Myo-inositol prevents copper-induced oxidative damage and changes in antioxidant capacity in various organs and the enterocytes of juvenile Jian carp (Cyprinus carpio var. Jian)

Innate immunity and antioxidant systems in different tissues of sea bass (Dicentrarchus labrax) exposed to crude oil dispersed mechanically or chemically with Corexit 9500

The aim of the study was to evaluate effects of chemically dispersed oil by the dispersant Corexit 9500 on innate immunity and redox defenses in a marine model fish. Sea bass (Dicentrarchus labrax) were exposed 48h to four experimental conditions: a control group (C), a group only exposed to the dispersant (D; 3.6mg/L) and two groups exposed to 80mg/L oil mechanically or chemically dispersed (MD; CD). Alternative pathway of complement activity and lysozyme concentration was measured in plasma in order to evaluate the general fish health status. Total glutathione, glutathione peroxidase (GPX) and superoxide dismutase (SOD) were analyzed in gills, liver, brain, intestine and muscle. The chemical dispersion induced a significant reduction of lysozyme concentration when compared to the controls, and the hemolytic activity of the alternative complement pathway was increased in mechanical and chemical dispersion. The analysis of SOD, GPX and total glutathione showed that antioxidant defenses were activated in liver and reduced in intestine and brain. Dispersant was also responsible for an SOD activity inhibition in these two last tissues, demonstrating a direct effect of this dispersant on reactive oxygen species homeostasis that can be interpreted as a signal of tissue toxicity. This result should raise concern about the use of dispersants and show that they can lead to adverse effects on marine species.

The tight junction protein transcript abundance changes and oxidative damage by tryptophan deficiency or excess are related to the modulation of the signalling molecules, NF-κB p65, TOR, caspase-(3,8,9) and Nrf2 mRNA levels, in the gill of young grass carp (Ctenopharyngodon idellus)

This study is for the first time to explore the possible effects of dietary tryptophan (Trp) on structural integrity and the related signalling factor gene expression in the gill of young grass carp (Ctenopharyngodon idella). Fish were fed with six different experimental diets containing graded levels of Trp at 0.7 (control), 1.7, 3.1, 4.0, 5.2 and 6.1 g kg(-1) diet for 8 weeks. The results firstly demonstrated that Trp deficiency or excess caused increases in reactive oxygen species (ROS) contents, and severe oxidative damage (lipid peroxidation and protein oxidation) in the gill of fish, and those negative effects could be reversed by optimal Trp levels. Secondly, compared with the optimal Trp levels, Trp deficiency could cause decreases in the mRNA levels of the barrier functional proteins (occludin, zonula occludens-1, claudin-c, and -3) and increases in the mRNA levels of the pore-formation proteins (claudin-12 and -15) mRNA levels in the gill of fish, and those were reversed by the optimal levels of Trp. The negative effects of Trp deficiency on those tight junction protein gene expression might be partly related to the increases in the mRNA levels of pro-inflammatory cytokines and related signalling factors (tumor necrosis factor α, interleukin 8, interleukin 1β and transcription factor-κB) and decreases in the mRNA levels of anti-inflammatory cytokines and related signalling factors [interleukin 10, transforming growth factor-β1, nuclear inhibitor factor κBα (iκBα), target of rapamyc and ribosome protein S6 kinase 1 (S6K1)] in the gill of fish. In addition, optimal dietary Trp protected the gill of fish against its deficiency-caused increases in the mRNA levels of the apoptosis signalling (caspase-3, caspase-8, caspase-9) and decreases in anti-superoxide radicals capacity, anti-hydroxyl radical capacity, glutathione contents and the activities of Cu/Zn superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) in the gill of fish. Additionally, compared with the Trp deficiency, optimal Trp up-regulated the mRNA levels of SOD, CAT, GPx, GR and GST, which might be partly ascribed to the up-regulation of the NF-E2-related factor 2 (Nrf2) mRNA levels and the down-regulation of Kelch-like-ECH-associated protein 1 (Keap1) mRNA levels in the gill of fish. Interestingly, excessive Trp caused similar results with its deficiency. Collectively, Trp deficiency or excess could cause antioxidant system disruption and change tight junction protein transcription abundances, which were partly related to the signalling factors, NF-κB p65, TOR, caspase-(3,8,9) and Nrf2, in fish gill, those could be blocked by the optimal Trp levels.

Effects of glutamate on growth, antioxidant capacity, and antioxidant-related signaling molecule expression in primary cultures of fish enterocytes

The present study explored the effects of glutamate (Glu) on the growth, antioxidant capacity, and gene expression of NF-E2-related nuclear factor 2 (Nrf2) signaling molecule in enterocytes of Jian carp (Cyprinus carpio var. Jian). The enterocytes were incubated in media containing 0, 2, 4, 6, 8, and 10 mM/L Glu for 96 h. The results showed that Glu could promote fish enterocytes proliferation and differentiation. Additionally, activities of alkaline phosphatase, Na(+), K(+)-ATPase, γ-glutamyl transpeptidase, and creatine kinase were significantly improved with the increase in Glu level up to 6 mM/L. Lactic acid dehydrogenase activity and malondialdehyde content in the medium and cellular protein carbonyls were depressed by Glu. Moreover, optimum Glu significantly enhanced glutathione content and the activities and gene expression of catalase, glutathione reductase, and glutathione peroxidase in enterocytes. Finally, the expression level of Nrf2 in enterocytes was significantly elevated by appropriate Glu content in the medium. Furthermore, optimum Glu significantly decreased Kelch-like ECH-associated protein 1 mRNA level in enterocytes. In conclusion, Glu improved the proliferation, function, and antioxidant capacity and regulated antioxidant-related signaling molecule expression of fish enterocytes.

Myo-inositol therapy for poor-responders during IVF: a prospective controlled observational trial

Background

The overall incidence of poor ovarian response in IVF cycles has been reported to be between 9 and 24 %. The management of these patients remains a significant challenge in assisted reproduction. The aim of the present study was to evaluate the effect of myo-inositol (MI) on ovarian function in poor responders undergoing ICSI.

Methods

The study is a prospective controlled observational trial, that involved 72 poor responders included in an ICSI program and divided into two groups; group A: 38 patients who have been assuming MI (4 g) + folic acid (FA) (400 μg) for the previous 3 months before the enrollment day; group B: 38 patients assuming FA (400 μg) alone for the same period. COH was carried out in the same manner in the two groups. The main goal was the assessment of oocytes retrieved number and quality; secondary endpoints were the Ovarian Sensitivity Index (OSI: n° oocytes retrieved/total Gonadotropins units × 1000), oestradiol levels on the day of hGC, fertilization rate, implantation rate, ongoing pregnancy rate.

Results

There was no significant difference between the two groups regarding oestradiol level, but total rec-FSH units were significantly lower (p = 0.004) and M2 oocytes rate significantly higer (p = 0.01) in group A. The ovarian sensitivity index was higher, reaching a statistical significance (p < 0.05), in the group of patients pre-treated with MI, showing an improvement in ovarian sensibility to gonadotropin.

Conclusions

Our results suggest that MI therapy in poor responders results in an increased of the number of oocytes recovered in MII and of the gonadotropin Ovarian Sensitivity Index (OSI), suggesting a MI role in improving ovarian response to gonadotropins. Therefore MI seems to be helpful in “poor responders” undergoing IVF cycles.

Perturbations in ROS-related processes of the fish Gambusia holbrooki after acute and chronic exposures to the metals copper and cadmium

Metallic contamination is a widespread phenomena, particularly in areas impacted by human activities, and has become a relevant environmental concern. However, the toxicity of metals on fish requires full characterization in terms of short- and long-term effects. Thus, the purpose of this study was to determine the acute and chronic oxidative stress response in liver and gills of Gambusia holbrooki exposed to copper and cadmium. To assess the effects of these two metals, we adopted a strategy of analyzing the pollution effects caused by salts of the two metallic elements, and we quantified the oxidative stress biomarkers catalase, glutathione reductase, glutathione-S-transferases, and lipid peroxidation after exposure (4 and 28 days) to ecologically relevant concentrations, thus simulating actual conditions of exposure in the wild. Our results showed that copper elicited strong effects in all tested biomarkers for both acute and chronic challenges. Cadmium caused a similar response and was shown to cause significant changes particularly in catalase and glutathione-S-transferases activities. These findings evidence that ecologically relevant concentrations of common anthropogenic contaminants are causative agents of serious imbalances (namely oxidative stress) that are likely to trigger life-threatening events.

Copper exposure induces toxicity to the antioxidant system via the destruction of Nrf2/ARE signaling and caspase-3-regulated DNA damage in fish muscle: amelioration by myo-inositol

The muscle is the main portion of fish that is consumed by humans. Copper (Cu) can induce oxidative damage in fish muscle. However, the effects of Cu exposure on the muscle antioxidant system and molecular patterns and preventive measures against these effects remain unclear. In this study, ROS production, enzymatic and mRNA levels of antioxidant enzymes and NF-E2-related factor 2 (Nrf2) signaling-related molecules, antioxidant response element (ARE) binding ability, DNA fragmentation and caspase-3 activities were analyzed in fish muscle following Cu exposure or myo-inositol (MI) pre-administration. The results indicated that contamination due to copper exposure caused an approximately three-fold increase in ROS production, induced lipid peroxidation and protein oxidation, and resulted in depletion of the glutathione (GSH) content of fish muscle. Moreover, Cu exposure caused decreases in the activities of total superoxide dismutase (T-SOD), CuZnSOD, and glutathione peroxidase (GPx) that were accompanied by decreases in CuZnSOD, GPx1a, GPx1b and signaling factor protein kinase C delta mRNA levels. The decreases in the antioxidant enzyme gene mRNA levels were confirmed to be partly due to the reduced nuclear Nrf2 protein levels, poor ARE binding ability and increased caspase-3 signaling-modulated DNA fragmentation in the fish muscle. Interestingly, MI pre-treatment prevented fish muscle from Cu-induced oxidative damages mainly through increasing the GSH content, and increasing the CuZnSOD and GPx activities and corresponding mRNA levels and ARE binding ability. Taken together, our results show for the first time that Cu exposure caused oxidative damage to the muscle by decreasing the antioxidant enzyme activities via the down-regulation of the expression of genes related to the disruption of the Nrf2/ARE signaling, and this down-regulation was partially caused by caspase-3-regulated DNA fragmentation. Finally, MI protects fish against Cu toxicity.

Copper exposure induces oxidative injury, disturbs the antioxidant system and changes the Nrf2/ARE (CuZnSOD) signaling in the fish brain: protective effects of myo-inositol

The brain is the center of the nervous system in all vertebrates, and homeostasis of the brain is crucial for fish survival. Copper (Cu) is essential for normal cellular processes in most eukaryotic organisms but is toxic in excess. Although Cu is indicated as a potent neurotoxicant, information regarding its threat to fish brain and underlying mechanisms is still scarce. In accordance, the objective of this study was to assess the effects and the potential mechanism of Cu toxicity by evaluating brain oxidative status, the enzymatic and mRNA levels of antioxidant genes, as well as the Nrf2/ARE signaling in the brain of fish after Cu exposure. The protective effects of myo-inositol (MI) against subsequent Cu exposure were also investigated. The results indicate that induction of oxidative stress by Cu is shown by increases in brain ROS production, lipid peroxidation and protein oxidation, which are accompanied by depletions of antioxidants, including total superoxide dismutase (T-SOD), CuZnSOD, glutathione-S-transferase (GST) and glutathione reductase (GR) activities and glutathione (GSH) content. Cu exposure increased the catalase (CAT) and glutathione peroxidase (GPx) activities. Further molecular results showed that Cu exposure up-regulated CuZnSOD, GPx1a and GR mRNA levels, suggesting an adaptive mechanism against stress. Moreover, Cu exposure increased fish brain Nrf2 nuclear accumulation and increased its ability of binding to ARE (CuZnSOD), which supported the increased CuZnSOD mRNA levels. In addition, Cu exposure caused increases of the expression of the Nrf2, Maf G1 (rather than Maf G2 gene) and PKCd genes, suggesting that de novo synthesis of those factors is required for the protracted induction of such antioxidant genes. However, the modulation of Keap1a (rather than Keap1b) of fish brain under Cu exposure might be used to turn off of the signaling cascade and avoid harmful effects. Interestingly, pre-treatment of fish with MI prevented the fish brain from Cu-induced oxidative damages mainly by increasing the GSH content and CuZnSOD and GST activities. Summarily, this study indicates that although Cu stimulates adaptive increases in the expression of some antioxidant enzyme genes through Nrf2/ARE signaling, it also induces oxidation and the depletion of most of antioxidant enzyme activities and GSH content due to the increase of ROS production, and MI protects the fish brain against Cu toxicity.

Oxidative damage repair by glutamine in fish enterocytes

Fish intestine is very sensitive to oxidative damage. Repair of damaged enterocytes may be involved to restore normal function of fish intestine. However, studies of fish enterocyte repair are scarce. The present study aimed to investigate the potential repair role of glutamine after a H2O2 challenge. In this study, fish enterocytes were post-treated with graded levels of glutamine (0, 4, 8, 12 and 20 mM of glutamine) after expose to 100 μM H2O2. The basal control cells were kept in the glutamine-free minimum essential medium only. Results showed that the H2O2-induced decreases in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide optical density, alkaline phosphatase and Na(+), K(+)-ATPase activities were completely restored by subsequent glutamine treatments. In addition, cellular injury (lactate dehydrogenase), lipid peroxidation (malondialdehyde) and protein oxidation (protein carbonyls) caused by H2O2 were reversed by subsequent glutamine treatments. Furthermore, the H2O2-induced decreases in glutathione contents, glutathione reductase, superoxide dismutase and glutathione peroxidase activities were completely restored by subsequent glutamine treatments. In summary, the present study indicated that glutamine improved the repair activity in fish enterocytes after challenge with H2O2.

Molecular basis for antioxidant enzymes in mediating copper detoxification in the nematode Caenorhabditis elegans

Antioxidant enzymes play a major role in defending against oxidative damage by copper. However, few studies have been performed to determine which antioxidant enzymes respond to and are necessary for copper detoxification. In this study, we examined both the activities and mRNA levels of SOD, CAT, and GPX under excessive copper stress in Caenorhabditis elegans, which is a powerful model for toxicity studies. Then, taking advantage of the genetics of this model, we assessed the lethal concentration (LC50) values of copper for related mutant strains. The results showed that the SOD, CAT, and GPX activities were significantly greater in treated groups than in controls. The mRNA levels of sod-3, sod-5, ctl-1, ctl-2, and almost all gpx genes were also significantly greater in treated groups than in controls. Among tested mutants, the sod-5, ctl-1, gpx-3, gpx-4, and gpx-6 variants exhibited hypersensitivity to copper. The strains with SOD or CAT over expression were reduced sensitive to copper. Mutations in daf-2 and age-1, which are involved in the insulin/insulin-like growth factor-1 signaling pathway, result in reduced sensitivity to stress. Here, we showed that LC50 values for copper in daf-2 and age-1 mutants were significantly greater than in N2 worms. However, the LC50 values in daf-16;daf-2 and daf-16;age-1 mutants were significantly reduced than in daf-2 and age-1 mutants, implying that reduced copper sensitivity is influenced by DAF-16-related functioning. SOD, CAT, and GPX activities and the mRNA levels of the associated copper responsive genes were significantly increased in daf-2 and age-1 mutants compared to N2. Additionally, the activities of SOD, CAT, and GPX were greater in these mutants than in N2 when treated with copper. Our results not only support the theory that antioxidant enzymes play an important role in copper detoxification but also identify the response and the genes involved in these processes.

Dietary tryptophan modulates intestinal immune response, barrier function, antioxidant status and gene expression of TOR and Nrf2 in young grass carp (Ctenopharyngodon idella)

The present research evaluated the effects of dietary tryptophan (Trp) on growth performance, intestinal mucosal immune, barrier function and antioxidant capacity and gene expression of young grass carp (Ctenopharyngodon idella). Fish were fed six different experimental diets containing graded levels of Trp at 0.7(control), 1.7, 3.1, 4.0, 5.2 and 6.1 g kg(-1) diet for 8 weeks. The results showed that Trp supplementation significantly enhanced the percent weight gain (PWG), feed intake and feed efficiency (P < 0.05), and decreased the plasma ammonia content (PAC) (P < 0.05). After the 8-week feeding trail, an environmental copper exposure trail was conducted for 4 days. Results from the copper exposure trail showed that dietary Trp enhanced the lysozyme, acid phosphatase activities and complement 3 contents in the intestine of young grass carp (P < 0.05). In addition, Trp supplementation increased the copper/zinc superoxide dismutase (SOD1), glutathione peroxidase (GPx) activities and glutathione contents (P < 0.05), and decreased the protein carbonyl and malondialdehyde contents (P < 0.05). Furthermore, the relative gene expression levels of interleukin 10, transforming growth factor-β1, occludin, zonula occludens 1, claudin-b, -c, and -3, SOD1, GPx and NF-E2-related factor 2 in the intestine were significantly up-regulated with increasing of dietary Trp up to a certain level (P < 0.05). Conversely, the mRNA levels of tumor necrosis factor α, interleukin 8, target of rapamycin, Kelch-like-ECH-associated protein 1, claudin-12 and -15a in the intestine were significantly down-regulated by Trp (P < 0.05). Collectively, appropriate dietary Trp level improves fish growth, intestinal immune response, barrier function and antioxidant status, and regulated the mRNA levels of related signal molecules of young grass carp. Based on the quadratic regression analysis of the PWG and PAC, the dietary Trp requirement of young grass carp (287-699 g) was estimated to be 3.81 g kg(-1) diet (12.7 g kg(-1) protein) and 3.89 g kg(-1) diet (13.0 g kg(-1) protein), respectively.

Goldfish brain and heart are well protected from Ni²⁺-induced oxidative stress

After 96 h goldfish exposure to 10, 25 or 50 mg/L of Ni(2+) no Ni accumulation was found in the brain, but lipid peroxide concentration was by 44% elevated in the brain, whereas carbonyl protein content was by 45-45% decreased in the heart. High molecular mass thiol concentration was enhanced by 30% in the heart, while in the brain low molecular mass thiol concentration increased by 28-88%. Superoxide dismutase activity was by 27% and 35% increased in the brain and heart, respectively. Glutathione peroxidase activity was lowered to 38% and 62% of control values in both tissues, whereas catalase activity was increased in the heart by 15-45%, accompanied by 18-29% decreased glutathione reductase activity. The disturbances of free radical processes in the brain and heart might result from Ni-induced injuries to other organs with more prominent changes in the heart, because of close contact of this organ with blood, whereas the blood-brain barrier seems to protect the brain.

Lithium carbonate teratogenic effects in chick cardiomyocyte micromass system and mouse embryonic stem cell derived cardiomyocyte--possible protective role of myo-inositol

The drug lithium carbonate (Li2CO3) use during pregnancy increases the possibility of cardiovascular anomalies. The earlier studies confirm its phosphatidylinositol cycle (PI) inhibition and Wnt pathways mimicking properties, which might contribute to its teratogenic effects. In this study the toxic effects of Li2CO3 in chick embryonic cardiomyocyte micromass system (MM) and embryonic stem cell derived cardiomyocyte (ESDC) were evaluated, with possible protective role of myo-inositol. In MM system the Li2CO3 did not alter the toxicity estimation endpoints, whereas in ESDC system the cardiomyocytes contractile activity stopped at 1500 μM and above with significant increase in total cellular protein contents. In ESDC system when myo-inositol was added along with Li2CO3 to continue PI cycle, the contractile activity was recovered with decreased protein content. The lithium toxic effects depend on the role of PI cycle at particular stage of cardiogenesis, while relation between myo-inositol and reduced cellular protein contents remains unknown.

Effects of chronic exposure to lead, copper, zinc, and cadmium on biomarkers of the European eel, Anguilla anguilla

Exposure to specific metallic compounds can cause severe deleterious modifications in organisms. Fishes are particularly prone to toxic effects from exposure to metallic compounds via their environment. Species that inhabit estuaries or freshwater environments can be chronically affected by persistent exposure to a large number of metallic compounds, particularly those released by industrial activities. In this study, we exposed yellow eels (European eel, Anguilla anguilla) for 28 days to environmentally relevant concentrations of four specific metals; lead (300, 600, and 1,200 μg/l), copper (40, 120, and 360 μg/l), zinc (30, 60, and 120 μg/l) and cadmium (50, 150, and 450 μg/l). The selected endpoints to assess the toxicological effects were neurotransmission (cholinesterasic activity in nervous tissue), antioxidant defense, and phase II metabolism (glutathione-S-transferase [GST] activity, in both gills and liver tissues), and peroxidative damage. The results showed an overall lack of effects on acetylcholinesterase for all tested metals. Lead, copper, and cadmium exposure caused a significant, dose-dependent, increase in GST activity in gill tissue. However, liver GST only significantly increased following zinc exposure. No statistically significant effects were observed for the thiobarbituric acid reactive substances assay, indicating the absence of peroxidative damage. These findings suggest that, despite the occurrence of an oxidative-based response after exposure to lead, copper, and cadmium, this had no consequence in terms of peroxidative membrane damage; furthermore, cholinergic neurotoxicity caused by lead, copper, and cadmium did not occur. The implications of these results are further discussed.

Effects of copper exposure on the hatching status and antioxidant defense at different developmental stages of embryos and larvae of goldfish Carassius auratus

This study aims to assess the effects of copper exposure on hatching status and antioxidant defense at different stages of embryos and larvae of goldfish Carassius auratus. In this study, day-old embryos were randomly grouped after fertilization and then exposed to copper concentrations of 0, 0.1, 0.4, 0.7, and 1.0mgL(-1). Copper-exposed fish embryos were sampled every 24h to determine superoxide dismutase (SOD), and catalase (CAT) activities, as well as malondialdehyde (MDA) content. In addition, cumulative mortality and larval deformity were also investigated. The findings showed that cumulative mortality and larval deformity rate increased gradually with copper concentration increase. SOD and CAT activities were inhibited at higher copper concentrations. At a lower concentration (0.1mgL(-1)), SOD activity increased in larvae, whereas CAT activity showed no significant change (p>0.05). MDA, as the lipid peroxidation product, gradually accumulated in embryos and larvae with increasing copper concentration and the extension of exposure time. At 0.4mgL(-1) and more, copper toxicity was shown in embryos and larvae. In conclusion, copper-exposed effects on hatching status and antioxidant defense in C. auratus embryos and larvae showed concentration- and time-dependent patterns. The biochemical parameters in this study can be used as effective indicators for evaluating the responses of copper-exposed fish embryos. In addition, this study demonstrates that 0.4mgL(-1) copper (corresponding to 1mgL(-1) copper sulfate), used to kill parasites in aquaculture, is not safe concentration, because it can result in toxicity to larvae. Therefore, the copper concentration to kill pathogen should be less than 0.4mgL(-1) for C. auratus.

Protective effect of hydroferrate fluid, MRN-100, against lethality and hematopoietic tissue damage in γ-radiated Nile tilapia, Oreochromis niloticus

Hydroferrate fluid, MRN-100, an iron-based compound derived from bivalent and trivalent ferrates, is a potent antioxidant compound. Therefore, we examined the protective effect of MRN-100 against γ-radiation-induced lethality and damage to hematopoietic tissues in fish. A total of 216 Nile tilapia fish (Oreochromis niloticus) were randomly divided into four groups. Group 1 served as a control that was administered no radiation and no MRN-100 treatment. Group 2 was exposed only to γ-radiation (15 Gy). Groups 3 and 4 were pre-treated with MRN-100 at doses of either 1 ml/l or 3 ml/l in water for 1 week, and subsequently exposed to radiation while continuing to receive MRN-100 for 27 days. The survival rate was measured, and biochemical and histopathological analyses of hematopoietic tissues were performed for the different treatment groups at 1 and 4 weeks post-radiation. Exposure to radiation reduced the survival rate to 27.7%, while treatment with MRN-100 maintained the survival rate at 87.2%. In addition, fish exposed to γ-radiation for 1 week showed a significant decrease in the total number of white blood cells (WBCs) and red blood cells (RBCs) series. However, treatment with MRN-100 protected the total WBC count and the RBCs series when compared with irradiated fish. Furthermore, significant histological lesions were observed in the hepatopancreas, spleen and gills of irradiated fish. However, treatment with MRN-100 protected the histopathology of various organs. We conclude that MRN-100 is a radioprotective agent in fish and may be useful as an adjuvant treatment to counteract the adverse side effects associated with radiation exposure.

In vitro interceptive and reparative effects of myo-inositol against copper-induced oxidative damage and antioxidant system disturbance in primary cultured fish enterocytes

Copper (Cu) is essential for normal cellular processes in most eukaryotic organisms but is toxic in excess. Our previous study reported that a nutrient antioxidant, myo-inositol (MI), can protect fish from Cu-induced oxidative injury; however, the mechanisms involved are not fully understood. Therefore, the present study aimed to analyze potential pathways. First, to investigate the hypothesis that MI protects enterocytes against Cu toxicity via the intercept pathway, enterocytes were treated with different concentrations of MI (0-75mg/L medium) in the presence of 6mg/L of Cu for 24h (Experiment 1). Next, we investigated the potential reparative role of MI after a Cu challenge (Experiment 2). The results of Experiment 1 indicated that cells exposed to Cu alone for 24h exhibited increases in lactate dehydrogenase release (LDH), malondialdehyde (MDA) formation and protein oxidation (P<0.05). Notably, a dose-dependent inhibitory effect on LDH release was observed with all doses of MI. Moreover, co-treatment with MI completely inhibited Cu-induced protein carbonyl (PC) formation. However, Cu-induced lipid peroxidation was not altered by MI co-treatment. Additionally, Cu exposure suppressed total-superoxide dismutase (T-SOD), CuZnSOD and catalase (CAT) activities, and these changes were completely blocked by co-treatment with sufficient MI concentrations. In contrast, cells exposed to Cu exhibited adaptive increases in reduced glutathione (GSH) content and the activities of anti-hydroxyl radical (AHR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR). Interestingly, the Cu-stimulated increases in these antioxidants were blocked by co-treatment with sufficient MI concentrations. The results of Experiment 2 indicated that cell injury (LDH release), lipid peroxidation (MDA formation) and protein oxidation induced by Cu were reversed by subsequent MI treatment. Meanwhile, Cu-induced decreases in alkaline phosphatase (AKP), anti-superoxide anion (ASA), T-SOD and CuZnSOD activities were completely restored by subsequent MI treatment, while the reduced CAT activity was partially restored. However, MI rescues partially restored the adaptive increase in GPx activity induced by Cu, whereas the adaptive increase in reduced GSH content was completely reversed by 75mg/L of MI. However, subsequent MI treatments did not alter the induction of GST activity by Cu. In conclusion, we demonstrated for the first time that MI not only protected enterocytes from Cu-induced oxidative damage but also increased the repair activity in primary enterocytes after challenge with Cu. Moreover, MI-mediated increases in antioxidant enzyme activities contributed to lipid and protein oxidant repair.

Oxidative stress parameters and anti-apoptotic response to hydroxyl radicals in fish erythrocytes: protective effects of glutamine, alanine, citrulline and proline

The present study explored the protective effects of glutamine (Gln), alanine (Ala), citrulline (Cit) and proline (Pro) on hydroxyl radical (·OH)-induced apoptosis in isolated carp erythrocytes. Hydroxyl radicals were generated by ferrous ion (Fe(2+))-mediated decomposition of hydrogen peroxide (H(2)O(2)) (Fenton reaction). In order to select an optimal ·OH concentration to induce apoptosis, cultures were treated with different concentrations of FeSO(4)/H(2)O(2) (0 μM/0 μM-50 μM/25 μM). The results showed that exposure to FeSO(4)/H(2)O(2) (0 μM/0 μM-40 μM/20 μM) increased apoptosis in a dose-dependent manner. Moreover, apoptosis was at its highest level at 40 μM FeSO(4)/20 μM H(2)O(2). We then examined the cytoprotective effects of Gln, Ala, Cit, Pro or the combination of Ala, Cit and Pro under conditions of apoptosis. Carp erythrocytes were treated with the substances listed above in the presence of 40 μM FeSO(4)/20 μM H(2)O(2) for 9 h. The controls were grown in Gln, Ala, Cit, Pro-free culture medium. The results showed that Gln, Ala, Cit, Pro and the combination of Ala, Cit and Pro effectively protected against annexin binding, decrease of forward scatter and DNA fragmentation in carp erythrocytes induced by ·OH. Furthermore, Gln, Ala, Cit, Pro and the combination of Ala, Cit and Pro effectively blocked ·OH-stimulated erythrocyte hemolysis, reduced the increase of superoxide anion and H(2)O(2) concentrations, inhibited the formation of malondialdehyde, protein carbonyls and met-hemoglobin, and prevented the decrease of superoxide dismutase, catalase and glutathione peroxidase activities and glutathione content in carp erythrocytes induced by ·OH. In addition, the results suggest that the combination of Ala, Cit and Pro produces a greater anti-apoptotic and anti-oxidative effect than their individual effects at the same concentrations. Taken together, the results showed that ·OH induces apoptosis and oxidative damage in carp erythrocytes. In addition to inhibiting apoptosis, Gln, Ala, Cit, Pro and the combination of Ala, Cit and Pro protected carp erythrocytes against oxidative damage induced by ·OH, which may be a major factor in the protection of erythrocytes from apoptosis.

Chronic treatment with myo-inositol reduces white adipose tissue accretion and improves insulin sensitivity in female mice

Type 2 diabetes is a complex disease characterized by a state of insulin resistance in peripheral tissues such as skeletal muscle, adipose tissue or liver. Some inositol isomers have been reported to possess insulin-mimetic activity and to be efficient in lowering blood glucose level. The aim of the present study was to assess in mice the metabolic effects of a chronic treatment with myo-inositol, the most common stereoisomer of inositol. Mice given myo-inositol treatment (0.9 or 1.2 mg g(-1) day(-1), 15 days, orally or intraperitoneally) exhibited an improved glucose tolerance due to a greater insulin sensitivity. Mice treated with myo-inositol exhibited a decreased white adipose tissue accretion (-33%, P<.005) compared with controls. The decrease in white adipose tissue deposition was due to a decrease in adipose cell volume (-33%, P<.05), while no change was noticed in total adipocyte number. In skeletal muscle, in vivo as well as ex vivo myo-inositol treatment increased protein kinase B/Akt phosphorylation under baseline and insulin-stimulated conditions, suggesting a synergistic action of myo-inositol treatment and insulin on proteins of the insulin signalling pathway. Myo-inositol could therefore constitute a viable nutritional strategy for the prevention and/or treatment of insulin resistance and type 2 diabetes.