THE EFFECT OF LIPOIC ACID ON LIPID PEROXIDATION AND VISUAL EVOKED POTENTIALS (VEPS) IN RATS EXPOSED TO CHRONIC RESTRAINT STRESS

Oxidative Stress in Wistar Rats Under Acute Restraint Stress and Its Modulation by Antioxidants and Nitric Oxide Modulators

BACKGROUND

Several pathogenic conditions leading to morbidity, including cancer, aging, diabetes, reperfusion injury, cardiovascular disease, and neurological disorders, are known to be exacerbated by oxidative stress. Antioxidant therapy is effective in the treatment of such disorders and appears to be a potential therapeutic technique to reduce oxidative stress. The aim of our study is to investigate the antioxidant effects of L-ascorbic acid and nitric oxide (NO) modulators on rats suffering from oxidative stress induced by acute restraint stress (RSx1).

METHODOLOGY

In this in vivo study, Wistar rats were subjected to one hour of restraint stress on day 21 to induce oxidative stress. Superoxide dismutase (SOD), total antioxidant capacity (TAC), catalase, glutathione (GSH), and malondialdehyde (MDA) were used to assess the antioxidant effects. IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp. was used for data analysis.

RESULTS

Compared to vehicle groups, acute restraint stress (RSx1) dramatically increased MDA levels while decreasing GSH, SOD, total antioxidant capacity, and catalase. L-NAME, 7-NI, AG (50 mg/kg each), and L-ascorbic acid (200 mg/kg) reversed the changes in SOD, MDA, GSH, total antioxidant capacity, and catalase levels. The NO precursor L-arginine (1000 mg/kg) and NO synthase inhibitors followed the same trend.

CONCLUSION

Our study findings highlight the complex role of antioxidants and NO modulators in the pathogenesis of diseases, as evidenced by the reversal of oxidative stress indicators. Antioxidant therapy, with its potential to mitigate oxidative stress, emerges as a viable treatment option for a range of pathological conditions associated with oxidative stress.

Static Magnetic Fields Modulate the Response of Different Oxidative Stress Markers in a Restraint Stress Model Animal

Stress is a state of vulnerable homeostasis that alters the physiological and behavioral responses. Stress induces oxidative damage in several organs including the brain, liver, kidney, stomach, and heart. Preliminary findings suggested that the magnetic stimulation could accelerate the healing processes and has been an effective complementary therapy in different pathologies. However, the mechanism of action of static magnetic fields (SMFs) is not well understood. In this study, we demonstrated the effects of static magnetic fields (0.8 mT) in a restraint stressed animal model, focusing on changes in different markers of oxidative damage. A significant increase in the plasma levels of nitric oxide (NO), malondialdehyde (MDA), and advanced oxidation protein products (AOPP), and a decrease in superoxide dismutase (SOD), glutathione (GSH), and glycation end products (AGEs) were observed in restraint stress model. Exposure to SMFs over 5 days (30, 60, and 240 min/day) caused a decrease in the NO, MDA, AGEs, and AOPP levels; in contrast, the SOD and GSH levels increased. The response to SMFs was time-dependent. Thus, we proposed that exposure to weak-intensity SMFs could offer a complementary therapy by attenuating oxidative stress. Our results provided a new perspective in health studies, particularly in the context of oxidative stress.

Neuroprotection of Brain Cells by Lipoic Acid Treatment after Cellular Stress

We have previously observed that in vivo lipoic acid (LA) treatment induced a protective effect onto primary cortical neurons after brain injury. In an effort to better understand LA action mechanism in the brain, in the present study, we stressed brain cells in vitro and ex vivo and then analyzed by inmmunocytochemistry and biochemical assays, the changes induced by LA on cell survival and on the concentration of oxidative stress markers, such as glutathione (GSH), oxidized glutathione (GSSG), and malondialdehyde (MDA). The stressors used were lipopolysaccharide (LPS), dopamine, and l-buthionine-S,R-sulfoximine (BSO). Our results showed that LA decreased cell death and increased GSH/GSSG ratio in cells stressed by LPS + dopamine, suggesting that the mechanism underlying LA action is regeneration of GSSG to GSH. When cells were stressed by BSO, LA diminished cell death and decreased GSH/GSSG ratio. In this case, it could be concluded that, due to the low GSH basal levels, GSSG reduction is not possible and therefore it might be thought that cell death prevention might be mediated through other mechanisms. Finally, we induced chemical oxidative damage in brain homogenate. After LA treatment, GSH and GSH/GSSG ratio increased and MDA concentration decreased, demonstrating again that LA was not able to increase de novo GSH synthesis but is able to increase GSSG conversion to GSH.

Preventive effect of α-lipoic acid on prepulse inhibition deficits in a juvenile two-hit model of schizophrenia

Some pathophysiological models of schizophrenia posit that prenatal inflammation sensitizes the developing brain to second insults in early life and enhances brain vulnerability, thereby increasing the risk of developing the disorder during adulthood. We previously developed a two-hit animal model, based on the well-established prenatal immune challenge with poly-inosinic/cytidylic acid (polyI:C), followed by juvenile restraint stress (RS). We observed an additive disruption of prepulse inhibition (PPI) of acoustic startle in juvenile mice submitted to both insults. Previous studies have also reported that oxidative stress is associated with pathophysiological mechanisms of psychiatric disorders, including schizophrenia. We report here that PPI disruption in our two-hit animal model of schizophrenia is associated with an increase in oxidative stress. These findings led us to assess whether α-lipoic acid, an antioxidant, can prevent both increase in oxidative status and PPI deficits in our juvenile in vivo model of schizophrenia. In the offspring submitted to prenatal injection of polyI:C and to RS, treatment with α-lipoic acid prevented the development of PPI deficits 24h after the last period of RS. α-Lipoic acid also improved PPI performance in control mice. The reversal effect of α-lipoic acid pretreatment on these behavioral alterations was further accompanied by a normalization of the associated oxidative status and dopaminergic and GABAergic abnormalities in the prefrontal cortex. Based on our double insult paradigm, these results support the hypothesis that oxidative stress plays an important role in the development of PPI deficits, a well-known behavior associated with schizophrenia. These findings form the basis of future studies aiming to unravel mechanistic insights of the putative role of antioxidants in the treatment of schizophrenia, especially during the prodromal stage.

Prophylaxis with alpha-lipoic acid against lipopolysaccharide-induced brain injury in rats

Introduction

Lipopolysaccharide (LPS) stimulates the synthesis and release of reactive oxygen species that play an important role in the pathogenesis of tissue injuries. In this study the effect of early administration of the antioxidant α-lipoic acid (α-LA) on brain lipid peroxidation, brain hydrogen peroxide (H₂O₂) concentration, and brain total sulfhydryl group (-SH group) content was evaluated in rats with endotoxic shock induced by administration of LPS (Escherichia coli 026:B6, 30 mg/kg i.v.)

Materials and Methods

Rats were treated intravenously with normal saline or α-LA (60 mg/kg) 30 min after LPS injection. After 5 h of observation, the animals were killed and their brains were isolated for the measurements.

Results

Injection of LPS alone resulted in the development of shock and oxidative stress, the latter indicated by a significant increase in brain concentrations of thiobarbituric acid-reacting substances (TBARS) and H₂O₂ and a decrease in total brain -SH group content. Administration of α-LA after the LPS challenge resulted in an increase in total -SH group content and a decrease in TBARS and H₂O₂ concentration in the brain tissue compared with the LPS group.

Conclusion

The results indicate that α-LA treatment effectively protected the brain tissue against endotoxin-induced oxidative stress. Administration of LA could be a useful adjunct to clinical application in the management of septic shock.