Studying neuroprotective effect of Atorvastatin as a small molecule drug on high glucose-induced neurotoxicity in undifferentiated PC12 cells: role of NADPH oxidase

Comparative effect of atorvastatin and risperidone on modulation of TLR4/NF-κB/NOX-2 in a rat model of valproic acid-induced autism

BACKGROUND

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that is significantly increasing, resulting in severe distress. The approved treatment for ASD only partially improves the sympoms, but it does not entirely reverse the symptoms. Developing novel disease-modifying drugs is essential for the continuous improvement of ASD. Because of its pleiotropic effect, atorvastatin has been garnered attention for treating neuronal degeneration. The present study aimed to investigate the therapeutic effects of atorvastatin in autism and compare it with an approved autism drug (risperidone) through the impact of these drugs on TLR4/NF-κB/NOX-2 and the apoptotic pathway in a valproic acid (VPA) induced rat model of autism.

METHODS

On gestational day 12.5, pregnant rats received a single IP injection of VPA (500 mg/kg), for VPA induced autism, risperidone and atorvastatin groups, or saline for control normal group. At postnatal day 21, male offsprings were randomly divided into four groups (n = 6): control, VPA induced autism, risperidone, and atorvastatin. Risperidone and atorvastatin were administered from postnatal day 21 to day 51. The study evaluated autism-like behaviors using the three-chamber test, the dark light test, and the open field test at the end of the study. Biochemical analysis of TLR4, NF-κB, NOX-2, and ROS using ELISA, RT-PCR, WB, histological examination with hematoxylin and eosin and immunohistochemical study of CAS-3 were performed.

RESULTS

Male offspring of prenatal VPA-exposed female rats exhibited significant autism-like behaviors and elevated TLR4, NF-κB, NOX-2, ROS, and caspase-3 expression. Histological analysis revealed structural alterations. Both risperidone and atorvastatin effectively mitigated the behavioral, biochemical, and structural changes associated with VPA-induced rat model of autism. Notably, atorvastatin group showed a more significant improvement than risperidone group.

CONCLUSIONS

The research results unequivocally demonstrated that atorvastatin can modulate VPA-induced autism by suppressing inflammation, oxidative stress, and apoptosis through TLR4/NF-κB/NOX-2 signaling pathway. Atorvastatin could be a potential treatment for ASD.

Daidzein ameliorates peripheral neuropathy in Sprague Dawley rats

Neuropathy is the most common disorder comprising peripheral nerve damage in diabetic patients. Prolonged hyperglycaemia and oxidative stress cause metabolic imbalance and are the key reasons for the development of diabetic neuropathy. Daidzein, a soy isoflavone possesses potent anti-hyperglycaemic and antioxidant activity. The present study aims to check the protective effect of Daidzein in diabetic neuropathy in rats. The experimental animal model involved induction of diabetes in rats by intraperitoneal injection of streptozotocin (55 mg/kg). Following confirmation of diabetes, the diabetic rats were subjected to oral treatment with varying doses of Daidzein (25, 50, and 100 mg/kg) and pregabalin (30 mg/kg) for a duration of 4 weeks, initiated 6 weeks after diabetes induction. Results indicated that Daidzein treatment led to a significant reduction in plasma glucose levels and an improvement in body weight among diabetic animals. Moreover, Daidzein demonstrated a positive impact on sensory functions, as evidenced by the effect on tail withdrawal and response latency. Mechanical hyperalgesia and allodynia, common symptoms of diabetic neuropathy, were also significantly reduced with both Daidzein and pregabalin treatment. Notably, nerve conduction velocities exhibited improvement following the administration of Daidzein and pregabalin. Further investigation into the molecular mechanisms revealed that Daidzein treatment resulted in a notable enhancement of antioxidant enzyme levels and a reduction in the overexpression of NOX-4 in the sciatic nerve. This suggests that Daidzein's therapeutic effect is associated with the inhibition of oxidative stress via NOX-4. In summary, the findings of study suggests that, Daidzein treatment significantly attenuated diabetic neuropathy by inhibiting oxidative stress via NOX-4 inhibition.

Does statin suppress oxaliplatin-induced peripheral neuropathy in patients with colorectal cancer? A single-center observational study

BACKGROUND

Oxaliplatin-induced peripheral neuropathy (OIPN) is a common and dose-limiting toxicity that markedly limits the use of oxaliplatin and affects quality of life. Statins have been shown to exert neuroprotective effects in preclinical settings. The aim of the present study was to clarify whether statins prevented OIPN in patients with colorectal cancer (CRC) receiving adjuvant CAPOX therapy.

METHODS

We examined 224 patients who received adjuvant CAPOX therapy for CRC between July 2010 and December 2021 at our hospital. Patients were divided into "Statin" and "Non-statin" groups based on statin use. Details on and the adverse events of adjuvant CAPOX therapy were examined in association with statin use.

RESULTS

Thirty-one patients (14%) were treated with statins. There were no intergroup differences in the relative dose intensity or number of CAPOX cycles between the Statin and Non-statin groups. In total, 94% of patients in the Statin group and 95% of those in the Non-statin group developed OIPN (p=0.67). The severity of OIPN was similar between the two groups (p=0.89). The frequency of treatment delays in CAPOX did not significantly differ between the Statin and Non-statin groups (16% vs. 11%, p=0.45).

CONCLUSIONS

The efficacy of statins to attenuate OIPN during adjuvant CAPOX therapy was not apparent in the current study. Further studies are needed to confirm the present results.

Statins and the risk of polyneuropathy: A systematic review and two meta-analyses

INTRODUCTION/AIMS

Previous studies have shown inconsistent data on the relationship between statin use and polyneuropathy (PN). The current systematic review and meta-analyses were conducted to comprehensively investigate the risk of incident PN among statin-users compared with non-users by identifying all available studies and summarizing their results.

METHODS

A systematic review was conducted from MEDLINE and EMBASE databases from inception to October 31, 2020. We included cohort and case-control studies that compared the risk of incident PN between statin-users and non-users. Point estimates and standard errors from eligible studies were pooled together using the generic inverse variance method.

RESULTS

Of 4968 retrieved articles, 6 studies in non-diabetic populations and 2 studies in diabetic populations fulfilled the inclusion criteria. Two meta-analyses were performed. The pooled analyses did not find a statistically significant association between the use of statins and risk of incident PN with the pooled odds ratio of 1.24 (95% confidence interval [CI], 0.88-1.76; I² 74%) and 0.82 (95% CI, 0.56-1.21; I² 80%) in non-diabetic and diabetic groups respectively.

DISCUSSION

No significant association between the use of statins and the risk of PN was observed in this systematic review and these two meta-analyses. However, there was a high degree of heterogeneity of the meta-analyses.

LncRNA MEG3 Alleviates Diabetic Cognitive Impairments by Reducing Mitochondrial-Derived Apoptosis through Promotion of FUNDC1-Related Mitophagy via Rac1-ROS Axis

Mitochondrial dysfunction and elevated ROS generation are predominant contributors of neuronal death that is responsible for the diabetes-related cognitive impairments. Emerging evidence has demonstrated that long noncoding RNA-MEG3 can serve as an important regulator in the pathogenesis of diabetes. However, the underlying mechanisms remain to be further clarified. Here, it was observed that MEG3 was significantly down-regulated in STZ (streptozotocin)-induced diabetic rats. MEG3 overexpression noticeably improved diabetes-induced cognitive dysfunctions, accompanied by the abatement of Rac1 activation and ROS production, as well as the inhibition of mitochondria-associated apoptosis. Furthermore, either MEG3 overexpression or Rac1 inhibition promoted FUNDC1 dephosphorylation and suppressed oxidative stress and neuro-inflammation. Similarly, in vitro studies confirmed that hyperglycemia also down-regulated MEG3 expression in PC12 cells. MEG3 reintroduction protected PC12 cells against hyperglycemia-triggered neurotoxicity by improving mitochondrial fitness and repressing mitochondria-mediated apoptosis. Moreover, these neuroprotective effects of MEG3 relied on FUNDC1-related mitophagy, since silencing of FUNDC1 abolished these beneficial outcomes. Additionally, MEG3 rescued HG-induced neurotoxicity was involved in inhibiting Rac1 expression via interaction with Rac1 3'UTR. Conversely, knockdown of MEG3 showed opposite effects. NSC23766, a specific inhibitor of Rac1, fully abolished harmful effects of MEG3 depletion. Consistently, knockdown of Rac1 potentiated FUNDC1-associated mitophagy. Meanwhile, colocalization of Rac1 and FUNDC1 was found in mitochondria under hyperglycemia, which was interrupted by MEG3 overexpression. Furthermore, silencing of Rac1 promoted PGAM5 expression, and FUNDC1 strongly interacted with LC3 in Rac1-deleted cells. Altogether, our findings suggested that the Rac1/ROS axis may be a downstream signaling pathway for MEG3-induced neuroprotection, which was involved in FUNDC1-associated mitophagy.

Combatting Nitrosative Stress and Inflammation with Novel Substituted Triazinoindole Inhibitors of Aldose Reductase in PC12 Cells Exposed to 6-Hydroxydopamine Plus High Glucose

Cellular redox dysregulation produced by aldose reductase (AR) in the presence of high blood sugar is a mechanism involved in neurodegeneration commonly observed in diabetes mellitus (DM) and Parkinson's disease (PD); therefore, AR is a key target for treatment of both diseases. The substituted triazinoindole derivatives 2-(3-thioxo-2H-[1,2,4]triazino[5,6-b]indol-5(3H)-yl) acetic acid (cemtirestat or CMTI) and 2-(3-oxo-2H-[1,2,4]triazino[5,6-b]indol-5(3H)-yl) acetic acid (COTI) are well-known AR inhibitors (ARIs). The neuroprotective properties of CMTI, COTI, the clinically used epalrestat (EPA), and the pyridoindole antioxidants stobadine and SMe1EC2 were all tested in the neurotoxic models produced by hyperglycemic glucotoxicity (HG, 75 mM D-glucose, 72 h), 6-hydroxydopamine (6-OHDA), and HG+6-OHDA models in PC12 cells. Cell viability decreased in all toxic models, increased by 1-5 μM EPA, and decreased by COTI at ≥ 2.5 μM. In the HG model alone, where compounds were present in the medium for 24 h after a continuous 24-h exposure to HG, cell viability was improved by 100 nM-5 μM EPA, 1-10 μM ARIs, and the antioxidants studied, but decreased by EPA at ≥ 10 μM. In the 6-OHDA model alone, where cells were treated with compounds for 24 h and further exposed to 100 μM 6-OHDA (8 h), only the antioxidants protected cell viability. In the HG+6-OHDA model, where cells were treated with all compounds (1 nM to 50 μM) for 48 h and exposed to 75 mM glucose for 24 h followed by incubation with 6-OHDA for 8 h, cell viability was protected by 100 nM-10 μM ARIs and 100-500 nM EPA, but not by antioxidants. All ARIs inhibited the HG+6-OHDA-induced increase in iNOS, IL-1β, TNF-α, 3-NT, and total oxidant status at 1-50 μM, while increased SOD, CAT, GPx, and total antioxidant status at 1-10 μM. EPA and CMTI also reduced the HG+6-OHDA-induced increase in the cellular levels of nuclear factor kB (NF-KB). The neuroprotective potential of the novel ARIs and the pyridoindole antioxidants studied constitutes a promising tool for the development of therapeutic strategies against DM-induced and PD-related neurodegeneration.

Dexmedetomidine exerts neuroprotective effects during high glucose-induced neural injury by inhibiting miR-125b

Diabetic neuropathy (DNP) is the most common complication of diabetes mellitus affecting approximately 50% of diabetes patients. Studying the effect of potential drugs with antioxidant properties and minimal toxicities on neural cells may lead to the development of new and safe pharmacotherapy. Dexmedetomidine (DEX), a highly selective α2-adrenoceptor agonist, is a clinically used sedative also known to have neural protection effect. In the present study, we aimed to investigate the protective role of DEX in high glucose (HG)-induced neural injury and its potential miRNA-related mechanisms. Our results showed that DEX exerted neuroprotective effects during high glucose-induced damage to PC12 cells in a dose-dependent manner. DEX restored cell viability and repressed LDH, Caspase-3 activity, ROS production, and cell apoptosis in HG-treated PC12 cells. MiR-125b-5p was significantly up-regulated in PC12 cells upon HG treatment and it was demonstrated as an target for DEX. The neuroprotective effects of DEX on HG-induced cellular injury were reversed through miR-125b-5p overexpression, and vitamin D receptor (VDR) is a direct targeted of the miR-125b-5p. Together, our results indicate that DEX displays neuroprotective effects on PC-12 cells under high glucose through regulating miR-125b-5p/VDR axis. Our findings might raise the possibility of potential therapeutic application of DEX for managing diabetic neuropathy neural injuries.

NADPH oxidase: A membrane-bound enzyme and its inhibitors in diabetic complications

The human body has a mechanism for balancing the generation and neutralization of reactive oxygen species. The body is exposed to many agents that are responsible for the generation of reactive oxygen/nitrogen species, which leads to disruption of the balance between generation of these species and oxidative stress defence mechanisms. Diabetes is a chronic pathological condition associated with prolonged hyperglycaemia. Prolonged elevation of level of glucose in the blood leads to the generation of reactive oxygen species. This generation of reactive oxygen species is responsible for the development of diabetic vasculopathy, which includes micro- and macrovascular diabetic complications. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is a membrane-bound enzyme responsible for the development of reactive oxygen species in hyperglycaemia. Phosphorylation of the cytosolic components of NOX, such as p47phox, p67phox, and RAC-1, in hyperglycaemia is one of the important causes of conversion of oxygen to reactive oxygen. Overexpression of NOX in pathological conditions is associated with activation of aldose reductase, advanced glycation end products, protein kinase C and the hexosamine pathway. In addition, NOX also promotes the activation of inflammatory cytokines, such as TGF-β, TNF-α, NF-kβ, IL-6, and IL-18, the activation of endothelial growth factors, such as VEGF and FGF, hyperlipidaemia, and the deposition of collagen. Thus, overexpression of NOX is linked to the development of diabetic complications. The present review focuses on the role of NOX, its associated pathways, and various NOX inhibitors in the management and treatment of diabetic complications, such as diabetic nephropathy, retinopathy, neuropathy and cardiomyopathy.

Protective effects of atorvastatin on high glucose-induced oxidative stress and mitochondrial apoptotic signaling pathways in cultured chondrocytes

The high glucose concentration is able to disturb chondrocyte homeostasis and contribute to OA pathogenesis. This study was designed to investigate the protective effects of atorvastatin (ATO) on high glucose (HG)-mediated oxidative stress and mitochondrial apoptosis in C28I2 human chondrocytes. The protective effect of ATO (0.01 and 0.1 μM) on HG (75 mM)-induced oxidative stress and apoptosis was evaluated in C28I2 cells. The effects of ATO on HG-induced intracellular ROS production and lipid peroxidation were detected and the protein expression levels of Bax, Bcl-2, caspase-3, total and phosphorylated JNK and P38 MAPKs were analyzed by Western blotting. The mRNA expression levels of antioxidant enzymes including heme oxygenase-1, NAD(P)H quinine oxidoreductase, glutathione S-transferase-P1, catalase, superoxide dismutase-1, glutathione peroxidase-1, -3, -4 were evaluated by reverse transcription-polymerase chain reaction. Pretreatment with ATO remarkably increased the gene expression levels of antioxidant enzymes and reduced HG-induced elevation of ROS, lipid peroxidation, Bax/Bcl-2 ratio, caspase-3 activation, and JNK and P38 phosphorylation. Atorvastatin could considerably reduce HG-induced oxidative stress and mitochondrial apoptosis through increasing the expression of antioxidant enzymes. Atorvastatin may be considered as a promising agent to prevent high glucose-induced cartilage degradation in OA patients.