title: Postpartum levels of 8-iso-prostaglandin F2α in plasma and milk phospholipid fractions as biomarker of oxidative stress in first-lactating dairy cows.
abstract: F2-isoprostanes such as 8-iso-prostaglandin F2<alpha> (8-iso-PGF2α) are formed by free radical-catalyzed mechanisms from membrane phospholipids and from low density lipoproteins through peroxidation of arachidonic acid. Esterified 8-iso-PGF2α is cleaved by phospholipases, circulates in blood and is excreted as putatively harmful oxidatively modified lipid via the kidney into urine. In this study we demonstrate that 8-iso-PGF2α concentrations in plasma samples from heifers are higher (p<0.005) compared to those from first-lactating dairy cows at 71 days postpartum. Furthermore, plasma 8-iso-PGF2α concentrations vary with ovarian activity and differ in response to luteolytic initiation as well as activation of the hypothalamic-pituitary-gonadal axis between heifers and first-lactating cows. Sustainable concentrations of 8-iso-PGF2α (50-150 pg/ml) are detectable in the phospholipid fraction of milk, suggesting milk as an additional excretion route for 8-isoprostanes. Plasma levels largely paralleled levels in milk (p<0.001). Plasma phospholipid 8-iso-PGF2α concentrations in cyclic cows decreased (p<0.05) from day 38 to day 71 postpartum, whereas milk phospholipid 8-iso-PGF2α rather increased (p<0.05). Cyclic cows tend to have higher 8-isoprostane levels compared to acyclic animals. In contrast to lipohydroperoxides, concentration of 8-iso-PGF2α were not correlated with milk yield (p>0.05). Our data indicate 8-iso-PGF2α may be a novel biomarker of oxidative stress in dairy cow, which is detectable in blood as well as in milk.
authors.affiliation: Leibniz Institute for Farm Animal Biology, Institute of Reproductive Biology, Dummerstorf, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Vernunft
authors.affiliation: Leibniz Institute for Farm Animal Biology, Institute of Reproductive Biology, Dummerstorf, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Viergutz
authors.affiliation: Leibniz Institute for Farm Animal Biology, Institute of Reproductive Biology, Dummerstorf, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Plinski
authors.affiliation: Leibniz Institute for Farm Animal Biology, Institute of Reproductive Biology, Dummerstorf, Germany. Electronic address: weitzel@fbn-dummerstorf.de.
authors.forename: J M
authors.initials: JM
authors.lastname: Weitzel
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D002417:Cattle / Q000502:physiology*; D015237:Dinoprost / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood; D005260:Female; D007774:Lactation / Q000502:physiology*; D008892:Milk / Q000737:chemistry*; D018384:Oxidative Stress / Q000502:physiology*; D010743:Phospholipids / Q000032:analysis / Q000097:blood / Q000737:chemistry; D049590:Postpartum Period / Q000097:blood / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D010743:Phospholipids; C075750:8-epi-prostaglandin F2alpha; D015237:Dinoprost
keywords: 8-Isoprostane; Biomarker; F(2)-isoprostane; Fertility; Oxidative stress