Lipids

, Volume 23, Issue 10, pp 948–954

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

Authors

  • Soad H. Abou-El-Ela
    • Department of Pharmacology and Toxicology, College of PharmacyUniversity of Georgia
  • Keith W. Prasse
    • Department of Pathology, College of Veterinary MedicineUniversity of Georgia
  • Richard Carroll
    • Department of Preventive Medicine and Community HealthThe University of Texas Medical Branch
  • Adelbert E. Wade
    • Department of Pharmacology and Toxicology, College of PharmacyUniversity of Georgia
  • Suniti Dharwadkar
    • Department of Pharmacology and Toxicology, College of PharmacyUniversity of Georgia
  • Opal R. Bunce
    • Department of Pharmacology and Toxicology, College of PharmacyUniversity of Georgia
Article

DOI: 10.1007/BF02536342

Cite this article as:
Abou-El-Ela, S.H., Prasse, K.W., Carroll, R. et al. Lipids (1988) 23: 948. doi:10.1007/BF02536342

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% or 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<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<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. The synthesis of PGE1 and LTB4 was significantly (p<0.05) higher in PO-fed rats than in CO-fed or MO-fed rats, although PGE values were significantly (p<0.05) higher in CO-fed rats than in Mo or PO groups. The synthesis of eicosanoids in both mammary fat pads and mammary carcinomas of MO-fed rats was lower (p<0.05) than in tissues of rats fed either CO or PO diets due to less AA precursor being fed and/or to competition between n−6 and n−3 fatty acids for cyclooxygenase and lipoxygenase. The ratios of monoenoic to dienoic eicosanoids in both mammary fat pads and mammary carcinomas were higher in the PO group than in the MO or CO groups. These results suggest that inclusion of GLA (PO feeding) or EPA and DHA (MO feeding) in the diet may decrease malignancy by altering eicosanoid profiles.

Abbreviations

AA

arachidonic acid

CO

corn oil

DGLA

dihomogamma-linolenic acid

DHA

doeosahexaenoic acid

DMBA

7,12-dimethylbenz(a)anthracene

D6D

delta-6 desaturase

EFA

essential fatty acid

EPA

eicosapentaenoic acid

GLA

gamma-linolenic acid

LA

linoleic acid

MO

menhaden oil

PO

primrose oil

RIA

radioimmunoassay

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Copyright information

© American Oil Chemists’ Society 1998