MiR-342-5p protects neurons from cerebral ischemia induced-apoptosis through regulation of Akt/NF-κB pathways by targeting CCAR2

Combined Analysis of Human and Experimental Rat Samples Identified Biomarkers for Ischemic Stroke

The genetic transcription profile and underlying molecular mechanisms of ischemic stroke (IS) remain elusive. To address this issue, four mRNA and one miRNA expression profile of rats with middle cerebral artery occlusion (MCAO) were acquired from the Gene Expression Omnibus (GEO) database. A total of 780 differentially expressed genes (DEGs) and 56 miRNAs (DEMs) were screened. Gene set and functional enrichment analysis revealed that a substantial number of immune-inflammation-related pathways were abnormally activated in IS. Through weighted gene co-expression network analysis, the turquoise module was identified as meaningful. By taking the intersection of the turquoise module genes, DEM-target genes, and all DEGs, 354 genes were subsequently obtained as key IS-related genes. Among them, six characteristic genes were identified using the least absolute shrinkage and selection operator. After validation with three external datasets, transforming growth factor beta 1 (Tgfb1) was selected as the hub gene. This finding was further confirmed by gene expression pattern analysis in both the MCAO model rats and clinical IS patients. Moreover, the expression of the hub genes exhibited a negative correlation with the modified Rankin scale score (P < 0.05). Collectively, these results expand our knowledge of the genetic profile and molecular mechanisms involved in IS and suggest that the Tgfb1 gene is a potential biomarker of this disease.

Dexmedetomidine pretreatment alleviates brain injury in middle cerebral artery occlusion (MCAO) model rats by activating PI3K/AKT/NF-κB signaling pathway

Cerebral ischemia-reperfusion injury (CIRI) is a prevalent clinical complication associated with reperfusion following ischemic stroke resulting in neuronal damage and cognitive impairment. Dexmedetomidine (DEX), a highly selective α2-adrenoceptor agonist with sedative, and analgesic properties, is frequently utilized as a sedative anesthetic in clinical surgeries, and believed to play a crucial role in the prognosis of patients suffering from CIRI. However, the mechanism underlying DEX in CIRI remains to be determined. This study aimed to investigate the neuroprotective effects of Dex in rats suffering from CIRI. In the treatment group, DEX (50 µg/kg) was administered intraperitoneally 30 min prior to surgery. Middle cerebral artery occlusion (MCAO) used as a model of CIRI occurred with cerebral artery occlusion for 2 h was followed by reperfusion with blood for 24, 72, 120 or 168 h. Neurological function as assessed by the Longa neurological function score test demonstrated significantly reduced neurological scores and increased % infarct size in MCAO group which was blocked by DEX suggesting that DEX might be effective in treating ischemic stroke. In the MCAO animals, 2,3,5-triphenyltetrazolium chloride (TTC) showed large marked areas of cerebral infarction which were diminished in size by DEX. Using Western blot analysis, results showed that in MCAO rats protein expression levels of TNF-α and IL-6 were increased accompanied by reduced protein expression levels of PI3K/AKT signaling pathway. DEX pretreatment reversed the effects of MCAO as evidenced by decrease in protein expression levels of TNF-α and IL-6 associated with elevated protein expression levels of PI3K/AKT/NF-κB signaling pathway. Data demonstrated that DEX pretreatment improved the neuromotor performance and cognitive functions in animals suffering from consequences of MCAO by diminishing inflammation and activation of the PI3K/AKT/NF-κB signaling pathway.

CircMETTL9 targets CCAR2 to induce neuronal oxidative stress and apoptosis via mitochondria-mediated pathways following traumatic brain injury

Traumatic brain injury (TBI) remains a principal factor in neurological disorders, often resulting in significant morbidity due to secondary neuroinflammatory and oxidative stress responses. While circular RNAs are recognized for their high expression levels in the nervous system and play crucial roles in various neurological processes, their specific contributions to the pathophysiology of TBI remain underexplored. In this study, the possible molecular mechanisms through which circMETTL9 modulated oxidative stress and neurological outcomes following TBI were investigated. In vitro model of oxidative stress utilizing SH-SY5Y cells revealed that circMETTL9 knockdown significantly attenuated H₂O₂-induced reactive oxygen species (ROS) production, reduced apoptosis, and preserved mitochondrial function. Additionally, CCAR2 has been identified as a circMETTL9-binding protein by mass spectrometry and RNA immunoprecipitation, with circMETTL9 positively regulating CCAR2 expression. Meanwhile, on the basis of silencing CCAR2, it was verified that the regulation of oxidative stress in SH-SY5Y cells by circMETTL9 was mediated by CCAR2. In vivo experiments using a TBI rat model further confirmed that CCAR2 knockdown alleviated central nervous system (CNS) injury, reduced oxidative stress and apoptosis, and protected mitochondrial integrity following TBI. These findings suggest a novel mechanism by which circMETTL9 targets CCAR2 via mitochondria-mediated Bax/Bcl-2/caspase-3 signaling to regulate apoptosis. CircMETTL9 may provide a viable therapeutic target for mitigating neurological dysfunction following TBI, offering new insights into potential interventions aimed at reducing secondary brain injury.

Molecular mechanisms underlying stress vulnerability and resilience in the chronic mild stress model: New insights from mRNA and miRNAs data combining

Stress is a major risk factor for the development of psychiatric disorders, including depression. However, its effects are not the same in all the subjects as only a portion of individuals exposed to stress will eventually develop negative mental outcomes, while others can be considered resilient. However, the biological processes underlying the development of a vulnerable or resilient phenotype are still poor understood. In order to cover this, we here used both transcriptomic and miRNomic based approaches in the ventral hippocampus of control (CON) and rats exposed to the chronic mild stress (CMS) paradigm, which were then divided into vulnerable (VULN) or resilient (RES) animals according to the sucrose consumption test. Transcriptomic analyses in VULN rats, compared to both the group of CON and RES animals, revealed the activation of inflammatory/immune-related pathways, specifically involved in antibodies and cytokine production, and the inhibition of pathways involved in protein synthesis. Conversely, transcriptomic data in RES animals suggested the activation of several pathways involved in neurotransmission. We then performed a mRNA-miRNA integration analysis by using miRComb R package, and we found that the most significant mRNA-miRNA pairs were involved in promoting the inflammatory status in VULN animals and, vice versa, by decreasing it in RES rats. Moreover, in VULN animals, the mRNA-miRNA combining analyses revealed the modulation of the olfactory sensory system, a key biological process that has been already found involved in the etiology of stress related disorders such as depression. Overall, our mRNA-miRNA integration-based approach identified distinct biological processes that are relevant for the development of a vulnerable or resilient phenotype in response to the negative effects of CMS exposure, which could allow the identification of novel targets for prevention or treatment.

Protective effect of melatonin against methamphetamine-induced attention deficits through miR-181/SIRT1 axis in the prefrontal cortex

INTRODUCTION

Methamphetamine (METH) is an addictive psychostimulant with deleterious effects on the central nervous system. Chronic use of METH in high doses impairs cognition, attention and executive functions, but the underlying mechanisms are still unclear. Sirtuin 1 (SIRT1) is a post-translational regulator that is downregulated following METH neurotoxicity. Melatonin is a neuroprotective hormone that enhances mitochondrial metabolism. Here, we evaluated the effect of melatonin on METH-induced attention deficits disorder and the involvement of the miR-181/SIRT1 axis in melatonin neuroprotection.

METHODS AND RESULTS

METH at a dose of 5 mg/kg was injected for 21 consecutive days. The animals were assigned to receive either melatonin or the vehicle after METH injections. Attention levels were evaluated with abject-based attention test. In the prefrontal cortex, the expression levels of miR-181a-5p, SIRT1, p53 and CCAR2, as well as the mtDNA copy numbers were evaluated using qRT-PCR and western blotting. The outcomes revealed that melatonin treatment following METH injections improved METH-induced attention deficits. METH toxicity can be associated with changes in the miR-181/SIRT1 axis, elevated levels of p53 and COXII, and decreased levels of mtDNA in the prefrontal cortex of adult rats. Interestingly, administration of melatonin can improve the expression of these molecules and reduces the toxic effects of METH.

CONCLUSION

Melatonin ameliorated the neurotoxicity of METH in the prefrontal cortex and the miR-181/SIRT1 axis is involve in the protective effects of melatonin. However, melatonin can be potentially administrated to improve attention impairment in METH use disorders.

Post-Anesthesia Cognitive Dysfunction in Mice Is Associated with an Age-Related Increase in Neuronal Intracellular [Ca2+]-Neuroprotective Effect of Reducing Intracellular [Ca2+]: In Vivo and In Vitro Studies

Background: Postoperative cognitive dysfunction (POCD) is a common disorder after general anesthesia in elderly patients, the precise mechanisms of which remain unclear. Methods: We investigated the effect of isoflurane with or without dantrolene pretreatment on intracellular calcium concentration ([Ca2+]i), reactive oxygen species (ROS) production, cellular lactate dehydrogenase (LDH) leak, calpain activity, and cognitive function using the Morris water maze test of young (3 months), middle-aged (12-13 months), and aged (24-25 months) C57BL6/J mice. Results: Aged cortical and hippocampal neurons showed chronically elevated [Ca2+]i compared to young neurons. Furthermore, aged hippocampal neurons exhibited higher ROS production, increased LDH leak, and elevated calpain activity. Exposure to isoflurane exacerbated these markers in aged neurons, contributing to increased cognitive deficits in aged mice. Dantrolene pretreatment reduced [Ca2+]i for all age groups and prevented or significantly mitigated the effects of isoflurane on [Ca2+]i, ROS production, LDH leak, and calpain activity in aged neurons. Dantrolene also normalized or improved age-associated cognitive deficits and mitigated the cognitive deficits caused by isoflurane. Conclusions: These findings suggest that isoflurane-induced cytotoxicity and cognitive decline in aging are linked to disruptions in neuronal intracellular processes, highlighting the reduction of [Ca2+]i as a potential therapeutic intervention.

The Role of microRNAs in Epigenetic Regulation of Signaling Pathways in Neurological Pathologies

In recent times, there has been a significant increase in researchers' interest in the functions of microRNAs and the role of these molecules in the pathogenesis of many multifactorial diseases. This is related to the diagnostic and prognostic potential of microRNA expression levels as well as the prospects of using it in personalized targeted therapy. This review of the literature analyzes existing scientific data on the involvement of microRNAs in the molecular and cellular mechanisms underlying the development of pathologies such as Alzheimer's disease, cerebral ischemia and reperfusion injury, and dysfunction of the blood-brain barrier.