Elimination of ascorbic acid-induced membrane lipid peroxidation and serotonin receptor loss by Trolox-C, a water soluble analogue of vitamin E

The Role of Antioxidants in the Management of Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a chronic neuropsychiatric disorder that has a significant effect on the quality of life. The most effective treatment for OCD is the combination of selective serotonin reuptake inhibitors (SSRI) with cognitive behavior therapy (CBT). However, several adverse effects have been linked with this usual pharmacotherapy, and it is unsuccessful in many patients. The exact pathophysiology of OCD is not completely known, though the role of oxidative stress in its pathogenesis has been proposed recently. This review presents an overview of animal and human studies of antioxidant treatment for OCD. The use of antioxidants against oxidative stress is a novel treatment for several neurodegenerative and neuropsychiatric disorders. Among antioxidants, NAC was one of the most studied drugs on OCD, and it showed a significant improvement in OCD symptoms. Thus, antioxidants could be promising as an adjuvant treatment for OCD. However, a limited number of human studies are conducted on these agents, and for better judgment, human studies with a large sample size are necessary.

Oxidative status and prolidase activities in generalized anxiety disorder

OBJECTIVE

Prolidase (Pro), an intracellular enzyme necessary for collagen turnover, matrix remodelling and cell growth has been shown to be related to Oxidative Stress (OS). To our knowledge, serum Pro activity in generalized anxiety disorder (GAD) has not been documented yet. In this study, we aimed to evaluate OS and its relation with Pro activity in patients diagnosed with GAD.

METHOD

Thirty untreated GAD patients and 30 healthy controls were included in the study. Blood samples were collected from all subjects to quantify total oxidant status (TOS), total antioxidant status (TAS) and Pro activity. Oxidative stress index (OSI), the ratio of TOS to TAS, is calculated to evaluate the balance between antioxidants and oxidants. Hamilton Anxiety Rating Scale (HARS) was used to determine the anxiety levels of all subjects.

RESULTS

GAD group demonstrated statistically significantly higher TOS, OSI and Pro levels, when compared with the control group (t=2.947, p=0.005; t=2.874, p=0.006; and t=9.396, p<0.001 respectively). HARS scores were found to be positively correlated with TOS, OSI and Pro levels (p=0.008, r=0.338; p=0.008, r=0.339; and p<0.001, r=0.751 respectively).

CONCLUSION

The degree of severity of OS is correlated with the levels of Pro. Thus, Pro might be the target enzyme, promising to be a marker for the follow-up of GAD patients. To the best of our knowledge, this study is the first to report a significant relation between Pro activity and GAD.

Trolox and ascorbic acid reduce direct and indirect oxidative stress in the IPEC-J2 cells, an in vitro model for the porcine gastrointestinal tract

Oxidative stress in the small intestinal epithelium is a major cause of barrier malfunction and failure to regenerate. This study presents a functional in vitro model using the porcine small intestinal epithelial cell line IPEC-J2 to examine the effects of oxidative stress and to estimate the antioxidant and regenerative potential of Trolox, ascorbic acid and glutathione monoethyl ester. Hydrogen peroxide and diethyl maleate affected the tight junction (zona occludens-1) distribution, significantly increased intracellular oxidative stress (CM-H₂DCFDA) and decreased the monolayer integrity (transepithelial electrical resistance and FD-4 permeability), viability (neutral red) and wound healing capacity (scratch assay). Trolox (2 mM) and 1 mM ascorbic acid pre-treatment significantly reduced intracellular oxidative stress, increased wound healing capacity and reduced FD-4 permeability in oxidatively stressed IPEC-J2 cell monolayers. All antioxidant pre-treatments increased transepithelial electrical resistance and viability only in diethyl maleate-treated cells. Glutathione monoethyl ester (10 mM) pre-treatment significantly decreased intracellular oxidative stress and monolayer permeability only in diethyl maleate-treated cells. These data demonstrate that the IPEC-J2 oxidative stress model is a valuable tool to screen antioxidants before validation in piglets.

Antioxidants as antidepressants: fact or fiction?

Depression is a medical condition with a complex biological pattern of aetiology, involving genetic and epigenetic factors, along with different environmental stressors. Recent evidence suggests that oxidative stress processes might play a relevant role in the pathogenic mechanism(s) underlying many major psychiatric disorders, including depression. Reactive oxygen and nitrogen species have been shown to modulate levels and activity of noradrenaline (norepinephrine), serotonin, dopamine and glutamate, the principal neurotransmitters involved in the neurobiology of depression. Major depression has been associated with lowered concentrations of several endogenous antioxidant compounds, such as vitamin E, zinc and coenzyme Q10, or enzymes, such as glutathione peroxidase, and with an impairment of the total antioxidant status. These observations introduce new potential targets for the development of therapeutic interventions based on antioxidant compounds. The present review focuses on the possible role of oxidative stress processes in the pathogenesis of depression. The therapeutic potential of antioxidant compounds as a co-adjuvant treatment to conventional antidepressants is discussed. For instance, N-acetyl-cysteine has been shown to have a significant benefit on depressive symptoms in a randomized placebo-controlled trial. Additionally, curcumin, the yellow pigment of curry, has been shown to strongly interfere with neuronal redox homeostasis in the CNS and to possess antidepressant activity in various animal models of depression, also thanks to its ability to inhibit monoamine oxidases. There is an urgent need to develop better tolerated and more effective treatments for depressive disorders and several antioxidant treatments appear promising and deserve further study.

Genetic variants in nuclear-encoded mitochondrial proteins are associated with oxidative stress in obsessive compulsive disorders

Obsessive compulsive disorder is a common psychiatric disorder defined by the presence of obsessive thoughts and repetitive compulsive actions. The mutations or polymorphic variants in mitochondrial DNA-encoded genes or nuclear genes result in oxidative stress, which has recently been associated with various psychiatric disorders. In order to understand the association of mitochondrial disorders with oxidative stress in obsessive compulsive disorder, we examined genetic variants of manganese superoxide dismutase and uncouple-2 antioxidant genes and malondialdehyde and glutathione, markers of oxidative stress. The study sample comprised 104 patients with OCD and 110 healthy controls. For manganese superoxide dismutase, the frequencies of CT (Ala/Val) genotype (p < 0.01) in patients were significantly lower than those of controls. In contrast, CC (Ala/Ala) genotype was significantly more frequent in patients than controls (p < 0.05). For uncouple-2 I/D, the frequencies of ID genotype (p < 0.01) and I allele (p < 0.05) were lower in patients as compared with controls. In contrast, DD genotype was more prevalent in patients than controls (p < 0.01). While whole blood glutathione was significantly diminished (p < 0.0001), serum malondialdehyde was significantly elevated in patients compared with controls (p < 0.0001). Malondialdehyde levels were significantly elevated in subjects with DD genotype of UCP-2 I/D (p < 0.05) and CC genotype of manganese superoxide dismutase (p < 0.05) as compared with II or ID and TT or CT genotype, respectively. Malondialdehyde levels in patients carrying CC (p < 0.05) or CT (p < 0.05) genotype were significantly higher than those of carrying TT genotype. In conclusion, CC genotype of manganese superoxide dismutase or DD genotype of UCP-2 might result in mitochondrial disorders by increasing oxidative stress in obsessive compulsive disorders.

Tryptophan hydroxylase: a target for neuroendocrine disruption

Tryptophan hydroxylase (TPH), the rate-limiting enzyme in serotonin (5-HT) synthesis, performs an essential role in the maintenance of serotonergic functions in the central nervous system (CNS), including regulation of the neuroendocrine system controlling reproduction. The results of recent studies in a teleost model of neuroendocrine disruption, Atlantic croaker, indicated that hypothalamic TPH is a major site of interference of hypothalamic-pituitary-gonadal function by environmental stressors. The effects of exposure to two different types of environmental stressors, low dissolved oxygen (hypoxia) and a polychlorinated biphenyl mixture (Aroclor 1254), on the stimulatory brain serotonergic system controlling reproductive neuroendocrine function in Atlantic croaker are reviewed. Exposure to both stressors produced decreases in TPH activity, which were accompanied by a fall in hypothalamic 5-HT and gonadotropin-releasing hormone (GnRH I) content in the preoptic-anterior hypothalamic area and were associated with reduction in luteinizing hormone (LH) secretion and gonadal development. Pharmacological restoration of hypothalamic 5-HT levels after exposure to both stressors also restored neuroendocrine and reproductive functions, indicating that the serotonergic system is an important site for hypoxia- and Aroclor 1254-induced inhibition of reproductive neuroendocrine functions. The mechanisms underlying downregulation of TPH activity by these stressors remain unclear but may involve alterations in hypothalamic antioxidant status. In support of this hypothesis, treatment with an antioxidant, vitamin E, was found to reverse the inhibitory effects of Aroclor 1254 on TPH activity. The results suggest that TPH is a major target for neuroendocrine disruption by diverse environmental stressors.

Invivo antioxidant status: a putative target of antidepressant action

Oxidative stress is a critical route of damage in various psychological stress-induced disorders, such as depression. Antidepressants are widely prescribed to treat these conditions; however, few animal studies have investigated the effect of these drugs on endogenous antioxidant status in the brain. The present study employed a 21-day chronic regimen of random exposure to restraint stress to induce oxidative stress in brain, and behavioural aberrations, in rodents. The forced swimming (FST) and sucrose preference tests were used to identify depression-like phenotypes, and reversal in these indices indicated the effectiveness of treatment with fluoxetine (FLU; 20 mg/kg/day, p.o.; selective serotonin reuptake inhibitor), imipramine (IMI; 10 mg/kg/day, p.o.; tricyclic antidepressant) and venlafaxine (VEN; 10 mg/kg/day, p.o.; dual serotonin/norepinephrine reuptake inhibitor) following restraint stress. The antioxidant status was investigated in the brain of these animals. The results evidenced a significant recovery in the activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR) and glutathione (GSH) levels by antidepressant treatments following a restraint stress-induced decline of these parameters. The severely accumulated lipid peroxidation product malondialdehyde (MDA) and protein carbonyl contents in stressed animals were significantly normalized by antidepressant treatments. The altered oxidative status is implicated in various aspects of cellular function affecting the brain. Thus, it is possible that augmentation of in vivo antioxidant defenses could serve as a convergence point for multiple classes of antidepressants as an important mechanism underlying the neuroprotective pharmacological effects of these drugs observed clinically in the treatment of various stress disorders. Consequently, pharmacological modulation of stress-induced oxidative damage as a possible stress-management approach should be an important avenue of further research.

Antioxidant enzyme and malondialdehyde levels in patients with social phobia

A growing body of reports have indicated that free radicals are involved in the etiopathogenesis of some neuropsychiatric disorders. In the present study, we aimed to evaluate whether antioxidant enzymes (superoxide dismutase; SOD, glutathione peroxidase; GSH-Px, and catalase; CAT) activity levels and malondialdehyde (MDA), a product of lipid peroxidation, were associated with social phobia (SP). Eighteen patients diagnosed with SP and 18 healthy controls were enrolled. A clinical evaluation and measurements of MDA, SOD, GSH-Px and CAT were performed. Additionally, all patients were assessed with the Liebowitz Social Anxiety Scale (LSAC). The mean MDA, SOD, GSH-Px and CAT levels in the patient group were significantly higher than those in the control group. There was a positive correlation between LSAC scores and MDA, SOD, GSH-Px and LSAC levels, and between the duration of illness, and MDA, SOD and CAT levels in the patient group. In conclusion, our results suggest that there may be a relationship between increased antioxidant enzyme levels and MDA, and SP.

Inactivation of nitric oxide by rat cerebellar slices

Nitric oxide (NO) functions as an intercellular messenger throughout the brain. For this role to be performed efficiently, there must be a mechanism for neutralizing NO, but whether an active biological process exists, or whether NO is lost mainly through diffusion is unclear. To investigate this issue, rat cerebellar slices were exposed to constant levels of NO and the cGMP generated within the slice used as an indicator of NO concentrations therein. NO was about 1000-fold less potent in slices (EC50, 1 microM) than in separated cells from the same tissue (EC50, 1.6 nM), consistent with access of NO to the slice interior being greatly hindered by inactivation. Supporting this interpretation, immunohistochemical analysis indicated a marked concentration gradient of cGMP across the thickness of slices exposed to subsaturating NO concentrations, signifying a marked NO gradient. Several known NO-degrading processes, including reaction with lipid peroxyl radicals, erythrocytes and superoxide ions, were eliminated as contributing factors, indicating a novel mechanism. A diffusion-inactivation model was used to estimate the kinetics of NO consumption by the slices. The best fits to experimental data indicated a Michaelis-Menten-type reaction having a Vmax of 1-2 microM s-1 and a Km of around 10 nM. The rates predict that inactivation would impose a very short half-life (<10 ms) on NO in physiological concentrations (up to 10 nM) and that it would play an important role in shaping the NO concentration profiles when it is synthesized by multiple nearby sites.

Examination of free radical metabolism and antioxidant defence system elements in patients with obsessive-compulsive disorder

Free radicals and oxidative stress are involved in the pathogenesis of various diseases. Malondialdehyde (MDA) is a natural product of lipid peroxidation in all mammalian cells. Vitamins C and E are nonenzymatic antioxidant structures. Our study investigated the role of free radicals in the obsessive-compulsive disorder (OCD). The participants were 30 patients with OCD that were drug-free at least for a month and a control group of 30 healthy subjects, matched with respect to age and sex. In both groups, the levels of erythrocyte malondialdehyde and the plasma vitamin C and E concentrations were measured. The levels of malondialdehyde were significantly higher in the patient group than in the control group (p<.01). The levels of plasma vitamin E were significantly lower in the patient than in the control group (p<.02). Although our patient group had slightly lower concentrations of plasma vitamin C compared to our control group, the difference between these two groups was not statistically significant. There was a significant correlation between increasing malondialdehyde levels and decreasing vitamin E concentrations. This study shows the presence of a significant relationship of OCD and oxidative stress, and consequently, an involvement of free radicals and of the antioxidant defence. Biochemical studies may contribute to the understanding of OCD and its treatment.

Protection from inflammation, immunosuppression and carcinogenesis induced by UV radiation in mice by topical Pycnogenol

Pycnogenol is a standardized extract of the bark of the French maritime pine, Pinus pinaster Ait., that has multiple biological effects, including antioxidant, anti-inflammatory and anticarcinogenic properties. This study describes the effect of topical application of lotions containing Pycnogenol to Skh:hr hairless mice undergoing minimally inflammatory daily exposures to solar-simulated UV radiation (SSUV). We report that concentrations of Pycnogenol of 0.05-0.2% applied to the irradiated dorsal skin immediately after exposure resulted in dose-dependent reduction of the inflammatory sunburn reaction, measured as its edema component. When mice received three consecutive daily exposures of minimally edematous SSUV, their ability to raise a contact hypersensitivity (CHS) reaction was suppressed by 54%. Pycnogenol lotions applied postirradiation reduced this immunosuppression to 22% (0.05% Pycnogenol) and 13% (0.1% Pycnogenol). Furthermore, when CHS was suppressed by 71% with exogenous treatment with cis-urocanic acid, the putative epidermal mediator of photoimmunosuppression, 0.2% Pycnogenol lotion reduced the immunosuppression to 18%. Chronic exposure to SSUV on 5 days/week for 10 weeks induced skin tumors from 11 weeks in both control mice and in mice receiving daily applications of 0.05% Pycnogenol, but tumor appearance was significantly delayed until 20 weeks in mice receiving 0.2% Pycnogenol. Furthermore, whereas 100% of control mice had at least one tumor by 30 weeks, and mice treated with 0.05% Pycnogenol by 33 weeks, the maximum tumor prevalence in mice treated with 0.2% Pycnogenol was significantly reduced to 85%, with some mice remaining tumor free. Average tumor multiplicity was also significantly reduced by 0.2% Pycnogenol, from 5.2 in control mice to 3.5 at 35 weeks. Thus, topical Pycnogenol offered significant and dose-dependent protection from SSUV-induced acute inflammation, immunosuppression and carcinogenesis, when applied to the skin after daily irradiation. Pycnogenol, therefore, in addition to its recognized health benefits in other organs, appears to have potential in providing photoprotection for humans in a complementary role with sunscreens, having demonstrable activity when applied to the skin after, rather than before, UV exposure.

Antioxidative enzyme activities and lipid peroxidation in major depression: alterations by antidepressant treatments

BACKGROUND

Reactive oxygen species (ROS) may play a role in some neuropsychiatric disorders. There is some evidence that the activation of immune-inflammatory process, increase of monoamines catabolism, and abnormalities in lipid compounds may cause overproduction of ROS and, in turn, antioxidative enzyme activities (AEAs) and lipid peroxidation (LP), and that these phenomena may be related to pathophysiology of major depression.

METHODS

The aims of this study were (i) to examine the AEAs and LP levels of the major depressed (MD) patients, and to compare these with healthy controls; and (ii) to investigate the effect of subchronic treatment with selective serotonin reuptake inhibitors (SSRIs) on AEAs and LP levels in MD subjects. Thirty MD patients, and 32 healthy controls (HC) participated in this study. AEAs and LP levels were determined by measuring several antioxidative enzymes and malondialdehyde (MDA) levels in plasma and/or in red blood cells.

RESULTS

Major depressed patients, especially melancholic patients, had higher AEA and LP levels than those of healthy controls. After treatment for 3 months with SSRIs, AEA and LP levels of the patients were significantly decreased to normal levels.

CONCLUSION

These findings suggest that (i) major depression, especially with melancholia, is associated with elevated AEAs and LP, and that (ii) subchronic treatment with SSRIs may have a suppressive effect on AEA and LP. CLINICAL IMPLICATION AND LIMITATION: AEAs might be used for monitoring SSRIs effects.

Endogenous Alzheimer's brain factor and oxidized glutathione inhibit antagonist binding to the muscarinic receptor

An endogenous inhibitor (< 3,500 Da) of antagonist binding to the muscarinic acetylcholine receptor has been extracted from Alzheimer's disease (AD) brain with trifluoracetic acid. Oxidized glutathione, (GSSG) has also been found to inhibit antagonist binding to the receptor. However, in its reduced form, glutathione (GSH) like other reducing agents, markedly enhances the inhibitory effect of both GSSG and the endogenous AD inhibitor. EDTA and the free radical scavengers Mn(2+) and Trolox, a vitamin E analog, block the action of the endogenous AD inhibitor but not of GSSG in the presence of GSH. Further, while GSSG inhibition is reversible, the action of the endogenous AD inhibitor is irreversible, consistent with a free radical mechanism. The enhancement of endogenous AD inhibitor activity by GSH suggested that GSH may be involved in formation of the free radical generated by the inhibitor. The glutathione thiyl radical is shown to inhibit antagonist binding to the receptor and is, therefore, a good candidate for the free radical formed by the endogenous AD inhibitor. The ability of Trolox to block the reduction in muscarinic receptor binding caused by the endogenous AD inhibitor is encouraging and suggests that free radical scavengers, such as vitamin E, may have a potential therapeutic role in AD by protecting the integrity of the muscarinic receptor.

Differential effects of in vitro peroxidation on peripheral- and central-type benzodiazepine receptors. Protection by diverse antioxidants

The influence of various concentrations of ferrous iron and ascorbate on in vitro peroxidation and drug binding of diverse membrane preparations (cerebral cortex and liver) was studied. Peroxidation was not simply dose-related to ascorbate and ferrous iron, but a complex relationship between iron and ascorbate when added in association was established. Under our conditions 0.01 mM Fe2+ and 0.5 mM ascorbate was the most peroxidative combination for cerebral and liver membranes. Under the same conditions, cerebral membranes were more peroxidated than liver membranes. Considering the consequences of drug binding, peripheral-type benzodiazepine receptors (PBRs) of liver were more affected by peroxidative events than central-type benzodiazepine receptors (CBRs) of the cerebral cortex. The degree of binding disturbance was generally inversely correlated to the degree of peroxidation and this was more significant for liver PBRs than for cerebral CBRs. The liver membrane model was retained for testing in vitro protection by diverse putative antioxidants. Under our conditions desferrioxamine, ethylene diamine tetra acetate (EDTA), trolox, and rutin were good protective antioxidants, whereas phenyl-butyl-nitrone (PBN) and tocopherol were not effective.

Partitioning and antioxidant action of the water-soluble antioxidant, Trolox, between the aqueous and lipid phases of phosphatidylcholine membranes: 14C tracer and product studies

The water-soluble antioxidant, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic (Trolox), (4-14C)-labelled, was used to trace its location in the aqueous and lipid phases of liposomes. Trolox was found to partition 20 to 25% into the lipid phase of multilamellar (MLV) and 38-46% into the lipid phase of unilamellar (ULV) egg lecithin liposomes. Trolox and its oxidation products partition readily (40%) into the lipid phase of dilinoleoylphosphatidylcholine (DLPC) MLV liposomes during inhibited peroxidation, thermally initiated by azo-bis(2,4-dimethylvaleronitrile) (ADVN). The time-course of the consumption of Trolox during peroxidation of DLPC liposomes, initiated by ADVN, was followed by separation and analyses of [4-14C]Trolox and its oxidation products. Such studies showed that the consumption of Trolox followed the profile of the inhibition of oxygen uptake. This indicates that Trolox can be used in quantitative studies of membrane peroxidation; for example, to measure the rate of chain initiation (Ri). The product distribution of hydroperoxides, the 9- and 13-cis,trans (c,t) and trans,trans (t,t) isomers, formed during inhibited peroxidation of linoleate, in DLPC and methyl linoleate in dimyristoyl PC (DMPC) liposomes was determined by HPLC of the derived hydroxy methyl esters. The c,t/t,t (kinetic/thermodynamic) ratios were related to the antioxidant activity of the inhibitors. Both Trolox and alpha-tocopherol (vitamin E) gave relatively high initial c,t/t,t ratios (6.6 and 7.1) during inhibited peroxidation of DLPC, initiated by water-soluble azo-bis(2-amidinopropane.HCl) (ABAP). High initial c,t/t,t ratios (6.2) were also observed for alpha-tocopherol-inhibited peroxidation of DLPC liposomes, initiated by lipid-soluble ADVN. On the other hand, the combination of Trolox with ADVN-initiated peroxidation of DLPC or of methyl linoleate in DMPC gave relatively low initial c,t/t,t ratios of 3.5 and 1.3. These results are interpreted in terms of the relative hydrogen atom donating ability of the antioxidants and the homogeneity of the system used. The 9/13 ratios of hydroperoxides were constant (0.9 to 1.0) in all experiments and did not give evidence for preferential trapping by Trolox of peroxyls at the 9-position.

Haemorrhagic toxicity of a large dose of alpha-, beta-, gamma- and delta-tocopherols, ubiquinone, beta-carotene, retinol acetate and L-ascorbic acid in the rat

Antioxidants occasionally have become prooxidants when a large amount was ingested. The haemorrhagic toxicity of butylated hydroxytoluene, a synthetic antioxidant, may involve such a mechanism. This study investigated whether haemorrhage is induced by overdoses of tocopherols, beta-carotene, ubiquinone or L-ascorbic acid, which are representative biological antioxidants. Male Jcl:SD rats (six rats/group) were fed d-alpha, d-beta, d-gamma or d-delta-tocopherols, ubiquinone Q-10, beta-carotene or retinol acetate at a level of 0.5%, or L-ascorbic acid at 5% in the diet for 7 days. Only two rats given retinol acetate died with lung haemorrhages. Haemorrhages were observed in five or six, six, one, one, one or one of six surviving rats given d-alpha, d-beta or d-gamma-tocopherols, ubiquinone Q-10, beta-carotene or retinol acetate, respectively (except for a retinol group in which four rats survived). Major haemorrhages were noted in the epididymis. In the alpha-, beta- and gamma-tocopherol, ubiquinone Q-10, beta-carotene or retinol acetate-treated groups, prothrombin and kaoline-activated partial thromboplastin time indices were 26-28, 37, 59, 42, 63 and 65% or 27-28, 35, 65, 38, 59 and 28%, respectively, of the control values. Only the prothrombin index was significantly decreased to 67% in delta-tocopherol-administered rates, whereas controls and those receiving L-ascorbic acid showed no signs of bleeding or coagulation defect. The same tendency was also seen in the decreasing effect on vitamin K-dependent blood coagulation factors. These results suggest that the four naturally occurring tocopherols have a tendency to cause haemorrhage in the order of alpha > beta > gamma > delta, and ubiquinone Q-10 and beta-carotene als0o have relatively strong and weak haemorrhagic effects, respectively, with regard to prothrombin and partial thromboplastin time indices.