The association effect of insulin and clonazepam on oxidative stress in liver of an experimental animal model of diabetes and depression

Variants in the Upstream Region of the Insulin Receptor Substrate-1 Gene Is Associated with Major Depressive Disorder in the Han Chinese Population

INTRODUCTION

Major depressive disorder (MDD) is one of the most prevalent and disabling mental disorders, although its underlying genetic mechanism remains unknown. Insulin receptor substrate-1 (IRS-1) is one of the critical downstream molecules in the insulin resistance signaling pathway, linking depression and diabetes. Therefore, we hypothesized that IRS-1 would be a susceptible gene for MDD, and we aimed to examine the genetic association between IRS-1 and MDD.

METHODS

This case-control study included 583 patients with MDD and 564 controls, and the genotypic and allelic distributions of the IRS-1 gene's four single nucleotide polymorphisms (SNPs) were detected by TaqMan SNP genotyping technology. Of the 583 patients, 191 underwent a further detailed interview about symptom severity and family history of mental illness. The chi-square or t test was used to analyze the data, and analyses were performed using SPSS19.0 software.

RESULTS

A haplotype in the 5'-upstream region of IRS-1 consisting of rs13411764 and rs3820926 was a risk factor of MDD. Patients with a family history of mental illness were more likely to have a GG genotype in rs13411764 and a G-T haplotype containing rs13411714-rs3820926.

DISCUSSION

The findings imply that the haplotype consisting of rs13411764 and rs3820926 in the upstream of IRS-1 is a risk factor for MDD. This haplotype could affect IRS-1 expression levels, and it is mostly inherited from parents. Thus, the presence of variants in the upstream region of IRS-1 is a risk factor of MDD, and this study could serve as a convincing reference for further studies.

DNA damage and repair in neuropsychiatric disorders. What do we know and what are the future perspectives?

Over the past two decades, extensive research has been done to elucidate the molecular etiology and pathophysiology of neuropsychiatric disorders. In majority of them, including Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), bipolar disorder (BD), schizophrenia and major depressive disorder, increased oxidative and nitrosative stress was found. This stress is known to induce oxidative damage to biomolecules, including DNA. Accordingly, increased mitochondrial and nuclear DNA, as well as RNA damage, were observed in patients suffering from these diseases. However, recent findings indicate that the patients are characterised by impaired DNA repair pathways, which may suggest that these DNA lesions could be also a result of their insufficient repair. In the current systematic, critical review, we aim to sum up, using available literature, the knowledge about the involvement of nuclear and mitochondrial DNA damage and repair, as well as about damage to RNA in pathoetiology of neuropsychiatric disorders, i.e., AD, PD, ALS, BD, schizophrenia and major depressive disorder, as well as the usefulness of the discussed factors as being diagnostic markers and targets for new therapies. Moreover, we also underline the new directions to which future studies should head to elucidate these phenomena.

The interplay between inflammation, oxidative stress, DNA damage, DNA repair and mitochondrial dysfunction in depression

A growing body of evidence suggests that inflammation, mitochondrial dysfunction and oxidant-antioxidant imbalance may play a significant role in the development and progression of depression. Elevated levels of reactive oxygen and nitrogen species - a result of oxidant-antioxidant imbalance - may lead to increased damage of biomolecules, including DNA. This was confirmed in depressed patients in a research study conducted by our team and other scientists. 8-oxoguanine - a marker of oxidative DNA damage - was found in the patients' lymphocytes, urine and serum. These results were confirmed using a comet assay on lymphocytes. Furthermore, it was shown that the patients' cells repaired peroxide-induced DNA damage less efficiently than controls' cells and that some single nucleotide polymorphisms (SNP) of the genes involved in oxidative DNA damage repair may modulate the risk of depression. Lastly, less efficient DNA damage repair observed in the patients can be, at least partly, attributed to the presence of specific SNP variants, as it was revealed through a genotype-phenotype analysis. In conclusion, the available literature shows that both oxidative stress and less efficient DNA damage repair may lead to increased DNA damage in depressed patients. A similar mechanism may result in mitochondrial dysfunction, which is observed in depression.

The role of oxidative and nitrosative stress in accelerated aging and major depressive disorder

Major depressive disorder (MDD) affects millions of individuals and is highly comorbid with many age associated diseases such as diabetes mellitus, immune-inflammatory dysregulation and cardiovascular diseases. Oxidative/nitrosative stress plays a fundamental role in aging, as well as in the pathogenesis of neurodegenerative/neuropsychiatric disorders including MDD. In this review, we critically review the evidence for an involvement of oxidative/nitrosative stress in acceleration of aging process in MDD. There are evidence of the association between MDD and changes in molecular mechanisms involved in aging. There is a significant association between telomere length, enzymatic antioxidant activities (SOD, CAT, GPx), glutathione (GSH), lipid peroxidation (MDA), nuclear factor κB, inflammatory cytokines with MDD. Major depression also is characterized by significantly lower concentration of antioxidants (zinc, coenzyme Q10, PON1). Since, aging and MDD share a common biological base in their pathophysiology, the potential therapeutic use of antioxidants and anti-aging molecules in MDD could be promising.

Diabetic encephalopathy-related depression: experimental evidence that insulin and clonazepam restore antioxidant status in rat brain

There is increasing evidence suggesting that oxidative stress plays an important role in the development of many chronic and degenerative conditions such as diabetic encephalopathy and depression. Considering that diabetic rats and mice present higher depressive-like behaviour when submitted to the forced swimming test and that treatment with insulin and/or clonazepam is able to reverse the behavioural changes of the diabetic rats, the present work investigated the antioxidant status, specifically total antioxidant reactivity and antioxidant potential of insulin and clonazepam, as well as the effect of this drugs upon protein oxidative damage and reactive species formation in cortex, hippocampus and striatum from diabetic rats submitted to forced swimming test. It was verified that longer immobility time in diabetic rats and insulin plus clonazepam treatment reversed this depressive-like behaviour. Moreover, data obtained in this study allowed to demonstrate through different parameters such as protein carbonyl content, 2'7'-dichlorofluorescein oxidation, catalase, superoxide dismutase, glutathione peroxidase assay, total radical-trapping antioxidant potential and total antioxidant reactivity that there is oxidative stress in cortex, hippocampus and striatum from diabetic rats under depressive-like behaviour and highlight the insulin and/or clonazepam effect in these different brain areas, restoring antioxidant status and protein damage.

Dihydromyricetin ameliorates the oxidative stress response induced by methylglyoxal via the AMPK/GLUT4 signaling pathway in PC12 cells

Dihydromyricetin (DMY), the major bioactive flavonoid ingredient extracted from the leaves of Ampelopsis grossedentata (Hand.-Mazz) W.T. Wang, displays multiple pharmacological activities, including oxidation resistance, antitumor properties and free radical scavenging capacities. However, the role of DMY in methylglyoxal (MG)-induced diabetes-associated cognitive decline and its underlying molecular mechanisms are unclear. The aim of the present study was to evaluate the effects of DMY on oxidative stress and glucose transport activity in a MG-induced PC12 cell line and to explore the related mechanisms. The effects of DMY on cell survival and apoptosis were examined, and the dysregulation of intracellular Ca(2+) was determined. Oxidative stress was evaluated by monitoring ROS production and the glutathione to glutathione disulfide ratio. The effects of DMY on glucose metabolism were investigated using a fluorescently labeled deoxyglucose analog and by measuring ATP and lactate production. Western blot analysis was performed to examine the protein levels of glyoxalase I (Glo-1), glucose transporter 4 (GLUT4), AMP-activated protein kinase (AMPKα) and phosphorylated AMPKα (p-AMPKα). The results revealed that DMY suppressed cellular oxidative stress in PC12 cells and balanced glucose metabolism. Additionally, DMY reduced GLUT4 translocation dysfunction and increased Glo-1 and p-AMPKα expression. We found that DMY protected PC12 cells against MG-induced apoptosis and glycometabolic disorders, at least in part by restraining the hyperactivation of p-AMPK activity and normalizing the translocation of GLUT4 from the intracellular compartment, resulting in a balance in glucose uptake. This result indicates that DMY may serve as a novel and effective candidate agent to treat diabetic encephalopathy by reducing the toxicity of MG.

Consumption of Coprinus comatus polysaccharide extract causes recovery of alcoholic liver damage in rats

CONTEXT

Excess use of alcohol is known to be associated with liver diseases such as fatty liver, alcoholic hepatitis, and cirrhosis. Various practices may be applied to prevent or treat the damage caused by chronic alcoholism. Coprinus comatus (O.F. Müll.) Pers. (Agaricaceae) is a macrofungus that has been reported to aid the recovery of murine livers damaged by benzopyrene.

OBJECTIVE

In this study, the possible therapeutic effects of three different doses (50, 100, and 150 mg/kg) of C. comatus polysaccharide (PS) extract were studied in rats subjected to an alcoholic diet. The histological and biochemical results were compared between the control and experimental groups.

MATERIALS AND METHODS

Modified Lieber-Decarli's calorie-adjusted liquid alcohol diet was given orally for 60 d. In addition to histopathology, alanine transaminase (ALT), aspartate transaminase (AST), mitochondrial membrane integrity, total cytochrome-c oxidase activity (TotalStCox), total mitochondrial cytochrome-c oxidase activity (TotalMtStCox), and caspase-3 values were used as liver parameters, and liver sections from all experimental groups were examined by electron microscopy.

RESULTS

Using histopathological assessment, it was observed that there was a decline in liver hepatocyte vacuolization in the treatment group fed 50 mg PS/kg. The TotalStCox and TotalMtStCox values of this group differed from the EtOH control group (p < 0.05).

DISCUSSION AND CONCLUSION

Daily administration of 50 mg/kg of C. comatus PS extract considerably reduced the negative effects of alcohol on liver structure and function.

Neuroprotective effects of folic acid on experimental diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is widely considered as a degenerative complication of diabetic patients. The clinical effectiveness of folic acid (FA) on DPN is uncertain. The objective of the present study was to determine the effect of FA in DPN using electromyography (EMG), histopathological examination, immunohistochemistry, inclined plane test, and malondialdehyde (MDA) levels as a marker for lipid peroxidation in experimental diabetic rats. A total of 21 Sprague Dawley rats were randomly divided into 3 groups: control group, diabetes group, and FA-treated group. In EMG, compound muscle action potential (CMAP) amplitude in the sciatic nerve was lower in the diabetes group compared with the control group. CMAP amplitude in the sciatic nerve was higher in the FA-treated group when compared with the diabetes group. Distal latency and CMAP duration in the sciatic nerve were lower in the FA-treated group when compared with the diabetes group. In histopathological examination of the sciatic nerve, peripheral fibrosis was present in the diabetic group; the fibrosis was lower in the FA-treated group. In comparison with the diabetes group, the expression of nerve growth factor (NGF) was higher in the FA-treated group. The scores for the inclined plane test were lower in the diabetes group and higher in the FA-treated group than the control group. The MDA levels were significantly lower in the FA-treated group when compared with the diabetes group.

The study suggests that FA can protect diabetic rats against DPN and that the underlying mechanism for this may be related to improvement of the expression of NGF and lower MDA levels.