engleski

The Role of HDL-Associated Enzymes in Bovine Reproduction

High-density lipoprotein plays an important role as an anti-oxidative/anti-inflammatory particle providing a non-specific defense of a host. This action of HDL is mediated by several structural proteins and enzymes carried on the particle, including paraoxonase-1 (PON1) and platelet-activating factor acetylhydrolase (PAF-AH). The physiological substrates of PON1 are pro-inflammatory oxidized phospholipids that appear on both LDL and HDL during oxidative stress. Although PON1 was previously investigated in toxicology, its role in anti-inflammatory and anti-oxidative properties of HDL has been extensively studied in the last two decades. PAF-AH is responsible for degradation of the platelet-activating factor (PAF) as well as PAF-like oxidatively fragmented lipid hydroperoxides. PAF is a bioactive phospholipid synthesized by a variety of mammalian cells being a mediator of inflammation and a well established activator of the immune system. PAF is also an important mediator for physiological processes associated with reproduction such as ovulation, sperm motility, fertilization, implantation, fetal tissue development and the initiation of parturition. In addition, PAF-AH activity was also demonstrated in the bovine reproductive system. Oxidative stress and inflammation seems to be implicated in the pathogenesis of many reproductive diseases of cows and subsequent decrease of animal fertility. Low energy availability during late pregnancy and early postpartum plays a major role in the development of oxidative stress in cows. Although the improvement of antioxidant status in cows to prevent reproductive disorders has been recognized for many years, understanding the role of HDL-associated enzymes in bovine reproduction could lead to the new approach to the diagnosis and the therapy of reproductive diseases.

HDL, paraoxonase, platelet-activating factor acetylhydrolase, oxidative stress, inflammation, reproduction, cows

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