Effects of Xenon-Based Anesthetic Exposure on the Expression Levels of Polysialic Acid Neural Cell Adhesion Molecule (PSA-NCAM) on Human Neural Stem Cell-Derived Neurons

Electroacupuncture Pretreatment Attenuates Learning Memory Impairment Induced by Repeated Propofol Exposure and Modulates Hippocampal Synaptic Plasticity in Rats

Background

Recurrent propofol anesthesia in the peak of neurodevelopment may lead to learning-memory decline. This study aimed to examine the efficacy of electroacupuncture pretreatment in ameliorating the aforementioned learning memory deficits and to explore its underlying mechanisms in a rat model of repeated propofol exposure.

Methods

10-day-old Sprague Dawley rats were randomly assigned to five groups: the control, fat emulsion, propofol, electroacupuncture pretreatment and electroacupuncture pretreatment combined with propofol groups. The electroacupuncture pretreatment involved three consecutive daily sessions, while propofol was received intraperitoneally once daily for five days. Following the modeling period, the rats' learning-memory performance was assessed using the New Novel Arm Y-maze, New Object Recognition, and Morris Water Maze. The Nissl staining method was used to observe the development of hippocampal neurons, while Golgi staining was employed to observe hippocampal synaptic development.

Results

The electroacupuncture pretreatment significantly attenuated the learning and memory impairment induced by recurring propofol exposure in rats. Additionally, it facilitated the development of hippocampal neurons and synaptic plasticity in the hippocampus. Immunofluorescence and Western Blot analyses were conducted to detect the expression of proteins related to apoptosis, learning memory, and synaptic plasticity. In the propofol group, the pro-apoptotic factors Caspase-3 and Bax was up-regulated, while the anti-apoptotic factor Bcl-2 was down-regulated, as compared to the blank group. Additionally, the phosphorylated cAMP-response element binding protein (pCREB), brain-derived neurotrophic factor (BDNF), synaptophysin, and growth associated protein-43 (GAP-43) was significantly decreased. In contrast, the electroacupuncture pretreatment combined with propofol group exhibited decreased the Caspase-3 and Bax and increased the Bcl-2, as compared to the propofol group, meanwhile, the pCREB, BDNF, Synaptophysin and GAP-43 was increased.

Conclusion

Our findings indicate that electroacupuncture pretreatment can alleviate the learning and memory impairment induced by recurring propofol exposure in rats. This is achieved by enhancing hippocampal synaptic plasticity, activating the pCREB/BDNF pathway and inhibiting neuronal apoptosis.

Xenon postconditioning attenuates neuronal injury after spinal cord ischemia/reperfusion injury by targeting endoplasmic reticulum stress-associated apoptosis

The purpose of the study is to explore the underlying mechanisms of xenon (Xe) which protects against spinal cord ischemia/reperfusion injury (SCIRI). A SCIRI rat model was induced by abdominal artery occlusion for 85 min and reperfusion. Xe postconditioning (50% Xe) was administered 1 h after 1 h of reperfusion. At reperfusion time points (2, 4, 6, and 24 h), rats were treated with spinal cord scans by MRI to assess the time of peak spinal cord injury after SCIRI. Subsequently, endoplasmic reticulum (ER) stress inhibitor sodium 4-phenylbutyrate (4-PBA) was administered by daily intraperitoneal injection (50 mg/kg) for 5 days before SCIRI. At 4 h after reperfusion, motor function, immunofluorescence staining, hematoxylin and eosin (HE) staining, Nissl staining, TUNEL staining, real-time reverse transcription polymerase chain (RT-PCR) reaction, and western blot analyses were performed to investigate the protective effects of Xe against SCIRI. In the rat I/R model, spinal cord edema peaked at reperfusion 4 h. SCIRI activated ER stress, which was located in neurons. Xe postconditioning remarkably alleviated hind limb motor function, reduced neuronal apoptosis rate, increased the number of normal neurons, and inhibited the expression of ER stress-related protein in spinal cord. Furthermore, the administration of the ER stress inhibitor 4-PBA strongly decreased ER stress-induced apoptosis following SCIRI. Xe postconditioning inhibits ER stress activation, which contributes to alleviate SCIRI by suppressing neuronal apoptosis.

Brain Damage in the Preterm Infant: Clinical Aspects and Recent Progress in the Prevention and Treatment

Although the prevalence of brain injury and related neurodevelopmental disabilities resulting from preterm birth are major public health concerns, there are no definite neuroprotective strategies to prevent or reduce brain injury. The pattern of brain injury seen in preterm infants has evolved into more subtle lesions that are still essential to diagnose regarding neurodevelopmental outcomes. There is no specific effective method for the treatment of premature infant brain injury, and the focus of clinical treatment is still on prevention. Prevention of this injury requires insight into the pathogenesis, but many gaps exist in our understanding of how neonatal treatment procedures and medications impact cerebral hemodynamics and preterm brain injury. Many studies provide evidence about the prevention of premature infant brain injury, which is related to some drugs (such as erythropoietin, melatonin, mesenchymal stem cells, etc.). However, there are still some controversies about the quality of research and the effectiveness of therapy. This review aims to recapitulate the results of preclinical studies and provide an update on the latest developments around etiological pathways, prevention, and treatment.

Noble gases and neuroprotection: summary of current evidence

PURPOSE OF REVIEW

To summarize the current data on neuroprotection derived by noble gas treatment focusing on xenon and argon.

RECENT FINDINGS

Both xenon and argon have demonstrated neuroprotective properties in an array of disease models. However, current data for argon after traumatic brain injury (TBI) is conflicting. Recent human data is only available for xenon showing some beneficial aspects (fewer adverse events) but no effect on outcomes, such as incidence of postoperative delirium.

SUMMARY

Promising results are available for neuroprotection derived by noble gas treatment. Results for xenon are more consistent than those for argon. The mechanism of action of xenon (noncompetitive NMDA-receptor inhibition) is also better understood compared with that of argon. The evidence for argon's neuroprotective actions (particularly after TBI) remains uncertain.

The Role of Pink1-Mediated Mitochondrial Pathway in Propofol-Induced Developmental Neurotoxicity

The mechanisms underlying propofol-induced toxicity in developing neurons are still unclear. The aim of present study was to explore the role of Pink1 mediated mitochondria pathway in propofol-induced developmental neurotoxicity. The primary Neural Stem Cells (NSCs) were isolated from the hippocampus of E15.5 mice embryos and then treated with propofol. The effects of propofol on proliferation, differentiation, apoptosis, mitochondria ultrastructure and MMP of NSCs were investigated. In addition, the abundance of Pink1 and a group of mitochondria related proteins in the cytoplasm and/or mitochondria were investigated, which mainly included CDK1, Drp1, Parkin1, DJ-1, Mfn1, Mfn2 and OPA1. Moreover, the relationship between Pink1 and these molecules was explored using gene silencing, or pretreatment with protein inhibitors. Finally, the NSCs were pretreated with mitochondrial specific antioxidant (MitoQ) or Drp1 inhibitor (Mdivi-1), and then the toxic effects of propofol on NSCs were investigated. Our results indicated that propofol treatment inhibited NSCs proliferation and division, and promoted NSCs apoptosis. Propofol induced significant NSCs mitochondria deformation, vacuolization and swelling, and decreased MMP. Additional studies showed that propofol affected a group of mitochondria related proteins via Pink1 inhibition, and CDK1, Drp1, Parkin1 and DJ-1 are the important downstream proteins of Pink1. Finally, the effects of propofol on proliferation, differentiation, apoptosis, mitochondrial ultrastructure and MMP of NSCs were significantly attenuated by MitoQ or Mdivi-1 pretreatment. The present study demonstrated that propofol regulates the proliferation, differentiation and apoptosis of NSCs via Pink1mediated mitochondria pathway.

Dusp4 Contributes to Anesthesia Neurotoxicity via Mediated Neural Differentiation in Primates

Background

Children who are exposed to anesthesia multiple times may undergo cognitive impairment during development. The underlying mechanism has been revealed as anesthesia-induced cognitive deficiency in young rodents and monkeys. However, the molecular mechanism of sevoflurane-induced neural development toxicity is unclear.

Methods

By combining RNA sequencing analysis of macaques’ prefrontal cortex and human neural differentiation, this study investigates the mechanism of sevoflurane-induced neurotoxicity in primates.

Results

The level of dual specificity protein phosphatase 4 (Dusp4) was significantly downregulated in non-human primates after sevoflurane treatment. We further uncovered the dynamical expression of Dusp4 during the human neural differentiation of human embryonic stem cells and found that knockdown of Dusp4 could significantly inhibit human neural differentiation.

Conclusion

This study indicated that Dusp4 is critically involved in the sevoflurane-induced inhibition of neural differentiation in non-human primate and the regulation of human neural differentiation. It also suggested that Dusp4 is a potential therapeutic target for preventing the sevoflurane-induced neurotoxicity in primates.