Impact of carob (Ceratonia siliqua L.) pulp inclusion and warm season on gastrointestinal morphological parameters, immune-redox defences and coccidiosis in concentrate-fed light lambs

This study aimed to evaluate the effects of dietary carob (Ceratonia siliqua L.) pulp and warm season on gastrointestinal morphological parameters, immune-redox defences and coccidiosis in concentrate-fed light lambs. Weaned lambs were assigned to one of three concentrate-based diets: C0 (without carob pulp), C15 (150 g/kg of carob pulp) and C30 (300 g/kg of carob pulp) from 40 to 80 days of age in two consecutive cold and warm batches. Blood samples were collected at Day 80 to determine the metabolic status. Rectal faeces were sampled at Days 50, 65 and 80 to determine consistency and oocyst count per gram. Inclusion of carob pulp in lamb diets did not affect lamb growth but reduced coccidia oocyst excretion, improved faecal consistency and gastrointestinal morphological parameters, enhancing the ruminal thickness of the papilla living strata and reducing the darkness of the epithelium colour. Moreover, carob condensed tannins in the lambs' diet enhanced the expression of antioxidant SOD2 in rumen, while down-regulated NRF2, SOD1, CAT and PPARG in ileum. There was no interaction between the treatments and season in the evaluated variables. Lambs from the warm season exhibited reduced growth performance, altered ruminal epithelium, lower circulating iron levels, increased protein concentrations and higher coccidiosis susceptibility. In addition, regulatory immune and antioxidant mechanisms to counterbalance reactive oxygen species production in gastrointestinal tissues were evident. Dietary inclusion of carob pulp (150 and 300 g/kg) in lamb diets improved gastrointestinal health and homeostasis but did not ameliorate the deleterious effects of warm season.

Bifurcaria bifurcata extract exerts antioxidant effects on human Caco-2 cells

The present research study investigated the potential protective effect of Bifurcaria bifurcata extract on cell viability and antioxidant defences of cultured human Caco-2 cells submitted to oxidative stress induced by tert-butylhydroperoxide (tert-BOOH). Aqueous extracts were firstly characterized in terms of total phenolic contents. Concentrations of reduced glutathione (GSH) and malondialdehyde (MDA), generation of reactive oxygen species (ROS), nitric oxide (NO) production, antioxidant enzymes activities [NADPH quinone dehydrogenase 1 (NQO1) and glutathione S-transferase (GST)], caspase 3/7 activity and gene expression linked to apoptosis, proinflammation and oxidative stress signaling pathways were used as markers of cellular oxidative status. B. bifurcata extract prevented the cytotoxicity, the decrease of GSH, the increase of MDA levels and the ROS generation induced by tert-BOOH. B. bifurcata extract prevented the significant decrease of NQO1 and GST activities, and the significant increase of caspase 3/7 activity induced by tert-BOOH. B. bifurcata extract also caused an over-expression of GSTM2, Nrf2 and AKT1 transcriptors, as well as reduced ERK1, JNK1, Bax, BNIP3, NFκB1, IL-6 and HO-1 gene expressions induced by tert-BOOH suggesting an increase in cellular resistance against oxidative stress. The results of the biomarkers analyzed show that treatment of Caco-2 cells with B. bifurcata extract enhance antioxidant defences, which imply an improved cell response to an oxidative challenge. B. bifurcata extract possesses strong antioxidant properties and may be a potential effective alternative to oxidant agents in the functional food industry.

Cadmium effects on the freshwater teleost Prochilodus lineatus: Accumulation and biochemical, genotoxic, and behavioural biomarkers

In order to evaluate the effects of Cd, juveniles of the Neotropical fish Prochilodus lineatus were exposed to 1 and 10 μg L^-1 Cd, for 24 and 96 h. Fish exposed to Cd showed metal accumulation in the gills, kidney, and liver, an increase in DNA damage in erythrocytes, and an increase in lipid peroxidation (LPO) in the kidney. Cd exposure also caused a reduction in catalase activity, metallothionein induction, and LPO in the liver. Cd stimulated the swimming activity of exposed fish, resulting in longer swimming times and distances travelled, especially for the shortest exposure time. Changes in acetylcholinesterase activity (AChE) in the muscle and brain are probably related to these behavioural responses. These results show that Cd affects the functioning of several organs in P. lineatus, which is indicated by the genotoxic damage and changes in the AChE and swimming pattern of the exposed fish.

Atomoxetine Decreases Mitochondrial Biogenesis, Fission and Fusion In Human Neuron-like Cells But Does Not Alter Antioxidant Defences

Atomoxetine (ATX) is a presynaptic norepinephrine transporter (NET) inhibitor widely prescribed for attention-deficit/hyperactivity disorder (ADHD) due to its low abuse potential and absence of psychostimulant effects. While NET inhibition is implicated in the clinical response, several additional pharmacoactivities may contribute to clinical efficacy or unwanted side effects. We recently reported that ATX can dose-dependently alter mitochondrial function and cellular redox status. Here, we assessed potential alterations in mitochondrial biogenesis, mitochondrial dynamics and cellular antioxidant capacity following high- and low-dose ATX treatment of differentiated human neuroblastoma cells. Human SH-SY5Y neuroblastoma cells were treated with ATX (1, 5, 10, 20 and 50 μM) for 7 days under differentiation culture conditions. Changes in the expression levels of protein markers for mitochondrial biogenesis, fusion and fission as well as of antioxidant proteins were analysed by Western blot. High-dose ATX (50 μM) reduced while low-dose ATX (10 μM) increased mitochondrial biogenesis as evidenced by parallel changes in SDHA, COX-I, PGC1α and TFAM expression. High-dose ATX also reduced mitochondrial fusion as evidenced by OPA1 and MFN2 downregulation, and mitochondrial fission as indicated by DRP1 and Fis1 downregulation. In contrast, ATX did not alter expression of the antioxidant enzymes SOD1 and catalase, the phase II transcription factor Nfr2, or the Nfr2-regulated antioxidant enzyme NQO1. Clinical responses and side effects of ATX may be mediated by dose-dependent modulation of mitochondrial biogenesis and dynamics as well as NET inhibition.

Stress response to trace elements mixture of different embryo-larval stages of Paracentrotus lividus

This study investigated for the first time the oxidative biomarkers responses in all larval stages of sea urchin. The contamination effects were reproduced by using contaminated seawater to concentrations measured in the area adjacent to an old asbestos mine at factors of 5 and 10. The results suggested that the concentrations were not sufficiently high to induce a major oxidative stress. The biometric differences make this method a more sensitive approach for assessing the effects on sea urchin larvae. Measurements of specific activities of antioxidant enzymes at each stage suggested a high capacity of the larvae to respond to oxidative stress. This normal activity of the organism must be considered in future research. This work also highlighted the importance of spawners provenance in ecotoxicological studies. These data are essential to better understand the stress responses of sea urchin larvae and provide baseline information for later environmental assessment research.

An Integrated Testing Strategy for Ecotoxicity (ITS-ECO) Assessment in the Marine Environmental Compartment using Mytilus spp.: A Case Study using Pristine and Coated CuO and TiO2 Nanomaterials

An integrated testing strategy for ecotoxicity assessment (ITS-ECO) was developed to aid in the hazard and fate assessment of engineered nanomaterials (ENMs) deposited in marine environments using the bivalve Mytilus spp. as a test species. The ENMs copper(II) oxide (CuO) and titanium dioxide (TiO₂ ), either in pristine form (core) or with functionalized coatings (polyethylene glycol [PEG], carboxyl [COOH], and ammonia [NH₃ ]) were selected as case study materials based on their production levels and use. High-throughput in vitro testing in Tier 1 of the ITS-ECO revealed CuO ENMs to elicit cytotoxic effects on lysosomes of hemocytes of mussels, with the hazard potential CuO PEG > CuO COOH > CuO NH₃  > CuO core, whereas TiO₂ ENMs were not cytotoxic. Genotoxicity in hemocytes as well as gill cells of mussels following in vivo exposure (48 h) to CuO ENMs was also seen. Longer in vivo exposures in Tier 2 (48 h-21 days) revealed subacute and chronic oxidative effects for both CuO and TiO₂ ENMs, in some cases leading to lipid peroxidation (core TiO₂ ENMs). In Tier 3 bioaccumulation studies, distinct patterns of uptake for Cu (predominantly in gills) and Ti (predominantly in digestive glands) and between the different core and coated ENMs were found. Clear NM-specific and coating-dependent effects on hazard and fate were seen. Overall, using a tiered testing approach, the ITS-ECO was able to differentiate the hazard (acute, subacute, and chronic effects) posed by ENMs of different compositions and coatings and to provide information on fate for environmental risk assessment of these ENMs. Environ Toxicol Chem 2022;41:1390-1406. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Oxidative damages and antioxidant defences after feeding a single meal in rainbow trout

Feeding and digestion are metabolically demanding causing a rise on metabolic rate called Specific Dynamic Action (SDA). Although SDA has been vastly reported in fish, its potential consequences on the oxidative-antioxidant balance has not been evaluated to date in fish, a model with a long alkaline tide associated with feeding as well. Using rainbow trout (Oncorhynchus mykiss) as a model species, the aims of the present study were to: (1) assess potential oxidative damages and changes in oxidative defences after feeding on a single meal, and (2) identify the timescale of such changes over a 96 h post-feeding period. Oxidative damage in proteins and lipids and the activities of four enzymatic antioxidant defences: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were measured in gill, stomach, intestine and liver. DNA damage was measured in red blood cells. Fish were sampled before and after 1.5, 6, 24, 48, 72 and 96 h of ingestion of a 3% body mass ration. Trends of post-prandial damage were present in all tissues, but only protein oxidation varied significatively during digestion in the stomach. The intestine and stomach presented the highest enzymatic activities, likely due to the high metabolic action that these tissues have during digestion, with peaks during post-feeding: at 24 h of SOD in stomach and at 48 h of CAT in intestine. Observed GPx peaks during post-feeding in gills are likely due to the exacerbated demands for ion fluxes and/or oxygen during feeding. The differential response of the antioxidant system observed in tissues of rainbow trout during digestion indicates a coordinated and tissue-specific antioxidant defence.

Bisphenol S leads to cytotoxicity-induced antioxidant responses and oxidative stress in isolated rainbow trout (Oncorhyncus mykiss) hepatocytes

BACKGROUND

Bisphenol S (BPS) is a chemical compound that is utilized in the plastic industry as an alternative to bisphenol A (BPA). The toxic effects of BPS in fish is less known and limited. Therefore, in the present study, the influence of BPS on rainbow trout (Oncorhyncus mykiss) hepatocytes in vitro was investigated.

METHODS AND RESULTS

For this purpose the fish hepatocytes were isolated, and then the cultured cells were treated with increasing concentrations of BPS (0, 15.63, 31.25, 62.50, 125, 250, and 500 µM) for 24 h. The cytotoxic impact of BPS was determined in the culture media using lactate dehydrogenase assay and then, the antioxidant defence indicators were assayed. The results showed that concentration-dependent increases were observed in the percentage of cytotoxicity. The superoxide dismutase activity was reduced, while the catalase and glutathione peroxidase activity increased with all of the BPS concentrations. The glutathione S-transferase (GST) activity significantly increased after a BPS concentration of 31.25 µM or higher, while GST Theta 1-1 activity was decreased by the same concentrations of BPS. The reduced glutathione content significantly decreased with a BPS concentration of 31.25 µM or higher, and the malondialdehyde content increased after BPS concentrations of 125, 250, and 500 µM.

CONCLUSIONS

The findings determined herein suggested that BPS causes cytotoxicity in fish hepatocytes and can lead to oxidative stress, resulting hepatotoxic in fish. Thus, the utilization of BPS instead of BPA as safe alternative in industry should be re-evaluated in the future for environmental health.

Circulating biomarkers of nitric oxide bioactivity and impaired muscle vasoreactivity to exercise in adults with uncomplicated type 1 diabetes

AIMS/HYPOTHESIS

Early compromised endothelial function challenges the ability of individuals with type 1 diabetes to perform normal physical exercise. The exact mechanisms underlying this vascular limitation remain unknown, but may involve either formation or metabolism of nitric oxide (NO), a major vasodilator, whose activity is known to be compromised by oxidative stress.

METHODS

Muscle microvascular reactivity (near-infrared spectroscopy) to an incremental exhaustive bout of exercise was assessed in 22 adults with uncomplicated type 1 diabetes (HbA_1c 64.5 ± 15.7 mmol/mol; 8.0 ± 1.4%) and in 21 healthy individuals (18-40 years of age). NO-related substrates/metabolites were also measured in the blood along with other vasoactive compounds and oxidative stress markers; measurements were taken at rest, at peak exercise and after 15 min of recovery. Demographic characteristics, body composition, smoking status and diet were comparable in both groups.

RESULTS

Maximal oxygen uptake was impaired in individuals with type 1 diabetes compared with in healthy participants (35.6 ± 7.7 vs 39.6 ± 6.8 ml min^-1 kg^-1, p < 0.01) despite comparable levels of habitual physical activity (moderate to vigorous physical activity by accelerometery, 234.9 ± 160.0 vs 280.1 ± 114.9 min/week). Compared with non-diabetic participants, individuals with type 1 diabetes also displayed a blunted exercise-induced vasoreactivity (muscle blood volume at peak exercise as reflected by ∆ total haemoglobin, 2.03 ± 5.82 vs 5.33 ± 5.54 μmol/l; interaction 'exercise' × 'group', p < 0.05); this was accompanied by lower K⁺ concentration (p < 0.05), reduced plasma L-arginine (p < 0.05)-in particular when HbA_1c was high (mean estimation: -4.0, p < 0.05)-and lower plasma urate levels (p < 0.01). Nonetheless, exhaustive exercise did not worsen lipid peroxidation or other oxidative stress biomarkers, and erythrocytic enzymatic antioxidant resources were mobilised to a comparable extent in both groups. Nitrite and total nitrosation products, which are potential alternative NO sources, were similarly unaltered. Graphical abstract CONCLUSIONS/INTERPRETATION: Participants with uncomplicated type 1 diabetes displayed reduced availability of L-arginine, the essential substrate for enzymatic nitric oxide synthesis, as well as lower levels of the major plasma antioxidant, urate. Lower urate levels may reflect a defect in the activity of xanthine oxidase, an enzyme capable of producing NO from nitrite under hypoxic conditions. Thus, both canonical and non-canonical NO production may be reduced. However, neither of these changes exacerbated exercise-induced oxidative stress.

TRIAL REGISTRATION

clinicaltrials.gov NCT02051504.

Application of response surface methodology (RSM) for the optimization of supercritical CO2 extraction of oil from patè olive cake: Yield, content of bioactive molecules and biological effects in vivo

The two-phase technology for olive oil extraction generates large amounts of patè olive cake (POC), a by-product that is rich in bioactive health-promoting compounds. Here, response surface methodology (RSM) was used to maximize supercritical-CO₂ oil extraction from POC, while minimizing operative temperature, pressure and time. Under the optimal parameters (40.2 °C, 43.8 MPa and time 30 min), the oil yield was 14.5 g·100 g^-1 dw (~65% of the total oil content of the freeze-dried POC matrix), as predicted by RSM. Compared with freeze-dried POC, the oil contained more phytosterols (13-fold), tocopherols (6-fold) and squalene (8-fold) and was a good source of pentacyclic triterpenes. When the biological effects of POC oil intake (20-40 µL·die^-1) were evaluated in the livers of BALB/c mice, no significant influence on redox homeostasis was observed. Notably, a decline in liver triglycerides alongside increased activities of NAD(P)H:Quinone Oxidoreductase 1, Carnitine Palmitoyl-CoA Transferase and mitochondrial respiratory complexes suggested a potential beneficial effect on liver fatty acid oxidation.

Toxicity beyond accumulation of Titanium after exposure of Mytilus galloprovincialis to spiked seawater

Mytilus galloprovincialis was exposed to seawater spiked with 5, 50 and 100 μg L^-1 of Titanium (Ti) for 14 days. Seawater was renewed after 96 h and new addition of Ti was done. A parallel experiment conducted in the absence of mussels showed that during the first 24 h after spiking, Ti concentrations in seawater rapidly decreased to values below 2 μg L^-1. For this reason, along the entire experimental period (14 days) mussels were exposed to Ti during two short periods, in the beginning of the experiment and after seawater renewal. At 96 h, mussels exhibited low Ti concentrations (<2.5 μg g^-1), close or not significantly different from a control condition (1.6 μg g^-1 in the absence of Ti). Despite the low accumulated Ti in mussels' tissues after both experimental periods (96 h and 14 days), biochemical markers indicated that mussels developed two main strategies: reduction of their metabolic capacity to avoid the uptake of Ti, and antioxidant and biotransformation defense mechanisms, such as the activation of SOD, CAT, GPx and GSTs enzymes that were triggered to prevent cellular damages. Nevertheless, oxidative stress occurred after 96 h or 14 days. The current study highlights that alterations of biological activity of M. galloprovincialis exposed to Ti goes beyond its accumulation in tissues.

Environmental conditions can modulate the links among oxidative stress, age, and longevity

Understanding the links between environmental conditions and longevity remains a major focus in biological research. We examined within-individual changes between early- and mid-adulthood in the circulating levels of four oxidative stress markers linked to ageing, using zebra finches (Taeniopygia guttata): a DNA damage product (8-hydroxy-2'-deoxyguanosine; 8-OHdG), protein carbonyls (PC), non-enzymatic antioxidant capacity (OXY), and superoxide dismutase activity (SOD). We further examined whether such within-individual changes differed among birds living under control (ad lib food) or more challenging environmental conditions (unpredictable food availability), having previously found that the latter increased corticosterone levels when food was absent but improved survival over a three year period. Our key findings were: (i) 8-OHdG and PC increased with age in both environments, with a higher increase in 8-OHdG in the challenging environment; (ii) SOD increased with age in the controls but not in the challenged birds, while the opposite was true for OXY; (iii) control birds with high levels of 8-OHdG died at a younger age, but this was not the case in challenged birds. Our data clearly show that while exposure to the potentially damaging effects of oxidative stress increases with age, environmental conditions can modulate the pace of this age-related change.

Oxidative responsiveness to multiple stressors in the key Antarctic species, Adamussium colbecki: Interactions between temperature, acidification and cadmium exposure

High-latitude marine ecosystems are ranked to be among the most sensitive regions to climate change since highly stenothermal and specially adapted organisms might be seriously affected by global warming and ocean acidification. The present investigation was aimed to provide new insights on the sensitivity to such environmental stressors in the key Antarctic species, Adamussium colbecki, focussing also on their synergistic effects with cadmium exposure, naturally abundant in this area for upwelling phenomena. Scallops were exposed for 2 weeks to various combinations of Cd (0 and 40 μgL-1), pH (8.05 and 7.60) and temperature (-1 and +1 °C). Beside Cd bioaccumulation, a wide panel of early warning biomarkers were analysed in digestive glands and gills including levels of metallothioneins, individual antioxidants and total oxyradical scavenging capacity, onset of oxidative cell damage like lipid peroxidation, lysosomal stability, DNA integrity and peroxisomal proliferation. Results indicated reciprocal interactions between multiple stressors and their elaboration by a quantitative hazard model based on the relevance and magnitude of effects, highlighted a different sensitivity of analysed tissues. Due to cellular adaptations to high basal Cd content, digestive gland appeared more tolerant toward other prooxidant stressors, but sensitive to variations of the metal. On the other hand, gills were more affected by various combinations of stressors occurring at higher temperature.

Differences in the oxidative balance of dispersing and non-dispersing individuals: an experimental approach in a passerine bird

BACKGROUND

Dispersal is often associated with a suite of phenotypic traits that might reduce dispersal costs, but can be energetically costly themselves outside dispersal. Hence, dispersing and philopatric individuals might differ throughout their life cycle in their management of energy production. Because higher energy expenditure can lead to the production of highly reactive oxidative molecules that are deleterious to the organism if left uncontrolled, dispersing and philopatric individuals might differ in their management of oxidative balance. Here, we experimentally increased flight costs during reproduction via a wing load manipulation in female collared flycatchers (Ficedula albicollis) breeding in a patchy population. We measured the effects of the manipulation on plasmatic markers of oxidative balance and reproductive success in dispersing and philopatric females.

RESULTS

The impact of the wing load manipulation on the oxidative balance differed according to dispersal status. The concentration of reactive oxygen metabolites (ROMs), a marker of pro-oxidant status, was higher in philopatric than dispersing females in the manipulated group only. Differences between dispersing and philopatric individuals also depended on habitat quality, as measured by local breeding density. In low quality habitats, ROMs as well as nestling body mass were higher in philopatric females compared to dispersing ones. Independently of the manipulation or of habitat quality, plasma antioxidant capacity differed according to dispersal status: philopatric females showed higher antioxidant capacity than dispersing ones. Nestlings raised by philopatric females also had a higher fledging success.

CONCLUSIONS

Our results suggest that dispersing individuals maintain a stable oxidative balance when facing challenging environmental conditions, at the cost of lower reproductive success. Conversely, philopatric individuals increase their effort, and thus oxidative costs, in challenging conditions thereby maintaining their reproductive success. Our study sheds light on energetics and oxidative balance as possible processes underlying phenotypic differences between dispersing and philopatric individuals.

Propensity to metal accumulation and oxidative stress responses of two benthic species (Cerastoderma edule and Nephtys hombergii): are tolerance processes limiting their responsiveness?

The chronic exposure of benthic organisms to metals in sediments can lead to the development of tolerance mechanisms, thus diminishing their responsiveness. This study aims to evaluate the accumulation profiles of V, Cr, Co, Ni, As, Cd, Pb and Hg and antioxidant system responses of two benthic organisms (Cerastoderma edule, Bivalvia; Nephtys hombergii, Polychaeta). This approach will provide clarifications about the ability of each species to signalise metal contamination. Organisms of both species were collected at the Tagus estuary, in two sites with distinct contamination degrees (ALC, slightly contaminated; BAR, highly contaminated). Accordingly, C. edule accumulated higher concentrations of As, Pb and Hg at BAR compared to ALC. However, antioxidant responses of C. edule were almost unaltered at BAR and no peroxidative damage occurred, suggesting adjustment mechanisms to the presence of metals. In contrast, N. hombergii showed a minor propensity to metal accumulation, only signalising spatial differences for As and Pb and accumulating lower concentrations of metals than C. edule. The differences in metal accumulation observed between species might be due to their distinctive foraging behaviour and/or the ability of N. hombergii to minimise the metal uptake. Despite that, the accumulation of As and Pb was on the basis of the polychaete antioxidant defences inhibition at BAR, including CAT, SOD, GR and GPx. The integrated biomarker response index (IBRv2) confirmed that N. hombergii was more affected by metal exposure than C. edule. In the light of current findings, in field-based studies, the information of C. edule as a bioindicator should be complemented by that provided by another benthic species, since tolerance mechanisms to metals can hinder a correct diagnosis of sediment contamination and of the system's health. Overall, the present study contributed to improve the lack of fundamental knowledge of two widespread and common estuarine species, providing insights of the metal accumulation profiles under a scenario of chronic contamination. Finally, this work provided useful information that can be applied in the interpretation of future environmental monitoring studies.

Gut morphology and hepatic oxidative status of European sea bass (Dicentrarchus labrax) juveniles fed plant feedstuffs or fishmeal-based diets supplemented with short-chain fructo-oligosaccharides and xylo-oligosaccharides

The effects of short-chain fructo-oligosaccharides (scFOS) and xylo-oligosaccharides (XOS) on gut morphology and hepatic oxidative status were studied in European sea bass juveniles weighing 60 g. Fish were fed diets including fishmeal (FM diets) or plant feedstuffs (PF diets; 30 FM:70 PF) as main protein sources (control diets). Four other diets were formulated similar to the control diets but including 1 % scFOS or 1 % XOS. At the end of the trial, fish fed PF-based diets presented histomorphological alterations in the distal intestine, whereas only transient alterations were observed in the pyloric caeca. Comparatively to fish fed FM-based diets, fish fed PF diets had higher liver lipid peroxidation (LPO), superoxide dismutase (SOD) and catalase (CAT) activities, and lower glutathione peroxidase, glutathione reductase and glucose 6-phosphate dehydrogenase activities. In fish fed the PF diets, prebiotic supplementation decreased SOD activity and XOS supplementation further decreased CAT activity. In fish fed the FM diets, XOS supplementation promoted a reduction of all antioxidant enzyme activities. Overall, dietary XOS and scFOS supplementation had only minor effects on gut morphology or LPO levels. However, dietary XOS reduced antioxidant enzymatic activity in both PF and FM diets, which indicate a positive effect on reduction of hepatic reactive oxygen species production.

Cocoa flavonoids protect hepatic cells against high-glucose-induced oxidative stress: relevance of MAPKs

SCOPE

Oxidative stress plays a main role in the pathogenesis of type 2 diabetes mellitus. Cocoa and (-)-epicatechin (EC), a main cocoa flavanol, have been suggested to exert beneficial effects in type 2 diabetes mellitus because of their protective effects against oxidative stress and insulin-like properties. In this study, the protective effect of EC and a cocoa phenolic extract (CPE) against oxidative stress induced by a high-glucose challenge, which causes insulin resistance, was investigated on hepatic HepG2 cells.

METHODS AND RESULTS

Oxidative status, phosphorylated mitogen-activated protein kinases (MAPKs), nuclear factor E2 related factor 2 (Nrf2) and p-(Ser)-IRS-1 expression, and glucose uptake were evaluated. EC and CPE regulated antioxidant enzymes and activated extracellular-regulated kinase and Nrf2. EC and CPE pre-treatment prevented high-glucose-induced antioxidant defences and p-MAPKs, and maintained Nrf2 stimulation. The presence of selective MAPK inhibitors induced changes in redox status, glucose uptake, p-(Ser)- and total IRS-1 levels that were observed in CPE-mediated protection.

CONCLUSION

EC and CPE recovered redox status of insulin-resistant HepG2 cells, suggesting that the functionality in EC- and CPE-treated cells was protected against high-glucose-induced oxidative insult. CPE beneficial effects on redox balance and insulin resistance were mediated by targeting MAPKs.

Selective dendritic susceptibility to bioenergetic, excitotoxic and redox perturbations in cortical neurons

Neurodegenerative and neurological disorders are often characterised by pathological changes to dendrites, in advance of neuronal death. Oxidative stress, energy deficits and excitotoxicity are implicated in many such disorders, suggesting a potential vulnerability of dendrites to these situations. Here we have studied dendritic vs. somatic responses of primary cortical neurons to these types of challenges in real-time.

Using a genetically encoded indicator of intracellular redox potential (Grx1-roGFP2) we found that, compared to the soma, dendritic regions exhibited more dramatic fluctuations in redox potential in response to sub-lethal ROS exposure, and existed in a basally more oxidised state. We also studied the responses of dendritic and somatic regions to excitotoxic NMDA receptor activity. Both dendritic and somatic regions experienced similar increases in cytoplasmic Ca²⁺. Interestingly, while mitochondrial Ca²⁺ uptake and initial mitochondrial depolarisation were similar in both regions, secondary delayed mitochondrial depolarisation was far weaker in dendrites, potentially as a result of less NADH depletion. Despite this, ATP levels were found to fall faster in dendritic regions. Finally we studied the responses of dendritic and somatic regions to energetically demanding action potential burst activity. Burst activity triggered PDH dephosphorylation, increases in oxygen consumption and cellular NADH:NAD ratio. Compared to somatic regions, dendritic regions exhibited a smaller degree of mitochondrial Ca²⁺ uptake, lower fold-induction of NADH and larger reduction in ATP levels. Collectively, these data reveal that dendritic regions of primary neurons are vulnerable to greater energetic and redox fluctuations than the cell body, which may contribute to disease-associated dendritic damage. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.

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Dendrites exhibit a greater shift in redox potential than the soma, following an oxidative insult.

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Dendritic mitochondria depolarise less than somatic ones during excitotoxicity.

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Nevertheless ATP falls faster in dendritic regions during excitotoxicity.

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Energetically demanding AP bursting induces adaptive metabolic responses.

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These responses are weaker in dendrites, and ATP levels are suppressed more strongly.

Developmental post-natal stress can alter the effects of pre-natal stress on the adult redox balance

Across diverse vertebrate taxa, stressful environmental conditions during development can shape phenotypic trajectories of developing individuals, which, while adaptive in the short-term, may impair health and survival in adulthood. Regardless, the long-lasting benefits or costs of early life stress are likely to depend on the conditions experienced across differing stages of development. Here, we used the Japanese quail (Coturnix coturnix japonica) to experimentally manipulate exposure to stress hormones in developing individuals. We tested the hypothesis that interactions occurring between pre- and post-natal developmental periods can induce long-term shifts on the adult oxidant phenotype in non-breeding sexually mature individuals. We showed that early life stress can induce long-term alterations in the basal antioxidant defences. The magnitude of these effects depended upon the timing of glucocorticoid exposure and upon interactions between the pre- and post-natal stressful stimuli. We also found differences among tissues with stronger effects in the erythrocytes than in the brain in which the long-term effects of glucocorticoids on antioxidant biomarkers appeared to be region-specific. Recent experimental work has demonstrated that early life exposure to stress hormones can markedly reduce adult survival (Monaghan et al., 2012). Our results suggest that long-term shifts in basal antioxidant defences might be one of the potential mechanisms driving such accelerated ageing processes and that post-natal interventions during development may be a potential tool to shape the effects induced by pre-natally glucococorticoid-exposed phenotypes.