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

The Role of miRNAs in Dexmedetomidine's Neuroprotective Effects against Brain Disorders

There are limited neuroprotective strategies for various central nervous system conditions in which fast and sustained management is essential. Neuroprotection-based therapeutics have become an intensively researched topic in the neuroscience field, with multiple novel promising agents, from natural products to mesenchymal stem cells, homing peptides, and nanoparticles-mediated agents, all aiming to significantly provide neuroprotection in experimental and clinical studies. Dexmedetomidine (DEX), an α2 agonist commonly used as an anesthetic adjuvant for sedation and as an opioid-sparing medication, stands out in this context due to its well-established neuroprotective effects. Emerging evidence from preclinical and clinical studies suggested that DEX could be used to protect against cerebral ischemia, traumatic brain injury (TBI), spinal cord injury, neurodegenerative diseases, and postoperative cognitive disorders. MicroRNAs (miRNAs) regulate gene expression at a post-transcriptional level, inhibiting the translation of mRNA into functional proteins. In vivo and in vitro studies deciphered brain-related miRNAs and dysregulated miRNA profiles after several brain disorders, including TBI, ischemic stroke, Alzheimer’s disease, and multiple sclerosis, providing emerging new perspectives in neuroprotective therapy by modulating these miRNAs. Experimental studies revealed that some of the neuroprotective effects of DEX are mediated by various miRNAs, counteracting multiple mechanisms in several disease models, such as lipopolysaccharides induced neuroinflammation, β-amyloid induced dysfunction, brain ischemic-reperfusion injury, and anesthesia-induced neurotoxicity models. This review aims to outline the neuroprotective mechanisms of DEX in brain disorders by modulating miRNAs. We address the neuroprotective effects of DEX by targeting miRNAs in modulating ischemic brain injury, ameliorating the neurotoxicity of anesthetics, reducing postoperative cognitive dysfunction, and improving the effects of neurodegenerative diseases.

Dexmedetomidine Can Reduce the Level of Oxidative Stress and Serum miR-10a in Patients with Lung Cancer after Surgery

OBJECTIVE

 Lung cancer is a primary cause of cancer death. This study assessed the action of dexmedetomidine (DEX) on oxidative stress (OS) and microRNA 10a (miR-10a) in patients with lung cancer.

METHODS

 Patients were given 1 µg/kg DEX before anesthesia and control patients were given saline. The duration of intraoperative one-lung ventilation (OLV) and fluid intake were determined, and mean arterial pressure, heart rate and bispectral index were observed at the time of before anesthesia (T0), immediately after endotracheal intubation (T1), 1 hour after OLV (T2), and 10 minutes before the end of surgery (T3). The expressions and correlations of miR-10a, inflammation and OS levels in the serum were analyzed. The effects of DEX intervention and miR-10a level on pulmonary complications were analyzed.

RESULTS

 Patients with DEX intervention had lower levels of inflammation and OS during perioperative period than the controls. DEX intervention reduced miR-10a levels in patients during perioperative period. miR-10a in serum of patients with DEX intervention after surgery was positively-correlated with the concentrations of malondialdehyde, and inflammatory factors, while negatively-correlated with superoxide dismutase. The total incidence of postoperative pulmonary complications after DEX intervention was lowered. Patients with high miR-10a expression had a higher cumulative incidence of pulmonary complications than those with low miR-10a expression.

CONCLUSION

 DEX can reduce postoperative OS and plasma miR-10a level in patients with lung cancer, and high expression of miR-10a predicts a high incidence of postoperative pulmonary complications.

Deletion of Neuronal CuZnSOD Accelerates Age-Associated Muscle Mitochondria and Calcium Handling Dysfunction That Is Independent of Denervation and Precedes Sarcopenia

Skeletal muscle suffers atrophy and weakness with aging. Denervation, oxidative stress, and mitochondrial dysfunction are all proposed as contributors to age-associated muscle loss, but connections between these factors have not been established. We examined contractility, mitochondrial function, and intracellular calcium transients (ICTs) in muscles of mice throughout the life span to define their sequential relationships. We performed these same measures and analyzed neuromuscular junction (NMJ) morphology in mice with postnatal deletion of neuronal Sod1 (i-mn-Sod1^-/- mice), previously shown to display accelerated age-associated muscle loss and exacerbation of denervation in old age, to test relationships between neuronal redox homeostasis, NMJ degeneration and mitochondrial function. In control mice, the amount and rate of the decrease in mitochondrial NADH during contraction was greater in middle than young age although force was not reduced, suggesting decreased efficiency of NADH utilization prior to the onset of weakness. Declines in both the peak of the ICT and force were observed in old age. Muscles of i-mn-Sod1^-/- mice showed degeneration of mitochondrial and calcium handling functions in middle-age and a decline in force generation to a level not different from the old control mice, with maintenance of NMJ morphology. Together, the findings support the conclusion that muscle mitochondrial function decreases during aging and in response to altered neuronal redox status prior to NMJ deterioration or loss of mass and force suggesting mitochondrial defects contribute to sarcopenia independent of denervation.