Eicosanoid synthesis in 7,12‐dimethylbenz(a)anthracene‐induced mammary carcinomas in Sprague‐Dawley rats fed primrose oil, menhaden oil or corn oil diet

Abstract

The comparative effects of high-fat diets (20%, w/w) on eicosanoid synthesis during mammary tumor promotion in 7,12-dimethylbenz(a)anthracene (DMBA)-induced rats were studied using diets containing 20% primrose oil (PO), 20% menhaden oil (MO) or 20% corn oil (CO). Sprague-Dawley rats fed the PO or MO diet had 21% of 24% fewer adenocarcinomas, respectively, than rats fed the CO diet. Histologically (i.e., mitotic figures, inflammatory cell infiltration and necrosis), the CO-fed rats exhibited the highest frequency of changes within tumors. Plasma fatty acid composition was significantly altered by diet, reflecting the composition of the oils which were being fed. Only the plasma of PO-fed rats contained detectable levels of gamma-linolenic acid (GLA). Arachidonic acid (AA) levels were significantly higher (p less than 0.05) in PO-fed than in CO- or MO-fed rats. MO-fed rats had significantly higher levels of plasma palmitic acid, while palmitoleic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were detected only in MO-fed rats. As expected, linoleic acid (LA) and AA levels were lower (p less than 0.05) in the MO-fed rats than in PO- or CO-fed groups. The plasma of the CO-fed rats contained significantly higher levels of oleic acid. Eicosanoid synthesis in mammary carcinomas of rats fed the 20%-fat diets was 2-10 times higher than in mammary fat pads of control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Mammary Gland Density Predicts the Cancer Inhibitory Activity of the N-3 to N-6 Ratio of Dietary Fat

“…Moreover, the preclinical data on the role of n-3 fatty acids in mammary carcinogenesis is similarly mixed (inhibition, no effect, or promotion of carcinogenesis), and the quality of the experiments varies so markedly that it is difficult to compare results across studies (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). These circumstances prompted the work reported herein.…”

Functional identification of a fatty acid Δ5 desaturase gene from Caenorhabditis elegans

“…The eicosanoids have many functions, and are particularly important in the in£ammatory response, reproductive function and the regulation of blood pressure [2]. Essential fatty acids may alleviate certain conditions such as eczema and mastalgia [2] and some studies suggest a possible application in the treatment of cancer and tumour growth [3,4].…”

Chemoprevention of Breast Cancer by Fish Oil in Preclinical Models: Trials and Tribulations

“…Other studies verified the chemical composition of the oil prior to adding it to the diet but not of the diet fed to the animals (5,9,10,12,14,15). In 4 studies (17)(18)(19)(20), the authors gave their rats fish oil supplement (Maxepa) intragastrically, instead of mixing it in the diet.…”

“…The studies that provided ratios showed protective effects at varying n-3/n-6 ratios: 0.16 (11), 0.33 to 0.55 (4,13,21) (14), and 10 (27). Promotion of carcinogenesis was observed with an n-3/n-6 ratio of 0.33 to 0.5 in a high-fat diet (39% calories from fat), whereas protection was observed with the same ratio in the presence of a low-fat diet (16% calories from fat; ref.…”

“…Analysis of plasma and mammary tissue FAs would reflect the influence of the experimental diet on circulating and target tissue FA composition. Out of the 24 studies reviewed, only 6 reported serum FA analysis (4,6,7,11,14,22), and 7 reported mammary tumor FA analysis (5, 7-9, 11, 12, 22). Again, this factor severely limits the ability to interpret results or to make cross-study comparisons.…”