Determination of glutathione peroxidase and superoxide dismutase-like activities in equine spermatozoa, seminal plasma, and reproductive tissues

OBJECTIVE: To determine glutathione peroxidase (GPX) and superoxide dismutase (SOD)-like activities in spermatozoa, seminal plasma, and reproductive tissues (ie, testis, epididymis, bulbourethral gland, prostate, vesicular gland, and ampulla) in horses. SAMPLE POPULATION: Seminal plasma from 17 stallions, spermatozoa from 5 stallions, and reproductive tissues from 3 stallions. PROCEDURE: Activity of GPX was determined by use of assays measuring oxidation of NADPH in the presence of exogenous glutathione, cumene hydroperoxide, and glutathione reductase. Activity of SOD-like enzymes was determined by use of the nitroblue tetrazolium assay. RESULTS: Mean GPX and SOD-like activities in seminal plasma were 1.3 +/- 0.1 nmol of NADPH oxidized/min/mg of protein and 29.2 +/- 6.6 U/mg of protein, respectively. Mean GPX activities in spermatozoa separated from seminal plasma by centrifugation and via Percoll gradient were 2.2 +/- 0.3 nmol and 6.1 +/- 1.3 nmol of NADPH oxidized/min/mg of protein, respectively. Mean SOD-like activity of spermatozoa separated by centrifugation was 58.6 +/- 22.3 U/mg of protein; SOD-like activity was not detected in Percoll-separated spermatozoa. Among reproductive tissues, the ampulla and prostate had the highest SOD-like activity, although this was not significantly different from activity in other tissues. Testes and spermatozoa from the cauda epididymis contained significantly more GPX activity than other tissues. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that although equine seminal plasma contains high SOD-like enzyme activity, spermatozoa have limited GPX and SOD-like activity. Enzymatic antioxidant activity in equine spermatozoa appears to be predominantly derived from seminal plasma adsorbed onto the plasma membrane. Removal of seminal plasma during semen processing may increase oxidative stress in equine-spermatozoa.     

Characteristics of Antioxidant Systems of Yellow Fraction of Red Deer's (Cervus elaphus L.) Semen During the Rutting Period

The objective of this study was to make the preliminary characterization of the antioxidant defence systems of the yellow fraction (YF) of red deer's (Cervus elaphus L.) semen during the rutting period. The semen was collected using artificial vagina (AV). The studies included spectrophotometric determination of antioxidant enzymes activities such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). We also analysed the contents of low‐molecular antioxidants such as L‐glutathione (GSH + GSSG), L‐ascorbate (ASC) and total antioxidant status (TAS). Additionally, the samples were subjected to PAGE and stained for SOD and GPx activities. It was demonstrated that the yellow fraction exhibited activities of SOD and GPx, with the highest activities in September and October. CAT activity was not detected. Staining for the SOD and GPx activities confirmed three protein bands with SOD activity and one protein band with GPx activity. The content of GSH + GSSG was similar in trials dating from October to December contrary to the content of ASC which was high in samples from September and October. The stable rate of TAS was observed during the whole rutting period. The results of this study showed that the YF of red deer semen is equipped with basic battery of antioxidant enzymes comprising SOD and GPx, with the supporting role of GSH + GSSG and ASC. Moreover, the samples obtained at the peak of the rutting period occurring from September to October had the highest enzymatic activity in comparison with remaining months of the rutting period, which contributed to the high quality of the semen by preventing it from the formation of oxidative stress during the short period of intense sexual activity of male red deer. The better understanding of the mechanisms of antioxidant defence systems in the YF of deer's semen may contribute to the potential use of this fraction in technology of wild ruminant semen preservation.     

Effects of dietary leucine on antioxidant activity and expression of antioxidant and mitochondrial‐related genes in longissimus dorsi muscle and liver of piglets

The study was conducted to investigate the effects of dietary leucine on antioxidant activity and expression of antioxidant‐ and mitochondrial‐related genes in longissimus dorsi muscle and liver of piglets. Three diets were formulated with different levels of supplemented leucine (0%, 0.25%, 0.5%). Results showed that supplementation of 0.25% leucine significantly increased antisuperoxide anion (ASA) and antihydroxyl radical (AHR) levels and activities of total superoxide dismutade (T‐SOD), glutathione peroxidase (GPx), glutathione S‐transferase (GST), and total antioxidant capacity (T‐AOC) in serum, longissimus dorsi muscle and liver of piglets as compared with the control group. The SOD2, catalase (CAT), GPx, GST, glutathione reductase (GR), and nuclear factor erythroid 2‐related factor 2 (Nrf2) mRNA levels in longissimus dorsi muscle and liver were significantly increased by 0.25% leucine supplementation. However, the malondialdehyde (MDA) content and the mRNA level of Kelch‐like ECH‐associated protein 1 (Keap1) exhibited an opposite tendency. Additionally, supplementation of 0.25% leucine significantly increased the mRNA levels of mitochondrial‐related genes in longissimus dorsi muscle and liver of piglets. Results suggested that supplementation of 0.25% leucine improved antioxidant activity and mitochondrial biogenesis and function of piglets, which was related to the increase in antioxidant enzymes activities and upregulation of expression of antioxidant‐ and mitochondrial‐related genes.     

奶牛性控精液与常规精液抗氧化物酶活性比较分析

通过比较常规精液和性控精液在活力、顶体完整率及精浆中四种抗氧化酶类活力的差异,对性控精液的品质进行综合评定。对用流式细胞仪分离后的性控精液和常规精液细管解冻(37.5℃,30s),分别分析精子活力和精子顶体完整率,并测定精浆中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH)、谷胱甘肽还原酶(GR)和过氧化氢酶(CAT)的活性。结果表明性控精液精子在活力显著低于常规精液,且精浆中四种抗氧化酶类的活力也都显著低于常规精液。     

Seasonal variation in testicular blood flow dynamics and their relation to systemic and testicular oxidant/antioxidant biomarkers and androgens in rams

The environmental temperature increased during summer and decreased during winter to the limits that might negatively affect animal and human reproduction. The responses of Egyptian rams to either hot or cold climatic conditions were studied in six mature rams subjected to weekly testicular Doppler ultrasonographic examination, blood sampling, seminal plasma collection and semen evaluation. The maximum environmental temperature and the relative humidity were used to classify the climatic condition according to the heat stress equation of sheep into hot months where temperature–humidity index (THI) was >26 (31.67 ± 0.54), and cold months where THI was <22 (18.39 ± 0.41). Testosterone, estradiol, superoxide dismutase (SOD), glutathione peroxidase (GPX) and lipid peroxide product (malondialdehyde, MDA) were measured in both blood and seminal plasma, while catalase (CAT) and reduced glutathione (GSH) were measured in blood and seminal plasma, respectively. Results revealed that, during the hot months, rams displayed significantly decreased testicular blood flow, increased seminal plasma MDA, decreased seminal plasma (SOD, GPx and GSH) and blood CAT antioxidant enzymes. The present study evidenced two novel findings: (a) the marked decrease in testicular blood flow volume, that is remarkable increase in both resistive index (RI) and pulsatility index (PI) values, during hot months could be negatively affected both seminal plasma enzymatic activities and seminal attributes, and (b) the SOD and GPx activities in seminal plasma of such animals were suitable predictive markers for seminal attribute evaluation.     

Ontogeny of glutathione and glutathione-related antioxidant enzymes in rat liver

We conducted a comprehensive characterization of the ontogeny of glutathione (GSH) and its related enzymes in rat liver. GSH content and activities of glutathione reductase (GR), cytosolic glutathione-S-transferases (GST), and glutathione peroxidase (GPx) were determined in male rat livers (n = 4) at different developmental stages. Our results indicate total hepatic GSH content and GR, GST, and GPx activity were low in the perinatal period. GSH content remained relatively constant throughout postnatal development, but GR, GST, and GPx activity underwent significant increases to attain adult levels by late post-weaning. Whether the ontogenic pattern of GSH and its related enzymes explain, in part, the altered susceptibility of neonates to some toxicants requires further investigation. Our study provides fundamental biological information on the ontogeny of cytosolic antioxidant/detoxification enzymes in a relevant toxicological risk assessment species. Additional studies are needed to fully characterize the ontogeny of other xenobiotic detoxification enzymes to further promote the rat as a developmental toxicology model that can identify toxicokinetic reasons for differences in susceptibility to toxicity between the neonate and adult.     

A comparative study on the chemical composition of plasma from the cauda epididymidis, semen fractions, and whole semen in boars

A comparative study was carried out on the chemical composition of plasma from the cauda epididymidis, semen fractions, and whole semen of boars. A total of 22 boars were used in this study. The boars, which ranged in age from 8 to 14 months, were of Swedish Landrace and Swedish Yorkshire breed. All boars used presented a normal semen picture. A dummy sow and an artificial vagina were employed for semen collection. The semen was collected as whole semen and as semen fractions in 10 nil volumes. The contents of the cauda epididymidis was removed post mortem.The following parameters were investigated: sperm concentration, dry weight of spermatozoa and of seminal plasma, osmotic pressure, sodium, potassium, chloride, inorganic phosphorus, calcium, magnesium, total protein, GOT, GPT, and alkaline phosphatase in seminal plasma. Paper electrophoresis was carried out on seminal plasma. Tlxe results of the analysis are summarized in Tables 1–6.The sperm concentration was approximately 3.2 mill./mm3 in the cauda epididymidis, 1 mill./mm³ in the sperm-richest fraction (II) and 0.25 mill./mm3 in whole semen. The dry weight (expressed in per cent dry matter) of spermatozoa was highest in the cauda epididymidis (25.47 %), showing a tendency to decreasing in semen fractions I—IV and was lowest in whole semen (15.29 %). The per cent dry weight in plasma was higher in the cauda epididymidis (4.56 %) than in semen fraction I (2.20 %). In semen fractions I—IV the per cent dry weight rose from 2.20 (U to 4.51 % and reached the level of approximately 3.80 % in the sperm-free fractions V—VII. The osmotic pressure was significantly higher in the cauda epidi-dymal plasma than in the whole seminal plasma or the seminal plasma fractions. The same phenomenon was observed in a boar where the cauda epididymal content was collected in vivo from a patent established fistula. There appears to be a connection between the per cent dry weight of spermatozoa and the osmotic pressure, which means that the per cent dry weight of the cauda epididymal spermatozoa decreases when mixed with the accessory gland secretions, which have a lower osmotic pressure. The fall in per cent dry weights is thought to be caused by an intake of water.The amount of sodium, chloride and magnesium was higher in ejaculated seminal plasma than in cauda epididymal plasma. The reverse was true for inorganic phosphorus and potassium. Moreover the sperm-free fractions contained more sodium, chlorides and magnesium than the sperm-containing fractions, while the concentration of potassium and inorganic phosphorus was comparatively higher in the sperm-containing fractions. A connection is apparent between sperm concentration and the potassium, inorganic phosphorus and magnesium levels. Statistical analysis of the values of chloride and magnesium revealed significant differences between individual boars for most of the semen fractions.The concentration of plasma proteins in the cauda epididymidis was approximately the same as in whole semen and in the semen fractions except for fraction I, which contained a relatively low concentration. As regards total protein there were significant differences between individual boars in most of the semen fractions as well.The paper electrophoretic pattern of epididymal plasma was different from that of semen plasma. Thus there were three or four distinct components in the cauda epididymidis numbered 1, 2, 3, and 4, and three distinct components in whole seminal plasma numbered 3, 4, and 5, while the sperm-richest semen fractions contained four components (2, 3, 4, and 5) and the others three components, namely 3, 4, and 5.The level of GOT was high in the cautlu cpiflidymill contents (99.1 i. u./ml) compared with that for whole seminal plasma (99.1 i.u/ml). In semen fractions there was a clear positive correlation between the level of GOT and the sperm concentration. The GPT concentration wis as a whole low and. in contrast to GOT. somewhat higher in the sperm-free fractions than in the sperm-containing fractions. The concentration of alkaline phosphatase was very high in cauda epididymal plasma (31,463 i. u./ml) as well as in the sperm-rich fractions (e.g. 7,096 i. u./ml in fraction II). Preliminary investigation has moreover revealed a very low alkaline phosphatase concentration in seminal plasma of vasectomized boars, which condition suggests thai the main origin for alkaline phosphatase in boars is the testis and epididymis.     

Motility of Fresh and Frozen-Thawed Stallion Sperm from Three Segments of the Epididymal Cauda and the Effect of Post-Thaw Seminal Plasma Addition on Motility

Preservation of epididymal spermatozoa is an advantageous method to preserve genetic material of endangered species or valuable breeding animals after sudden death and injuries. Despite lower pregnancy rates, fertilization with epididymal sperm has been proven successful. Variable sperm quality after cryopreservation among individual stallions and the usually terminal chance to preserve epididymal sperm are opportunities for the development of a freezing procedure suitable for the majority of stallions. To evaluate the effect of the preservation procedure, we analyzed the sperm motion characteristics after every step of processing. In addition, we investigated the influence of seminal plasma on motility of frozen-thawed semen. We compared three segments of the cauda epididymidis and harvested spermatozoa by retrograde flushing (most caudal part) and mincing (more cranial segments) to augment the number of spermatozoa. During processing, there were differences in sperm motion characteristics depending on the segment of the cauda epididymidis. Distinct increases in motility due to different extenders and the effect of seminal plasma suggest that motion characteristics of raw and frozen-thawed spermatozoa are strongly influenced by microenvironment and must be interpreted with caution.     

Effect of soya bean and fish oil inclusion in diets on milk and plasma enzymes from sheep and goat related to oxidation

This study investigated the effects of dietary inclusion of soya bean oil combined with fish oil (SFO) on the activities of a) superoxide dismutase (SOD), glutathione reductase (GR), catalase (CAT) and glutathione transferase (GST) in blood plasma and b) SOD, GR, CAT and lactoperoxidase (LPO) in the milk of sheep and goats. Furthermore, the oxidative stress indicators for measuring total antioxidant activity and free radical scavenging activity [ferric reducing ability of plasma ( FRAP) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) assays] and oxidative stress biomarkers [malondialdehyde (MDA) and protein carbonyl (PC)] were also determined in the blood plasma and milk of the animals. For this purpose, twelve dairy sheep and twelve dairy goats were assigned each to two homogenous subgroups. Treatments in both animal species involved a control diet without added oil and a diet supplemented with 5% soya bean oil and 1% fish oil. The results showed that the inclusion of SFO in the diets of sheep and goats increased significantly the activities of CAT and GR in their blood plasma. The same effect was observed for the activities of GST and FRAP in the blood plasma of goats. Moreover, the fact that the goats had significantly higher average daily PUFA intake (3.62 g/kg BW^0.75) compared to sheep (2.51 g/kg BW^0.75) resulted in an enhancement in the MDA content in their plasma. A significant increase in CAT activity in the milk in both animal species fed with SFO diets was also found. Finally, due to the higher apparent transfer rate of n‐3 FA from the diet to the milk in sheep, the PC concentrations were found to be enhanced in their plasma and milk. In conclusion, the impact of dietary SFO supplementation on the oxidative status of body and/or on the milk of small ruminants depends not only on the daily PUFA intake, but also on the amount of n‐3 FA that reach their milk.     

Catalase activity in equine semen

OBJECTIVE: To characterize the activity of catalase in equine semen. ANIMALS: 15 stallions of known and unknown reproductive history. PROCEDURE: Seminal plasma was collected from raw equine semen by centrifugation, and samples of seminal plasma were frozen prior to assay for catalase activity. Tissue samples (n = 3 stallions) from the bulbourethral gland, prostate gland, vesicular gland, and testis were homogenized, and cauda epididymal fluid was collected for determination of catalase activity. Catalase activity was determined as an enzyme kinetic assay by the disappearance of H2O2 as measured by ultraviolet spectrophotometry. RESULTS: Catalase activity in equine seminal plasma was 989.3 +/- 1678 U/ml (mean +/- SEM), and the specific activity of catalase in equine seminal plasma was 98.7 +/- 29.2 U/mg of protein. Specific activity of catalase in tissue homogenates was significantly higher in the prostate gland (954 +/- 270 U/mg of protein) than in the ampulla (59 +/- 5 U/mg of protein), bulbourethral gland (54 +/- 11 U/mg of protein), vesicular gland (39 +/- 3 U/mg of protein), cauda epididymal fluid (11 +/- 3 U/mg protein), or testis (54 +/- 6 U/mg of protein). CONCLUSIONS AND CLINICAL RELEVANCE: Equine seminal plasma contains a high activity of catalase that is derived primarily from prostatic secretions. Procedures such as semen cryopreservation that remove most seminal plasma from semen may reduce the ability to scavenge H2O2 and thereby increase the susceptibility of spermatozoa to oxidative stress.     

维生素E对秦川牛冷冻精液的抗氧化保护作用

本试验旨在研究维生素E对秦川牛细管冷冻精液品质和精浆中抗氧化酶活性的影响.在稀释液中分别添加0.00、0.02、0.04、0.06、0.08、0.10 mg·mL~(-1)的维生素E,将细管冻精解冻(37.5℃,30 s)后用伟力精子分析系统分析精子活力和精子顶体完整率等标准参数,并用相关试剂盒测定精浆中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH)、谷胱甘肽还原酶(GR)和过氧化氢酶(CAT)的活性.结果表明:当维生素E添加量为0.04mg·mL~(-1)时,精子活力与对照组相比差异显著(P<0.05),SOD、GSH、CAT 3种酶活性与对照组相比差异显著(P<0.05).当维生素E的添加量为0.06 mg·mL~(-1)时,冷冻-解冻后精子活力显著高于对照组(P<0.05),顶体完整率极显著高于对照组(P<0.01);GR和CAT酶活性与对照组相比均差异显著(P<0.05).当维生素E的添加量为0.08 mg·mL~(-1)时,精子活力、活率及顶体完整率与对照组相比差异显著(P<0.05),GSH与对照相组比差异极显著(P<0.01),GR及CAT与对照组相比差异显著(P<0.05).在冷冻精液稀释液中添加维生素E可以有效提高冷冻-解冻后秦川牛精液品质及精浆中SOD、CAT、GSH、GR酶的活性,稀释液中维生素E的适宜添加量为0.04～0.08 mg·mL~(-1).     

Extracellular Superoxide Dismutase of Boar Seminal Plasma

Superoxide dismutase (SOD) is an enzymatic component of the antioxidant defense system that protects spermatozoa by catalysing the dismutation of superoxide anions to hydrogen peroxide and oxygen. Age and season effects on SOD activity in the seminal plasma were measured in boars at the onset of 8 months through a 35-month period. It was found that age-related changes in SOD activity in the seminal plasma were markedly higher in boars less than 2 years of age. However, it appeared that SOD activity was established at the early sexual maturity age (8–12 months). There were variations in SOD activity throughout the season, being significantly higher in spring and autumn than in summer. A secretory extracellular form of SOD (EC-SOD) was purified to homogeneity (350-fold) from boar seminal plasma, using a three-step purification protocol (affinity chromatography followed by ion exchange and ceramic hydroxyapatite chromatography). The molecular properties and specificity of SOD (molecular mass, isoelectric point, optimum pH, thermostability and susceptibility to inhibitors) confirmed that the purified enzyme is an extracellular form of Cu/Zn-superoxide dismutase occurring in boar seminal plasma. The results of this study indicate that EC-SOD is an important antioxidant enzyme of boar seminal plasma, which plays an important physiological role in counteracting oxidative stress in spermatozoa.     

The effect of dietary Chlorella vulgaris inclusion on goat's milk chemical composition,fatty acids profile and enzymes activities related to oxidation

The impact of dietary supplementation with microalgae on goat's milk chemical composition, fatty acids (FA) profile and enzymes activities related to antioxidant mechanism has not been well documented. Thus, this study aimed to investigate the effects of dietary inclusion of Chlorella vulgaris on the following: (i) milk yield, chemical composition and FA profile, (ii) the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione transferase (GST) and glutathione peroxidase (GSH‐Px) in blood plasma and (iii) the activities of SOD, GR and lactoperoxidase (LPO) in milk of goats. Furthermore, the oxidative stress indicators for measuring total antioxidant and free radical scavenging activity [ferric reducing ability of plasma (FRAP) and 2, 2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) assays] and oxidative stress biomarkers [malondialdehyde (MDA) and protein carbonyls (PC)] were also determined in blood plasma and milk of the animals. For this purpose, 16 cross‐bred goats were divided into two homogenous groups. Each goat of both groups was fed individually with alfalfa hay and concentrates separately. The concentrates of the control group (Control) had no microalgae, while those of the Chlorella group were supplemented with 10 g lyophilized Chlorella vulgaris/kg concentrates (Chlorella). Thus, the average intake was 5.15 g Chlorella vulgaris/kg DM. The results showed that the dietary inclusion of Chlorella vulgaris had not noticeable impact on goat's milk yield, chemical composition and FA profile. Significantly higher SOD (by 10.31%) and CAT (by 18.66%) activities in the blood plasma of goats fed with Chlorella vulgaris compared with the control were found. Moreover, the dietary supplementation with Chlorella vulgaris caused a significant increase in SOD (by 68.84%) activity and a reduction in PC (by 24.07%) content in goat's milk. In conclusion, the Chlorella vulgaris inclusion in goat's diets improved the antioxidant status of both animals and milk.     

GPx6在大白猪附睾细胞中的表达及其与繁殖性能的相关性

本试验旨在研究谷胱甘肽过氧化物酶6（glutathione peroxidase 6,GPx6）在大白公猪附睾细胞中的表达和定位,并探究其与公猪繁殖性能的相关性。选取15月龄的公猪和母猪各3头,取睾丸、附睾、前列腺、尿道球腺、精囊腺、卵巢和输卵管,提取蛋白,通过蛋白免疫印迹和免疫组化（IHC）检测组织和细胞中GPx6蛋白的表达和定位;根据评定大白公猪受精能力的数学模型,按照公猪配种胎次≥20胎、3次配种公猪为同一头的标准,筛选并采集符合要求的20头公猪精液,同时,统计相对应的1 279头母猪的生产成绩,计算得到公猪繁殖性能指标（包括窝产总仔数、窝产活仔数、分娩率和繁殖力）。提取精子蛋白和精清蛋白,通过BCA和ELISA检测精子和精清中GPx6蛋白的含量。使用SPSS软件的独立样本t检验及单因素方差分析（one-way ANOVA）,进行差异显著性分析,用双变量Pearson进行相关性分析,P<0.05表示差异或相关显著。结果表明,GPx6蛋白在附睾中高表达,IHC结果显示,GPx6蛋白在附睾的顶细胞、基底细胞、晕细胞、主细胞和精子中表达,在肌样细胞中不表达;精清蛋白中GPx6的含量是精子蛋白的7倍,精液中GPx6蛋白的含量与窝产活仔数、窝产总仔数呈负相关关系。结果提示,GPx6在附睾的顶细胞、基底细胞、晕细胞、主细胞和精子中表达,且其在精液中的含量会影响公猪的繁殖性能,这为GPx6对公猪受精能力影响的研究奠定了理论和试验基础。     

Enzymatic antioxidant defense in isolated rat hepatocytes exposed to cadmium

The aim of the study was the evaluation of cadmium effects on the activity of antioxidant enzymes in rat hepatocytes. The studies were conducted with isolated rat hepatocytes incubated for 1 or 2 hours in a modified (deprived of carbonates with phosphates) Williams' E medium (MWE) in the presence of cadmium chloride (25, 50 and 200 microM). Hepatocytes incubated in the MWE medium without cadmium chloride were used as a control. The application of the modified Williams' E medium allowed for the appearance of cadmium compounds in a soluble form that is indispensable for suitable estimation of its toxic action. There were evaluated markers of the oxidative stress such as: concentration of thiobarbiturate reactive substances (TBARS)--proportional to the level of lipid peroxidation, concentration of reduced glutathione (GSH), and the activity of antioxidant enzymes, including superoxide dismutase (SOD1 and SOD2), catalase (CAT), total glutathione peroxidase (GSHPx), selenium--dependent glutathione peroxidase (SeGSHPx), glutathione transferase (GST) and glutathione reductase (GSHR). Alterations of antioxidant enzymes activity, the level of TBARS and GSH in isolated rat hepatocytes caused by cadmium in vitro, were shown to depend on the concentration and time of exposure of cells to this metal. The increased level of TBARS and GSH was observed as well as changes in the activity of antioxidant enzymes. The activity of SOD isoenzymes and CAT was increased, whereas GSHPx and GST were decreased. These results indicate that cadmium induces oxidative stress followed by alterations in the cellular antioxidant enzyme system in isolated rat hepatocytes.     

Effect of lead exposure on the erythrocytic antioxidant levels in goats

Fifteen adult female goats were orally exposed to 5.46 mg lead (as lead acetate) per kg body weight daily for 2 weeks to study the antioxidant enzymes of the erythrocyte, lipid peroxide level, total thiol groups and total antioxidant status (TAS) in plasma. Ten goats served as unexposed control. Blood samples were collected before exposure (day 0) and on days 7 and 14. Ten per cent erythrocyte haemolysate was prepared and analysed for glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), total thiol groups and lipid peroxide. TAS was determined in plasma. There was a significant (P < 0.05) increase of erythrocytic GPx, SOD, CAT, total thiol groups and TAS on day 7 which was followed by a significant (P < 0.05) decrease of all these parameters on day 14. Lipid peroxide level increased significantly (P < 0.05) and the maximum level was attained by day 14. The results obtained indicate a possible role of free radicals in lead poisoning pathogenicity.     

Effect of under‐ and overfeeding on sheep and goat milk and plasma enzymes activities related to oxidation

Twenty‐four dairy sheep and goats, respectively, were assigned each to three homogenous subgroups per animal species and fed the same diet in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed that the underfed sheep in comparison with the control had significantly lower glutathione reductase (GR), superoxide dismutase (SOD), catalase and glutathione peroxidase (GPX) activities and total antioxidant capacity (measured with Ferric Reducing Ability of Plasma [FRAP] assay) in their blood plasma. A significant increase in the glutathione transferase (GST) and GPX activities, malondialdehyde content and total antioxidant capacity (measured with 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) [ABTS] assay) in the blood plasma of underfed goats compared with controls was observed, while the opposite happened for the GR and SOD activities. The underfeeding in both animal species caused a significant increase in the protein carbonyls (PC) content of their blood plasma. The overfeeding, compared with the control, caused a significant decline in the GPX activity and total antioxidant capacity (measured with FRAP) in the blood plasma of sheep while the opposite happened for the GPX and GST activities in the case of goats. The overfed animals, of both species, compared with the respective controls, had higher PC content in their blood plasma. The feeding level had no noticeable impact on the antioxidants' enzymes activities of milk in both animal species. Moreover, the underfeeding in the blood plasma and the overfeeding in milk of both animal species resulted into a significant increase in the PC content. Finally, only in sheep milk, the underfeeding, compared with the respective control, and overfeeding reduced significantly the total antioxidant capacity (measured with ABTS). The feeding level caused oxidative stress in both organism and milk but the response was different in animal species and needs further investigation.     

Antioxidant effects of supplementation of 3,4-dihydroxyphenyl glycol on sperm parameters and oxidative markers following cryopreservation in canine semen

Supplementing the extender with antioxidants with low molecular weight can enhance the quality of the post-thaw sperm during the freezing process. This study was aimed at determining the impacts of 3,4-dihydroxyphenyl glycol (DHPG) on the spermatozoa of the canine undergoing freeze-thawing process. In this study, 24 ejaculates were obtained from three mixed-breed dogs and were diluted in a Tris-based extender. The diluted semen was divided into aliquots for supplementation of 10, 30, 50 and 70 µg/ml of DHPG, control (without antioxidant) and control sham (DMSO). After being extended, the semen was equilibrated at a temperature of 4°C and then transferred to the straws and kept 4 cm above the liquid nitrogen for 20 min and was finally immersed in the liquid nitrogen. They were cryopreserved for seven days; then, sperm parameters including sperm motility evaluation, motility characteristics, viability, DNA and plasma membrane integrity, total antioxidant capacity (TAC), reduced glutathione content (GSH), antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT] and glutathione peroxidase [GPx]) activity malondialdehyde (MDA) levels were evaluated. This study showed that spermatozoa cryopreservation with 50, 30 and 70 µg/ml of DHPG concentrations had better progressive motility, Curvilinear Velocity, Linearity, viability, intact plasma membrane and the levels of TAC, GPx and GSH were higher than the control group. The 50, 30 and 70 µg/ml of DHPG concentrations led to the significant decrease of DNA damage compared to the control group. Total motility, average path velocity, straight-line velocity and CAT activity were significantly improved in 30 and 50 µg/ml of DHPG concentrations, compared to the control group. Also, the 50 and 30 µg/ml of DHPG concentrations, decreased MDA levels compared to the other groups, significantly. In conclusion, our study showed that the addition 50 µg/ml of DHPG to the canine semen extender improved the semen characteristics and oxidative markers in the cryopreservation process.