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

Dexmedetomidine Alleviates Acute Stress-Induced Acute Kidney Injury by Attenuating Inflammation and Oxidative Stress via Inhibiting the P2X7R/NF-κB/NLRP3 Pathway in Rats

This study aimed to investigate the potential protective effects of Dexmedetomidine (DEX) against acute kidney injury (AKI) induced by acute stress (AS). Wistar rats were divided into five groups: Control, DEX, AS, AS + DEX, and AS + A438079. The results showed that AS led to AKI by increasing inflammatory biomarkers and oxidative stress-related indicators. The acute stress model in rats was successfully established. Renal function, histopathology, oxidative stress, and inflammation were assessed. Localization of P2X7 receptor (P2X7R) was determined by immunofluorescence. Additionally, the key inflammatory proteins of the P2X7R/NF-κB/NLRP3 signaling pathway were measured by Western blotting. DEX significantly improved kidney function, alleviated kidney injury, and reduced oxidative stress and inflammation. DEX inhibited the activation of the P2X7R, decreased the expression of NF-κB, NLRP3 inflammasome, and Caspase-1, and inhibited the expression of interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα). Furthermore, DEX also alleviated AS-induced AKI by inhibiting the excessive production of reactive oxygen species (ROS) and reducing oxidative stress. In conclusion, DEX attenuates AS-induced AKI by mitigating inflammation and oxidative stress through the inhibition of the P2X7R/NF-κB/NLRP3 pathway in rats.

Sodium tanshinone IIA sulfonate suppresses microglia polarization and neuroinflammation possibly via regulating miR-125b-5p/STAT3 axis to ameliorate neuropathic pain

The spinal cord microglia play a pivotal role in neuroinflammation and neuropathic pain (NP). Sodium tanshinone IIA sulfonate (STS), a derivative of tanshinone IIA, has anti-inflammatory and anti-hyperalgesic effects. However, its underlying mechanism in NP remains unclear. This study aimed to investigate the effect of STS and elucidate possible mechanisms in a rat model of spared nerve injury. In vivo experiments, STS and AG490 were administered intraperitoneally once daily for 14 consecutive days after surgery. The results showed that the expression of miR-125b-5p in the spinal dorsal horn was substantially reduced, whereas signal transducer and activator of transcription 3 (STAT3) signaling was increased. After treatment with STS, the mechanical thresholds, expression of miR-125b-5p, and microglial M2 marker such as Arg-1 in the spinal cord horn increased significantly, whereas multiple pro-inflammatory cytokines and apoptosis were significantly reduced. Moreover, STAT3 pathway-related proteins and expression of the microglial M1 marker, CD68, were appreciably inhibited. In vitro, lipopolysaccharide (LPS) was used to induce an inflammatory response in BV-2 microglial cells. STS pretreatment inhibited LPS-stimulated pro-inflammatory cytokine secretion, reduced STAT3 pathway related-proteins and apoptosis, increased miR-125b-5p and proopiomelanocortin expression, and enhanced microglia transformation from M1 to M2 phenotype in BV-2 cells. These effects were reversed after the inhibition of miR-125b-5p expression in BV-2 cells. A dual-luciferase reporter assay confirmed that STAT3 binds to miR-125b-5p. In summary, these results suggest that STS exerts anti-hyperalgesic and anti-neuroinflammatory effects in rats with NP possibly via the miR-125b-5p/STAT3 axis.

Non-coding RNAs in diabetic peripheral neuropathy: their role and mechanisms underlying their effects

Diabetic peripheral neuropathy (DPN) is a complication of diabetes with a high rate of disability. However, current clinical treatments for DPN are suboptimal. Non-coding RNAs (ncRNAs) are a type of RNAs that are not translated into proteins. NcRNAs perform functions that regulate epigenetic modifications, transcriptional or post-transcriptional regulators of proteins, and thus participate in the physiological and pathological processes of the body. NcRNAs play a role in the progress of DPN by affecting the processes of inflammation, oxidative stress, cellular autophagy or apoptosis. Therefore, ncRNAs treatment is regarded as a promising therapeutic approach for DPN. In addition, since some ncRNAs present stably in the blood of DPN patients, they are considered as potential biomarkers that contribute to early clinical diagnosis. In this paper, we review the studies on the role of ncRNAs in DPN in the last decade, and discuss the mechanisms of ncRNAs, aiming to provide a reference for the future research on the treatment and early diagnosis of DPN.

Dexmedetomidine alleviates oxidative stress and mitochondrial dysfunction in diabetic peripheral neuropathy via the microRNA-34a/SIRT2/S1PR1 axis

OBJECTIVE

Dexmedetomidine (Dex) is a highly selective α₂-adrenoceptor agonist with sedative, analgesic, sympatholytic, and hemodynamic-stabilizing properties, which plays a neuroprotective role in diabetic peripheral neuropathy (DPN) and diabetes-induced nerve damage. However, the related molecular mechanisms are not fully understood. Therefore, our study explored the mechanism of Dex in DPN using rat and RSC96 cell models.

METHODS

Sciatic nerve sections were observed under an optical microscope and the ultrastructure of the sciatic nerves was observed under a transmission electron microscope. Oxidative stress was assessed by detecting MDA, SOD, GSH-Px, and ROS levels. The motor nerve conduction velocity (MNCV), mechanical withdrawal threshold (MWT), and thermal withdrawal latency (TWL) of rats were measured. Cell viability, apoptosis, and the changes in the expression of related genes and proteins were examined. Furthermore, the relationship between microRNA (miR)-34a and SIRT2 or SIRT2 and S1PR1 was analyzed.

RESULTS

Dex reversed DPN-induced decreases in MNCV, MWT, and TWL. Dex alleviated oxidative stress, mitochondrial damage, and apoptosis in both the rat and RSC96 cell models of DPN. Mechanistically, miR-34a negatively targeted SIRT2, and SIRT2 inhibited S1PR1 transcription. The overexpression of miR-34a or S1PR1 or the inhibition of SIRT2 counteracted the neuroprotective effects of Dex in DPN in vivo and in vitro.

CONCLUSION

Dex alleviates oxidative stress and mitochondrial dysfunction associated with DPN by downregulating miR-34a to regulate the SIRT2/S1PR1 axis.

Amelioration of myocardial ischemia/reperfusion injury in diabetes: A narrative review of the mechanisms and clinical applications of dexmedetomidine

Mechanisms contributing to the pathogenesis of myocardial ischemia-reperfusion (I/R) injury are complex and multifactorial. Many strategies have been developed to ameliorate myocardial I/R injuries based on these mechanisms. However, the cardioprotective effects of these strategies appear to diminish in diabetic states. Diabetes weakens myocardial responses to therapies by disrupting intracellular signaling pathways which may be responsible for enhancing cellular resistance to damage. Intriguingly, it was found that Dexmedetomidine (DEX), a potent and selective α2-adrenergic agonist, appears to have the property to reverse diabetes-related inhibition of most intervention-mediated myocardial protection and exert a protective effect. Several mechanisms were revealed to be involved in DEX’s protection in diabetic rodent myocardial I/R models, including PI3K/Akt and associated GSK-3β pathway stimulation, endoplasmic reticulum stress (ERS) alleviation, and apoptosis inhibition. In addition, DEX could attenuate diabetic myocardial I/R injury by up-regulating autophagy, reducing ROS production, and inhibiting the inflammatory response through HMGB1 pathways. The regulation of autonomic nervous function also appeared to be involved in the protective mechanisms of DEX. In the present review, the evidence and underlying mechanisms of DEX in ameliorating myocardial I/R injury in diabetes are summarized, and the potential of DEX for the treatment/prevention of myocardial I/R injury in diabetic patients is discussed.

Dexmedetomidine Protects Against Kidney Fibrosis in Diabetic Mice by Targeting miR-101-3p-Mediated EndMT

Objective: Our main purpose is to explore the effect and mechanism of Dexmedetomidine (DEX)  in diabetic nephropathy fibrosis.

Methods: Diabetic model was established by intraperitoneal injection of streptozotocin (STZ) treated CD-1 mice and high glucose cultured human dermal microvascular endothelial cells (HMVECs). Immunofluorescence was used to detect renal endothelial-mesenchymal transition (EndMT); Hematoxylin and Eosin (HE) staining and Masson’s Trichrome Staining (MTS) was used to analyze renal fibrosis; CCK-8 was used to evaluate cell viability; Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to assess the expression of miR-101-3p; Western blots were utilized to judge the protein expression levels of EndMT, extracellular matrix and TGF-β1/Smad3 signal pathway.

Results: In this study, we first found that the protective effect of DEX on DN was related to EndMT. DEX alleviated kidney fibrosis by inhibiting EndMT in diabetic CD-1 mice. DEX could also inhibit high glucose-induced HMVECs EndMT. Then, we confirmed that miR-101-3p was the regulatory target of DEX. The expression of miR-101-3p was decreased in diabetic CD-1 mice and high glucose-induced HMVECs. After DEX treatment, the miR-101-3p increased, and the inhibition of miR-101-3p could counteract the protective effect of DEX and aggravate the EndMT. Finally, we found that the TGF- β1/Smad3 signal pathway was involved in the protective effect of DEX on DN. DEX inhibited the activation of TGF-β1/Smad3 signal pathway. On the contrary, inhibiting miR-101-3p promoted the expression of TGF-β1/Smad3.

Conclusion: DEX protects kidney fibrosis in diabetic mice by targeting miR-101-3p-mediated EndMT.

Regulation of Oxidative Stress by Long Non-Coding RNAs in Vascular Complications of Diabetes

Diabetes mellitus is a well-known metabolic disorder with numerous complications, such as macrovascular diseases (e.g., coronary heart disease, diabetic cardiomyopathy, stroke, and peripheral vascular disease), microvascular diseases (e.g., diabetic nephropathy, retinopathy, and diabetic cataract), and neuropathy. Multiple contributing factors are implicated in these complications, and the accumulation of oxidative stress is one of the critical ones. Several lines of evidence have suggested that oxidative stress may induce epigenetic modifications that eventually contribute to diabetic vascular complications. As one kind of epigenetic regulator involved in various disorders, non-coding RNAs have received great attention over the past few years. Non-coding RNAs can be roughly divided into short (such as microRNAs; ~21–25 nucleotides) or long non-coding RNAs (lncRNAs; >200 nucleotides). In this review, we briefly discussed the research regarding the roles of various lncRNAs, such as MALAT1, MEG3, GAS5, SNHG16, CASC2, HOTAIR, in the development of diabetic vascular complications in response to the stimulation of oxidative stress.

The potential role of dexmedetomidine on neuroprotection and its possible mechanisms: Evidence from in vitro and in vivo studies

Neurological disorders following brain injuries and neurodegeneration are on the rise worldwide and cause disability and suffering in patients. It is crucial to explore novel neuroprotectants. Dexmedetomidine, a selective α2-adrenoceptor agonist, is commonly used for anxiolysis, sedation and analgesia in clinical anaesthesia and critical care. Recent studies have shown that dexmedetomidine exerts protective effects on multiple organs. This review summarized and discussed the current neuroprotective effects of dexmedetomidine, as well as the underlying mechanisms. In preclinical studies, dexmedetomidine reduced neuronal injury and improved functional outcomes in several models, including hypoxia-induced neuronal injury, ischaemic-reperfusion injury, intracerebral haemorrhage, post-traumatic brain injury, anaesthetic-induced neuronal injury, substance-induced neuronal injury, neuroinflammation, epilepsy and neurodegeneration. Several mechanisms are associated with the neuroprotective function of dexmedetomidine, including neurotransmitter regulation, inflammatory response, oxidative stress, apoptotic pathway, autophagy, mitochondrial function and other cell signalling pathways. In summary, dexmedetomidine has the potential to be a novel neuroprotective agent for a wide range of neurological disorders.

Exosomes from mesenchymal stem cells expressing microribonucleic acid-125b inhibit the progression of diabetic nephropathy via the tumour necrosis factor receptor-associated factor 6/Akt axis

Diabetic nephropathy (DN) seriously threatens the health of patients with diabetes. Moreover, it has been reported that mesenchymal stem cell (MSC)-derived exosomal miRNAs can modulate the progression of multiple diseases, including DN. It has been suggested that miR-125b is involved in DN. However, the biological functions of exosomal miRNAs, especially miR-125b, in DN are still unclear. To establish a DN model in vitro, we used a model of human embryonic kidney epithelial cells (HKCs) injury induced by high glucose (HG). Then, miR-125b was delivered to the model cells in vitro via MSC-derived exosomes (MSC-Exos), and the effect of exosomal miR-125b on HKCs apoptosis was evaluated by flow cytometry. qRT-PCR or western blotting was performed to measure miR-125b or tumour necrosis factor receptor-associated factor 6 (TRAF6) expression in HKC. The effect of MSC-Exos on HKCs apoptosis after miR-125b knockdown was determined by flow cytometry. Moreover, dual-luciferase reporter assays were used to determine the targeting relationship between miR-125b and TRAF6 in HKCs. Our data revealed that MSC-Exos increased HG-induced autophagy in HKCs and reversed HKCs apoptosis. Moreover, our study found that miR-125b was enriched in MSC-Exos and directly targeted TRAF6 in HKCs. In addition, exosomally transferred miR-125b inhibited the apoptosis of HG-treated HKCs by mediating Akt signalling. In summary, MSC-derived exosomal miR-125b induced autophagy and inhibited apoptosis in HG-treated HKCs via the downregulation of TRAF6. Therefore, our study provided a new idea for DN treatment.

Protective effect of dexmedetomidine on neuronal hypoxic injury through inhibition of miR-134

OBJECTIVE

To explore the mechanism of dexmedetomidine (DEX)-mediated miR-134 inhibition in hypoxia-induced damage in PC12 cells.

METHODS

Hydrogen peroxide (H₂O₂)-stimulated PC12 cells were divided into control, H₂O₂, DEX + H₂O₂, miR-NC/inhibitor + H₂O₂, and miR-NC/ mimic + DEX + H₂O₂ groups. Cell viability and apoptosis were assessed by the 3-(4,5-dimethylthiazol(-2-y1)-2,5-diphenytetrazolium bromide (MTT) assay and Annexin V-FITC/PI staining, while gene and protein expression levels were detected by qRT-PCR and western blotting. Reactive oxygen species (ROS) levels were tested by 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) staining, and malondialdehyde (MDA) content was determined with a detection kit.

RESULTS

DEX treatment decreased H₂O₂-elevated miR-134 expression. H₂O₂-induced PC12 cell damage was improved by DEX and miR-134 inhibitor; additionally, cell viability was increased, while cell apoptosis was reduced. In addition, both DEX and miR-134 inhibitor reduced the upregulated expression of cleaved caspase-3 and increased the downregulated expression of Bcl-2 in H₂O₂-induced PC12 cells. However, compared to that in the DEX + H₂O₂ group, cell viability in the mimic + DEX + H₂O₂ group was decreased, and the apoptotic rate was elevated with increased cleaved caspase-3 and decreased Bcl-2 expression. Inflammation and oxidative stress were increased in H₂O₂-induced PC12 cells but improved with DEX or miR-134 inhibitor treatment. However, this improvement of H₂O₂-induced inflammation and oxidative stress induced by DEX in PC12 cells could be reversed by the miR-134 mimic.

CONCLUSION

DEX exerts protective effects to promote viability and reduce cell apoptosis, inflammation, and oxidative stress in H₂O₂-induced PC12 cells by inhibiting the expression of miR-134.