Early changes in oxidative stress markers in a rat model of acute stress: effect of l-carnitine on the striatum

Ecdysterone prevents negative effect of acute immobilization stress on energy metabolism of rat liver mitochondria

Ecdysterone is a naturally occurring steroid hormone, which presents in arthropods and in a number of plants as an insect defence tool. There are many studies showing that application of ecdysterone can alter mitochondrial functions of mammalian cells, however it is not clear whether its effects are direct or mediated by activation of other cellular processes. In our study, we have shown how ecdysterone acts at the mitochondrial level in normal conditions and in certain pathology. We have demonstrated that application of immobilization stress to male rats causes uncoupling of mitochondrial oxidative phosphorylation, the preliminary application of ecdysterone prevents negative effect of immobilization stress on mitochondria. In-vitro experiments with isolated mitochondria have shown that ecdysterone can increase mitochondrial coupling and hyperpolarise mitochondria but without a noticeable effect on ADP/O ratio. Molecular docking experiments revealed that ecdysterone has high binding energy with mitochondrial F_OF₁ ATP synthase, but further biochemical analysis have not revealed either stimulatory or inhibitory effect of ecdysterone on F_OF₁ ATPase activity of the enzyme. Thus, ecdysterone can directly affect mitochondrial bioenergetics, though we assume that its preventive effect on mitochondria during immobilization stress is also coupled with the activation of some other cellular processes.

The Protective Effects of L-Carnitine and Zinc Oxide Nanoparticles Against Diabetic Injury on Sex Steroid Hormones Levels, Oxidative Stress, and Ovarian Histopathological Changes in Rat

Diabetes mellitus is a common chronic metabolic disorder. This study aimed to investigate the effects of co-treatment with L-carnitine (LC) and zinc oxide nanoparticles (ZnONPs) on serum levels of sex hormones, oxidative stress, and ovarian histopathology in streptozotocin (STZ)-induced diabetic rats. Female Wistar rats (n = 56, 180-220 g) received a single intraperitoneal (IP) injection of STZ (65 mg/kg). They were randomly assigned into the following groups: diabetic group (Dia), Dia+Met group (100 mg metformin/kg/day), Dia+LC group (200 mg/kg/day), Dia+ZnONPs group (10 mg/kg/day), and Dia+LC+ZnONPs group (200 mg LC/kg/day and 10 mg ZnONPs/kg/day). Control group (Ctl) received the same volume of STZ solvent. After 21 days of treatment, blood serum was centrifuged for sex hormone assays. The right ovary was used for biochemical analysis, and the left ovary was fixed in 10% neutral buffered formalin for histological assessment. The levels of estradiol, progesterone, FSH, and LH significantly increased in the Dia+ZnONPs+LC group (P < 0.001) compared with the Dia group. Co-treatment with LC and ZnONPs reduced malondialdehyde and carbonyl protein and increased glutathione, catalase, and superoxide dismutase activities in ovarian tissue compared with the Dia group (P < 0.05). Moreover, the number of all ovarian follicles significantly increased in this group compared with the Dia group (P < 0.05). The results of this study indicated that co-treatment with LC and ZnONPs could preserve ovarian function by increasing sex hormones levels and antioxidant activity and decreasing lipid peroxidation in diabetic rats. Therefore, this compound supplementation may improve ovulation and fertility in people with diabetes mellitus.

Metabolic signature in nucleus accumbens for anti-depressant-like effects of acetyl-L-carnitine

Emerging evidence suggests that hierarchical status provides vulnerability to develop stress-induced depression. Energy metabolic changes in the nucleus accumbens (NAc) were recently related to hierarchical status and vulnerability to develop depression-like behavior. Acetyl-L-carnitine (LAC), a mitochondria-boosting supplement, has shown promising antidepressant-like effects opening therapeutic opportunities for restoring energy balance in depressed patients. We investigated the metabolic impact in the NAc of antidepressant LAC treatment in chronically-stressed mice using ¹H-magnetic resonance spectroscopy (¹H-MRS). High rank, but not low rank, mice, as assessed with the tube test, showed behavioral vulnerability to stress, supporting a higher susceptibility of high social rank mice to develop depressive-like behaviors. High rank mice also showed reduced levels of several energy-related metabolites in the NAc that were counteracted by LAC treatment. Therefore, we reveal a metabolic signature in the NAc for antidepressant-like effects of LAC in vulnerable mice characterized by restoration of stress-induced neuroenergetics alterations and lipid function.

The protective effects of L-carnitine on myocardial ischaemia-reperfusion injury in patients with rheumatic valvular heart disease undergoing CPB surgery are associated with the suppression of NF-κB pathway and the activation of Nrf2 pathway

Myocardial ischaemia-reperfusion injury (MIRI) is a main pathophysiologic change following CPB surgery. L-carnitine, a natural amino acid, is able to transport fatty acids for generating energy and has a protective effect on MIRI. We aim to investigate the protective effect of L-carnitine on MIRI in patients with rheumatic valvular heart disease (RVHD) performed CPB surgical operation and the underlying mechanism. In this study, patients were randomized to three groups. L-carnitine was added to the crystalloid cardioplegic solution for experimental group 1 (6 g/L) and experimental group 2 (12 g/L), whereas no L-carnitine was used in the control group. Our results showed that L-carnitine significantly attenuated myocardial injury after surgery in these patients. L-carnitine decreased serum markers of myocardial injury including CK-MB, cTnI, hs-cTnT and IMA. L-carnitine increased left ventricular ejection fraction (LVEF) but reduced wall motion score index (WMSI) after operation. L-carnitine also inhibited myeloperoxidase (MPO) activity and inflammatory cytokines in the myocardium of patients after unclamping the aorta. Additionally, L-carnitine increased levels of superoxide dismutase (SOD) and catalase (CAT) while decreased levels of malondialdehyde (MDA) and protein carbonyl content in the myocardium of patients after unclamping the aorta. Moreover, L-carnitine suppressed the activation of nuclear factor kappa B (NF-κB) and activated nuclear factor erythroid 2-related factor 2 (Nrf2). There was also no significant difference in these indices between two experimental groups after unclamping the aorta. Taken together, L-carnitine had a protective effect against CPB-induced MIRI in patients with RVHD, which might be related to its modulation of NF-κB and Nrf2 activities.

In vivo immunoprotective role of Indigofera tinctoria and Scoparia dulcis aqueous extracts against chronic noise stress induced immune abnormalities in Wistar albino rats

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Chronic noise stress was suppressed both innate and adaptive immune response of wistar albino rats.

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Noise stress also caused DNA damage in the liver and spleen tissues.

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Aqueous extracts of I. tinctoria and S. dulcis prevent the immune abnormalities caused by noise stress.

Indigofera tinctoria and Scoparia dulcis are being widely used in Indian folk medicine for the treatment of various disorders. Environmental noise pollution is thought to be an important factor for many health problems and it causes immune abnormalities. In the present study immune-regulating potential of I. tinctoria and S. dulcis aqueous extracts on innate and adaptive immune system of wistar albino rats was evaluated during normal and chronic noise induced stress conditions. The results demonstrated that both I. tinctoria and S. dulcis aqueous extracts (200 mg/kg b.w) showed immunostimulant effect on both innate and adaptive immune response of wistar albino rat compared to control group under normal condition. The noise stress (100 dB for 1 h, 20 days) induced animals showed suppressive effects on immune response by decreasing macrophage phagocytosis, antibody secretion by spleen cells, humoral immune response, proliferation of lymphocytes, cytotoxicity, TNF α expression, granzyme B and perforin expression in splenic NK cells. Similarly, noise stress also caused DNA damage in tissues. However, the suppressed effects induced by noise stress on rat immune system were significantly prevented by oral administration of both I. tinctoria and S. dulcis aqueous extracts. Considering all these results it is suggested that the selected medicinal plant’s aqueous extracts have the potential to prevent the effects of noise stress induced rat immune system and explore a strong immunostimulant potential applicable to clinical practices.

Acute restraint stress induces rapid changes in central redox status and protective antioxidant genes in rats

The stress-induced imbalance in reduction/oxidation (redox) state has been proposed to play a major role in the etiology of neurological disorders. However, the relationship between psychological stress, central redox state, and potential protective mechanisms within specific neural regions has not been well characterized. In this study, we have used an acute psychological stress to demonstrate the dynamic changes that occur in the redox system of hippocampal and striatal tissue. Outbred male Wistar rats were subject to 0 (control), 60, 120, or 240min of acute restraint stress and the hippocampus and striatum were cryodissected for redox assays and relative gene expression. Restraint stress significantly elevated oxidative status and lipid peroxidation, while decreasing glutathione ratios overall indicative of oxidative stress in both neural regions. These biochemical changes were prevented by prior administration of the glucocorticoid receptor antagonist, RU-486. The hippocampus also demonstrated increased glutathione peroxidase 1 and 4 antioxidant expression which was not observed in the striatum, while both regions displayed robust upregulation of the antioxidant, metallothionein 1a. This was observed with concurrent upregulation of 11β-hydroxysteroid dehydrogenase 1, a local reactivator of corticosterone, in addition to decreased expression of the cytosolic regulatory subunit of superoxide-producing enzyme, NADPH-oxidase. Together, this study demonstrates distinctive regional redox profiles following acute stress exposure, in addition to identifying differential capabilities in managing oxidative challenges via altered antioxidant gene expression in the hippocampus and striatum.

Activation of the hypothalamic-pituitary-adrenal stress axis induces cellular oxidative stress

Glucocorticoids released from the adrenal gland in response to stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis induce activity in the cellular reduction-oxidation (redox) system. The redox system is a ubiquitous chemical mechanism allowing the transfer of electrons between donor/acceptors and target molecules during oxidative phosphorylation while simultaneously maintaining the overall cellular environment in a reduced state. The objective of this review is to present an overview of the current literature discussing the link between HPA axis-derived glucocorticoids and increased oxidative stress, particularly focussing on the redox changes observed in the hippocampus following glucocorticoid exposure.

Guanosine prevents behavioral alterations in the forced swimming test and hippocampal oxidative damage induced by acute restraint stress

Guanosine is a guanine-based purine that modulates glutamate uptake and exerts neurotrophic and neuroprotective effects. In a previous study, our group demonstrated that this endogenous nucleoside displays antidepressant-like properties in a predictive animal model. Based on the role of oxidative stress in modulating depressive disorders as well as on the association between the neuroprotective and antioxidant properties of guanosine, here we investigated if its antidepressant-like effect is accompanied by a modulation of hippocampal oxidant/antioxidant parameters. Adult Swiss mice were submitted to an acute restraint stress protocol, which is known to cause behavioral changes that are associated with neuronal oxidative damage. Animals submitted to ARS exhibited an increased immobility time in the forced swimming test (FST) and the administration of guanosine (5mg/kg, p.o.) or fluoxetine (10mg/kg, p.o., positive control) before the exposure to stressor prevented this alteration. Moreover, the significantly increased levels of hippocampal malondialdehyde (MDA; an indicator of lipid peroxidation), induced by ARS were not observed in stressed mice treated with guanosine. Although no changes were found in the hippocampal levels of reduced glutathione (GSH), the group submitted to ARS procedure presented enhanced glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) activities and reduced catalase (CAT) activity in the hippocampus. Guanosine was able to prevent the alterations in GPx, GR, CAT activities, and in SOD/CAT activity ratio, but potentiated the increase in SOD activity elicited by ARS. Altogether, the present findings indicate that the observed antidepressant-like effects of guanosine might be related, at least in part, to its capability of modulating antioxidant defenses and mitigating hippocampal oxidative damage induced by ARS.

Agmatine abolishes restraint stress-induced depressive-like behavior and hippocampal antioxidant imbalance in mice

Agmatine has been recently emerged as a novel candidate to assist the conventional pharmacotherapy of depression. The acute restraint stress (ARS) is an unavoidable stress situation that may cause depressive-like behavior in rodents. In this study, we investigated the potential antidepressant-like effect of agmatine (10mg/kg, administered acutely by oral route) in the forced swimming test (FST) in non-stressed mice, as well as its ability to abolish the depressive-like behavior and hippocampal antioxidant imbalance induced by ARS. Agmatine reduced the immobility time in the mouse FST (1-100mg/kg) in non-stressed mice. ARS caused an increase in the immobility time in the FST, indicative of a depressive-like behavior, as well as hippocampal lipid peroxidation, and an increase in the activity of hippocampal superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities, reduced catalase (CAT) activity and increased SOD/CAT ratio, an index of pro-oxidative conditions. Agmatine was effective to abolish the depressive-like behavior induced by ARS and to prevent the ARS-induced lipid peroxidation and changes in SOD, GR and CAT activities and in SOD/CAT activity ratio. Hippocampal levels of reduced glutathione (GSH) were not altered by any experimental condition. In conclusion, the present study shows that agmatine was able to abrogate the ARS-induced depressive-like behavior and the associated redox hippocampal imbalance observed in stressed restraint mice, suggesting that its antidepressant-like effect may be dependent on its ability to maintain the pro-/anti-oxidative homeostasis in the hippocampus.

Disruption of non-enzymatic antioxidant defense systems in the brain of rats with water-immersion restraint stress

We examined whether non-enzymatic antioxidant defense systems are disrupted in the brain of rats with water-immersion restraint stress. When rats were exposed to water-immersion restraint stress for 1.5, 3 or 6 h, the brain had decreased ascorbic acid and reduced glutathione contents and increased lipid peroxide and nitric oxide metabolites contents at 3 h and showed further changes in these components with a reduction of vitamin E content at 6 h. Increased serum levels of stress markers were found at 1.5, 3 or 6 h of WIRS. Oral pre-administration of L-ascorbic acid (1.5 mmol/kg) or vitamin E (0.5 mmol/kg) to rats with 6 h of water-immersion restraint stress attenuated the increases in lipid peroxide and nitric oxide metabolites contents and the decrease in vitamin E content in the brain. Pre-administered L-ascorbic acid attenuated the decreases in brain ascorbic acid and reduced glutathione contents at 6 h of water-immersion restraint stress, while pre-administered vitamin E enhanced the decreases in those contents. Pre-administered L-ascorbic acid or vitamin E did not affect the increased serum levels of stress markers in rats with 6 h of water-immersion restraint stress. These results indicate that water-immersion restraint stress causes disruption of non-enzymatic antioxidant defense systems through enhanced lipid peroxidation and nitric oxide generation in the brain of rats with water-immersion restraint stress.

Disruption of redox homeostasis in cerebral cortex of developing rats by acylcarnitines accumulating in medium-chain acyl-CoA dehydrogenase deficiency

Medium-chain fatty acids and acylcarnitines accumulate in medium-chain acyl-CoA dehydrogenase deficiency (MCADD), the most frequent fatty acid oxidation defect clinically characterized by episodic crises with vomiting, seizures and coma. Considering that the pathophysiology of the neurological symptoms observed in MCADD is poorly known and, to our knowledge, there is no report on the involvement of acylcarnitines in the brain damage presented by the affected patients, the objective of the present study was to investigate the in vitro effects of hexanoylcarnitine (HC), octanoylcarnitine, decanoylcarnitine (DC) and cis-4-decenoylcarnitine (cDC) at concentrations varying from 0.01 to 1.0mM on important oxidative stress parameters in cerebral cortex of young rats. HC, DC and cDC significantly induced lipid peroxidation, as determined by increased thiobarbituric acid-reactive substances (TBA-RS) values. In addition, carbonyl formation was significantly augmented and sulfhydryl content diminished by DC, reflecting induction of protein oxidative damage. HC, DC and cDC also decreased glutathione (GSH) levels, the most important brain antioxidant defense. Furthermore, DC-induced elevation of TBA-RS values and decrease of GSH levels were prevented by the free radical scavengers melatonin and α-tocopherol, indicating the involvement of reactive oxygen species in these effects. We also found that l-carnitine itself did not induce lipid and protein oxidative damage, neither reduced the antioxidant defenses. Our present data show that the major medium-chain acylcarnitines accumulating in MCADD elicit oxidative stress in rat brain. It is therefore presumed that these compounds may be involved to a certain extent in the pathogenesis of the neurologic dysfunction of MCADD.