Sevoflurane‑induced neurotoxicity is driven by OXR1 post‑transcriptional downregulation involving hsa‑miR‑302e

Brain DNA damaging effects of volatile anesthetics and 1 and 2 Gy gamma irradiation in vivo: Preliminary results

Although both can cause DNA damage, the combined impact of volatile anesthetics halothane/sevoflurane/isoflurane and radiotherapeutic exposure on sensitive brain cells in vivo has not been previously analyzed. Healthy Swiss albino male mice (240 in total, 48 groups) were exposed to either halothane/sevoflurane/isoflurane therapeutic doses alone (2 h); 1 or 2 gray of gamma radiation alone; or combined exposure. Frontal lobe brain samples from five animals were taken immediately and 2, 6, and 24 h after exposure. DNA damage and cellular repair index were analyzed using the alkaline comet assay and the tail intensity parameter. Elevated tail intensity levels for sevoflurane/halothane were the highest at 6 h and returned to baseline within 24 h for sevoflurane, but not for halothane, while isoflurane treatment caused lower tail intensity than control values. Combined exposure demonstrated a slightly halothane/sevoflurane protective and isoflurane protective effect, which was stronger for 2 than for 1 gray. Cellular repair indices and tail intensity histograms indicated different modes of action in DNA damage creation. Isoflurane/sevoflurane/halothane preconditioning demonstrated protective effects in sensitive brain cells in vivo. Owing to the constant increases in the combined use of radiotherapy and volatile anesthetics, further studies should explore the mechanisms behind these effects, including longer and multiple exposure treatments and in vivo brain tumor models.

Down-regulation of miR-204-5p ameliorates sevoflurane-induced brain injury in neonatal rats through targeting VCAM1

To confirm the regulation of miR-204-5p on VCAM1 and its effect on sevoflurane-induced brain injury in neonatal rats. We adopted the sevoflurane-induced brain injury model, and the double luciferase reporter gene assay was applied to explore the targeting relationship between vascular adhesion factor 1 (VCAM1) and miR-204-5p. RT-qPCR was applied to assess the levels of miR-204-5. VCAM1, LC3, P62 and cleaved-caspase 3 levels in the hippocampus were estimated by western blot. The number of autophagosomes in the cerebral cortex was assessed via Transmission electron microscopy (TEM), and histopathological changes within the hippocampus by HE staining. miR-204-5p levels were remarkably increased, but VCAM1 expression was decreased after neonatal rat brain injury. Furthermore, miR-204-5p directly targeted VCAM1. The escape latency, swimming distance, autophagosome number, neuronal apoptosis ratio, LC3 II and Cleaved-caspase 3 expression were reduced after miR-204-5p inhibition interference, whereas crossing times, and P62 expression increased in the sevoflurane-induced brain injury model. Furthermore down-regulation of VCAM1 reversed the trend of these indices. These results suggest that down-regulation of miR-204-5p ameliorates sevoflurane-induced cognitive impairment and hippocampal pathology and inhibits neuronal autophagy and apoptosis by targeting VCAM1.

Expression Profile of mRNAs and miRNAs Related to the Oxidative-Stress Phenomenon in the Ishikawa Cell Line Treated Either Cisplatin or Salinomycin

The oxidative stress phenomenon is a result of anticancer therapy. The aim of this study was the assessment of gene expression profile changes, and to determine the miRNAs regulating genes’ transcriptional activity in an Ishikawa endometrial cancer culture exposed to cisplatin or salinomycin, compared to a control culture. The molecular analysis comprised the microarray technique (mRNAs and micro RNA (miRNA), the real-time quantitative reverse transcription reaction (RTqPCR), enzyme-linked immunosorbent assay (ELISA) reactions, and Western blot. NR4A2, MAP3K8, ICAM1, IL21, CXCL8, CCL7, and SLC7A11 were statistically significantly differentiated depending not only on time, but also on the drug used in the experiment. The conducted assessment indicated that the strongest links were between NR4A2 and hsa-miR-30a-5p and has-miR-302e, MAP3K8 and hsa-miR-144-3p, CXCL8 and hsa-miR-140-3p, and SLC7A11 and hsa-miR-144-3p. The obtained results suggest that four mRNAs—NR4A2, MAP3K8, CXCL8 and SLC7A11—and four miRNAs—hsa-miR-30a-5p, hsa-miR-302e, hsa-miR-144-3p and hsa-miR-140-3—changed their expressions regardless of the chemotherapeutic agent used, which suggests the possibility of their use in monitoring the severity of oxidative stress in endometrial cancer. However, considering the results at both the mRNA and the protein level, it is most likely that the expressions of NR4A2, MAP3K8, CXCL8 and SLC7A11 are regulated by miRNA molecules as well as other epigenetic mechanisms.

The effects of dietary stachyose as prebiotic on immunity and anti-oxidant related genes’ expression and lipid metabolism in zebrafish (Danio rerio)

An 8-week feeding trial was conducted to examine the efficacy of stachyose as a prebiotic on immune parameters, antioxidant-/immune-related genes’ expression, and lipid metabolism of zebrafish. Three hundred zebrafish (0.45 ± 0.08 g) were fed four diets containing different stachyose levels at 0, 1, 2 and 4 g kg-1, respectively. After eight weeks of the feeding trial, immunity, anti-oxidant defence and lipid metabolism were tested. It was observed that the addition of stachyose to the diet induced no significant influence (P>0.05) in SOD, GPX, and CAT, gene’s expression, compared to the control diet. The inclusion of stachyose resulted in no significant changes in immune gene expression (Lyz, IL-1, IL-6, and TNF) in zebrafish (P>0.05) compared to the control diet. Total cholesterol, triglyceride and LDL (low-density lipoprotein) significantly (P<0.05) decreased with the addition of 2 and 4 g kg-1 stachyose, while fish fed the control diet and 1 g.kg-1 recorded the highest significant value of LDL (P<0.05). Fish fed diet, either control or diet supplemented with 0.5 g kg-1 stachyose, recorded the lowest HDL value (P<0.05) compared to other treatments. In conclusion, stachyose can be potentially used as a feed additive to modulate lipid metabolism. However, this prebiotic couldn’t benefit immune parameters and anti-oxidant defence.

miR-424 inhibits apoptosis and inflammatory responses induced by sevoflurane through TLR4/MyD88/NF-κB pathway

BACKGROUND

Side effects of sevoflurane in anterograde and retrograde memory have been widely reported. However, there is no convincing evidence that sevoflurane directly causes the development of neurotoxicity. miR-424 has the potential to regulate the neurotoxicity caused by isoflurane anesthesia, and it has a complementary sequence with the 3'UTR region of TLR4. Thus, our study aims to explore whether sevoflurane directly causes neurotoxicity, the effects of miR-424 on sevoflurane induced apoptosis and inflammation, and the underlying mechanism.

METHODS

Sevoflurane effects were identified both in mouse and in PC12 cells. Western blots and ELISA were used for protein detection, while micro (mi) RNA expression was measured with RT-qPCR. Dual luciferase reporter assays were employed to study the interaction between miR-424 and Toll-like receptor 4 (TLR4) using miR-424 mimics and TLR4 over-expression.

RESULTS

Sevoflurane stimulated expression of Bax2 and Caspase-3, and increased apoptosis ratio both in vivo and vitro (P < 0.05). Inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, were up-regulated by sevoflurane, while IL-10 was downregulated (P < 0.05). Sevoflurane treatment enhanced the phosphorylation of NF-κB, and up-regulated the expressions of TLR4 and MyD88 (P < 0.05), which demonstrated that sevoflurane inhibited proliferation and differentiation of neuronal cells by activating TLR4/MyD88/NF-κB signaling both in vitro and vivo. However, up-regulation of miR-424 attenuated the negative effects of sevoflurane by targeting the 3'-untranslated region (UTR) of TLR4 and inducing the degradation of mRNA (P < 0.05).

CONCLUSIONS

In vitro, sevoflurane induces activation of the endogenous TLR4 signaling pathway, thereby promoting apoptosis and inflammatory cytokine expression. Exogenous TLR4 acts as an agonist to stimulate TLR4 signaling, whereas miR-424 inhibits both endogenous and exogenous TLR4 signaling, thereby preserving proliferation and differentiation of neuronal cells.

6-Shogaol Inhibits Oxidative Stress-Induced Rat Vascular Smooth Muscle Cell Apoptosis by Regulating OXR1-p53 Axis

Apoptosis of vascular smooth muscle cells (VSMCs) is closely related to the pathogenesis of cardiovascular diseases, and oxidative stress is an important cause of VSMCs' death. Inhibiting VSMCs apoptosis is an effective preventive strategy in slowing down the development of cardiovascular disease, especially for atherosclerosis. In this study, we found that oxidation resistance protein 1 (OXR1), a crucial participator for responding to oxidative stress, could modulate the expression of p53, the key regulator of cell apoptosis. Our results revealed that oxidative stress promoted VSMCs apoptosis by overexpression of the OXR1-p53 axis, and 6-shogaol (6S), a major biologically active compound in ginger, could effectively attenuate cell death by preventing the upregulated expression of the OXR1-p53 axis. Quantitative proteomics analysis revealed that the degradation of p53 mediated by OXR1 might be related to the enhanced assembly of SCF ubiquitin ligase complexes, which is reported to closely relate to the modification of ubiquitination or neddylation and subsequent degradation of p53.

Inhibitive Effect of Luteolin on Sevoflurane-Induced Neurotoxicity through Activation of the Autophagy Pathway by HMOX1

Luteolin is a flavone compound occurring in a variety of medicinal plants, which is reported to have neuroprotective properties. In this study, we aimed to explore the effects of luteolin in alleviating sevoflurane-induced neurotoxicity. GeneCards and Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform were employed to screen luteolin, sevoflurane, and neurotoxicity-related genes. Subsequently, we isolated primary neurons from the hippocampus of 1-day-old C57BL/6J mice and tested for cytotoxicity after treatment of different concentrations of luteolin. Next, we measured the expression of apoptosis by flow cytometry and assessed inflammation-related factors, including heme oxygenase-1 expression detected by immunohistochemical staining and neuronal apoptosis. Finally, water maze, open field, and fear conditioning tests were conducted to observe the interaction between luteolin and sevoflurane in cognitive impairment of mice. Luteolin had the lowest cytotoxicity at concentrations of 30 or 60 μg/mL; we selected 30 μg/mL for drug administration experiments in vitro. Luteolin inhibited sevoflurane-induced neuronal apoptosis and inflammatory responses through the autophagic pathway and thus ameliorated sevoflurane-induced cognitive impairment in mice. Mechanistically, luteolin up-regulated heme oxygenase-1 expression, which activated the autophagy pathway in vitro. This was confirmed by subsequent histological experiments in mice and behavioral results showing rescue cognitive impairment. Our findings uncovered an inhibitory role of luteolin in sevoflurane-induced neuronal apoptosis and inflammatory response through activation of autophagy arising from up-regulation of heme oxygenase-1, thereby alleviating sevoflurane-induced cognitive impairment in mice.

Oxidative Stress Resistance 1 Gene Therapy Retards Neurodegeneration in the rd1 Mutant Mouse Model of Retinopathy

Purpose

Oxidative stress is a major factor underlying many neurodegenerative diseases. However, antioxidant therapy has had mixed results, possibly because of its indiscriminate activity. The purpose of our study was to determine if the human OXR1 (hOXR1) antioxidant regulatory gene could protect neurons from oxidative stress and delay photoreceptor cell death.

Methods

The cone-like 661W cell line was transfected to stably express the hOXR1 gene. Oxidative stress was induced by the addition of hydrogen peroxide (H2O2). Intracellular levels of reactive oxygen species (ROS), caspase cleavage, and cellular resistance to oxidative stress were determined and compared between the control and hOXR1 cells. For in vivo analysis, AAV8-hOXR1 was injected subretinally into the rd1 mouse model of retinal degeneration. Functional and structural integrity of the photoreceptors were assessed using electroretinography (ERG), histology, and immunofluorescence analysis.

Results

Expression of hOXR1 increased cellular resistance and reduced ROS levels and caspase cleavage in the 661W cell line after H2O2-induced oxidative stress. Subretinal injection of AAV8-hOXR1 in the rd1 mice improved their photoreceptor light response, expression and localization of photoreceptor-specific proteins, and delayed retinal degeneration.

Conclusions

Our results suggest that OXR1 is a potential therapy candidate for retinal degeneration. Because OXR1 targets oxidative stress, a common feature of many retinal degenerative diseases, it should be of therapeutic value to multiple retinal degenerative diseases.

Apoptosis inhibition is involved in improvement of sevoflurane-induced cognitive impairment following normobaric hyperoxia preconditioning in aged rats

Sevoflurane, a commonly used anesthetic agent has been confirmed to induce cognitive impairment in aged rats. Normobaric hyperoxia preconditioning has been demonstrated to induce neuroprotection in rats. The present study aimed to determine whether normobaric hyperoxia preconditioning could ameliorate cognitive deficit induced by sevoflurane and the possible mechanism by which it may exert its effect. A total of 66, 20-month-old male Sprague-Dawley rats were randomly divided into 3 groups (n=22 each): Rats in the control (C) and sevoflurane anesthesia (S) groups received no normobaric hyperoxia preconditioning before sevoflurane exposure, rats in the normobaric hyperoxia pretreatment (HO) group received normobaric hyperoxia preconditioning before sevoflurane exposure (95% oxygen for 4 continuous h daily for 6 consecutive days). The anesthesia rats (S and HO groups), were exposed to 2.5% sevoflurane for 5 h, while the sham anesthesia rats (C group) were exposed to no sevoflurane. The neurobehavioral assessment was performed using a Morris water maze test, the expressions of the apoptosis proteins were determined using western blot analysis, and the apoptosis rate and cytosolic calcium concentration were measured by flow cytometry. Normobaric hyperoxia preconditioning improved prolonged escape latency and raised the number of platform crossings induced by sevoflurane in the Morris water maze test, increased the level of bcl-2 protein, and decreased the level of bax and active caspase-3 protein, the apoptosis rate and cytosolic calcium concentration in the hippocampus 24 h after sevoflurane exposure. The findings of the present study may imply that normobaric hyperoxia preconditioning attenuates sevoflurane-induced spatial learning and memory impairment, and this effect may be partly related to apoptosis inhibition in the hippocampus. In conclusion, normobaric hyperoxia preconditioning may be a promising strategy against sevoflurane-induced cognitive impairment by inhibiting the hippocampal neuron apoptosis.

Preventing Neurodegeneration by Controlling Oxidative Stress: The Role of OXR1

Parkinson’s disease, diabetic retinopathy, hyperoxia induced retinopathy, and neuronal damage resulting from ischemia are among the notable neurodegenerative diseases in which oxidative stress occurs shortly before the onset of neurodegeneration. A shared feature of these diseases is the depletion of OXR1 (oxidation resistance 1) gene products shortly before the onset of neurodegeneration. In animal models of these diseases, restoration of OXR1 has been shown to reduce or eliminate the deleterious effects of oxidative stress induced cell death, delay the onset of symptoms, and reduce overall severity. Moreover, increasing OXR1 expression in cells further increases oxidative stress resistance and delays onset of disease while showing no detectable side effects. Thus, restoring or increasing OXR1 function shows promise as a therapeutic for multiple neurodegenerative diseases. This review examines the role of OXR1 in oxidative stress resistance and its impact on neurodegenerative diseases. We describe the potential of OXR1 as a therapeutic in light of our current understanding of its function at the cellular and molecular level and propose a possible cascade of molecular events linked to OXR1’s regulatory functions.