Isoproturon phytotoxicity to wheat (Triticum aestivum L.) is a worry for many farmers in chemical control of weeds in wheat fields, especially in subzero weather conditions. Iron chlorin e6 (ICe6), a new plant growth regulator, has been reported to enhance crop stress resistance to alleviate damage caused by stress; however, it is not clear whether ICe6 has an alleviative effect on isoproturon phytotoxicity to wheat. We determined the alleviative effect of ICe6 on isoproturon phytotoxicity to wheat, and 0.018 g ai ha−1 was the optimal dose. Meanwhile, we also studied the photosynthetic pigment content, photosynthetic parameters, oxidative stress indicators, and antioxidant enzyme activity of wheat treated with the three different treatments. We found that the photosynthetic pigment content, antioxidant enzyme activity, and photosynthesis of wheat damaged by isoproturon were significantly lower than those of the control, and the hydrogen peroxide (H2O2) and malondialdehyde (MDA) content increased. These results indicate that isoproturon stress significantly weakened the photosynthetic and antioxidant capacity of wheat. The photosynthetic pigment content, photosynthetic parameters (excluding intercellular CO2 concentration), and antioxidant enzyme activity of isoproturon+ICe6– treated wheat were significantly higher than those of isoproturon-treated wheat. The H2O2 and MDA content was significantly lower than that of isoproturon-treated wheat. These results indicate that ICe6 treatment maintained the photosynthetic pigment content of wheat and relatively improved photosynthetic capacity, allowing photosynthesis to proceed normally. ICe6 treatment also limits the decrease in antioxidant enzyme activity, effectively clearing excess reactive oxygen species and ultimately alleviating membrane lipid peroxidation damage. In summary, ICe6 not only enhances stress resistance and increases yield in crops such as soybean [Glycine max (L.) Merr.] and canola (Brassica napus L.), but also has an alleviating effect on the isoproturon phytotoxicity to wheat, which is manifested by the improvement of photosynthetic and antioxidant abilities, ultimately leading to an increase in wheat shoot height and shoot fresh weight.

Lack of water at limiting levels results in drought stress, which may have an impact on the various stages of a crop's life cycle. Four different genotypes of snapmelon (Cucumis melo L. var. momordica) responded differently to 0, 7 and 21 d of simulated drought stress. Information was collected on a range of morpho-physiological, biochemical and molecular characteristics. Each genotype had longer roots, though BAM-VR-312 had the longest roots overall. As the severity of the drought grew, the net photosynthetic rate (Pn) and stomatal conductance (Gs) dropped. In BAM-VR-312, a smaller decline in relative water content (RWC) was recorded, despite the fact that drought stress caused a significant fall in RWC. BAM-VR-312 had smaller accumulations of electrolyte leakage, hydrogen peroxide, phenol and malondialdehyde, although proline content was greater. A decrease in photosynthetic pigments was noted, though BAM-VR-312 had the least reduction. Antioxidant enzyme activity increased in BAM-VR-312, as evidenced by records of ascorbate peroxidase, catalase, guaiacol peroxidase, glutathione reductase and superoxide dismutase. Similarly, expression level of their respective genes was recorded highest in BAM-VR-312. Overall, the study clearly identified distinct genotype based on morpho-physiological, biochemical and molecular properties under drought stress and revealed that the genotype BAM-VR-312 had more efficient drought tolerance mechanisms than the other genotypes under the drought stress condition.

Drought is a substantial threat to cereal production under global climatic change scenarios, albeit its aftermath on arthropod pests is yet contentious. To address this issue, demographic characteristics of Metopolophium dirhodum (Walker, 1849) (Hemiptera: Aphididae) were studied on one drought-susceptible wheat cultivar and one drought-tolerant wheat cultivar under different water treatments. Some physiological and biochemical features of wheat cultivars including leaf soluble sugar and proline contents and antioxidant enzymes activities were also investigated. Significant differences occurred in the developmental period, survival, and fecundity of M. dirhodum between wheat cultivars under various water treatments. The impact of intermediate and severe water stress on M. dirhodum was neutral and negative for the tolerant cultivar and negative for the water-susceptible cultivar, respectively. Under severe water stress, on both wheat cultivars, the aphids had low net reproductive rates and finite and intrinsic rates of increase in comparison with those reared on unstressed plants. In total, drought resulted in lower growth of population and reduced survival of aphids. Hence, in the context of projected climatic changes, acute water deficiency could probably result in reducing the abundance and menace of outburst of M. dirhodum. However, it should be noted that the potential likelihood of M. dirhodum eruptions can be drastically affected by the degree of drought intensity and host plant cultivar.

Maternal age is a significant factor influencing in vitro fertilization (IVF) outcomes. Oxidative stress (OS) is one of the major causes of age-related cellular and molecular damage. The purpose of this work was to investigate the correlation between maternal age with intrafollicular antioxidants and OS markers in follicular fluid (FF), and also to determine the OS status in patients of advanced age. This study was a prospective study including 201 women undergoing IVF whose age was between 24 and 45 years old. FF samples were obtained from mature follicles at the time of oocyte retrieval. After treatment of FF, lipid peroxidation levels (MDA) and enzyme activities such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione (GSH) level were evaluated using spectrophotometry. The results indicated that the age cutoff point for increasing the MDA level was fixed at 37 years, allowing the study to be differentiated into two age groups. Group I included patients whose age was less than 37 years, and group II included patients whose age was greater than or equal 37 years. Statistical analysis revealed that MDA and GSH levels and GR activity were significantly higher in group II compared with group I. The SOD and CAT activities were significantly less in group II compared with group I. We concluded that from 37 years old a reproductive ageing was accompanied by a change in the antioxidant pattern in FF that impaired reactive oxygen species scavenging efficiency.

Sustaining adequate nutritional needs of a population is a challenging task in normal times and a priority in times of crisis. There is no ‘one-size-fits-all’ solution that addresses nutrition. In relevance to the COVID-19 (coronavirus disease 2019) pandemic crisis, viral infections in general and RNA viruses in particular are known to induce and promote oxidative stress, consequently increasing the body’s demand for micronutrients, especially those related to antioxidant enzymic systems, thus draining the body of micronutrients, and so hindering the human body’s ability to cope optimally with oxidative stress. Common polymorphisms in major antioxidant enzymes, with world population minor allele frequencies ranging from 0·5 to 50 %, are related to altered enzymic function, with substantial potential effects on the body’s ability to cope with viral infection-induced oxidative stress. In this review we highlight common SNP of the major antioxidant enzymes relevant to nutritional components in the context of viral infections, namely: superoxide dismutases, glutathione peroxidases and catalase. We delineate functional polymorphisms in several human antioxidant enzymes that require, especially during a viral crisis, adequate and potentially additional nutritional support to cope with the pathological consequences of disease. Thus, in face of the COVID-19 pandemic, nutrition should be tightly monitored and possibly supplemented, with special attention to those carrying common polymorphisms in antioxidant enzymes.

Gall formation is associated with multiple changes in plant cells, which still requires a better understanding. In this study, galls caused by sexual generation (♀♂) of Neuroterus quercusbaccarum (L.) (Hymenoptera: Cynipidae) on pedunculate oak trees (Quercus robur L.) were used as a model. Cytoplasmic membrane condition, concentration of hydrogen peroxide (H2O2), the activity of antioxidant enzymes and amino acid decarboxylase as well as chlorophyll fluorescence parameters were determined. Changes in physiological and biochemical parameters were analyzed in foliar tissues with galls and gall tissues themselves and compared to control. The presence of galls on oak leaves caused an increase of lipid peroxidation level. A significant decline in H2O2 and TBARS content with the reduction of guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) activity were observed in gall tissues. The activity amino acid decarboxylase, i.e., LDC, ODC and TyDC varied between samples, which may affect the content of amino acids. The presence of N. quercusbaccarum galls caused an insignificant increase of the chlorophylls, carotenoids and anthocyanin contents, while the content of pigments and their ratios in gall tissues was extremely low. Moreover, photosynthetic parameters (F0, Fm, Fv/Fm, Y, qP) were significantly decreased. Data generated in this study indicate that the development of N. quercusbaccarum galls on pedunculate oak leaves has a negative effect on host plant related to the disruption of cell membrane integrity, disturbance of photosynthesis and reduction of the antioxidant potential of the host plant.

The present study aimed to assess the antioxidant and oxidant status of goats naturally infected with Haemonchus contortus. Based upon the parasite burden, infection in goats was categorized as heavy (> 500 worms), mild (100–500 worms) or low (< 100 worms). Abomasal tissues from non-infected and infected goats were used for the determination of catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), aspartate (AST) and alanine (ALT) aminotransferases, acid (ACP) and alkaline (ALP) phosphatases, superoxide content (O2−), protein carbonyl (PC), malondialdehyde (MDA) and reduced glutathione (GSH). A significantly higher level of CAT, GST and GR activity and a lower level of GPx activity were recorded in infected compared to non-infected tissue. A significant increase in the level of AST, ALT, ALP and ACP was found in the abomasal tissue of the infected animals, which was related to the worm burden. The oxidative stress markers were also altered, with a significant decline in GSH levels, whereas MDA, PC and O2− concentrations showed a marked increase. In conclusion, it has been demonstrated that haemonchosis in goats resulted in considerable oxidative stress, which was directly related to the worm burden.

In this study, polyploidy level was determined by flow cytometry analysis. The effect of polyploidy by colchicine treatment was examined on the growth parameters, malondealdehyde (MDA), as well as activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in response to different levels of salinity in Dunaliella salina. The results of algal growth indicated that 3 M NaCl was the optimal concentration of salt, since the highest enhancement in fresh and dry weight, chlorophyll and carotenoids, soluble sugar, glycerol, protein and starch content was observed in comparison to other concentrations. The amount of these metabolites declined in the concentrations under optimum salinity. The least and highest amounts of MDA were observed at 1 and 4 M NaCl respectively. Polyploidy in optimum concentration of salt, caused further increment of the above growth parameters. In relation to this, in most cases, treatment of 0.1% colchicine was most effective. The beneficial effects of polyploidy in non-optimal conditions were also found in some parameters such as biomass, chlorophyll, carotenoids, proteins and starch. Furthermore, the activity of antioxidant enzymes CAT, SOD and POD showed a positive significant correlation with salt stress and these were maximized at 4 M NaCl. Polyploidy (especially colchicine 0.1%) affected activity of these antioxidant enzymes in some concentrations of salt. Overall, our results suggest that the microalgae has significantly different responses to salt stress based on ploidy levels.

Chilling injury is an important natural stress that can threaten cotton production, especially at the sowing and seedling stages in early spring. It is therefore important for cotton production to improve chilling tolerance at these stages. The current work examines the potential for glycine betaine (GB) treatment of seeds to increase the chilling tolerance of cotton at the seedling stage. Germination under cold stress was increased significantly by GB treatment. Under low temperature, the leaves of seedlings from treated seeds exhibited a higher net photosynthetic rate (PN), higher antioxidant enzyme activity including superoxide dismutase, ascorbate peroxidase and catalase, lower hydrogen peroxide (H2O2) content and less damage to the cell membrane. Enzyme activity was correlated negatively with H2O2 content and degree of damage to the cell membrane but correlated positively with GB content. The experimental results suggested that although GB was only used to treat cotton seed, the beneficial effect caused by the preliminary treatment of GB could play a significant role during germination that persisted to at least the four-leaf seedling stage. Therefore, it is crucial that this method is employed in agricultural production to improve chilling resistance in the seedling stage by soaking the seeds in GB.

This study was undertaken to evaluate whether cigarette smoke is associated with changes in the expression of antioxidant enzymes in granulosa cells of women undergoing IVF treatments. For this aim, the expression of three antioxidant enzymes (SOD1, SOD2 and catalase) in non-smokers (n = 20) and smokers (n = 20) was analyzed. There was a statistically significant overexpression of SOD2 and catalase mRNA levels in smokers in comparison with non-smokers. Cigarette smoking was associated with a lower fertilization rate, implantation rate and pregnancy rate in comparison with non-smokers. There was no effect on retrieved oocytes number, metaphase II oocytes number, quality of embryos transferred and live birth rate. These findings suggest that cigarette smoke initiates oxidative stress in granulosa cells.

Oxidative stress plays a major role in the pathogenesis of diabetes mellitus, which further exacerbates damage of cardiac, hepatic and other tissues. We have recently reported that Zn supplementation beneficially modulates hyperglycaemia and hypoinsulinaemia, with attendant reduction of associated metabolic abnormalities in diabetic rats. The present study assessed the potential of Zn supplementation in modulating oxidative stress and cardioprotective effects in diabetic rats. Diabetes was induced in Wistar rats with streptozotocin, and groups of diabetic rats were treated with 5- and 10-fold dietary Zn interventions (0·19 and 0·38 g Zn/kg diet) for 6 weeks. The markers of oxidative stress, antioxidant enzyme activities and concentrations of antioxidant molecules, lipid profile, and expressions of fibrosis and pro-apoptotic factors in the cardiac tissue were particularly assessed. Supplemental Zn showed significant attenuation of diabetes-induced oxidative stress in terms of altered antioxidant enzyme activities and increased the concentrations of antioxidant molecules. Hypercholesterolaemia and hyperlipidaemia were also significantly countered by Zn supplementation. Along with attenuated oxidative stress, Zn supplementation also showed significant cardioprotective effects by altering the mRNA expressions of fibrosis and pro-apoptotic factors (by >50 %). The expression of lipid oxidative marker 4-hydroxy-2-nonenal (4-HNE) protein in cardiac tissue of diabetic animals was rectified (68 %) by Zn supplementation. Elevated cardiac and hepatic markers in circulation and pathological abnormalities in cardiac and hepatic tissue architecture of diabetic animals were ameliorated by dietary Zn intervention. The present study indicates that Zn supplementation can attenuate diabetes-induced oxidative stress in circulation as well as in cardiac and hepatic tissues.

ρ-Cymene was one of the major components of volatiles released by croftonweed. The allelopthy of ρ-cymene on the growth of upland rice seedlings was performed. Hydrogen peroxide generation, malondialdehyde (MDA) content, proline content, total ascorbate (ascorbate/dehydroascorbate), reduced/oxidized glutathione, and the levels of induction of antioxidant enzyme were studied in the seedlings of upland rice. ρ-Cymene inhibited the growth of upland rice seedlings. Exposure of upland rice seedlings to ρ-cymene increased levels of H2O2, MDA, and proline, indicating lipid peroxidation and induction of oxidative stress. Activities of the antioxidant enzymes superoxide dismutase, catalase, peroxidase, guaiacol peroxidase, ascorbate peroxidase, and glutathione reductase were significantly elevated during the treatment period (7–15 d) compared with enzymes in the upland rice seedlings unexposed to ρ-cymene, thereby indicating the enhanced generation of reactive oxygen species (ROS) upon ρ-cymene exposure. These results suggest that activation of the antioxidant system by ρ-cymene led to the formation of ROS that resulted in cellular damage and decreased growth of upland rice seedlings.

The oriental army worm Mythimna separata (Lepidoptera: Noctuidae) is a migratory pest in Eastern Asia and China. Seasonal high temperatures in Southern China and low temperatures in Northern China are pressures favouring the annual migration of this species, while cold tolerance determines the northern limit of its overwintering range. A number of physiological stress responses occur in insects as a result of variations in temperature. One reaction to thermal stress is the generation of reactive oxygen species (ROS), which can be harmful by causing oxidative damage. The time-related effects (durations of 1, 4 and 7 h) of thermal stress treatments of M. separata at comparatively low (5, 10, 15 and 20°C) and high (30, 35, 40 and 45°C) temperatures on the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POX) and glutathione S-transferases (GSTs), and total antioxidant capacity (T-AOC) were determined. Thermal stress resulted in significant elevation of the activities of SOD, CAT and GSTs, indicating that these enzymes contribute to defence mechanisms counteracting oxidative damage caused by an increase in ROS. However, at high-temperatures, POX and T-AOC were also found to contribute to scavenging ROS. Our results also indicate that extreme temperatures lead to elevated ROS production in M. separata. The present study confirms that thermal stress can be responsible for oxidative damage. To overcome such stress, antioxidant enzymes play key roles in diminishing oxidative damage in M. separata.

Data are scarce regarding combined high Se and Mn supplementation in livestock diets, however, as Se and Mn are functionally related as cofactors of glutathione peroxidase (GPx) and Mn-superoxide dismutase (SOD), respectively, beneficial synergistic effects on oxidative stability of tissues may result. This experiment evaluated the effect of an oversupply of Se and Mn within European legal limits compared with recommendations on performance, oxidative stability of the organism and meat quality in a randomised complete block design. A total of 60 crossbred gilts were fed maize–barley–soya bean meal diets formulated in a 2×2 factorial approach with inorganic Se (0.2 v. 0.5 mg/kg Se dry matter (DM)) or inorganic Mn (20 v. 150 mg/kg Mn DM) from 31 to 116 kg BW. Se supplementation reduced feed intake, whereas high Mn diets impaired average daily gain (P<0.05). Qualitative carcass characteristics were impaired by Se and Mn predominantly in the semimembranosus muscle. Activity of GPx in liver was increased by high Se diets (P<0.05). Mn supplementation increased catalase (CAT) activity in liver, GPx in plasma and total antioxidative capacity (TAC) in muscle, whereas it decreased CAT activity in plasma (P<0.05). Cu/Zn-SOD in muscle showed higher activity in high-Se-low-Mn diets but lower activity when both high Se and Mn were combined (Se×Mn P<0.05). Mn supplementation increased Mn concentration in longissimus thoracis et lumborum, but simultaneously reduced Se concentration (P<0.05). Upon retail display, Mn increased lipid oxidation more pronouncedly (higher thiobarbituric acid reactive substances; P<0.05) than Se (P<0.10). Despite some positive effects (Mn increased TAC, Se increased GPx, Se and Mn increased tenderness), no synergistic effects of high Se and Mn diets or an overall beneficial impact on meat quality, especially during storage, could be observed. Including the negative effects on performance, feeding Se and Mn up to the maximum legal level cannot be recommended.

This study aimed to evaluate the effects of dietary lipid source and carbohydrate content on the oxidative status of European sea bass (Dicentrarchus labrax) juveniles. For that purpose, four diets were formulated with fish oil (FO) and vegetable oils (VO) as the lipid source and with 20 or 0 % gelatinised starch as the carbohydrate source, in a 2×2 factorial design. Liver and intestine antioxidant enzyme activities (catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD)), hepatic and intestinal lipid peroxidation (LPO), as well as hepatic oxidative stress index (OSI), were measured in fish fed the experimental diets for 73 d (n 9 fish/diet). Carbohydrate-rich diets promoted a decrease in hepatic LPO and OSI, whereas the lipid source induced no changes. Inversely, dietary lipid source, but not dietary carbohydrate concentration, affected LPO in the intestine. Lower intestinal LPO was observed in VO groups. Enzymes responsive to dietary treatments were GR, G6PD and CAT in the liver and GR and GPX in the intestine. Dietary carbohydrate induced GR and G6PD activities and depressed CAT activity in the liver. GPX and GR activities were increased in the intestine of fish fed VO diets. Overall, effects of diet composition on oxidative status were tissue-related: the liver and intestine were strongly responsive to dietary carbohydrates and lipid sources, respectively. Furthermore, different metabolic routes were more active to deal with the oxidative stress in the two organs studied.

The cardio-ankle vascular index is a measure of arterial stiffness, whereas oxidative stress underlies arterial pathology. This study aimed to investigate the association between the cardio-ankle vascular index and antioxidant-related gene polymorphisms in young Russians. A total of 89 patients (mean age, 21.6 years) were examined by the cardio-ankle vascular index and for 15 gene polymorphisms related to antioxidant enzymes including FMO3 (flavin-containing monooxygenase 3), GPX1 (glutathione peroxidase 1), and GPX4 (glutathione peroxidase 4). A higher cardio-ankle vascular index level was detected in carriers with the KK-genotype of FMO3 polymorphism rs2266782 than in those without (mean levels: 6.2 versus 5.6, respectively, p<0.05). Similarly, a higher cardio-ankle vascular index level was seen in carriers with the CC-genotype of GPX4 polymorphism rs713041 than in those without (6.0 versus 5.5, respectively, p<0.05). We did not observe significant associations between the cardio-ankle vascular index levels and the other gene polymorphisms. Although carriers with the LL-genotype of GPX1 polymorphism rs1050450 showed a higher diastolic blood pressure level than those without, the polymorphism did not affect the cardio-ankle vascular index level. This study showed a significant association between rs2266782 and rs713041 polymorphisms and arterial stiffness, as measured by the cardio-ankle vascular index, in young Russians. The pathways utilised by antioxidant enzymes may be responsible for early arterial stiffening in the Russian population.

The aim of the current study was to asses the effect of goat or cow milk-based diets, either normal or Fe-overloaded and folic acid supplement on some aspects of hepatic physiology, enzymatic antioxidant defence and lipid peroxidation in liver, brain and erythrocyte of control and anaemic rats after chronic Fe repletion. 160 male Wistar rats were placed on 40 d in two groups, a control group receiving normal-Fe diet and the Fe-deficient group receiving low Fe diet. Lately, the rats were fed with goat and cow milk-based diets during 30 d, with normal-Fe content or Fe-overload and either with normal folic or folic acid supplemented. Fe-overload increased plasma alanine transaminase and aspartate transaminase levels when cow milk was supplied. Dietary folate supplementation reduced plasma transaminases levels in animals fed goat milk with chronic Fe overload. A remarkable increase in the superoxide dismutase activity was observed in the animals fed cow milk. Dietary folate supplement lead to a decrease on the activity of this enzyme in all the tissues studied with both milk-based diets. A concomitant increment in catalase was also observed. The increase in lipid peroxidation products levels in rats fed cow milk with Fe-overload, suggest an imbalance in the functioning of the enzymatic antioxidant defence. In conclusion, dietary folate-supplemented goat milk reduces both plasma transaminases levels, suggesting a hepatoprotective effect and has beneficial effects in situation of Fe-overload, improving the antioxidant enzymes activities and reducing lipid peroxidation.

In the present study, the protective effects of dietary Spirulina (SP) and germanium-containing Spirulina (GeSP) were compared in rats with liver injury induced by an intraperitoneal injection of d-galactosamine and lipopolysaccharide (GalN/LPS). Wistar rats were fed one of the following diets: the basal diet (GalN/LPS-CON group; n 6), the basal diet supplemented with 5 % SP or GeSP (GalN/LPS-SP and GalN/LPS-GeSP group, respectively; n 7 each). After administering these diets for 7 d, each rat was intraperitoneally injected with GalN/LPS. Increases in plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were suppressed in the GalN/LPS-GeSP group (GalN/LPS-CON v. GalN/LPS-GeSP: ALT 1052 (sem 187) v. 509 (sem 88) IU/l and AST 2183 (sem 368) v. 1170 (sem 196) IU/l) following the injection of GalN/LPS. Plasma levels of interferon-γ (IFN-γ) and TNF-α in GeSP-fed rats were significantly lower when compared with those in the GalN/LPS-CON group (GalN/LPS-CON v. GalN/LPS-GeSP: IFN-γ 142·8 (sem 17·5) v. 66·8 (sem 9·7) pg/ml and TNF-α 72·3 (sem 15·4) v. 31·2 (sem 6·8) pg/ml). However, the decrease in these levels observed in the GalN/LPS-SP group was not as prominent as those observed in the GalN/LPS-GeSP group. Furthermore, the increase in liver catalase (CAT) and glutathione peroxidase (GPx) activities, as well as the level of oxidised glutathione (GSSG), was more suppressed in GeSP-fed rats (GalN/LPS-CON v. GalN/LPS-GeSP: CAT 457 (sem 47) v. 262 (sem 54) U/mg liver protein; GPx 1·30 (sem 0·11) v. 0·53 (sem 0·09) U/mg liver protein; GSSG 2·18 (sem 0·33) v. 1·31 (sem 0·24) mmol/kg liver) after the injection of GalN/LPS. These changes were more pronounced in the GalN/LPS-GeSP group than in the GalN/LPS-SP group. These results suggest that GeSP could afford a significant protective effect in the alleviation of GalN/LPS-induced hepatic damage. In addition, the results indicate that GeSP is more effective than SP.

The aim of the study was to determine changes of serum cortisol and biochemical, haematological and antioxidant enzyme variables in the blood of horses sampled during the pre-slaughter period (in the lairage and in the stunning box) and during exsanguination. A total of 24 Slovenian warm-blooded horses were observed. Blood samples for determination of serum cortisol and biochemical, haematological (red blood cell count, haematocrit, haemaglobin concentration) and antioxidant enzyme (whole blood superoxide dismutase and glutathione peroxidase) variables were collected by venipuncture of the left jugular vein in the lairage pen, 60 min before stunning (lairage) and immediately before stunning (stunning box). At exsanguination, blood samples were collected from the wound at the time of jugular vein sticking. During blood collection in the lairage pen and in the stunning box, horses were gently restrained with a halter. They were stunned using a penetrating captive bolt pistol impelled by air and were bled by jugular vein sticking. Horses were physically active in the lairage pen and in the race before entering the stunning box. After stunning, the horses showed paddling movements with their legs. In horses, the plasma lactate and glucose concentrations, the serum potassium concentration, the activities of the serum muscle enzymes aspartate aminotransferase and creatine kinase, and values of most of the other biochemical (Table 1) and haematological variables (Table 2), were significantly (P < 0.05) higher at exsanguination, than in blood sampled while they were in the lairage and in the stunning box. The serum concentrations of cortisol and chloride and the activities of alanine aminotransferase and antioxidant enzymes were not significantly different between the pre-slaughter period and exsanguination. All selected blood variables were not significantly different between the lairge and the stunning box sampling time, indicating no physiological stress responses of the investigated horses to stressors, such as novelty of the pre-slaughter environment and handling, present in the slaughterhouse between the lairage and the stunning box. However, the significantly higher values, at exsanguination, for the plasma lactate and glucose concentrations, serum muscle enzyme activities and haematological variables, than during the pre-slaughter period, might partially be attributed to stimulation of the sympathetic nervous system, caused by stunning and bleeding.