhlP), and negative controls received the diets alone. A positive control group was given 2 mg N-nitrosomethylurea (NMU) intrarectally four times in a 2-week period. All rats were killed after 9 weeks. The intestinal tract was rinsed with Krebs-Ringer buffer. After staining a 6-cm segment of the descending colon and rectum with 0.2% methylene blue, foci of aberrant crypts were evaluated microscopically. With PhlP as a carcinogen, the rats on a high-fat, low-calcium level had more foci of aberrant crypts than animals on a low-fat level. With the higher calcium level, there were fewer foci and aberrant crypts, but the effect of fat was still significant. With NMU and a low-calcium level, the effect of fat level was evident. However, with the higher calcium intake, there were considerably more foci of aberrant crypts than on the low-calcium level, and the effect of the dietary fat level was not obvious.(ABSTRACT TRUNCATED AT 250 WORDS)
Weisburger
J H
JH
American Health Foundation, Valhalla, New York 10595-1599.
Braley
J
J
Reinhardt
J
J
Aliaga
C
C
Rivenson
A
A
Hard
G C
GC
Zhang
X M
XM
Takahashi
M
M
Esumi
H
H
Sugimura
T
T
D000818:Animals; D002136:Calcium, Dietary / Q000494:pharmacology; D002273:Carcinogens / Q000633:toxicity*; D003110:Colonic Neoplasms / Q000139:chemically induced*; D004032:Diet; D004041:Dietary Fats / Q000494:pharmacology; D005069:Evaluation Studies as Topic; D007093:Imidazoles / Q000633:toxicity*; D008297:Male; D009153:Mutagens / Q000633:toxicity*; D011230:Precancerous Conditions / Q000139:chemically induced*; D051381:Rats; D011916:Rats, Inbred F344
D002136:Calcium, Dietary; D002273:Carcinogens; D004041:Dietary Fats; D007093:Imidazoles; D009153:Mutagens; C049584:2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine