Effect of fish oil on the development of AOM‐induced glutathione S‐transferase placental form positive hepatocellular foci in male F344 Rats

Abstract

Omega-3 fatty acids, which are contained in fish oils and certain vegetable oils in contrast to corn oil or safflower oil rich in omega-6 fatty acids (linoteic acid), have been reported to reduce the carcinogenesis in several organs. In this study, the modifying effect of menhaden fish oil was investigated on the occurrence of azoxymethane (AOM)-induced glutathione S-transferase placental form (GST-P) positive hepatocellular foci, recognized preneoplastic lesions in the liver, in male F344 rats. Starting at five weeks of age, groups of animals were fed ad libitum a semipurified diet containing 5% corn oil (low fat). At seven weeks of age, all animals except the vehicle-treated groups were injected subcutaneously with AOM (15 mg/kg body wt, 1x/wk for 2 wks). Four days after the second injection, groups of animals were fed the diets containing 4% menhaden oil + 1% corn oil (low fish oil diet), 22.5% menhaden oil + 1% corn oil (high fish oil diet), and 5% corn oil. Thirty-four weeks after AOM injections, all animals were necropsied. Livers were sectioned and performed immunohistochemical staining of GST-P for quantitative analysis of enzyme altered foci of the liver. The results demonstrate that the density and the unit area of AOM-induced enzyme altered foci in the liver were significantly lower in the high fish oil group (0.60 +/- 0.08/cm2, 3.0 +/- 0.4 x 10(-4)) than in the 5% corn oil group (2.71 +/- 0.33/cm2, 16.6 +/- 2.6 x 10(-4)) and the low fish oil group (1.66 +/- 0.33/cm2, 11.1 +/- 1.9 x 10(-4)).(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of Chemoprevention or Promotion Effects of Docosahexaenoic Acid on Small Intestine, Colon, Liver, Lung, Thyroid, Esophagus, Kidney, and Forestomach Carcinogenesis in a Rat Medium-Term Multi-Organ Carcinogenesis Model

“…The sardine oil inhibited the number of DEN-induced GST-P positive foci when administered in the initiation period, but enhanced the area of GST-P positive foci when administered in the post-initiation period. However, in another study, fish oil inhibited AOM-induced GST-P positive foci in the post- initiation stage 29 . These results suggest that the effects of fish oil appear to be dependent on the types of carcinogens.…”

Suppressive effect of low amounts of safflower and perilla oils on diethylnitrosamine‐induced hepatocarcinogenesis in male F344 rats

“…Three 3-u.m-thick serial sections were prepared. One section was stained with hematoxylin and eosin, and the others were used for the analysis of GST-P and argyrophilic nucleolar organizer region protein (AgNOR), as described previously (7,21). Liver cell foci and neoplasms were diagnosed according to the histological criteria of the Institute of Laboratory Animal Resources (27) on the hematoxylin and eosin-stained sections.…”

“…Some studies have suggested that n-6 PUFA, rather than saturated fatty acids (SFA), enhanced hepatocarcinogenesis when given during the postinitiation (10) or the promotion phase (17)(18)(19)(20). On the other hand, recent studies have suggested a suppressive effect of fish oil rich in n-3 PUFA given in the postinitiation (21) and the promotion phase (20) on chemical carcinogenesis of the liver.…”

“…Safflower oil is rich in an n-6 PUFA, linoleic acid; olive oil is rich in a monounsaturated fatty acid (MUFA), oleic acid (C18:ln-9); beef tallow is rich in SFA, palmitic acid (C16:0) and stearic acid (C18:0). We also assessed the development of placental GST (GST-P)-positive foci, which are precursor lesions of liver cell carcinoma (21)(22)(23)(24). Most of the primary liver cancer (hepatocellular carcinoma) develops in patients with chronic liver disease in Japan (25).…”

Compositions of fatty acids and phytosterols of plant-based oils and their associations with anti-oxidative capacity: Application of principal component analysis

“…However, associations between dietary nutrients and cognitive function remain inconsistent (Hayden et al 2007). Even though many efforts have been made to address protective effects of different types of vegetable oils on health outcomes, by utilizing different in vivo and in vitro models (Sugie et al 1995, Ossani et al 2012, few studies have explored the association between whole fatty acid content of edible oils and their protective effects against oxidative stress in a neuronal model. Therefore, in the present study, we analyzed the complete fatty acid profile and the phytosterol content of vegetable oils commonly used in Republic of Korea, investigated the antioxidant capacity of each oil, and determined the protective effects of oil components on this antioxidant activity via principal component analysis (PCA), a type of multivariate analysis.…”