Authors
Komaki C. Okuno M. Onogi N. Moriwaki H. Kawamori T. Tanaka T. Mori H.
Muto Y.
Institution
First Department of Internal Medicine, Gifu University School of Medicine,
Japan.
Title
Synergistic suppression of azoxymethane-induced foci of colonic aberrant
crypts by the combination of beta-carotene and perilla oil
in rats.
Source
Carcinogenesis. 17(9):1897-901, 1996 Sep.
Abstract
The modulating effect of the combined dietary feeding of beta-carotene and
perilla oil, which is rich in alpha-linolenic acid, on the
development of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF)
was investigated in male F344 rats. Rats received oral administration of
beta-carotene (0, 50 or 200 mg/kg body weight/day) and fed a basal diet
containing either 12% olive oil, 3% perilla oil plus 9%
olive oil, or 12% perilla oil. A dose-dependent suppressive
effect of perilla oil was found. The numbers of ACF were
42.0 and 18.4% of those of the 12% olive oil-fed controls in the rats fed 3%
perilla oil plus 9% olive oil and 12%
perilla oil, respectively. The development of ACF was also
reduced significantly by the addition of dietary beta-carotene in each of the
oil-fed groups (P < 0.05, respectively). The suppression by the combination
of beta-carotene and perilla oil was synergistic, as the
numbers of ACF were 12.9 and 8.9% of those of the 12% olive oil-fed controls
in beta-carotene-treated rats fed 3% perilla oil plus 9%
olive oil and 12% perilla oil, respectively. beta-carotene
plus perilla oil also suppressed the numbers of
silver-stained nucleolar organizer regions and the expression of ras mRNA in
the colonic mucosa (cell proliferation biomarkers). Following administration
of beta-carotene, a significant increase in the concentration of intact
beta-carotene molecules was found in the colonic mucosa, livers, and sera.
However, no accumulation of retinoids was observed in the colonic mucosa,
suggesting that the inhibitory effect may not be related to the provitamin A
activity. These results suggest that the combination of beta-carotene and
perilla oil may be useful in the prevention of colon cancer.