Evaluating lipopolysaccharide-induced oxidative stress in bovine granulosa cells

Enzymatic Recording of Local Hydrogen Peroxide Generation Using Genetically Encodable Enzyme

Reactive oxygen species (ROS) are endogenously generated in live cells and essential for cell signaling. However, excess ROS generation can cause oxidative damage to biomolecules, which are implicated in various human diseases, including aging. Here, we developed an in vivo hydrogen peroxide monitoring method using a genetically encodable peroxidase (APEX2)-based system. We confirmed that APEX2 is activated by endogenous H₂O₂ and generates phenoxyl radicals to produce biotinylated signals (i.e., biotin-phenol) and fluorescent signals (i.e., AmplexRed), which can be detected using a fluorescence microscope. We observed that all subcellular targeted APEX2s were activated by local H₂O₂ generation by menadione treatment. Among them, the endoplasmic reticulum lumen and lysosome-targeted APEX2 showed the highest response upon addition of menadione which implies that local H₂O₂ levels in those spaces are highly increased by menadione treatment. Using APEX2, we also found that a minimum amount of menadione (>10 μM) is required to generate detectable levels of H₂O₂ in all subcellular compartments. We also checked the local H₂O₂-quenching effect of N-acetylcysteine using our system. As APEX2 can be genetically expressed in diverse live organisms (e.g., cancer cell lines, mice, fly, worm, and yeast), our method can be effectively used to detect local generation of endogenously produced H₂O₂ in diverse live models.

The effect of light on follicular development in laying hens

OBJECTIVE

The oxidative stress status and changes of chicken ovary tissue after shading were studied, to determine the mechanism of the effect of shading on follicular development.

METHODS

Twenty healthy laying hens (40 weeks old) with uniform body weight and the same laying rate were randomly divided into two groups (the shading group and normal light group). In the shading group, the cage was covered to reduce the light intensity inside the cage to 0 without affecting ventilation or food intake. The normal lighting group received no additional treatment. After 7 days of shading, oxidative stress related indicators and gene expression were detected.

RESULTS

Analysis of paraffin and ultrathin sections showed that apoptosis of ovarian granulosa cells (GCs) increased significantly after light shading. Enzyme linked immunosorbent assay results revealed that the levels of total antioxidant capacity, malondialdehyde, superoxide dismutase (SOD), glutathione, catalase (CAT), and other substances in the sera, livers, ovaries, and follicular GCs of laying hens increased significantly after shading for 7 days; and reactive oxygen species (ROS) levels in the livers of laying hens also increased significantly. ROS in the serum, ovarian and GCs also increased. After shading for 7 days, the levels of 8-hydroxy-2 deoxyguanosine in the sera and ovarian tissues of laying hens increased significantly. Cell counting kit-8 detection showed that the proliferation activity of GCs in layer follicles decreased after shading for 7 days; the expression level of the anti-apoptotic gene B-cell lymphoma-2 in ovarian tissue and follicular GCs was significantly reduced, and the expression levels of pro-apoptotic caspase 3 (casp3), and SOD, glutathione peroxidase 2 (GPX2), and CAT were all significantly increased.

CONCLUSION

Oxidative stress induced by shading light has a serious inhibitory effect on follicular development during reproduction in laying hens.

Acetyl-L-carnitine confers neuroprotection against lipopolysaccharide (LPS) -induced neuroinflammation by targeting TLR4/NFκB, autophagy, inflammation and oxidative stress

Acetyl-L-carnitine has been shown to exert neuroprotection against neurodegenerative diseases. The present study was performed to evaluate neuroprotection effects of acetyl-L-carnitine against lipopolysaccharide (LPS) -induced neuroinflammation and clarify possible mechanisms. A single dose (500 µg/kg) of LPS was intraperitoneally injected to rats to induce model. The animals were intraperitoneally treated with different doses of acetyl-L-carnitine (30, 60, and 100) for 6 days. Y-maze task, single-trial passive avoidance and novel object recognition tests were used to evaluate memory impairments. ELISA assay was used to evaluate the expression of TLR4/NFκB, autophagic and oxidative stress markers. Our result showed that intraperitoneal injection of LPS resulted in initiation of neuroinflammation by activation of TLR4/NFκB, suppression of autophagic markers such as LC3 II/ LC3 I ratio and becline-1, and excessive production of ROS and MDA. Intraperitoneal administration of acetyl-L-carnitine contributed to neuroprotection against LPS -induced neuroinflammation by suppression of TLR4/NFκB pathway, restoring activity of autophagy and inhibition of oxidative stress. Collectively, our findings show that acetyl-L-carnitine attenuated LPS-induced neuroinflammation by targeting TLR4/NFκB pathway, autophagy and oxidative stress.

Incidence and effects of subacute ruminal acidosis and subclinical ketosis with respect to postpartum anestrus in grazing dairy cows

Subclinical Ruminal Acidosis (SARA) and Subclinical Ketosis (SCK) are two of the most prevalent metabolic diseases of dairy cows, with impacts on reproductive performance. There is scarce literature about these diseases in dairy regions in Colombia. In 29 randomly selected herds in Pasto, Colombia, 249 dairy cows were followed weekly for two months postpartum to determine: 1) incidence risk of SARA and SCK; and 2) effects of SARA and SCK on the occurrence of postpartum anestrus (PA) at two months. Samples from ruminal liquor and blood were obtained one time per cow during the first week postpartum to determine presence of SARA (pH < 5.6) and SCK (1.0-2.9 mmol/L of blood Beta-Hydroxy-Butyrate), respectively. PA diagnosis was determined with ultrasound. Pregnancy risks at 30 and 60 days post-breeding (and assumed embryo losses between these days) were determined. Risk factors associated with PA were estimated through a mixed multi-level multivariable logistic regression model, adjusting for clustering of cows within herds. The incidence risks of SARA and SCK were 23.3% and 46.2%, respectively. Simultaneous occurrence of SCK and SARA (SCASCK) was present in 5.2% of the cows. In the final multivariable model, the occurrence of SARA (Odds Ratio: OR = 39.4), SCK (OR = 47.4) and SCASCK (OR = 68.5) was associated with increased odds of PA. Feeding a transition period diet was associated with reduced odds of PA (OR = 0.15). Second parity cows had significantly lower odds of PA than first parity cows (OR = 0.21). In conclusion, inadequate pre-partum and postpartum nutritional management of the herds increased the occurrence of SARA and SCK, which had adverse effects on reproductive performance.

Diet starch concentration and starch fermentability affect markers of inflammatory response and oxidant status in dairy cows during the early postpartum period

Our objective was to evaluate the effects of diet starch concentration and starch fermentability on inflammatory response markers and oxidant status during the early postpartum (PP) period and its carryover effects. Fifty-two multiparous Holstein cows were used in a completely randomized block design experiment with a 2 × 2 factorial arrangement of treatments. Treatments were starch concentration and starch fermentability of diets; diets were formulated to 22% (low starch, LS) or 28% (high starch, HS) starch with dry-ground corn (DGC) or high-moisture corn (HMC) as the primary starch source. Treatments were fed from 1 to 23 d PP and then switched to a common diet until 72 d PP to measure carryover (CO) effects. Treatment period (TP) diets were formulated to 22% forage neutral detergent fiber and 17% crude protein. The diet for the CO period was formulated to 20% forage neutral detergent fiber, 17% crude protein, and 29% starch. Coccygeal blood was collected once a week during the TP and every second week during the CO period. Liver and adipose tissue biopsies were performed within 2 d PP and at 20 ± 3 d PP. Blood plasma was analyzed for concentrations of albumin, haptoglobin, reactive oxygen and nitrogen species (RONS), and antioxidant potential (AOP), with lipopolysaccharide-binding protein (LBP) and TNFα evaluated during the TP only. Oxidative stress index (OSi) was calculated as RONS/AOP. Abundance of mRNA from genes involved in inflammation and glucose metabolism in liver and genes involved in lipogenesis in adipose tissue were determined. Data were analyzed separately for the TP and CO periods. During the TP, treatments interacted to affect concentrations of TNFα, haptoglobin, and LBP, with HMC increasing their concentrations for HS (9.38 vs. 7.45 pg/mL, 0.45 vs. 0.37 mg/mL, and 5.94 vs. 4.48 μg/mL, respectively) and decreasing their concentrations for LS (4.76 vs. 12.9 pg/mL, 0.27 vs. 0.41 mg/mL, and 4.30 vs. 5.87 μg/mL, respectively) compared with DGC. Effects of treatments diminished over time for LBP and haptoglobin with no differences by the end of the TP and no main CO effects of treatment for haptoglobin. The opposite treatment interaction was observed for albumin, with HMC tending to decrease its concentration for HS (3.24 vs. 3.34 g/dL) and increase its concentration for LS (3.35 vs. 3.29 g/dL) compared with DGC, with no carryover effect. Feeding DGC increased the OSi during the first week of the TP compared with HMC, with this effect diminishing over time; during the CO period HMC increased OSi for HS and decreased it for LS compared with DGC, with this effect diminishing toward the end of CO. Feeding HMC increased the abundance of genes associated with inflammation and gluconeogenesis in liver for HS and decreased it for LS compared with DGC. Feeding HS increased the mRNA abundance of genes associated with adipose tissue lipogenesis compared with LS. Results during the TP suggest that feeding LS-DGC and HS-HMC elicited a more pronounced inflammatory response and induced an upregulation of genes associated with inflammation and gluconeogenesis in liver, without effects on OSi, but effects on plasma markers of inflammation diminished during the CO period.

Troxerutin exerts neuroprotection against lipopolysaccharide (LPS) induced oxidative stress and neuroinflammation through targeting SIRT1/SIRT3 signaling pathway

This study was conducted to clarify the potential mechanisms of Troxerutin neuroprotection against Lipopolysaccharide (LPS) induced oxidative stress and neuroinflammation through targeting the SIRT1/SIRT3 signaling pathway. To establish a model, a single dose of LPS (500μg/kg body weight) was injected to male Wistar rats intraperitoneally. Troxerutin (100 mg/kg body weight) was injected intraperitoneally for 5 days after induction of the model. Cognitive and behavioral evaluations were performed using Y-maze, single-trial passive avoidance, and novel object recognition tests. The expression of inflammatory mediators, SIRT1/SIRT3, and P53 was measured using the ELISA assay. Likewise, the expression levels of SIRT1/SIRT3 and NF-κB were determined using Western blot assay. Brain acetyl-cholinesterase activity was determined by utilizing the method of Ellman. Reactive oxygen species (ROS) was detected using Fluorescent probe 2, 7-dichlorofluorescein diacetate (DCFH-DA). Furthermore, malondialdehyde (MDA) levels were determined. A single intraperitoneal injection of LPS was led to ROS production, acute neuroinflammation, apoptotic cell death, and inactivation of the SIRT1/SIRT3 signaling pathway. Likewise, ELISA assay demonstrated that post-treatment with Troxerutin considerably suppressed LPS-induced acute neuroinflammation, oxidative stress, apoptosis and subsequently memory impairments by targeting SIRT1/SIRT3 signaling pathway. Western blot assay confirmed ELISA results about SIRT1/SIRT3 and NF-κB proteins. These results suggest that Troxerutin can be a suitable candidate to treat neuroinflammation caused by neurodegenerative disorders.

ROS-Induced GATA4 and GATA6 Downregulation Inhibits StAR Expression in LPS-Treated Porcine Granulosa-Lutein Cells

LPS is a major endotoxin produced by gram-negative bacteria, and exposure to it commonly occurs in animal husbandry. Previous studies have shown that LPS infection disturbs steroidogenesis, including progesterone production, and subsequently decreases animal reproductive performance. However, little information about the underlying mechanisms is available thus far. In the present study, an in vitro-luteinized porcine granulosa cell model was used to study the underlying molecular mechanisms of LPS treatment. We found that LPS significantly inhibits progesterone production and downregulates the expressions of progesterone synthesis-associated genes (StAR, CYP11A1, and 3β-HSD). Furthermore, the levels of ROS were significantly increased in an LPS dose-dependent manner. Moreover, transcriptional factors GATA4 and GATA6, but not NR5A1, were significantly downregulated. Elimination of LPS-stimulated ROS by melatonin or vitamin C could restore the expressions of GATA4, GATA6, and StAR. In parallel, StAR expression was also inhibited by the knockdown of GATA4 and GATA6. Based on these data, we conclude that LPS impairs StAR expression via the ROS-induced downregulation of GATA4 and GATA6. Collectively, these findings provide new insights into the understanding of reproductive losses in animals suffering from bacterial infection and LPS exposure.