Assessment of oxidative stress in dry and lactating cows

Upregulation Sestrin2 protects against hydrogen peroxide-induced oxidative damage bovine mammary epithelial cells via a Keap1-Nrf2/ARE pathway

Sestrin2 (SESN2) is a highly conservative oxidative stress protein that can regulate energy metabolism, cell proliferation, apoptosis, and mitochondria autophagy processes. It plays a role as an antioxidant in various diseases. The aims of the present study were to explore the underlying role of SESN2 after hydrogen peroxide (H₂ O₂ ) treatment in bovine mammary epithelial cells (MAC-T cells) by the methods of knockout or overexpression of SESN2. The results show that knockout of Sestrin2 exacerbate apoptosis, upregulate the expressions of Bax/Bcl2 in H₂ O₂ -treated MAC-T cells. Moreover, knockout of SESN2 also promoted reactive oxygen species (ROS) generation and exacerbated oxidative damage in H₂ O₂ -treated MAC-T cells. On the contrary, overexpression of SESN2 decreased apoptosis by downregulation of Bax/Bcl2 level decreased ROS generation and blocked oxidative damage in H₂ O₂ -treated MAC-T cells. In addition, results indicate that the Kelch-like ECH-associated protein-1 (Keap1)-nuclear factor (erythroid-derived 2) like2 (Nrf2)/antioxidant response element (ARE) signaling pathway was activated by H₂ O₂ ; upregulation of SESN2 could relieve oxidative stress by inducing the expression of Keap1, Nrf2, HO-1, and NDPH: quinone oxidoreductase-1 protein. In conclusion, this study demonstrates that expression of SESN2 was significantly increased after H₂ O₂ treatment and that SESN2 can alleviate oxidative stress and cell apoptosis in H₂ O₂ -treated MAC-T cells through activation of the Keap1-Nrf2/ARE pathway.

Moringa oleifera leaf flavonoids protect bovine mammary epithelial cells from hydrogen peroxide-induced oxidative stress in vitro

Bovine mammary epithelial cells (BMECs) of high-producing dairy cows are subject to constant oxidative stress as a result of high metabolic rate and physiological adaptation to intensive farming. Moringa (Moringa oleifera) leaf has been proposed to have the antioxidant potential in scavenging free radicals due to the presence of flavonoids. In this study, we investigated the cytoprotective effects of moringa leaf flavonoids in alleviating oxidative stress in BMECs in vitro. Oxidative stress was established by exposing isolated BMECs to H₂ O₂ for 2 hr. Doses of moringa leaf flavonoids were evaluated by treating BMECs for 12 hr. The optimal concentrations of H₂ O₂ and moringa leaf flavonoids were 500 μmol/L and 1.0 mg/ml, respectively. The results showed that moringa leaf flavonoids increased the activities of superoxide dismutase, catalase, and glutathione peroxidase; and reduced malondialdehyde activity and intracellular accumulation of reactive oxygen species (ROS) in the H₂ O₂ -induced oxidative stress system. A Hoechst33258 staining assay revealed that moringa leaf flavonoids decreased the apoptosis rate in BMECs, while leaving membrane integrity and nucleolar morphology unchanged. We concluded that moringa leaf flavonoids have the antioxidant capacity to effectively reduce oxidative stress in BMECs.

Protection of Bovine Mammary Epithelial Cells from Hydrogen Peroxide-Induced Oxidative Cell Damage by Resveratrol

The mammary epithelial cells (MECs) of high-producing dairy cows are likely to be subject to oxidative stress (OS) due to the intensive cell metabolism. The objectives of this study were to investigate the cytoprotective effects of resveratrol against hydrogen peroxide- (H2O2-) induced OS in cultured bovine MECs (MAC-T). Pretreatment of MAC-T cells with resveratrol could rescue the decrease in cell viability and resulted in lower intracellular reactive oxygen species (ROS) accumulation after H2O2 exposure. Resveratrol helped MAC-T cells to prevent H2O2-induced endoplasmic reticulum stress and mitochondria-related cell apoptosis. Moreover, resveratrol induced mRNA expression of multiple antioxidant defense genes in MAC-T cells under normal/oxidative conditions. Nuclear factor erythroid 2-related factor 2 (Nrf2) was required for the cytoprotective effects on MAC-T cells by resveratrol, as knockdown of Nrf2 significantly abolished resveratrol-induced cytoprotective effects against OS. In addition, by using selective inhibitors, we further confirmed that the induction of Nrf2 by resveratrol was mediated through the prolonged activation of PI3K/Akt and ERK/MAPK pathways but negatively regulated by p38/MAPK pathway. Overall, resveratrol has beneficial effects on bovine MECs redox balance and may be potentially used as a therapeutic medicine against oxidative insult in lactating animals.

Effect of dietary energy intake on erythrocytic antioxidant defence in growing lambs fed a wheat straw-based diet

Twenty-four Muzaffarnagari lambs (~8 months, 26.56 ± 2.04 kg), consisting 12 each of male and female, were used for ascertaining the effect of dietary energy restriction on the erythrocytic antioxidant defence including lipid peroxidation. The lambs, allotted randomly into three equal groups, were fed on wheat straw-based diets to provide 100, 80 and 70% of calculated metabolisable energy (ME) requirements. Bodyweight gain and feed intake were recorded. Blood samples were collected at the start and thereafter at 60-day intervals during 180 days of experimental duration and analysed for malonyl dialdehyde (MDA), reduced glutathione (GSH) and total thiol groups in addition to catalase, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione S-transferase. Dietary treatments imparted significant (P < 0.001) effects on feed intake and average daily gain. The haemoglobin and haematocrit contents in blood reduced significantly (P < 0.001) on reduction in dietary energy levels. The dietary alterations elicited no change in the activities of SOD, catalase and glutathione S-transferase, but reduced activities of GSH-Px (P < 0.001) and GSH (P = 0.133) were evident on feeding the diet with 70% ME. Concentrations of total thiols decreased (P < 0.001) with reduced energy level. Both the energy-restricted groups exhibited a significant (P < 0.001) increase in MDA, indicative of increased lipid peroxidation. It was concluded that long-term energy malnutrition on a wheat straw-based diet reduces the erythrocytic antioxidant defence in growing lambs.