Conjugated dienes: a critical trait of lipoprotein oxidizability in renal fibrosis.
BACKGROUND
We assessed whether a differential oxidizability of apolipoprotein B (apo B)-containing lipoproteins (LDL and VLDL) may explain the oxidative stress that we had observed at the onset of renal fibrosis in Zucker obese (ZO) rats (Nephrol Dial Transplant 2000, 15: 467--476).


METHODS
Ex vivo copper-induced oxidation of lipoproteins was performed in 1-, 3-, and 9-month-old ZO and age-matched lean (ZL) rats. LDL/VLDL oxidizability was determined by spectrophotometry at 234 nm by monitoring the formation of conjugated diene hydroperoxides.


RESULTS
A significant increase in lag time (reflecting the resistance to oxidation) was observed in ZO rats at 3 months while the maximal diene production (reflecting the amount of hydroperoxides formed during oxidation) was higher in ZO than in ZL rats as early as 1 month. Lipoproteins were larger in ZO than in ZL rats, as shown by their core to surface component ratio. Furthermore, ZO lipoproteins had increased vitamin E and polyunsaturated fatty acid (PUFA) content, with no change in vitamin E/PUFA ratio.


CONCLUSIONS
Rather than oxidizability of apo B-containing lipoproteins, the ability of these molecules to produce high levels of conjugated dienes, which can act as toxic tissue messengers, appears to be a critical trait in the development of renal fibrosis in this rat model of obesity and renal fibrosis.
Poirier
B
B
INSERM U 430, Broussais Hospital and Claude Bernard Association, Paris, France.
Michel
O
O
Bazin
R
R
Bariéty
J
J
Chevalier
J
J
Myara
I
I
D000475:Alkenes / Q000378:metabolism*; D000818:Animals; D001055:Apolipoproteins B / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005355:Fibrosis; D007668:Kidney / Q000473:pathology; D007674:Kidney Diseases / Q000378:metabolism*; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D009765:Obesity / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D011924:Rats, Zucker; D013851:Thinness; D014810:Vitamin E / Q000378:metabolism
D000475:Alkenes; D001055:Apolipoproteins B; D005231:Fatty Acids, Unsaturated; D008074:Lipoproteins; D014810:Vitamin E