Effect of iron overload and dietary fat on indices of oxidative stress and hepatic fibrogenesis in rats.
OBJECTIVE
Oxidative stress is presumed to play an important role in hepatic fibrogenesis. Diets high in polyunsaturated fatty acids (PUFA) enhance fibrosis and have been associated with increased oxidative damage in some models of liver injury. The aim of this study was to determine the effects of dietary fat of varying PUFA content on iron-induced oxidative stress and fibrosis.


METHODS
Rats were given parenteral iron and diets supplemented with coconut oil, safflower oil or menhaden oil.


RESULTS
Hepatic iron overload was associated with induction of heme oxygenase-1, a sensitive indicator of oxidative stress, and with modest increases in hydroxyproline and procollagen I mRNA levels without histologically evident fibrosis, all of which were unaffected by dietary fat. In addition, iron loading was associated with increases in cysteine, gamma-glutamylcysteine and glutathione. Dietary fat brought about the expected alterations in peroxidizability, but did not alter indices of oxidative damage.


CONCLUSIONS
These data highlight the distinction between oxidative stress and oxidative damage and suggest that the former is not sufficient to elicit overt fibrosis. Furthermore, while hepatic iron overload leads to oxidative stress, there is an associated upregulation of antioxidant defenses involving thiol metabolism that may be a critical factor limiting the accumulation of oxidative damage.
Brown
Kyle E
KE
Gastroenterology Section, John Cochran VAMC, St. Louis, MO, USA. kyle-brown@uiowa.edu
Dennery
Phyllis A
PA
Ridnour
Lisa A
LA
Fimmel
Claus J
CJ
Kladney
Raleigh D
RD
Brunt
Elizabeth M
EM
Spitz
Douglas R
DR
D000818:Animals; D024042:Collagen Type I / Q000096:biosynthesis / Q000235:genetics; D003545:Cysteine / Q000378:metabolism; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage*; D004151:Dipeptides / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis / Q000235:genetics; D051547:Heme Oxygenase-1; D006909:Hydroxyproline / Q000096:biosynthesis / Q000235:genetics; D007124:Immunoenzyme Techniques; D019190:Iron Overload / Q000378:metabolism*; D019266:Iron, Dietary / Q000633:toxicity*; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000178:diet therapy / Q000378:metabolism* / Q000473:pathology; D008297:Male; D018384:Oxidative Stress; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D024042:Collagen Type I; D004042:Dietary Fats, Unsaturated; D004151:Dipeptides; D019266:Iron, Dietary; D012333:RNA, Messenger; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D005978:Glutathione; D003545:Cysteine; C017341:gamma-glutamylcysteine; D006909:Hydroxyproline