Comparison of metabolic effects of vegetables and teas with colorectal proliferation and with tumour development in DMH-treated F344 rats.
The aim of this study was to screen potentially chemopreventive vegetables and teas for their effects as human dietary components for the colorectal epithelium and also to seek biomarkers of preventive efficacy. Groups of F344 rats were adapted to a human basal diet supplemented with vegetables or teas, having known contents of glucosinolates, polyphenols and anti-oxidants. Both inductions and suppressions were found for overall glutathione S-transferase (GST) and quinone reductase activities. The mitotic index (MI) showed a three-fold range between groups, with substantial reductions by black tea, spinach, petit pois and peppers. Changes to PCNA labelling index and proliferation zone were marginal. No correlation was found between colonic and hepatic enzyme activities, nor with glucosinolate intake. Colonic MI was associated with the activity ratio GST(hepatic)/GST(colonic) (r = 0.49, P < 0.002), possibly reflecting a need for direct induction rather than exposure to products of hepatic conjugation.
O'Neill
I K
IK
MRC Dunn Clinical Nutrition Centre, Cambridge, UK.
Loktionov
A
A
Manson
M M
MM
Ball
H
H
Bandaletova
T
T
Bingham
S A
SA
D000818:Animals; D003106:Colon / Q000187:drug effects / Q000201:enzymology*; D003296:Cooking; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004032:Diet; D005982:Glutathione Transferase / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008940:Mitotic Index / Q000187:drug effects; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344; D013662:Tea; D014675:Vegetables
D018809:Proliferating Cell Nuclear Antigen; D013662:Tea; D003577:Cytochrome P-450 Enzyme System; D016660:NAD(P)H Dehydrogenase (Quinone); D005982:Glutathione Transferase