Reactive oxygen species are key mediators of the nitric oxide apoptotic pathway in anterior pituitary cells

Protective effect of Dunaliella sp., lipid extract rich in polyunsaturated fatty acids, on hepatic and renal toxicity induced by nickel in rats

AIMS

The present study was undertaken to investigate the protective effect of lipid extract of Dunaliella sp. (LE) rich in polyunsaturated fatty acids (PUFA), against oxidative stress induced by nickel in experimental rats.

METHODS

Our investigation evaluated the antioxidant activity of LE using both DPPH and NBT assays. Twenty female albino Wistar rats, randomly allocated into four experimental groups, namely (C): control, (Nit): nickel-treated rats with 5 mg/kg/d of NiCl2 during 30 days, (LEa): lipid extract-administered rats with 5  mg/kg BW/d during 30 days and (Nit + LEa): rats treated with Ni and LE-administered during 30 days.

RESULTS

The in vitro antioxidant activity demonstrated that LE presents an important antioxidant potential. In vivo, the (Nit + LEa) cotreatment decreased the level of malondialdehyde and restored the antioxidant enzyme activities (superoxide dismutase, catalase and glutathione peroxidase) in livers and kidneys in comparison with those treated with Ni only. LE administration to rats treated with Ni also ameliorated biochemical and histological parameters as compared to only Ni-treated group. LE of Dunaliella sp., rich in polyunsaturated fatty acids showed a significant hepato- and reno-protective effect against metal-induced toxicity.

CONCLUSION

LE of Dunaliella sp., rich in PUFA has been proven to be effective in protection against Ni-induced toxicity.

Nitric oxide-induced eosinophil apoptosis is dependent on mitochondrial permeability transition (mPT), JNK and oxidative stress: apoptosis is preceded but not mediated by early mPT-dependent JNK activation

Background

Eosinophils are critically involved in the pathogenesis of asthma. Nitric oxide (NO) is produced in high amounts in asthmatic lungs and has an important role as a regulator of lung inflammation. NO was previously shown to induce eosinophil apoptosis mediated via c-jun N-terminal kinase (JNK) and caspases. Our aim was to clarify the cascade of events leading to NO-induced apoptosis in granulocyte macrophage-colony stimulating factor (GM-CSF)-treated human eosinophils concentrating on the role of mitochondria, reactive oxygen species (ROS) and JNK.

Methods

Apoptosis was determined by flow cytometric analysis of relative DNA content, by Annexin-V labelling and/or morphological analysis. Immunoblotting was used to study phospho-JNK (pJNK) expression. Mitochondrial membrane potential was assessed by JC-1-staining and mitochondrial permeability transition (mPT) by loading cells with calcein acetoxymethyl ester (AM) and CoCl₂ after which flow cytometric analysis was conducted. Statistical significance was calculated by repeated measures analysis of variance (ANOVA) or paired t-test.

Results

NO-donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) induced late apoptosis in GM-CSF-treated eosinophils. SNAP-induced apoptosis was suppressed by inhibitor of mPT bongkrekic acid (BA), inhibitor of JNK SP600125 and superoxide dismutase-mimetic AEOL 10150. Treatment with SNAP led to late loss of mitochondrial membrane potential. Additionally, we found that SNAP induces early partial mPT (1 h) that was followed by a strong increase in pJNK levels (2 h). Both events were prevented by BA. However, these events were not related to apoptosis because SNAP-induced apoptosis was prevented as efficiently when BA was added 16 h after SNAP. In addition to the early and strong rise, pJNK levels were less prominently increased at 20–30 h.

Conclusions

Here we demonstrated that NO-induced eosinophil apoptosis is mediated via ROS, JNK and late mPT. Additionally, our results suggest that NO induces early transient mPT (flickerings) that leads to JNK activation but is not significant for apoptosis. Thereby, we showed some interesting early events in NO-stimulated eosinophils that may take place even if the threshold for irreversible mPT and apoptosis is not crossed. This study also revealed a previously unknown physiological function for transient mPT by showing that it may function as initiator of non-apoptotic JNK signalling.

Beneficial role of naringin, a flavanoid on nickel induced nephrotoxicity in rats

This study was conducted to investigate the beneficial role of naringin on nickel induced nephrotoxicity. Nickel (Ni) (20mg/kg body weight (b.w.) was administered intraperitoneally (i.p.) for 20 days. Naringin was administered orally (20, 40 and 80 mg/kg b.w.) with i.p. administration of Ni. Ni administration increased the levels of serum urea, uric acid and creatinine with a significant decrease in creatinine clearance and decreased levels of urea, uric acid and creatinine in urine. The levels of lipid peroxidation markers and nickel concentration in blood and kidney were also increased. While, the activities of enzymic and non-enzymic antioxidants were decreased. Treatment with naringin attenuated the alterations in the renal and urine markers, decreasing lipid peroxidation markers, increasing the antioxidant cascade and decreasing the nickel concentration in blood and kidney. All these changes were supported by histopathological observations. These findings demonstrate that naringin exerts a protective effect against nickel toxicity.

Cyclic GMP protects human macrophages against peroxynitrite-induced apoptosis

Background

Nitric oxide (NO) can be both pro- and anti-apoptotic in various cell types, including macrophages. This apparent paradox may result from the actions of NO-related species generated in the microenvironment of the cell, for example the formation of peroxynitrite (ONOO^-). In this study we have examined the ability of NO and ONOO^- to evoke apoptosis in human monocyte-derived macrophages (MDMϕ), and investigated whether preconditioning by cyclic guanosine monophosphate (cGMP) is able to limit apoptosis in this cell type.

Methods

Characterisation of the NO-related species generated by (Z)-1- [2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA/NO) and 1,2,3,4-oxatriazolium, 5-amino-3-(3,4-dichlorophenyl)-, chloride (GEA-3162) was performed by electrochemistry using an isolated NO electrode and electron paramagnetic resonance (EPR) spectrometry. Mononuclear cells were isolated from peripheral blood of healthy volunteers and cultured to allow differentiation into MDMϕ. Resultant MDMϕ were treated for 24 h with DETA/NO (100 – 1000 μM) or GEA-3162 (10 – 300 μM) in the presence or absence of BAY 41–2272 (1 μM), isobutylmethylxanthine (IBMX; 1 μM), 1H- [1,2,4]oxadiazolo [4,3-a]quinoxalin-1-one (ODQ; 20 μM) or 8-bromo-cGMP (1 mM). Apoptosis in MDMϕ was assessed by flow cytometric analysis of annexin V binding in combination with propidium iodide staining.

Results

Electrochemistry and EPR revealed that DETA/NO liberated free NO radical, whilst GEA-3162 concomitantly released NO and O₂^-, and is therefore a ONOO^- generator. NO (DETA/NO) had no effect on cell viability, but ONOO^- (GEA-3162) caused a concentration-dependent induction of apoptosis in MDMϕ. Preconditioning of MDMϕ with NO in combination with the phosphodiesterase inhibitor, 3-Isobutyl-1-methylxanthine (IBMX), or the NO-independent stimulator of soluble guanylate cyclase, BAY 41–2272, significantly attenuated ONOO^--induced apoptosis in a cGMP-dependent manner.

Conclusion

These results demonstrate disparities between the ability of NO and ONOO^- to induce apoptosis in human MDMϕ. Furthermore, this study provides evidence for a novel cGMP-dependent pre-conditioning mechanism to limit ONOO^--induced apoptosis in human MDMϕ.

Effects of tetrabrominated diphenyl ether and hexabromocyclododecanes in single and complex exposure to hepatoma HepG2 cells

This study was designed to determine cytotoxic effects of PBDE-47 and HBCDs individually or with a mixture of both compounds exposure to Hep G2 cells. The results showed PBDE-47 and HBCDs induced increase of nitric oxide synthase (NOS) activity, release of NO, dissipation of mitochondria membrane potential and cell apoptosis. Exposure to HBCDs induced ROS formation. Moreover, preincubation with PTIO (NO scavanger) and N-acetylcysteine (ROS scavanger) partially reversed cytotoxic effects of these compounds. The possible mechanism is that PBDE-47 and HBCDs could boost generation of NO and/or ROS, impact mitochondria, and result in start-ups of apoptosis program. Cells exposed to mixture of both compounds and each of them showed non-apoptotic rate significant difference, but the combination of them caused more adverse effects on cells. These results suggest that PBDE-47 and HBCDs in single and complex exposure have the cytotoxic activity of anti-proliferation and induction of apoptosis in tumor cells in vitro.

Discovery of transcriptional regulators and signaling pathways in the developing pituitary gland by bioinformatic and genomic approaches

We report a catalog of the mouse embryonic pituitary gland transcriptome consisting of five cDNA libraries including wild type tissue from E12.5 and E14.5, Prop1(df/df) mutant at E14.5, and two cDNA subtractions: E14.5 WT-E14.5 Prop1(df/df) and E14.5 WT-E12.5 WT. DNA sequence information is assembled into a searchable database with gene ontology terms representing 12,009 expressed genes. We validated coverage of the libraries by detecting most known homeobox gene transcription factor cDNAs. A total of 45 homeobox genes were detected as part of the pituitary transcriptome, representing most expected ones, which validated library coverage, and many novel ones, underscoring the utility of this resource as a discovery tool. We took a similar approach for signaling-pathway members with novel pituitary expression and found 157 genes related to the BMP, FGF, WNT, SHH and NOTCH pathways. These genes are exciting candidates for regulators of pituitary development and function.

Protective effect of cactus (Opuntia ficus indica) cladode extract upon nickel-induced toxicity in rats

The purpose of this study carried out on male Wistar rats, was to evaluate the protective effects of regular ingestion of juice from the prickly pear cactus (Opuntia ficus indica) cladodes against nickel chloride toxicity. Rats were given either normal tap water or water containing 25% of cactus juice for one month. Then, rats of each group were injected daily, for 10 days, with either NiCl(2) solution (4mg (30micromol)/kg body weight) or with the same volume of saline solution (300mM NaCl). Significant increases of lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase activities and of cholesterol, triglycerides and glucose levels were observed in blood of nickel-treated rats. In the liver, nickel chloride was found to induce an oxidative stress evidenced by an increase in lipid peroxidation and changes in antioxidant enzymes activities. Superoxide-dismutase (SOD) activity was found to be increased whereas glutathione peroxidase and catalase activities were decreased. These changes did not occur in animals previously given cactus juice, demonstrating a protective effect of this vegetal extract.