Response of TRPM2 Channel to Hypercapnic Acidosis and Role of Zn, Se, and GSH.

Hypercapnia can increase the production of reactive oxygen species (ROS) by inducing oxidative stress in cells. Transient receptor potential melastatin 2 (TRPM2) channel activation that is realized by ROS plays a critical role in the cellular mechanism. It was shown that antioxidants such as zinc (Zn), selenium (Se), and glutathione (GSH) can partake in the structures of enzymes and create a protective effect against oxidative stress. This study revealed the relationship between TRPM2 channel and hypercapnia, and the interaction of zinc, selenium, and glutathione. In our study, normoxia, hypercapnia, hypercapnia + Zn, hypercapnia + Se, and hypercapnia + GSH were created, in transfected HEK293 cells. The cells were exposed to normoxia or hypercapnia gasses in two different times (30 min and 60 min), while Zn, Se, and GSH were applied to the cells in the other groups before being exposed to the gas mixtures. The statistical evaluation showed a significant increase in lipid peroxidation (LPO) level and lactate dehydrogenase (LDH)% in the hypercapnia 30 min and 60 min groups, compared to the normoxia 30 min and 60 min groups, and an increase in LPO level and LDH% in the hypercapnia groups that Zn, Se, and GSH were applied. It was determined that in comparison with the normoxia 30 min and 60 min groups, the amount of inward Ca+2 current across TRPM2 channels and mean current density increased in the groups that were exposed to hypercapnia for 30 min and 60 min, while the same values significantly decreased in the hypercapnia groups that Zn, Se, and GSH were applied. Also, it was shown that oxidative stress rose as the duration of hypercapnia exposure increased. It was concluded that hypercapnia increased oxidative stress and caused cellular membrane damage, while the addition of Zn, Se, and GSH could protect the cell membrane from these damaging effects.

Involvement of apoptosis and calcium accumulation through TRPV1 channels in neurobiology of epilepsy.

Calcium ion accumulation into the cytosol of the hippocampus and dorsal root ganglion (DRG) are main reasons in etiology of epilepsy. Transient receptor potential vanilloid type 1 (TRPV1) channel is a cation-permeable calcium channel found in the DRG and hippocampus. Although previous studies implicate TRPV1 channels in the generation of epilepsy, suppression of ongoing seizures by TRPV1 antagonists has not yet been investigated. We tested the effects of TRPV1-specific antagonists, capsazepine (CPZ) and 5'-iodoresiniferatoxin (IRTX) on the modulation of calcium accumulation, apoptosis and anticonvulsant properties in the hippocampus and DRG of pentylentetrazol (PTZ) and capsaicin (CAP) administrated rats. Forty rats were divided into five groups as follows; control, PTZ, CAP+PTZ, IRTX, and IRTX+PTZ. Fura-2 and patch-clamp experiments were performed on neurons dissected from treated animals by CAP and CPZ. PTZ and CAP+PTZ administrations increased intracellular free Ca(2+) concentrations, TRPV1 current densities, apoptosis, caspase 3 and 9 values although the values were reduced by IRTX and CPZ treatments. Latency time was extended by application CPZ and IRTX although CAP produced acceleration of epileptic seizures. Taken together, these results support a role for TRPV1 channels in the inhibition of apoptosis, epileptic seizures and calcium accumulation, indicating that TRPV1 inhibition may possibly be a novel target in the DRG and hippocampus for prevention of epileptic seizures and peripheral pain.

N-acetyl cysteine reduces oxidative toxicity, apoptosis, and calcium entry through TRPV1 channels in the neutrophils of patients with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a common inflammatory and oxidant disease with an uncertain pathogenesis. N-acetyl cysteine (NAC) decreases oxidative stress, intracellular free calcium ion [Ca(2+)]i, and apoptosis levels in human neutrophil. We aimed to investigate the effects of NAC on apoptosis, oxidative stress, and Ca(2+) entry through transient receptor potential vanilloid 1 (TRPV1) and TRP melastatin 2 (TRPM2) channels in neutrophils from patients with PCOS. Neutrophils isolated from PCOS group were investigated in three settings: (1) after incubation with TRPV1 channel blocker capsazepine or TRPM2 channel blocker 2-aminoethyl diphenylborinate (2-APB), (2) after supplementation with NAC (for 6 weeks), and (3) with combination (capsazepine + 2-APB + NAC) exposure. The neutrophils in TRPM2 and TRPV1 experiments were stimulated by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP; 1 µM) and capsaicin (10 µM) as concentration agonists, respectively. Neutrophil lipid peroxidation and capsaicin-induced increase in [Ca(2+)]i concentrations were reduced by capsazepine and NAC treatments. However, the [Ca(2+)]i concentration did not change by fMLP stimulation. Neutrophil lipid peroxidation, apoptosis, caspase-3, caspase-9, cytosolic reactive oxygen species production, and mitochondrial membrane depolarization values were decreased by NAC treatment although neutrophil glutathione peroxidase and reduced glutathione levels were increased by the NAC treatment. Serum lipid peroxidation, luteinizing hormone, testosterone, insulin, interleukin-1 beta, and homocysteine levels were decreased by NAC treatment although serum vitamin A, beta-carotene, vitamin E, and total antioxidant status were increased by the NAC treatment. In conclusion, NAC reduced oxidative stress, apoptosis, cytokine levels, and Ca(2+) entry through TRPV1 channel, which provide supportive evidence that oxidative stress and TRPV1 channel plays a key role in etiology of PCOS.

Homocysteine and cytosolic GSH depletion induce apoptosis and oxidative toxicity through cytosolic calcium overload in the hippocampus of aged mice: involvement of TRPM2 and TRPV1 channels.

Oxidative stress and apoptosis were induced in neuronal cultures by inhibition of glutathione (GSH) biosynthesis with d,l-buthionine-S,R-sulfoximine (BSO). Transient receptor potential melastatin 2 (TRPM2) and transient receptor potential vanilloid 1 (TRPV1) cation channels are gated by oxidative stress. The oxidant effects of homocysteine (Hcy) may induce activation of TRPV1 and TRPM2 channels in aged mice as a model of Alzheimer's disease (AD). We tested the effects of Hcy, BSO and GSH on oxidative stress, apoptosis and Ca2+ and influx via TRPM2 and TRPV1 channels in the hippocampus of mice. Native mice hippocampal neurons were divided into five groups as follows; control, Hcy, BSO, Hcy+BSO and Hcy+BSO+GSH groups. The neurons in TRPM2 and TRPV1 experiments were stimulated by hydrogen peroxide and capsaicin, respectively. BSO and Hcy incubations increased intracellular free Ca2+ concentrations, reactive oxygen species, apoptosis, mitochondrial depolarization, and levels of caspase 3 and 9. All of these increases were reduced by GSH treatments. Treatment with 2-aminoethoxydiphenyl borate (2-APB) and N-(p-amylcinnamoyl)anthranilic acid (ACA) as potent inhibitors of TRPM2, capsazepine as a potent inhibitor of TRPV1, verapamil+diltiazem (V+D) as inhibitors of the voltage-gated Ca2+ channels (VGCC) and MK-801 as a N-methyl-d-aspartate (NMDA) channel antagonist indicated that GSH depletion and Hcy elevation activated Ca2+ entry into the neurons through TRPM2, TRPV1, VGCC and NMDA channels. Inhibitor roles of 2-APB and capsazepine on the Ca2+ entry higher than in V+D and MK-801 antagonists. In conclusion, these findings support the idea that GSH depletion and Hcy elevation can have damaging effects on hippocampal neurons by perturbing calcium homeostasis, mainly through TRPM2 and TRPV1 channels. GSH treatment can partially reverse these effects.

Melatonin and amfenac modulate calcium entry, apoptosis, and oxidative stress in ARPE-19 cell culture exposed to blue light irradiation (405 nm).

PURPOSE: Under conditions of oxidative stress, cell apoptosis is triggered through the mitochondrial intrinsic pathway. Increased levels of reactive oxygen species (ROS) are linked to excess cell loss and mediate the initiation of apoptosis in a diverse range of cell types. The aims of this study were to assess intracellular Ca(2+) release, ROS production, and caspase-3, and -9 activation in ARPE-19 cells during the blue light-mediated cell death, and to examine a potential protective effect of melatonin and amfenac, in the apoptotic cascade. METHODS: ARPE-19 cells were cultured in their medium. First, MTT tests were performed to determine the protective effects of amfenac and melatonin. Cells were then exposed to blue light irradiation in an incubator. Intracellular Ca(2+) release experiments, mitochondrial membrane depolarization, apoptosis assay, glutathione (GSH), glutathione peroxidase (GSH-Px), and ROS experiments were done according to the method stated in the Materials and methods section. RESULTS: Cell death was clearly associated with increased levels of ROS production, as measured by 2',7'-dichlorofluorescein fluorescence, and associated increase in Ca(2+) levels, as measured by Fura-2-AM. Blue light-induced cell death was associated with an increased level of caspase-3 and 9, suggesting mediation via the apoptotic pathway. Cell death was also associated with mitochondrial depolarization. Melatonin was shown to delay these three steps. CONCLUSION: Melatonin, amfenac, and their combination protect ARPE-19 cells against blue light-triggered ROS accumulation and caspase-3 and -9 activation. The antiapoptotic effect of melatonin and amfenac at doses inhibiting caspase synthesis modified Ca(2+) release and prevented excessive ROS production, suggesting a new therapeutic approach to age-related macular degeneration.

Modulation of oxidative stress and Ca(2+) mobilization through TRPM2 channels in rat dorsal root ganglion neuron by Hypericum perforatum.

A main component of St. John's Wort (Hypericum perforatum, HP) is hyperforin which has antioxidant properties in dorsal root ganglion (DRG) neurons, due to its ability to modulate NADPH oxidase and protein kinase C. Recent reports indicate that oxidative stress through NADPH oxidase activates TRPM2 channels. HP may be a useful treatment for Ca(2+) entry and oxidative stress through modulation of TRPM2 channels in the DRG. We aimed to investigate the protective role of HP on Ca(2+) entry and oxidative stress through TRPM2 channels in DRG neurons of rats. The native rat DRG neurons were used in whole-cell patch-clamp, Fura-2 and antioxidant experiments. Appropriate, nontoxic concentrations and incubation times for HP were determined in the DRG neurons by assessing cell viability. The H2O2-induced TRPM2 currents were inhibited by 2-aminoethyl diphenylborinate (2-APB) and N-(p-amylcinnamoyl)anthranilic acid (ACA). TRPM2 current densities and cytosolic free Ca(2+) concentration in the neurons were also reduced by HP (2 and 24h). In Fura-2 experiments, cytosolic Ca(2+) mobilization was reduced by voltage-gated calcium channel blockers (verapamil+diltiazem, V+D) and HP. Glutathione peroxidase activity and GSH values in the DRG were high in HP, 2-APB and V+D groups although lipid peroxidation level was low in the groups. In conclusion, we observed a protective role for HP on Ca(2+) entry through a TRPM2 channel in the DRG neurons. Since over-production of oxidative stress and Ca(2+) entry are implicated in the pathophysiology of neuropathic pain and neuronal inflammation, our findings may be relevant to the etiology and treatment of neuropathology in DRG neurons.

Protective effects of melatonin against oxidative injury in rat testis induced by wireless (2.45 GHz) devices.

Wireless devices have become part of everyday life and mostly located near reproductive organs while they are in use. The present study was designed to determine the possible protective effects of melatonin on oxidative stress-dependent testis injury induced by 2.45-GHz electromagnetic radiation (EMR). Thirty-two rats were equally divided into four different groups, namely cage control (A1), sham control (A2), 2.45-GHz EMR (B) and 2.45-GHz EMR+melatonin (C). Group B and C were exposed to 2.45-GHz EMR during 60 min day(-1) for 30 days. Lipid peroxidation levels were higher in Group B than in Group A1 and A2. Melatonin treatment prevented the increase in the lipid peroxidation induced by EMR. Also reduced glutathione (GSH) and glutathione peroxidase (GSH-Px) levels in Group D were higher than that of exposure group. Vitamin A and E concentrations decreased in exposure group, and melatonin prevented the decrease in vitamin E levels. In conclusion, wireless (2.45 GHz) EMR caused oxidative damage in testis by increasing the levels of lipid peroxidation and decreasing in vitamin A and E levels. Melatonin supplementation prevented oxidative damage induced by EMR and also supported the antioxidant redox system in the testis.

Calcium ion--the key player in cerebral ischemia.

Role of calcium ion (Ca2+) in the functioning of neurons from their naïve state to mature state is of vital importance. It controls functions such as neuronal functioning, neuronal ATP production, central nervous system migration and many others. Failure in Ca2+ homeostasis mechanisms and the resulting cellular Ca2+ ion load initiates a cascade of reactions involving various cytosolic enzymes and proteins. This total mechanism leads to the neuronal death. The ability of neurons to resist such death mechanisms fails as a result of extensive cell death signaling cascade reactions and later brings brain damage. The role of neuronal endoplasmic reticulum and protein channels like CaVs, TRP channels, and NMDAR as the mediators of cell damage and death has been evaluated in the studies related to cerebral ischemia. Here, we portray Ca2+ ion as one of the role players in neuronal death and cerebral damage following ischemia. The role of Ca2+ in neuronal functioning, its regulatory mechanisms and the failure of homeostatic mechanisms are discussed in detail.

Neuroprotection induced by N-acetylcysteine against cytosolic glutathione depletion-induced Ca2+ influx in dorsal root ganglion neurons of mice: role of TRPV1 channels.

Glutathione (GSH) and N-acetylcysteine (NAC) are thiol-containing antioxidants, and also act through a direct reaction with free radicals. Transient receptor potential vanilloid 1 (TRPV1) is the principal transduction channel serving as a polymodal detector. Despite the importance of oxidative stress in pain sensitivity, its role in TRPV1 modulation is poorly understood. NAC may also have a regulator role on TRPV1 channel activity in the dorsal root ganglion (DRG) neuron. Therefore, we tested the effects of GSH and NAC on TRPV1 channel current, Ca(2+) influx, oxidative stress and caspase activity in the DRG of mice. DRG neurons were freshly isolated from mice and the neurons were incubated for 6 and 24h with buthionine sulfoximine (BSO). Pretreatment of cultured DRG neurons with NAC, results in a protection against oxidative damages. This neuroprotection is associated with the attenuation of a Ca(2+) influx triggered by oxidative agents such as H2O2, 5,5'-dithiobis-(2-nitrobenzoic acid) and GSH depletion via BSO. Here, we demonstrate the contribution of cytosolic factors (related to thiol group depletion) on the activation of TRPV1 channels in this mechanism. TRPV1 channels are activated by various agents including capsaicin (CAP), the pungent component of hot chili peppers, and are blocked by capsazepine. An oxidative environment also increased CAP-evoked TRPV1 currents in the neurons. When NAC and GSH were included in the patch pipette as well as extracellularly in the chamber, TRPV1 channels were not activated by CAP and H2O2. TRPV1 inhibitors, 2-aminoethyl diphenylborinate and N-(p-amylcinnamoyl)anthranilic acid strongly reduced BSO-induced oxidative toxicity and Ca(2+) influx, in a manner similar to pretreatment with NAC and GSH. Caspase-3 and -9 activities of all groups were not changed by the agonists or antagonists. In conclusion, in our experimental model, TRPV1 channels are involved in the oxidative stress-induced neuronal death, and negative modulation of this channel activity by GSH and NAC pretreatment may account for their neuroprotective activity against oxidative stress.

N-acetyl cysteine attenuates diazinon exposure-induced oxidative stress in rat testis.

The aim of this study was to investigate the gonadotoxic effects of diazinon and its mechanism of action with special reference to its possible reactive oxygen species generating potential in rat testis and the protective effect of N-Acetyl Cysteine (NAC) on the exposure of diazinon. The vehicle was given orally to the control group and NAC, diazinon, combination of NAC and diazinon were given to three treatment groups for 4 weeks. Testis lipid peroxidation levels were higher in diazinon group than in control although lipid peroxidation levels were lower in diazinon + NAC group than in diazinon group. The reduced glutathione (GSH) levels were lower in diazinon group than in control and NAC group although its levels were higher in diazinon + NAC group than in diazinon group. Vitamin C, Vitamin E and ß-carotene concentrations were also lower in diazinon group than in control and NAC groups. Vitamin E and ß-carotene concentrations were higher in diazinon + NAC group than diazinon group. Glutathione peroxidase activity and vitamin A concentrations in the testis did not show any difference between the four groups. In conclusion, we observed that NAC treatment modulated diazinon-induced oxidative injury in the rat testis. These findings suggest that NAC supplementation can be useful in testis oxidative injury caused by the organophosphate insecticides.

TRPM2 channel protective properties of N-acetylcysteine on cytosolic glutathione depletion dependent oxidative stress and Ca2+ influx in rat dorsal root ganglion.

N-acetylcysteine (NAC) is a thiol-containing (sulphydryl donor) antioxidant, which contributes to regeneration of glutathione (GSH) and also acts through a direct reaction with free radicals. Thiol depletion has been implicated in the neurobiology of sensory neurons and pain. We reported recently an activator role of intracellular GSH depletion on calcium influx through transient receptor potential melastatin-like 2 (TRPM2) channels in rat dorsal root ganglion (DRG). NAC may have a protective role on calcium influx through regulation of TRPM2 channels in the neurons. Therefore, we tested the effects of NAC on TRPM2 channel currents in cytosolic GSH depleted DRG in rats. DRG neurons were freshly isolated from rats and the neurons were incubated for 24 h with buthionine sulfoximine (BSO). In whole-cell patch clamp experiments, TRPM2 currents in the DRG incubated with BSO were gated by H(2)O(2). TRPM2 channels current densities, cytosolic free Ca(2+) content, and lipid peroxidation values in the neurons were higher in H(2)O(2) and BSO + H(2)O(2) group than in controls; however GSH and GSH peroxidase (GSH-Px) values were decreased. BSO + H(2)O(2)-induced TRPM2 channel gating was totally inhibited by extracellular NAC and partially inhibited by 2-aminoethyl diphenylborinate. GSH-Px activity, lipid peroxidation and GSH levels in the DRG neurons were also modulated by NAC. In conclusion, we observed a modulator role of NAC on Ca(2+) influx through a TRPM2 channel in intracellular GSH depleted DRG neurons. NAC incubation before BSO exposure appears to be more protective than NAC incubation after BSO exposure. Since cytosolic thiol group depletion is a common feature of neuropathic pain, our findings are relevant to the etiology and treatment of pain neuropathology in DRG neurons.

Melatonin modulates wireless (2.45 GHz)-induced oxidative injury through TRPM2 and voltage gated Ca(2+) channels in brain and dorsal root ganglion in rat.

We aimed to investigate the protective effects of melatonin and 2.45 GHz electromagnetic radiation (EMR) on brain and dorsal root ganglion (DRG) neuron antioxidant redox system, Ca(2+) influx, cell viability and electroencephalography (EEG) records in the rat. Thirty two rats were equally divided into four different groups namely group A1: Cage control, group A2: Sham control, group B: 2.45 GHz EMR, group C: 2.45 GHz EMR+melatonin. Groups B and C were exposed to 2.45 GHz EMR during 60 min/day for 30 days. End of the experiments, EEG records and the brain cortex and DRG samples were taken. Lipid peroxidation (LP), cell viability and cytosolic Ca(2+) values in DRG neurons were higher in group B than in groups A1 and A2 although their concentrations were increased by melatonin, 2-aminoethyldiphenyl borinate (2-APB), diltiazem and verapamil supplementation. Spike numbers of EEG records in group C were lower than in group B. Brain cortex vitamin E concentration was higher in group C than in group B. In conclusion, Melatonin supplementation in DRG neurons and brain seems to have protective effects on the 2.45 GHz-induced increase Ca(2+) influx, EEG records and cell viability of the hormone through TRPM2 and voltage gated Ca(2+) channels.

Sildenafil citrate as a phosphodiesterase inhibitor has an antioxidant effect in the blood of men.

BACKGROUND AND OBJECTIVE: Sildenafil citrate enhances the action of nitric oxide by preventing the hydrolysis of cGMP, and is widely used to treat erectile dysfunction. We investigated the effects of sildenafil citrate administration on lipid peroxidation and antioxidant redox enzymes in blood of healthy men. METHOD: Thirty healthy male subjects were divided equally into two groups. The first group was used as the control. A single dose of sildenafil citrate was administrated orally to subjects constituting the second group. Blood samples were obtained at 0, 2, 6 and 24 h after intake of the single dose of 100 mg sildenafil citrate or placebo. RESULTS AND DISCUSSION: The dose of sildenafil citrate resulted in significant increase in the erythrocyte superoxide dismutase and catalase activities at 6 and 24 h. Plasma lipid peroxidation levels decreased slightly. There was no statistical difference in erythrocyte glutathione peroxidase activity between the placebo and sildenafil citrate groups. CONCLUSION: Treatment of blood with 100 mg sildenafil citrate has protective effects on oxidative stress by inhibiting free radical formation and by supporting antioxidant redox systems.

Serum soluble Fas levels in patients with autoimmune rheumatic diseases.

OBJECTIVE: The role of the serum soluble Fas (sFAS) system is unclear in diagnosis of several autoimmune rheumatic diseases although there are present contradictory reports on the levels of serum sFas. We therefore assessed levels of sFAS in serum of patients with autoimmune rheumatic diseases. PATIENTS AND METHODS: We analyzed sFas levels and their relationship to clinical and laboratory data in patients with systemic lupus erythematosus (SLE, n=32), rheumatoid arthritis (RA, n=28), Sjögren's syndrome (SS, n=20) systemic sclerosis (SSc, n=21), polymyositis/dermatomyositis (PM/DM, n=15). Patients with osteoarthritis (OA, n=20) and healthy volunteers (n=20) were used as controls. Serum levels of sFAS were determined by ELISA. sFas levels greater than mean (normals)+2 SD were considered as elevated. RESULTS: The mean sFas values were found higher in RA, PM/DM and OA than in control although no differences were found in SSc and SS patients. The mean sFas levels in SLE patients were lower than healthy controls. Elevated sFas rates in RA, PM/DM and SS were found to be 21.4%, 60%, 10% higher than in healthy controls, respectively. sFas levels in SLE and SSc did not differ from control values. Mean sFas levels did not show significant difference between active and inactive patients in all disease groups except PM/DM, RA and OA. No correlations of sFas with relevant disease subsets, laboratory findings and treatment modalities were found. CONCLUSIONS: The findings indicate that the serum sFas molecule may provide a useful additional marker for presence and assessment of disease in patients with RA and PM/DM.

Moderate exercise with a dietary vitamin C and e combination protects against streptozotocin-induced oxidative damage to the kidney and lens in pregnant rats.

Moderate exercise and vitamin C and E (VCE) supplementation can be beneficial to diabetes due to reducing free radical production in lens and kidney of diabetic pregnant rats. We investigated the effect of VCE supplementation and moderate exercise on lipid peroxidation (MDA) and scavenging enzyme activity in the kidneys and lens of STZ-induced diabetic pregnant rats. Fifty female Wistar rats were used and were randomly divided into five groups. First and second were used as the control and pregnant control group. Third group was the pregnant diabetic group. The fourth group was the diabetic-pregnant-exercise group. VCE-supplemented feed was given to pregnant-diabetic-exercise rats constituting the fifth group. Animals in the exercised groups were moderately exercised daily on a treadmill (16.1 m/min, 45 min/d) for three weeks (five days a week). Diabetes was induced on day zero of the study. Plasma, lens, and kidney samples were taken from all animals on day 20. Exercise and administration of VCE to pregnant diabetic rats resulted in significant decrease in the albumin and total protein values and the elevated MDA, plasma creatinine, and urea levels as an indicator of oxidative stress and renal functional parameters. Exercise and VCE supplementation also increased glutathione peroxidase (GSH-Px), reduced glutathione (GSH), vitamin E, and beta-carotene levels in the kidney, GSH-Px and GSH in the lens, the albumin and total protein values in plasma. In the diabetic pregnant animals, the decreased vitamins A and E concentration and GSH levels in kidney, creatinine, and urea values in plasma did not improve through exercise only although their concentrations were increased by VCE supplementation. Kidney weight did not also affect either by exercise or VCE supplementation. In conclusion, these results suggest that exercise plus VCE affects antioxidant metabolism and reduces lipid peroxidation, thereby improving the damage caused by oxidative stress involved in the pathogenesis of lens and kidney in diabetic pregnant rats. Moderate exercise with dietary VCE may play a role in preventing nephropathy and cataract formation in diabetic pregnant rat.

Aprotinin reduces ischemia-reperfusion injury in the retina of guinea pigs.

PURPOSE: The aim of this study was investigate the role of aprotinin on retinal lipid peroxidation and histopathological changes during ischemia/reperfusion (I/R) of guinea pigs. METHODS: Three groups of seven pigmented guinea pigs each were formed: a control (group 1), ischemia/saline (group 2) and ischemia/aprotinin (group 3). One eye of each animal was selected for histopathological evaluation and the other for biochemical assay. Bilateral pressure-induced retinal ischemia was instigated for 90 min and was followed by 24 hours of reperfusion. Animals in the ischemia/aprotinin and ischemia/saline groups received either 20,000 KIU/kg of aprotinin or saline, repeated four times at 6-hour intervals, with the first dose administered 5 min prior to the ischemic insult. The animals were killed at 24 hours of reperfusion. Retinal malondialdehyde (MDA) levels and the thickness of the inner plexiform layers were measured. RESULTS: The level of MDA in group 1 was significantly (p<0.001) lower than the other groups. The mean MDA level in group 2 was significantly (p<0.01) higher than in group 3. The inner plexiform layer in group 1 was significantly (p<0.001) thinner than in the other groups. The mean thickness of the inner plexiform layer in group 2 was significantly (p<0.01) higher than in group 3. CONCLUSIONS: These data indicate that intraperitoneally administrated aprotinin has a protective effect against I/R injury in the retina of guinea pig as evidenced by reduced retinal MDA level and retinal thickness.

Beneficial effects of intraperitoneally administered alpha-tocopheryl acetate on the levels of lipid peroxide and activity of glutathione peroxidase and superoxide dismutase in skin, blood and liver of thermally injured guinea pigs.

The aim of this study was to investigate the effects of intraperitoneal alpha-tocopheryl acetate administration on concentration of lipid peroxide (as malonyldialdehyde, MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in plasma, red blood cells (RBC), skin and liver of thermally injured guinea pigs. MDA levels in the plasma, skin and liver were increased at the 15th min after the thermal injury compared to the control group. However, they were significantly lower in the alpha-tocopheryl-acetate-treated groups than both control and thermally injured groups from the 15th min to the 6th day. SOD activity of the skin and RBC and vitamin E levels in the plasma were significantly decreased between the 15th min and 6th day and then both parameters, i.e. SOD and vitamin E, were significantly increased by alpha-tocopheryl acetate administration. GSH-Px activity in the skin was also significantly decreased in groups from the 15th min to the 6th day, whereas it remained unchanged by the alpha-tocopheryl acetate administration. On the other hand, GSH-Px activity and GSH levels in the RBC remained the same during both thermal injury and alpha-tocopheryl acetate administration. In conclusion, we observed that the intraperitoneal administration of alpha-tocopheryl acetate protects the skin against thermal injury, which suggests that it may be due to the upregulation of enzymatic antioxidants.

Effects of palm oil on lipid peroxidation, reduced glutathione, glutathione peroxidase, and vitamin A levels in the corpus uteri, cornu uteri and corpus luteum of young and adult female sheep.

The aim of the current study was to determine whether a rumen protected palm oil based diet affect malondialdehyde (MDA), glutathione peroxidase (GSH-Px), reduced glutathione (rGSH) and vitamin A levels in the tissues of cornu uteri, corpus uteri and corpus luteum over the barley based isoenergetic and isonitrogenous diet, and whether the response is different between ewes and ewe-lambs. During the breeding season, half of Morkaraman ewes (2-4-year-old, n = 10) and ewe-lambs (7-8-months-old, n = 10) was offered a barley based diet and the other half was offered a protected palm oil based diet for 42 +/- 0.7 days. At the end of the experiment all animals were slaughtered and measurements carried out in the tissues collected. In all animals tested, cornu uteri had the highest MDA levels followed by corpus uteri and corpus luteum (P < 0.01) but no differences were between the tissues observed in GSH-Px and rGSH levels (P > 0.05). Vitamin A levels were, however, higher in corpus luteum than in cornu uteri and corpus uteri (P < 0.05). Corpus uteri MDA levels were not different (P > 0.05) but rGSH levels were higher for the palm oil fed groups (P < 0.05). GSH-Px and rGSH levels were higher for ewe-lambs than ewes (P < 0.05). In conclusion, it appears that MDA, rGSH, GSH-Px, and vitamin A work in a different fashion for corpus uteri, cornu uteri and corpus luteum, and for ewes and ewe-lambs. Dietary palm oil did not significantly affect the parameters studied except higher rGSH levels in corpus uteri. Levels of antioxidatively active substances, such as rGSH and GSH-Px were lower in ewes compared with those in ewe-lambs.

Protective effects of topical alpha-tocopherol acetate on UVB irradiation in guinea pigs: importance of free radicals.

Reactive oxygen species can be generated by daily exposure of the skin to ultraviolet light and may cause some subchronic and chronic skin disorders. The aim of this study was to investigate a possible preventive role of alpha-tocopherol acetate (ATA) on ultraviolet B (UVB) induced peroxidation by assessing lipid peroxide (LPO) levels and activity of reactive oxygen scavenging enzymes including glutathione peroxidase and superoxide dismutase (SOD) in guinea pigs. ATA was topically applied to the skin for three weeks before a single dose of 0.9 J/cm2 UVB irradiation on the skin and lipid peroxide levels and antioxidants in plasma, skin and liver and erythrocytes were determined after decapitation. Topical application of ATA prevented the UVB irradiation-induced reduction of scavenging enzyme activities in skin and erythrocytes. In conclusion, we suggest that topical applications of ATA before UVB irradiation is effective in protecting the skin from unwanted effects of UVB irradiation.

Effect of vitamin E on ruminal fermentation in vitro.

The effects of vitamin E on pH value, total protozoa counts, volatile fatty acid (VFA), ammonia nitrogen and lactate levels were examined using an in vitro ruminal incubation system. The ruminal fluid (100 ml) of the first and second group was supplemented with 0.4 mg or 0.8 mg of vitamin E, respectively. Samples were taken immediately before and following 3, 6, 12 and 24 h of incubation at 39 degrees C and analysed for the total protozoa counts, the pH and the levels of ammonia nitrogen, lactate and VFA. Levels of propionate at 24 h and ammonia nitrogen at 12 and 24 h were significantly higher in the second group than in the control. In contrast, the levels of butyrate at 6, 12 and 24 h and lactate at 6, 12 and 24 h were lower in the second group than in the control. Propionate at 24 h, acetate levels at 6, 12 and 24 hand ammonia nitrogen levels at 6, 12 and 24 h and total rumen protozoa counts at 6, 12 and 24 h were significantly higher in the second group as compared with control. In contrary, butyrate levels at 6, 12 and 24 h, lactate levels at 6, 12 and 24 h were lower in second group than in control. There was no statistically significant difference among the groups in the pH values. In conclusion, the addition of vitamin E to in vitro ruminal fluid was found to increase the concentrations of acetate and propionate, total counts of protozoa, levels of ammonia nitrogen, but to decrease the butyrate and lactate levels of the ruminal aliquots in in vitro ruminal fermentation.