Oxidative stress in patients with differentiated thyroid cancer: early effects of radioiodine therapy.

Ionizing radiation in differentiated thyroid cancer (DTC) patients treated with radioiodine (131-I) produces reactive oxygen species (ROS), which could induce oxidative stress with disturbance of redox balance. The aim of this study was to evaluate oxidative stress in DTC patients treated with 3.7 or 5.5 GBq of 131-I using values for serum malondialdehyde (MDA, a marker of oxidative stress), uric acid (to determine antioxidant status) and total antioxidative status (TAS). The study population included 20 DTC patients and 20 healthy controls. Significant differences in MDA concentrations were found between DTC patients before 131-I therapy and control subjects (p = 0.001), while TAS values were similar in both populations (p > 0.05). There was a negative correlation between MDA concentrations and TAS in the DTC group before therapy (R2 = 0.2973, p = 0.013). Three days after 131-I therapy, MDA concentrations were higher than the pretreatment values (3.36 +/- 1.69 nmol/mL vs. 2.93 +/- 1.31 nmol/mL; p = 0.006), while serum uric acid concentrations declined progressively from 341.0 +/- 80.39 micromol/L to 304.25 +/- 77.25 micromol/L (p = 0.026) in 3 days and 291.2 +/- 88.86 micromol/L (p = 0.009) in 7 days after 131-I therapy. There was no dose-dependent effect on MDA, or uric acid concentrations and TAS. Thus, 131-I therapy in DTC patients induced oxidative stress, which was accompanied by a simultaneous and extended reduction in uric acid concentration, but without significant disturbances in TAS. This is the first study that evaluated TAS capacity in DTC patients before and 7 days after 131-I therapy. The relatively stabile TAS values in these patients indicated a good protection from oxidative stress induced by high doses of ionizing radiation.

Protective effects of glucose-6-phosphate dehydrogenase on neurotoxicity of aluminium applied into the CA1 sector of rat hippocampus.

BACKGROUND & OBJECTIVES: Aluminum (Al) toxicity is closely linked to the pathogenesis of Alzheimer's disease (AD). This experimental study was aimed to investigate the active avoidance behaviour of rats after intrahippocampal injection of Al, and biochemical and immunohistochemical changes in three bilateral brain structures namely, forebrain cortex (FBCx), hippocampus and basal forebrain (BF). METHODS: Seven days after intra-hippocampal (CA1 sector) injection of AlCl3 into adult male Wistar rats they were subjected to two-way active avoidance (AA) tests over five consecutive days. Control rats were treated with 0.9% w/v saline. The animals were decapitated on the day 12 post-injection. The activities of acetylcholinesterase (AChE) and glucose-6-phosphate dehydrogenase (G6PDH) were measured in the FBCx, hippocampus and BF. Immunohistochemical staining was performed for transferrin receptors, amyloid ß and tau protein. RESULTS: The activities of both AChE and G6PDH were found to be decreased bilaterally in the FBCx, hippocampus and basal forebrain compared to those of control rats. The number of correct AA responses was reduced by AlCl3 treatment. G6PDH administered prior to AlCl 3 resulted in a reversal of the effects of AlCl3 on both biochemical and behavioural parameters. Strong immunohistochemical staining of transferrin receptors was found bilaterally in the FBCx and the hippocampus in all three study groups. In addition, very strong amyloid ß staining was detected bilaterally in all structures in AlCl3-treated rats but was moderate in G6PDH/AlCl3-treated rats. Strong tau staining was noted bilaterally in AlCl3-treated rats. In contrast, tau staining was only moderate in G6PDH/AlCl3-treated rats. INTERPRETATION & CONCLUSIONS: Our findings indicated that the G6PDH alleviated the signs of behavioural and biochemical effects of AlCl3-treatment suggesting its involvement in the pathogenesis of Al neurotoxicity and its potential therapeutic benefit. The present model could serve as a useful tool in AD investigations.

Influence of the green tea leaf extract on neurotoxicity of aluminium chloride in rats.

Aluminium may have an important role in the aetiology/pathogenesis/precipitation of Alzheimer's disease. Because green tea (Camellia sinensis L.) reportedly has health-promoting effects in the central nervous system, we evaluated the effects of green tea leaf extract (GTLE) on aluminium chloride (AlCl3 ) neurotoxicity in rats. All solutions were injected into the cornu ammonis region 1 hippocampal region. We measured the performance of active avoidance (AA) tasks, various enzyme activities and total glutathione content (TGC) in the forebrain cortex (FbC), striatum, basal forebrain (BFb), hippocampus, brain stem and cerebellum. AlCl3 markedly reduced AA performance and activities of cytochrome c oxidase (COX) and acetylcholinesterase (AChE) in all regions. It decreased TGC in the FbC, striatum, BFb, hippocampus, brain stem and cerebellum, and increased superoxide dismutase activity in the FbC, cerebellum and BFb. GTLE pretreatment completely reversed the damaging effects of AlCl3 on AA and superoxide dismutase activity, markedly corrected COX and AChE activities, and moderately improved TGC. GTLE alone increased COX and AChE activities in almost all regions. GTLE reduces AlCl3 neurotoxicity probably via antioxidative effects and improves mitochondrial and cholinergic synaptic functions through the actions of (-)-epigallocatechin gallate and (-)-epicatechin, compounds most abundantly found in GTLE. Our results suggest that green tea might be beneficial in Alzheimer's disease.

Cytochrome c oxidase activity and nitric oxide synthase in the rat brain following aluminium intracerebral application.

In the present study we investigated the cytochrome C oxidase (CO) activity and nitric oxide synthase (NOS) isoenzyme expression after intrahippocampal AlCl3 application in selective vulnerable brain structures. A single dose of AlCl3 was applied in the CA1 sector of rats hippocampus. For biochemical analysis, the animals were killed 10 min and three days after the treatment and forebrain cortex, basal forebrain and hippocampus were removed. Activity of CO was decreased bilaterally in the AlCl3-treated groups in all examined brain structures. We also applied immunohistochemical techniques to identify changes induced by AlCl3 injection after survival periods of 10 min and three days. Both the nNOS and eNOS stains were detected in the hippocampus of controls and AlCl3-treated animals, but iNOS labelling was present in the hippocampus only three days after AlCl3 application. An increased iNOS expression three days post AlCl3 administration could be involved in the mechanism of CO activity depletion.

Influence of NG-nitro-L-arginine methyl ester on clinical and biochemical effects of methylene blue in pentylenetetrazole-evoked convulsions.

BACKGROUND/AIM: Despite years of research in a number of experimental models the question whether nitric oxide (NO) and methylene blue (MB) have pro- or anticonvulsant effects remains to be fully resolved. Methods. In adult Wistar rats the influence of a nonselective inhibitor of nitric oxide synthase NG-nitro-L-arginine methyl ester (L-NAME, 10 microg) on clinical and biochemical effects of MB (10 microg) given before the intraperitoneally administered chemical convulsant pentylenetetrazole (PTZ, 80 mg/kg) was examined. MB and L-NAME were applied intracerebroventricularly. PTZ application was followed by a 4-minute observation time, after which rats were sacrificed and elements of oxido-reductive balance were measured in a crude mitochondrial fraction of forebrain cortex, hippocampus and striatum. RESULTS: Convulsive responses (forelimb dystonia--FLD, generalised clonic- and clonic-tonic convulsions--GCC and GCTC respectively) were observed in all rats received PTZ, together with significantly decreased lipid peroxidation in the forebrain cortex and striatum and increased superoxide dismutase activity in the hippocampus, in comparison to controls (saline treated). It was registered anticonvulsant effects of L-NAME pretreatment. However, these effects were insignificant. In the hippocampus of these animals there was decreased lipid peroxidation (p < 0.01, p < 0.05 vs saline-treated and PTZ-treated rats, respectively) and reverted PTZ-induced increase of superoxide dismutase activity. But MB individually pretreatment significantly decreased the incidence of CTCs and GCCs (FLD: p = 0.0513), prolonged the convulsive latent time for FLD, GCTCs and GCCs, in all the examined brain regions increased lipid peroxidation and decreased the level of superoxide anion. Administration of L-NAME 10 minutes before MB reverted all MB-evoked clinical and biochemical effects. CONCLUSION: Methylene blue applied individually before PTZ has strong anticonvulsant effects that were eliminated by L-NAME pretreatment. These effects and changed biochemical parameters in the brains of animals treated by L-NAME before MB in comparison to MB-treated group suggest involvement of NO in MB's effects in the animal model of PTZ-evoked convulsions.

Protective role of glutathione reductase in paraquat induced neurotoxicity.

Paraquat (PQ), a widely used herbicide is a well-known free radical producing agent. The mechanistic pathways of PQ neurotoxicity were examined by assessing oxidative/nitrosative stress markers. Focus was on the role of glutathione (GSH) cycle and to examine whether the pre-treatment with enzyme glutathione reductase (GR) could protect the vulnerable brain regions (VBRs) against harmful oxidative effect of PQ. The study was conducted on Wistar rats, randomly divided in five groups: intact-control group, (n = 8) and four experimental groups (n = 24). All tested compounds were administered intrastriatally (i.s.) in one single dose. The following parameters of oxidative status were measured in the striatum, hippocampus and cortex, at 30 min, 24 h and 7 days post treatment: superoxide anion radical (O2·â»), nitrate (NO3⁻), malondialdehyde (MDA), superoxide dismutase (SOD), total GSH (tGSH) and its oxidized, disulfide form (GSSG) and glutathione peroxidase (GPx). Results obtained from the intact and the sham operated groups were not statistically different, confirming that invasive i.s. route of administration would not influence the reliability of results. Also, similar pattern of changes were observed between ipsi- and contra- lateral side of examined VBRs, indicating rapid spatial spreading of oxidative stress. Mortality of the animals (10%), within 24h, along with symptoms of Parkinsonism, after awakening from anesthesia for 2-3 h, were observed in the PQ group, only. Increased levels of O2·â», NO3⁻ and MDA, increased ratio of GSSG/GSH and considerably high activity of GPx were measured at 30 min after the treatment. Cytotoxic effect of PQ was documented by drastic drop of all measured parameters and extremely high peak of the ratio GSSG/GSH at 24th hrs after the PQ i.s. injection. In the GR+PQ group, markedly low activity of GPx and low content of NO3⁻ (in striatum and cortex) were measured during whole experiment, while increase value was observed only for O2·â», at 7th days. We concluded that oxidative/nitrosative stress and excitotoxicity are the most important events since the early stage of PQ induced neurotoxicity. Based on the ratio GSSG/GSH, the oxidation of GSH to GSSG is probably dominant way of GHS depletion and main reason for reduced antioxidative defense against PQ harmful oxidative effect. The GR pre-treatment resulted in the absence of Parkinson's disease-like symptoms and mortality of the rats. Additionally, oxidative/nitrosative stress did not developed, as well as almost diminished metabolism of the VBRs at 24th hours (as has been documented in the PQ group) did not occurred in the GR+PQ, suggesting a neuroprotective role for the GR in PQ induced neurotoxicity.

Intrastriatal pre-treatment with L-NAME protects rats from diquat neurotoxcity.

INTRODUCTION: Contact herbicide diquat (DQ), redox cycling compound, mediates its systemic toxicity throughout the enlarged production of free radicals. Target organs are liver and kidney in humans. To-date, the mechanism of DQ-induced neurotoxicity has not been rationalized. OBJECTIVE: The objectives of the study were to examine the ability of DQ to induce oxidative stress (OS) and/or nitrosative stress (NS) upon intrastriatal (i.s.) administration and to investigate the role of nitric oxide (NO(x)) using NG-nitro-L-arginine methyl ester (L-NAME), a non-selective inhibitor of nitric oxide synthase (NOS) in the pretreatment of DQ i.s. administration. MATERIAL AND METHODS: The experiment was conducted on Wistar rats, randomly divided in experimental groups, receiving different treatments i.s. applied. Parameters of OS/NS such as: superoxide anion radical (O(2)(•-)), superoxide dismutase (SOD), malondialdehyde (MDA) and nitrates (NO(3)(-)) were measured in the cortex (bilaterally), at 30(th) min, 24 hours and 7 days after the treatments. RESULTS: Lethargy and high mortality rate were observed only in the DQ group (within 24 hours and 2-3 hours, respectively) after awakening from anesthesia. Markedly increased production of NO(x) and O(2)(•-) along with elevated lipid peroxidation altogether contributed to DQ neurotoxicity. The most importantly, the L-NAME i.s. pretreatment protected treated animals from dying and diminished OS/NS response against DQ-induced neurotoxicity. CONCLUSION: The i.s. pretreatment with L-NAME resulted in neuroprotection against DQ neurotoxity, based on animal survival and reduced LPO in the cortex.

N-nitro-L-arginine methyl ester influence on aluminium toxicity in the brain.

We investigated the influence of a non-specific nitric oxide synthase (NOS) inhibitor, N-nitro-L-arginine methyl ester (L-NAME), on brain nitrite concentration and acetylcholine esterase activity in AlCl3-treated Wistar rats. Animals were killed 10 min, three hours, three days and 30 days after the treatment and hippocampus and basal forebrain were removed. The biochemical changes observed in neuronal tissues show the involvement of NO in the AlCl3 toxicity and cholinergic neurotransmission, and that L-NAME may have potential neuroprotective effects. Active avoidance learning was significantly impaired after AlCl3 application, while pretreatment with L-NAME prevented the behavioural deficits caused by AlCl3. We also applied immunohistochemical techniques to identify changes induced by AlCl3, L-NAME+AlCl3, as well as L-NAME injections after survival periods of three days and 30 days. Immunoreactivity of astrocytes and phagocytic microglia based on glial fibrillary acidic protein (GFAP) and a useful marker for rat macrophages (ED1), respectively, revealed a greater inflammatory response in AlCl3-injected animals compared to controls.

Nitric oxide synthase inhibitors protect cholinergic neurons against AlCl3 excitotoxicity in the rat brain.

The present experiment was carried out to determine the effectiveness of nitric oxide synthase inhibitors: 7-nitroindazole and aminoguanidine in modulating the toxicity of aluminium chloride on acetylcholine esterase activity, as well as behavioural and morphological changes of Wistar rats. For biochemical analysis the animals were killed 10 min, 3 h, 3 days and 30 days after the treatment and forebrain cortex, striatum, basal forebrain and hippocampus were removed. The biochemical changes observed in neuronal tissues show that nitric oxide synthase inhibitors exert as protective action in aluminium chloride-treated animals. In the present study, active avoidance learning was significantly impaired after aluminium chloride injection, while pretreatment with nitric oxide synthase inhibitors prevented the behavioural deficits caused between 26th and 30th day after intrahippocampal application of neurotoxin. Our data suggest that aluminium may cause learning and memory deficits, while the treatment with specific nitric oxide synthase inhibitors may prevent learning and memory deficits caused by aluminium chloride. We have also applied immunohistochemical techniques to identify neuronal- and inducible-nitric oxide synthase expression 30 days after aluminium chloride and nitric oxide synthase inhibitors injections. Our data suggest that 7-nitroindazole and aminoguanidine can be effective in the protection of toxicity induced by aluminium chloride.

The effect of inhibition of nitric oxide synthase on aluminium-induced toxicity in the rat brain.

The goal of the present study was to examine the effectiveness of a non-specific nitric oxide synthase (NOS) inhibitor N-nitro-L-arginine methyl ester (L-NAME) to modulate the toxicity of aluminium chloride (AlCl3). Rats were killed at 3 h and at 30 days after treatments and the striatum was removed. Nitrite, superoxide, superoxide dismutase activity, malondialdehyde and reduced glutathione were determined. AlCl3 exposure promoted oxidative stress in the striatum. The biochemical changes observed in neuronal tissues show that aluminium acts as pro-oxidant, while the NOS inhibitor exerts antioxidant action in AlCl3-treated rats. We conclude that L-NAME can efficiently protect neuronal tissue from AlCl3-induced toxicity.

Nitric oxide synthase inhibitors partially inhibit oxidative stress development in the rat brain during sepsis provoked by cecal ligation and puncture.

IOxidative stress development in different brain structures and the influence of nitric oxide (NO) overproduction during sepsis was investigated using male Wistar rats. Rats were subjected to cecal ligation and puncture (CLP) or were sham-operated. To evaluate the source of NO production, 30 min before the operation septic and control animals were treated with single intraperitoneal doses of NO synthase (NOS) inhibitors: L-NAME and aminoguanidine (AG) (10, 30 or 90 mg/kg) and 7-nitroindazole (7-NI) (30 mg/kg). The concentration of GSH in the cortex, brain stem, cerebellum, striatum and hippocampus significantly decreased post CLP at both early and late stage sepsis. Lipid peroxidation also occurred in the cortex and cerebellum in late stage sepsis. Pre-treatment with a non-selective NOS inhibitor (L-NAME) and with selective inducible and neuronal NOS inhibitors (AG and 7-NI) revealed benefit effects on the GSH concentrations. Unexpectedly, NOS inhibition resulted in diverse effects on TBARS concentrations, suggesting the importance of specific quantities of NO in specific brain structures during sepsis.

Effects of L-NAME, a non-specific nitric oxide synthase inhibitor, on AlCl3-induced toxicity in the rat forebrain cortex.

The present experiments were done to determine the effectiveness of a non-specific nitric oxide synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME), on oxidative stress parameters induced by aluminium chloride (AlCl(3)) intrahippocampal injections in Wistar rats. Animals were sacrificed 3 h and 30 d after treatments, heads were immediately frozen in liquid nitrogen and forebrain cortices were removed. Crude mitochondrial fraction preparations of forebrain cortices were used for the biochemical analyses: nitrite levels, superoxide production, malondialdehyde concentrations, superoxide dismutase (SOD) activities and reduced glutathione contents. AlCl(3) injection resulted in increased nitrite concentrations, superoxide anion production, malondialdehyde concentrations and reduced glutathione contents in the forebrain cortex, suggesting that AlCl(3) exposure promoted oxidative stress in this brain structure. The biochemical changes observed in neuronal tissues showed that aluminium acted as a pro-oxidant. However, the nonspecific nitric oxide synthase (NOS) inhibitor, L-NAME, exerted anti-oxidant actions in AlCl(3)-treated animals. These results revealed that NO-mediated neurotoxicity due to intrahippocampal AlCl3 injection spread temporally and spatially to the forebrain cortex, and suggested a potentially neuroprotective effect for L-NAME.

Beneficial effects of ceftriaxone against pentylenetetrazole-evoked convulsions.

Although considered to be generally safe, a number of beta-lactam antibiotics have been associated with epileptic seizures in humans. Furthermore, some beta-lactam antibiotics, including ceftriaxone, are used to evoke convulsions under experimental conditions. Recently it was demonstrated that ceftriaxone increased expression of the glutamate transporter (GLT1) and its biochemical and functional activity in the brain of rodents. GLT1 regulates extracellular concentrations of glutamate, an excitatory amino acid involved in the pathogenesis of seizures and epilepsy. Because of its rapid transfer of glutamate into neurons and adjacent glial cells, GLT1 diminishes glutamate toxicity. We investigated whether ceftriaxone (200 mg/kg body wt) administered intraperitoneally (ip) for 6 days could modify the convulsant effects of pentylenetetrazole (PTZ, 100 mg/kg ip) in inbred male BALBcAnNCR and C57 black (BL)/6 mice aged 4 and 12 weeks. Ceftriaxone pretreatment provided significant protective effects against PTZ-evoked generalized clonic convulsions (GCCs), generalized clonic-tonic convulsions (GCTCs), and convulsion-induced mortality during a period of 30 mins after PTZ administration. The incidence of GCCs, GCTCs, and death was statistically significantly lower for BALBcAnNCR mice of both ages, particularly younger mice. The latency time for each of the three parameters was significantly greater, with the exception of GCCs in adult mice. Protective effects of ceftriaxone were also noticed in adult C57BL/6 mice but not in prepubertal C57BL/6 mice. This is the first demonstration of anticonvulsant effects of ceftriaxone or any other beta-lactam antibiotic, which are not uniform across the mouse population. Our results provide new insight into the effects of ceftriaxone, which need further investigation.

The effects of exposure to extremely low-frequency magnetic field and amphetamine on the reduced glutathione in the brain.

Continuous exposure to extremely low-frequency magnetic field (ELF-MF, 50 Hz, 0.5 mT) alone and combined with D-amphetamine (1.5 mg/kg) affected the reduced glutathione content in brain regions of rats. Compared to sham-exposed rats, the glutathione content in the forebrain cortex of the ELF-MF-exposed rats decreased (P < 0.001), but this reverted after giving amphetamine upon ELF-MF exposure. In this group, the glutathione content was increased in the brain stem and cerebellum (P < 0.05 compared to the sham-exposed, ELM-MF-exposed, and amphetamine-treated groups). It is suggested that biogenic monoamines are involved in the reduced glutathione changes observed. The changes are not uniform in the brain regions examined.

Changes of cortisol levels and index of lipid peroxidation in cerebrospinal fluid of patients in the acute phase of completed stroke.

BACKGROUND: Brain ischemia initiates series of biochemical reactions that could, directly or indirectly, induce and extend processes that damage numerous cellular and subcellular structures. One of the reactions of organism to ischemia is the increased release of glucocorticoid hormones, included in regulation of effects of numerous mediators/modulators that could be released in the acute phase of brain ischemia. Considering that brain infarction induced systemic response of organism to stress, we presumed that it reflected the contents of cortisol in the cerebrospinal fluid (CSF) during the acute phase of the disease, and that cortisol influenced damaging processes of lipid peroxidation in CNS initiated by ischemia. The aim of our investigation was to define temporal dynamics and manner correlation of cortisol concentration and index of lipid peroxidation (ILP) in the CSF patients in the acute phase of completed stroke. METHODS: In this investigation we followed changes of cortisol concentration and ILP in the CSF of 53 patients in the acute phase of completed stroke. Control group included 14 age and sex matched patients, subjected to diagnostic lumbar radiculography because of the sudden motor deficiency onset, without disturbances in the CSF passage and without pain and the consequences of anti-pain and anti-inflammatory therapy. From the perspective of the duration of period after an ischemic episode patients were divided into four groups: group A: 0-6 hours (n = 12), group B: 7-12 hours (n = 14), group C: 13-24 hours (n = 14), and group D: 24-48 hours of postischemic period (n = 13). Concentration of cortisol in the CSF was measured by quantitative RIA method (Cortisol Bridge kit, Biodata). The ILP was determined according to the spectrophotometric method. RESULTS: Concentration of cortisol in the CSF of patients with completed stroke was of amount 69 +/- 6.7 pmol/ml CSF and was significantly increased (p < 0.001) compared to the values of the control group (2.49 +/- 0.29 pmol/ml CSF). From 0 to 6 hours after the ischemic insults concentration of cortisol in the CSF the amount was 15.9 +/- 2.4 pmol/ml CSF (p < 0.001), then was progressively increasing and was maximal from 13 to 24 hours after insults (123.2 +/- 7.1 pmol/ml CSF), (p < 0.001). In patients with completed stroke ILP in the CSF was twice increased in the course of 48 hours compared to controls (0.54 +/- 0.08 nmolMDA/ml CSF), (p < 0.05). By comparing the observed parameters we found significant negative correlation between this two indicators in period from 7 to 24 hours (r = -0.77), (p < 0.001). CONCLUSION: The main potentially protective effect of the increased CSF cortisol concentration in patients with completed stroke in the acute phase could be the decrease of deleterious effects of lipid peroxidation reactions induced by ischemia. This mechanism could be the attempt of organism to compensate ischemia-disturbed homeostasis.

Effects of nerve and fibroblast growth factors on the production of nitric oxide in experimental model of Huntington's disease.

The role of nitric oxide (NO) in neurological diseases represents one of the most studied, yet controversial subjects in physiology. The aim was to examine the effects of intrastriatal injection neurotrophins (nerve growth factors-NGF, fibroblast growth factors-FGF) in order to investigate the possible involvement of NO in quinolinic acid (QA) induced striatal toxicity in the rat model of Huntington's disease (HD). QA was administered unilaterally into the striatum of adult Wistar rats in a single dose of 150 nM. The other two groups of animals were pretreated immediately before QA application with NGF and FGF, respectively. Control group was treated with 0.9% saline solution in the same manner. Animals were decapitated 7 days after the treatment. Nitrite levels were significantly decreased both in the ipsi- and contralateral striatum and forebrain cortex of NGF- and FGF-treated animals compared with QA treatment. These results indicated a temporal and spatial propagation of oxidative stress and spread protective effects of NGF and FGF on the forebrain cortex, the distant structure, but tightly connected with striatum, the place of direct neurotoxic damage. Neurotrophins could be the potential neuroprotective agents in HD.