title: Menhaden oil inhibited gamma-glutamyltransferase-positive altered hepatic foci in female Sprague-Dawley rats.
abstract: Feeding menhaden oil, high in n-3 fatty acids, or a mixture of lard and corn oil with a polyunsaturated-to-monounsaturated fatty acid ratio of 1:1 was hypothesized to inhibit promotion of hepatocarcinogenesis in rats by decreasing hepatic prostaglandin (PG) levels. Ten-day-old female Sprague-Dawley rats were injected with diethylnitrosamine (DEN, 15 mg/kg body wt ip). At 4 wk of age, rats were fed fumonisin B1(50 mg/kg diet) for 5 wk in diets containing 14% lard + 6% corn oil, 10% lard + 10% corn oil, 14% menhaden oil + 6% corn oil, and 7% menhaden oil + 13% corn oil. Plasma alanine aminotransferase activity was 20% lower in rats fed 10% lard than in rats fed the other diets (P < 0.05). In menhaden oil-fed rats, total plasma cholesterol concentrations decreased 26% (P < 0.05) and hepatic phospholipid C20:5n-3, C22:5n-3, and C22:6n-3 fatty acid concentrations increased compared with lard-fed rats. Hepatic n-3 fatty acids were threefold greater in rats fed 10% lard than in rats fed 14% lard. The liver-associated natural killer cell activity in rats fed menhaden oil was 58% lower than in rats fed lard (P < 0.03). Rats fed lard had threefold (P < 0.05) greater area of _-glutamyltransferase-positive altered hepatic foci (AHF) than did rats fed menhaden oil. There was no significant difference in placental glutathione S-transferase-positive AHF among the groups. Hepatic PGF2alpha production was 60-80% greater in rats fed 14% lard than in rats fed the other diets (P < 0.05). Hepatic PGE2 was 48% less in rats fed 14%; menhaden oil than in rats fed 14% lard (P < 0.05). Although gamma-glutamyltransferase-positive focal area was inhibited by menhaden oil, only 14% menhaden oil inhibited PGE2. Feeding 10% lard inhibited PGF2alpha, but not the development of AHF. Therefore, decreased hepatic PGs did not explain the inhibition of carcinogenesis.
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames 50011, USA.
authors.forename: Sun-Ok
authors.initials: SO
authors.lastname: Lee
authors.forename: Hongjun
authors.initials: H
authors.lastname: Liu
authors.forename: Joan E
authors.initials: JE
authors.lastname: Cunnick
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Murphy
authors.forename: Suzanne
authors.initials: S
authors.lastname: Hendrich
mesh_terms: D000818:Animals; D003314:Corn Oil; D004041:Dietary Fats; D004052:Diethylnitrosamine / Q000633:toxicity; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000201:enzymology / Q000517:prevention & control*; D011448:Prostaglandin Antagonists; D011453:Prostaglandins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
chemical_list: D004041:Dietary Fats; D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D011448:Prostaglandin Antagonists; D011453:Prostaglandins; C033266:Menhaden oil; D004052:Diethylnitrosamine; D003314:Corn Oil; D005723:gamma-Glutamyltransferase; C029310:lard