Investigation of the effect of naringenin on oxidative stress‐related alterations in testis of hydrogen peroxide‐administered rats

Testis tissue is prone to oxidation because its plasma membrane contains many polyunsaturated fatty acids. Naringenin is a plant‐derived natural flavonoid. We investigated the possible ameliorative role of naringenin on the hydrogen peroxide (H₂O₂)‐induced testicular damage in Wistar rats. Animals received 12 mg/kg H₂O₂ by intraperitoneal injection, and 50 mg/kg naringenin via orogastric gavage for 4 weeks. In the H₂O₂ group, the testis malondialdehyde level increased, while the amount of reduced glutathione, glutathione transferase activities, and the testis weight decreased. There were severe testicular damages in the H₂O₂ group otherwise their grade were less in the naringenin + H₂O₂ group. However, the serum testosterone concentrations decreased in both the H₂O₂ and the naringenin + H₂O₂ groups. The testicular zinc and calcium levels reduced in the H₂O₂‐treated rats. In conclusion, the administration of H₂O₂ caused oxidative stress in the testes and naringenin supplementation decreased the H₂O₂‐induced effects, except for changes in testosterone levels.     

Antioxidant properties of chromium and zinc

The effects of chromium (chromium picolinate, CrPic) and zinc (ZnSO₄H₂O) supplementation on serum concentrations of malondialdehyde (MDA) (an indicator of lipid peroxidation) and serum status of some antioxidant vitamins and minerals of laying hens (Hy-Line) reared at a low ambient temperature (6.8°C) were evaluated. One hundred twenty laying hens (Hy-Line; 32 wk old) were divided into 4 groups, 30 hens per group. The hens were fed either a basal diet or the basal diet supplemented with either 0.4 mg Cr/kg of diet, 30 mg Zn/kg of diet, or 0.4 mg Cr plus 30 mg Zn/kg of diet. Digestibility of nutrients (dry matter [DM], organic matter [OM], crude protein [CP], and ether extract [EE]) increased by supplementation of chromium and zinc (p<0.05). Supplemental chromium and zinc increased serum vitamins C and E but decreased MDA concentrations (p<0.05). Additionally, supplemental chromium and zinc caused an increase in the serum concentrations of Fe, Zn, Mn, and Cr (p < 0.05). The present study showed that low ambient temperature causes detrimental effects on the digestibility of nutrients and antioxidant status and that such detrimental effects caused by low ambient temperature can be alleviated by chromium and zinc supplementation, particularly when Cr and Zn were simultaneously included into the diet. Data obtained in the present study suggest that such supplementation can be considered as a protective management practice in a diet of laying hens for alleviating negative effects of cold stress.     

The effect of iron and/or zinc diet supplementation and termination of this practice on the antioxidant status of the reproductive tissues and sperm viability in rats

AimsThe aim of this study was to investigate the effect of iron or/and zinc supplementation and termination of this treatment on the antioxidant defence of the male reproductive system and sperm viability in rats.MethodsThe study consisted of 3 stages: I) 4-week adaptation to the diets (C-control or D-iron deficient); II) 4-week iron and/or zinc supplementation (10-times more than in the C diet of iron: CSFe, DSFe; zinc: CSZn, DSZn; or iron and zinc: CSFeZn, DSFeZn; and III) 2-week post-supplementation period (the same diets as during stage I). Parameters of antioxidant status (total antioxidant capacity and SOD, GPx, and CAT activiy), oxidative damage (lipid and protein peroxidation), and sperm viability were measured.ResultsSimultaneous iron and zinc supplementation compared to iron supplementation (CSFeZn vs CSFe) increased SOD activity in the testes and decreased the level of malondialdehyde in the epididymis after stage II, and increased the percentage of live sperm after stage III. After discontinuation of the iron and zinc supplementation and a return to the control diet, the following was observed a decrease of SOD activity in the testes and GPx activity in the epididymis, and a increase malondialdehyde concentration in prostates. After stage III, in DSFeZn vs DSFe rats, an increase of SOD and CAT activity in the epididymis was found.ConclusionZinc supplementation simultaneous with iron may protect the male reproductive system against oxidative damage induced by high doses of iron and may have a beneficial effect on sperm viability. The effect of this supplementation was observed even two weeks after the termination of the intervention.     

N-acetylcysteine reduces inflammation in the small intestine by regulating redox, EGF and TLR4 signaling

This study determined whether N-acetylcysteine (NAC) could affect intestinal redox status, proinflammatory cytokines, epidermal growth factor (EGF), EGF receptor (EGFR), Toll-like receptor-4 (TLR4), and aquaporin-8 in a lipopolysaccharide (LPS)-challenged piglet model. Eighteen piglets (35-day-old) were randomly allocated into one of the three treatments (control, LPS and NAC). The control and LPS groups were fed a basal diet, and the NAC group received the basal diet +500 mg/kg NAC. On days 10, 13, and 20 of the trial, the LPS- and NAC-treated piglets received intraperitoneal administration of LPS (100 μg/kg BW), whereas the control group received the same volume of saline. On days 10 and 20, venous blood samples were obtained at 3 h post LPS or saline injection. On day 21 of the trial, piglets were killed to obtain the intestinal mucosa for analysis. Compared with the control group, LPS challenge reduced (P < 0.05) the activities of superoxide dismutase, catalase, and glutathione peroxidase in jejunal mucosae, while increasing (P < 0.05) the concentrations of malondialdehyde, H₂O₂, O₂ ^·? and the ratio of oxidized to reduced glutathione in jejunal mucosae, and concentrations of TNF-α, cortisol, interleukin-6, and prostaglandin E₂ in both plasma and intestinal mucosae. These adverse effects of LPS were attenuated (P < 0.05) by NAC supplementation. Moreover, NAC prevented LPS-induced increases in abundances of intestinal HSP70 and NF-κB p65 proteins and TLR4 mRNA. NAC supplementation enhanced plasma EGF concentration and intestinal EGFR mRNA levels. Collectively, these results indicate that dietary NAC supplementation alleviates LPS-induced intestinal inflammation via regulating redox, EGF, and TLR4 signaling.     

Effects of N-acetyl-l-cysteine on bleomycin induced oxidative stress in malignant testicular germ cell tumors

Testicular cancer is a very common cancer in males aged 15–44 years. Bleomycin is used in chemotherapy regimens in the treatment of patients having testicular germ-cell tumor. Bleomycin generates oxygen radicals, induces oxidative cleavage of DNA strand and induces apoptosis in cancer cells. There is no study in the literature investigating effects of N-Acetyl-l-Cysteine (NAC) on bleomycin-induced oxidative stress in testicular germ cell tumors. For this reason, we studied effects of NAC on oxidative stress produced in wild-type NTera-2 and p53-mutant NCCIT testis cancer cells incubated with bleomycin and compared the results with H₂O₂ which directly produces oxidative stress. We determined protein carbonyl content, thiobarbituric acid reactive substances (TBARS), glutathione (GSH), 8-isoprostane, lipid hydroperoxide levels and total antioxidant capacity in both testicular cancer cells. Bleomycin and H₂O₂ significantly increased 8-isoprostane, TBARS, protein carbonyl and lipid hydroperoxide levels in NTera-2 and NCCIT cells. Bleomycin and H₂O₂ significantly decreased antioxidant capacity and GSH levels in both cell lines. Co-incubation with NAC significantly decreased lipid hydroperoxide, 8-isoprostane, protein carbonyl content and TBARS levels increased by bleomycin and H₂O₂. NAC enhanced GSH levels and antioxidant capacity in the NTera-2 and NCCIT cells. It can be concluded that NAC diminishes oxidative stress in human testicular cancer cells induced by bleomycin and H₂O₂.     

Bromelain from Ananas comosus stem attenuates oxidative toxicity and testicular dysfunction caused by aluminum in rats

BACKGROUNDAluminum (Al) has been reported to induce testicular injury via oxidative stress. Ananas comosus stem extract is an inexpensive byproduct waste rich in bromelain which is a group of sulfur-containing enzymes known for its biological activities and medicinal applications. So, the current investigation aims to evaluate the efficacy of bromelain in counteracting oxidative injury and testicular dysfunction stimulated by aluminum in rats.METHODSMale adult Wistar rats were divided into four groups. The first group used as control, however, the second and third groups were received bromelain (250 mg/kg) and AlCl₃ (34 mg/Kg, 1/25 LD₅₀), and the fourth group supplemented with bromelain one hour before AlCl₃ intoxication, respectively. Bromelain was administered daily while AlCl₃ was given every other day by oral gavages for one month.RESULTSAl intoxicated animals revealed an elevation in lipid peroxidation (TBARS and H₂O₂) level and lactate dehydrogenase (LDH) activity. However, reduced glutathione (GSH) and protein contents, antioxidant enzymes (SOD, CAT, GPx, GR, GST), phosphatases (ALP, AcP) and aminotransferases (AST, ALT) activities were significantly reduced. Additionally, considerable amendments in hormonal levels (testosterone, luteinizing and follicle-stimulating hormone) and sperm characteristics were spotted. Further, histological variations in the testes section were detected and this supports the biochemical observations. Otherwise, rats supplemented with bromelain alone diminished TBARS and H₂O₂ and augmented mostly other parameters. Furthermore, supplementation with bromelain before Al intoxication in rats exhibited worthy betterment in oxidative stress markers, hormones, and sperm quality compared to Al treated group.CONCLUSIONIn conclusion, bromelain had a powerful protective role against Al-induced testicular dysfunction so, it represents a novel approach in metal toxicity processing.     

The antioxidant defense system of isolated guinea pig Leydig cells

Utilization of highly enriched preparations of steroidogenic Leydig cells have proven invaluable for studying the direct effects of various hormones and agents on Leydig cell functionin vitro. However, recent work indicates that isolated Leydig cells are often subjected to oxygen (O₂) toxicity when cultured at ambient (19%) oxygen concentrations. Because intracellular antioxidants play an important role in protecting cells against oxygen toxicity, we have investigated the intracellular antioxidant defense system of isolated Leydig cells. The cellular levels of several antioxidants including catalase, glucose-6-phosphate dehydrogenase (G-6-PDH), superoxide dismutase (SOD) of the Cu/Zn & Mn variety, glutathione peroxidase, glutathione reductase and total glutathione were quantitated using enriched populations of Leydig cells isolated from adult male guinea pig testes. Compared to whole testicular homogenates, Leydig cells contained significantly (P<0.01) less G-6-PDH, total SOD, glutathione reductase and total glutathione, but significantly (P<0.001) more glutathione peroxidase. Compared to hepatic values previously reported in the guinea pig, Leydig cells contain nearly 400 times less catalase, about 14 times less glutathione peroxidase and almost 11 times less glutathione reductase. Since G-6-PDH and glutathione reductase are both necessary to regenerate reduced gluthathione (GSH) which couples with glutathione peroxidase to breakdown hydrogen peroxide (H₂O₂) under normal conditions, it is plausible that the oxygen toxicity observed in isolated Leydig cells is due to the intracellular accumulation of H₂O₂. Using the dichlorofluorescin diacetate (DCF-DA) assay, we found that Leydig cells incubated in the presence of 19% O₂ produced significantly (P<0.001) higher levels of H₂O₂ with time in culture compared to Leydig cells maintained at 3% O₂. These results support the hypothesis that the increased susceptibility of isolated Leydig cells to oxygen toxicity may be due, in part, to decreased amounts of certain antioxidant defenses and an increased production of the reactive oxygen species H₂O₂.     

Molecular Modeling of the Ternary Complex of Rusticyanin-Cytochrome c4-Cytochrome Oxidase: An Insight to Possible H-Bond Mediated Recognition and Electron Transfer Reaction in T.ferrooxidans

Abstract

The metabolism of Thiobacillus ferrooxidans involves electron transfer from the Fe⁺² ions in the extracellular environment to the terminal oxygen in the bacterial cytoplasm through a series of periplasmic proteins like Rusticyanin (RCy), Cytochrome (Cyt c₄), and Cytochrome oxidase (CcO). The energy minimization and MD studies reveal the stabilization of the three redox proteins in their ternary complex through the direct and water mediated H-bonds and electrostatic interaction. The surface exposed polar residues of the three proteins, i.e., RCy (His 143, Thr 146, Lys 81, Glu 20), Cyt c₄ (Asp 5, 15, 52, Ser 14, Glu 61), and CcO (Asp 135, Glu 126, 140, 142, Thr 177) formed the intermolecular hydrogen bonds and stabilized the ternary complex. The oxygen (O^εl) of Glu 126, 140, and 142 on subunit II of the CcO interact to the exposed side-chain and O^b atoms of the Asp 52 of Cyt c₄ and Glu 20 and Leu 12 of RCy. The Asp 135 of subunit II also forms H-bond with the N^ε atom of Lys 81 of RCy. The O^εl of Glu 61 of Cyt c₄ is also H-bonded to O^γ atom of Thr 177 of CcO. Solvation followed by MD studies of the ternary protein complex revealed the presence of seven water molecules in the interfacial region of the interacting proteins. Three of the seven water molecules (W 79, W 437, and W 606) bridged the three proteins by forming the hydrogen bonded network (with the distances ～ 2.10–2.95 Å) between the Lys 81 (RCy), Glu 61 (Cyt c₄), and Asp 135 (CcO). Another water molecule W 603 was H-bonded to Tyr 122 (CcO) and interconnected the Lys 81 (RCy) and Asp 135 (CcO) through the water molecules W 606 and W 437. The other two water molecules (W 21 and W 455) bridged the RCy to Cyt c₄ through H-bonds, whereas the remaining W 76 interconnected the His 53 (Cytc₄) to Glu 126 (CcO) with distances ～ 2.95–3.0 Å.     

Bacillus amyloliquefaciens BLCC1-0238 Can Effectively Improve Laying Performance and Egg Quality Via Enhancing Immunity and Regulating Reproductive Hormones of Laying Hens

In this study, we sought to evaluate the effects of dietary Bacillus amyloliquefaciens (B. amyloliquefaciens) BLCC1-0238 supplementation on laying performance, egg quality, antioxidant enzyme activities, reproductive hormone, and immunity of laying hens. A total of 240 Hy-Line Brown laying hens (28 weeks old) were randomly divided into four groups, and three replicates per group (n = 20 per replicate). The control group was fed a standard basal diet, and the three treatment groups were provided the basal diet supplemented with either 0.01%, 0.03%, or 0.06% B. amyloliquefaciens BLCC1-0238 (2 × 10¹⁰ CFU/g), respectively. Hens were allowed 2 weeks to acclimate prior to initiation of the 8-week experiment. It was observed that dietary supplementation with 0.01% or 0.03% B. amyloliquefaciens BLCC1-0238 significantly increased egg production and egg mass. However, no significant differences in feed intake, egg weight, and feed conversion ratio among the four groups were observed. Different levels of B. amyloliquefaciens BLCC1-0238 supplementation also significantly increased egg shell strength and thickness. With respect to the levels of reproductive hormones in the hens, B. amyloliquefaciens BLCC1-0238 supplementation significantly reduced serum adrenal cortical hormone (ACTH) levels, while increasing estradiol (E2) and follicle-stimulating hormone (FSH) secretion in the treatment groups compared to the control group. Relative to the control group, supplementation with 0.03% and 0.06% B. amyloliquefaciens BLCC1-0238 was observed to significantly increase serum glutathione S-transferase (GST) concentration, and supplementation significantly reduced serum IL-1 and IL-6 levels, whereas IL-4 levels increased for all concentrations tested. In conclusion, supplementation of a basal chicken diet with B. amyloliquefaciens BLCC1-0238 can improve laying performance and egg quality through the reduction of stress responses, up-regulation of growth hormones, and supporting immunity in laying hens.

     

H2O2 at physiological concentrations modulates Leydig cell function inducing oxidative stress and apoptosis

H₂O₂ is one of the active reactive oxygen species secreted by macrophages that are seen closely aligned with Leydig cells in the testicular interstitium. The present study was initiated to investigate the role of H₂O₂ on Leydig cell function in vitro at physiological concentrations. Significant decrease in both testosterone production (p < 0.05) and 3 β-hydroxysteroid dehydrogenase activity (p < 0.05) in adult Leydig cells were observed even with H₂O₂ at low concentrations (30 – 50 μM). H₂O₂ exposure increased oxidative stress in Leydig cells with the rise in lipid peroxidation and fall in the activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT) & glutathione-s-transferase (GST). There was also a marginal increase (∼8%) in cell apoptosis accompanied by rise in FasL expression and caspase-3 activation. The above findings indicate that H₂O₂ as a bio-molecule modulates Leydig cell function at or below physiological concentrations through a variety of actions like decrease in steroidogenic enzyme activity and increase in oxidative stress and apoptosis.     

4-Vinylcyclohexene diepoxide disrupts sperm characteristics,endocrine balance and redox status in testes and epididymis of rats

Objectives: Exposure to 4-vinylcyclohexene diepoxide (VCD) was reported to induce testicular germ cell toxicity in rodents. However, there is paucity of information on the precise biochemical and molecular mechanisms of VCD-induced male reproductive toxicity.

Methodology: This study investigated the influence of VCD on testicular and epidydimal functions following oral exposure of Wistar rats to VCD at 0, 100, 250 and 500?mg/kg for 28 consecutive days.

Results: Administration of VCD significantly decreased the body weight gain and organo-somatic indices of the testes and epididymis. When compared with the control, VCD significantly decreased superoxide dismutase and catalase activities in the testes whereas it significantly decreased superoxide dismutase activity but increased catalase activity in the epididymis. Moreover, while glutathione peroxidase activity and glutathione level remain unaffected, exposure of rats to VCD significantly increased glutathione S-transferase activity as well as hydrogen peroxide and malondialdehyde levels in testes and epididymis of the treated rats. The spermiogram of VCD-treated rats showed significant decrease in epididymal sperm count, sperm progressive motility, testicular sperm number and daily sperm production when compared with the control. Administration of VCD significantly decreased circulatory concentrations of follicle-stimulating hormone, luteinizing hormone and testosterone along with testicular and epididymal degeneration in the treated rats. Immunohistochemical analysis showed significantly increased cyclooxygenase-2, inducible nitric oxide synthase, caspase-9 and caspase-3 protein expressions in the testes of VCD-treated rats.

Conclusion: Exposure to VCD induces testicular and epidydimal dysfunctions via endocrine suppression, disruption of antioxidant enzymes activities, increase in biomarkers of oxidative stress, inflammation and apoptosis in rats.     

Redox status of the testes and sperm of rats following exposure to 2,5-hexanedione

Objectives: Exposure to 2,5-hexanedione (2,5-HD) is well known to be associated with reproductive dysfunctions in both humans and animals. However, the role of oxidative stress in 2,5-HD-induced toxicity in testes and sperm has not yet been studied.

Methodology: The present study investigated the influence of 2,5-HD on antioxidant systems in the testes and epididymal sperm of rats following exposure to 0, 0.25, 0.5, and 1% 2,5-HD in drinking water for 21 consecutive days.

Results: Administration of 0.5% 2,5-HD significantly (P?<?0.05) decreased epididymis weight, whereas 1% 2,5-HD-treated rats showed significantly decreased body weight, testis, and epididymis weights compared with the control group. Exposure to 2,5-HD caused a significant dose-dependent increase in the activities of superoxide dismutase, catalase, and glutathione peroxidase in both testes and sperm compared with the control group. Moreover, 2,5-HD-exposed rats showed significant decrease in glutathione-S-transferase activity and glutathione level with concomitant significant elevation in the levels of hydrogen peroxide and malondialdehyde in both testes and sperm. Testicular and epididymal atrophy with significant, dose-dependent, decrease in epididymal sperm number, sperm motility, and viability were observed in 2,5-HD-treated rats.

Conclusion: 2,5-HD exposure impaired testicular function and sperm characteristics by disruption of the antioxidant systems and consequently, increased oxidative stress in the treated rats.     

Involvement of G6PDH in heat stress tolerance in the calli from Przewalskia tangutica and Nicotiana tabacum

Glucose-6-phosphate dehydrogenase (G6PDH) has been implicated in supplying reduced nicotine amide cofactors for biochemical reactions and in modulating the redox state of cells. In this study, the role of G6PDH in thermotolerance of the calli from Przewalskia tangutica and tobacco (Nicotiana tabacum L.) was investigated. Results showed that Przewalskia tangutica callus was more sensitive to heat stress than tobacco callus. The activity of G6PDH and antioxidant enzymes (ascorbate peroxidase, catalase, peroxidase and superoxide dismutase) in calli from Przewalskia tangutica and tobacco increased after 40 °C treatment, although two calli exhibited a difference in the degree and timing of response to heat stress. When G6PDH was partially inhibited by glucosamine pretreatment, the antioxidant enzyme activities and thermotolerance in both calli significantly decreased. Simultaneously, the heat-induced H₂O₂ content and the plasma membrane NADPH oxidase activity were also reduced. Application of H₂O₂ increased the activity of G6PDH and antioxidant enzymes in both calli. Diphenylene iodonium, a NADPH oxidase inhibitor, counteracted heatinduced H₂O₂ accumulation and reduced the heat-induced activity of G6PDH and antioxidant enzymes. Moreover, exogenous H₂O₂ was effective in restoring the activity of G6PDH and antioxidant enzymes after glucosamine pretreatment. Western blot analysis showed that G6PDH gene expression in both calli was also stimulated by heat and H₂O₂, and blocked by DPI and glucosamine under heat stress. Taken together, under heat stress G6PDH promoted H₂O₂ accumulation via NADPH oxidase and the elevated H₂O₂ was involved in regulating the activity of antioxidant enzymes, which in turn facilitate to maintain the steady-state H₂O₂ level and protect plants from the oxidative damage.     

Source of Selenium Supplementation Influences Testis Selenium Content and Gene Expression Profiles in Single Comb White Leghorn Roosters

Spermatogenesis is a tightly regulated, selenium-dependent process. Nutritional deficiencies, including Se, have been associated with decreased fertility. During Se depletion, testes preferentially retain Se while other tissues are depleted. This study was aimed at evaluating the effect of Se source (inorganic or organic yeast derived) on testes weight, Se content, and gene expression. At 17 weeks of age, roosters were randomly assigned to one of three treatments: basal diet (control), basal diet?+?0.3 mg organic Se/kg organic yeast-derived Se (YS; Sel-Plex®, Alltech Inc.), or basal diet?+?0.3 mg inorganic Se /kg inorganic Se as sodium selenite (SS). At 40 weeks of age, seven roosters from each treatment were euthanized and testes removed. Testes weight did not differ between treatments, but Se content was greater (P?≤?0.01) in YS than SS and control. Testicular differential gene expression profiling was accomplished using the Affymetrix Genechip® chicken genome array. Ingenuity® pathway analysis revealed that Se supplementation, regardless of source, results in the up-regulation of genes governing cell structure/morphology. The enrichment of such pathways was greater with YS than SS. These expression patterns suggest that aside from playing a role in antioxidant defense, Se, especially in the organic YS form, is useful for maintaining testicular cell structure.     

GLYCOSYLATION PATTERN IN THE APPENDIX TESTIS IN CHILDREN WITH CRYPTORCHIDISM

In humans, at about week 6, sex cords develop within the forming testes. Testes normally descend to the scrotum; cryptorchidism occurs when one or two testes do not descend to scrotum and in some case are accompanied by the appendix testis. The appendix testis is a small sessile or polypoid structure located at the antero superior pole of the testis, adjacent to the head of the epididymis. Glycans can be involved in development of the appendix testis and cryptorchidism. In this work, lectin histochemistry was used to evaluate glycans expression in appendix testis in children with cryptorchidism. Our results showed that lectin from Lens culinaris, Ulex europaeus I., Canavalia ensiformis, Artocarpus integrifolia, Glycine max, and Griffonia simplicifolia recognizes epithelial and estromal cells. Not interaction was observed with lectin from Amaranthus leucocarpus, while lectin from Dolichus biflorus lectin only recognizes epithelial cells. Our results suggest that O-glycans linked in some glycoproteins represent important elements in appendix testis development.     

Changes in photosynthesis and antioxidant defenses of Picea asperata seedlings to enhanced ultraviolet-B and to nitrogen supply

The paper mainly studied the effects of ultraviolet‐B (UV‐B) radiation, nitrogen, and their combination on photosynthesis and antioxidant defenses of Picea asperata seedlings. The experimental design included two levels of UV‐B treatments (ambient UV‐B, 11.02 KJ m⁻² day⁻¹; enhanced UV‐B, 14.33 KJ m⁻² day⁻¹) and two nitrogen levels (0; 20 g m⁻² a⁻¹ N) – to determine whether the adverse effects of UV‐B are eased by supplemental nitrogen. Enhanced UV‐B significantly inhibited plant growth, net photosynthetic rate (A), stomatal conductance to water vapor (Gs), transpiration rate and photosynthetic pigment, and increased intercellular CO₂ concentration, UV‐B absorbing compounds, proline content, malondialdehyde (MDA) content, and activity of antioxidant enzymes (peroxidase (POD), superoxide dimutase, and glutathione reductase). Enhanced UV‐B also reduced needle DW and increased hydrogen peroxide (H₂O₂) content and the rate of superoxide radical (O₂⁻) production only under supplemental nitrogen. On the other hand, supplemental nitrogen increased plant growth, A, Gs, chlorophyll content and activity of antioxidant enzymes (POD, ascorbate peroxidase, and catalase), and reduced MDA content, H₂O₂ content, and the rate of O₂⁻ production only under ambient UV‐B, whereas supplemental nitrogen reduced activity of antioxidant enzymes under enhanced UV‐B. Carotenoids content, proline content, and UV‐B absorbing compounds increased under supplemental nitrogen. Moreover, significant UV‐B × nitrogen interaction was found on plant height, basal diameter, A, chlorophyll a, activity of antioxidant enzymes, H₂O₂, MDA, and proline content. These results implied that supplemental nitrogen was favorable for photosynthesis and antioxidant defenses of P.asperata seedlings under ambient UV‐B. However, supplemental nitrogen made the plants more sensitive to enhanced UV‐B, although some antioxidant indexes increased.     

Short-term zinc deficiency in diet induces increased oxidative stress in testes and epididymis of rats

In order to determine the effects of Zinc deficient diet on oxidative stress in testis and epididymis, various parameters viz: total proteins, lipid peroxidation, hydroperoxides, antioxidant capacity and enzymatic activities are evaluated in rats fed on zinc deficient diet for 2, 4 and 6 weeks. Total proteins, water and lipid solouble antioxidant capacity decreased while lipid peroxidation (TBARS) and hydroperoxides concentration increased in testes, caput and cauda epididymis except in 2ZD (testes) where hydroperoxides revealed a significant decrease. GSH decreased in testes and caput and cauda epididymis. GPx and gamma-GT activities increased in testes and caput and cauda epididymis of zinc deficient rats. Further, GST increased in testes but exhibited decreases after 2 and 4 weeks and an increase after 6 weeks in caput and cauda epididymis of zinc deficient rats. GR activities decreased in testes but it increased in caput and cauda epididymis of zinc deficient rats. Thus, zinc deprivation results in increased sensitivity to oxidative stress. All these may have been as a consequence of increased ROS generation and/or decreased zinc dependent antioxidant processes.     

Study of antioxidant enzymes activity and isozymes pattern in hairy roots and regenerated plants in <Emphasis Type="Italic">Nicotiana tabacum</Emphasis>

Hairy root disease is caused by the infection of wounded higher plants with Agrobacterium rhizogenes. Transformation of tissues or plants with A. rhizogenes, and with rol genes, as well as hairy roots may produce alterations in the plant secondary metabolism. H₂O₂ and other ROS are involved as a signal in secondary metabolite production pathway and play a key role in plant defensive reactions. In this work, the effect of A. rhizogenes T-DNA on nicotine content, antioxidant enzymes activity, H₂O₂ production, pattern of peroxidase (POX) and superoxide dismutase (SOD) isozymes in hairy roots and regenerated plants were studied. Rise in SOD and POX activities in the transformed lines of TRa and TRb and in the resultant regenerated plants, also the decreased level of H₂O₂ in them, compared with the untransformed lines indicates that, the T-DNA genes expression of A. rhizogenes probably decreases H₂O₂ level by increasing the production of antioxidant enzymes. Decrees the level of H₂O₂ content in TRc line in spite of the similarity of antioxidant enzyme activity in comparison with normal root, indicate that A. rhizogenes activate other mechanisms except SOD and POX enzyme for reducing H₂O₂ level.     

Immediate response of Chara braunii exposed to zinc and hydrogen peroxide

The immediate effect of zinc (Zn) and hydrogen peroxide (H₂O₂) in Chara braunii was analyzed in short-time exposure experiments. The exposure concentrations were 12.3, 18.4, and 24.5 μmol L^?1 H₂O₂, 12, 60, and 120 mg L^?1 Zn, and 12.3 μmol L^?1 H₂O₂ + 12 mg L^?1 Zn, 12.3 μmol L^?1 H₂O₂ + 60 mg L^?1 Zn, and 18.4 μmol L^?1 H₂O₂ + 12 mg L^?1 Zn. The stress response of C. braunii was analyzed by measuring photosynthetic photosystem II activity, chlorophyll a and b and carotenoid contents, the H₂O₂ concentration, and antioxidant enzyme activities of ascorbic peroxidase, catalase, and guaiacol peroxidase. The short-term addition of Zn reduced pigment contents in C. braunii. Chlorophyll a and b and carotenoid contents in H₂O₂-exposed C. braunii were as high as in control plants. Photosynthesis was reduced in H₂O₂-treated C. braunii and the short-term addition of Zn did not affect the electron transport rate. H₂O₂ concentration and antioxidant enzyme activities in C. braunii were not significantly different between control and exposed plants. Trends of enzymatic adaptation were described: the H₂O₂-induced stress response was characterized by increased antioxidant enzyme activities, whereas Zn inactivated catalase in C. braunii.     

Release of endogenous excitatory amino acids in the neostriatum of the rat under physiological and pharmacologically-induced conditions

Summary There is immunohistochemical evidence suggesting that glutamate (Glu) is released from nerve terminals and acts, via several receptor subtypes, as a major excitatory neurotransmitter in the cortico-striatal pathway of the rat. Aspartate (Asp) is also present in cortico-striatal neurons, but its role as a neurotransmitter has been questioned, since, in contrast to Glu, it has not been demonstrated in presynaptic vesicles. Glu and Asp can be found at subM concentrations in the extracellular compartment of most areas of the basal ganglia. Their concentrations are largely regulated by transport mechanisms, but also by a synaptotagmin-dependent exocytotic release, and are sufficiently high to occupy junctional and extrajunctional receptors.We have investigated whether Glu and Asp release in the neostriatum can be selectively modulated by different neuronal systems. Dopamine (DA) and cholecystokinin (CCK) selectively stimulate Asp release, via D₁ and CCK_B receptor subtypes, respectively. Also opioid -agonists increase Asp release. We propose that the selective modulation of Asp release by D_1–, CCK_B- and agonists involves striatal neurons containing Asp, but not Glu. In contrast, local perfusion with the ,-opioid antagonist D-Phe-Cys-Tyr-D-Trp-Orn-ThrPen-Thr-NH₂ (CTOP) increases both Glu and Asp release. This effect is probably exerted on cortico-striatal terminals, via presynaptic inhibitory -receptors. Thus, these results demonstrate that extracellular levels of Glu and Asp are modulated differentially by different neuronal systems, and suggest that in the neostriatum of the rat there are neuronal populations using Glu and/or Asp as messenger(s).