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Antioxidative activity of paraoxonase-1 (PON1) and malondialdehyde (MDA) level throughout pregnancy and postpartum period in dairy cows

Serum PON1 is HDL-associated enzyme that hydrolyzes oxidized phospholipids generated on LDL and HDL during oxidative stress and it is considered as an anti-oxidative/anti-inflammatory component of HDL. The aim of this study was to investigate serum PON1 activity and MDA level as well as the relationship between PON1 activity and total cholesterol and HDL-C concentrations in dairy cows during pregnancy and postpartum period. A total of 133 dairy cows were distributed into six groups: pregnant cows in 1st trimester (P1, n=21), 2nd trimester (P2, n=17) and 3rd trimester of pregnancy (P3, n=10) ; lactating cows in the early puerperium (L1, 1-15 days postpartum, n=23), late puerperium (L2, 16-30 days postpartum, n=27) and mid-lactation (L3, 40-60 days postpartum, n=11). The median PON1 activity was significantly lower (P<0.05) in groups P3 (216 U/L), L1 (223 U/L) and L2 (189 U/L) compared to P1 (283 U/L), P2 (257 U/L) and L3 (329 U/L). MDA concentration was significantly higher (P<0.05) in P3 (2.43 mmol/L) than in P1 and P2 (1.78 mmol/L and 1.5 mmol/L, respectively). A significant correlations were found between PON1 activity and total cholesterol (r=0.536 ; P<0.001) and HDL-C (r=0.52 ; P<0.001). There was no significant correlation between PON1 activity and MDA level (P>0.05). Results demonstrate lower PON1 activity in late pregnancy and early postpartum and higher MDA level in late pregnancy indicating that reproductive stress in dairy cows could influence an imbalance of antioxidans/prooxidants equilibrium.

Oxidative stress; paraoxonase; MDA; dairy cows; reproduction

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