J. Perinat. Med. 2017; aop Marianne Ullestad Huun*, Håvard T. Garberg, Javier Escobar, Consuelo Chafer, Maximo Vento, Ingar M. Holme, Ola Didrik Saugstad and Rønnaug Solberg DHA reduces oxidative stress following hypoxia- ischemia in newborn piglets: a study of lipid peroxidation products in urine and plasma DOI 10.1515/jpm-2016-0334 Received October 18, 2016. Accepted May 11, 2017. Abstract Background: Lipid peroxidation mediated by reactive oxygen species is a major contributor to oxidative stress. Docosahexaenoic acid (DHA) has anti-oxidant and neuroprotective properties. Our objective was to assess how oxidative stress measured by lipid peroxidation was modified by DHA in a newborn piglet model of hypoxia- ischemia (HI). Methods: Fifty-five piglets were randomized to (i) hypoxia, (ii) DHA, (iii) hypothermia, (iv) hypothermia + DHA or (v) sham. All groups but sham were subjected to hypoxia by breathing 8% O 2 . DHA was administered 210 min after end of hypoxia and the piglets were euthanized 9.5 h after end of hypoxia. Urine and blood were harvested at these two time points and analyzed for F 4 -neuroprostanes, F 2 -iso- prostanes, neurofuranes and isofuranes using UPLC-MS/ MS. Results: F 4 -neuroprostanes in urine were significantly reduced (P = 0.006) in groups receiving DHA. Hypoxia (median, IQR 1652 nM, 610–4557) vs. DHA (440 nM, 367–738, P = 0.016) and hypothermia (median, IQR 1338 nM, 744–3085) vs. hypothermia + DHA (356 nM, 264–1180, P = 0.006). The isoprostane compound 8-iso-PGF2α was significantly lower (P = 0.011) in the DHA group compared to the hypoxia group. No significant differences were found between the groups in blood. Conclusion: DHA significantly reduces oxidative stress by measures of lipid peroxidation following HI in both nor- mothermic and hypothermic piglets. Keywords: Docosahexaenoic acid (DHA); hypoxia- ischemia (HI); isoprostanes; lipid peroxidation; neuropro- stanes; neuroprotection; oxidative stress; reactive oxygen species. Introduction During perinatal asphyxia, the body is deprived of oxygen and glucose, initiating a cascade of harmful processes including necrosis, apoptosis, production of reactive oxygen species (ROS) and lipid peroxidation [1]. These processes can lead to the clinical condition of hypoxic-ischemic encephalopathy (HIE) [2]. ROS- mediated lipid peroxidation is especially important in the brain due to its high content of lipids. Polyunsatu- rated fatty acids (PUFAs) are highly susceptible to lipid peroxidation through oxidative stress because of their high content of double bonds. When major PUFAs like arachidonic acid and docosahexaenoic acid (DHA) are oxidized, they can be measured in different tissue fluids through their downstream metabolites F 2 -isoprostanes, F 4 -neuroprostanes, isofuranes and neurofurane [3]. These metabolites may be measured though rigorous ultra performance liquid chromatography- tandem mass spectrometry (UPLC-MS/MS) [4]. F 2 -isoprostanes are products of non-enzymatic free radical catalyzed oxidation of arachidonic acid and they are currently thought to be the most reliable markers of oxidative damage in humans [5]. Welin et al. [6] showed how F 2 -isoprostane increased in plasma, hours after *Corresponding author: Marianne Ullestad Huun, Department of Pediatric Research, Institute of Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway, Tel.: +47-23-07-27-90, E-mail: marianne.ullestad.huun@rr-research.no Håvard T. Garberg and Ola Didrik Saugstad: Department of Pediatric Research, Institute of Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway Javier Escobar: Department of Pediatric Research, Institute of Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway; and Neonatal Research Unit, Health Research Institute Hospital La Fé, Valencia, Spain Consuelo Chafer and Maximo Vento: Neonatal Research Unit, Health Research Institute Hospital La Fé, Valencia, Spain Ingar M. Holme: Department of Sports Medicine, Norwegian School of Sports Sciences, Oslo, Norway Rønnaug Solberg: Department of Pediatric Research, Institute of Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway; and Department of Pediatrics, Vestfold Hospital Trust, Tønsberg, Norway