Ca2+-PKCα-ERK1/2 signaling pathway is involved in the suppressive effect of propofol on proliferation of neural stem cells from the neonatal rat hippocampus

Research progress of propofol in alleviating cerebral ischemia/reperfusion injury

Ischemic stroke is a leading cause of adult disability and death worldwide. The primary treatment for cerebral ischemia patients is to restore blood supply to the ischemic region as quickly as possible. However, in most cases, more severe tissue damage occurs, which is known as cerebral ischemia/reperfusion (I/R) injury. The pathological mechanisms of brain I/R injury include mitochondrial dysfunction, oxidative stress, excitotoxicity, calcium overload, neuroinflammation, programmed cell death and others. Propofol (2,6-diisopropylphenol), a short-acting intravenous anesthetic, possesses not only sedative and hypnotic effects but also immunomodulatory and neuroprotective effects. Numerous studies have reported the protective properties of propofol during brain I/R injury. In this review, we summarize the potential protective mechanisms of propofol to provide insights for its better clinical application in alleviating cerebral I/R injury.

Anaesthesia and brain development: a review of propofol-induced neurotoxicity in pediatric populations

With the advancement of medical technology, there are increasing opportunities for new-borns, infants, and pregnant women to be exposed to general anaesthesia. Propofol is commonly used for the induction of anaesthesia, maintenance of general intravenous anaesthesia and sedation of intensive-care children. Many previous studies have found that propofol has organ-protective effects, but growing evidence suggests that propofol interferes with brain development, affecting learning and cognitive function. The purpose of this review is to summarize the latest progress in understanding the neurotoxicity of propofol. Evidence from case studies and clinical studies suggests that propofol has neurotoxicity on the developing brain. We classify the findings on propofol-induced neurotoxicity based on its damage mechanism. We end by summarizing the current protective strategies against propofol neurotoxicity. Fully understanding the neurotoxic mechanisms of propofol can help us use it at a reasonable dosage, reduce its side effects, and increase patient safety.

Dexmedetomidine Protects Cortical Neurons from Propofol-Induced Apoptosis via Activation of Akt-IKK-NF-κB Signaling Pathway by α2A-adrenoceptor

CONTEXT

Propofol can induce neuroapoptosis. It has been reported that dexmedetomidine (DEX) has a protective effect on propofol-induced neuroapoptosis, but the specific mechanism needs to be further explored to provide a theoretical basis for their combined use.

OBJECTIVE

We aimed to explore the neuroprotective effect of DEX on primary cortical neurons treated by propofol and to elucidate the underlying mechanistic pathways.

METHODS

Cortical neurons were isolated from fetal rats and treated with propofol. MTT assays were performed to detect cell viability, α-tubulin immunofluorescent assays were conducted to observe cell abnormalities, and c-caspase3 immunofluorescent assays and flow cytometry were performed to examine cell apoptosis. Further, neurons were cotreated with propofol and DEX to study DEX's neuroprotective effects on propofol-caused neuronal injuries. Finally, the α2A-adrenoceptor was knocked out and/or the Akt activator (SC-79) was added to cells co-treated with propofol and DEX. The expression levels of Akt-IKK-NF-κB pathway-related proteins were detected by western blot.

RESULTS

Propofol decreased cell viability in a dose-dependent manner, triggered apoptosis, caused morphological abnormalities and down-regulated the phosphorylation levels of Akt, IKK, NF-κB and IκB in cortical neurons. DEX ameliorated the decrease of cell viability, alleviated neuronal apoptosis and promoted the downregulated expression levels of p-Akt, IKK, NF-κB, and IκB proteins which had been induced by propofol treatment. Western blot findings following the transfection of α2A-siRNA and the addition of SC-79 suggested that DEX's neuroprotective functions arose from the stimulation of α2A-adrenoceptors to activate the Akt-IKK-NF-κB signal pathway.

CONCLUSION

DEX protected neurons against propofol-induced apoptosis via activation of the Akt-IKK-NF-κB signal pathway through α2A-adrenoceptors.

Inhibition of Calcium-Sensing Receptor Alleviates Chronic Intermittent Hypoxia-Induced Cognitive Dysfunction via CaSR-PKC-ERK1/2 Pathway

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is typically characterized by chronic intermittent hypoxia (CIH), associated with cognitive dysfunction in children. Calcium-sensing receptor (CaSR) mediates the apoptosis of hippocampal neurons in various diseases. However, the effect of CaSR on OSAHS remains elusive. In the present study, we investigated the role of CaSR in CIH-induced memory dysfunction and underlying mechanisms on regulation of PKC-ERK1/2 signaling pathway in vivo and in vitro. CIH exposures for 4 weeks in mice, modeling OSAHS, contributed to cognitive dysfunction. CIH accelerated apoptosis of hippocampal neurons and resulted in the synaptic plasticity deficit via downregulated synaptophysin (Syn) protein level. The mice were intraperitoneally injected with CaSR inhibitor (NPS2143) 30 min before CIH exposure and the results demonstrated CaSR inhibitor alleviated the apoptosis and synaptic plasticity deficit in the hippocampus of CIH mice. We established intermittent hypoxia PC12 cell model and found that the activation of CaSR accelerated CIH-induced PC12 apoptosis and synaptic plasticity deficit by upregulated p-ERK1/2 and PKC. Overall, our findings revealed that CaSR held a critical function on CIH-induced cognitive dysfunction in mice by accelerating hippocampal neuronal apoptosis and reducing synaptic plasticity via augmenting CaSR-PKC-ERK1/2 pathway; otherwise, inhibition of CaSR alleviated CIH-induced cognitive dysfunction.

Research progress on the effects and mechanisms of anesthetics on neural stem cells

Exposure to anesthetic drugs has been proven to seriously affect developing animals in terms of neural stem cells' (NSCs') proliferation, differentiation, and apoptosis. This can severely hamper the development of physiological learning and memory skills. Studies on the effects of anesthetics on NSCs' proliferation and differentiation are thus reviewed here, with the aim to highlight which specific drug mechanisms are the least harmful to NSCs. PubMed has been used as the preferential searching database of relevant literature to identify studies on the effects and mechanisms of NSCs' proliferation and differentiation. It was concluded that propofol and sevoflurane may be the safest options for NSCs during pregnancy and in pediatric clinical procedures, while dexmedetomidine has been found to reduce opioid-related damage in NSCs. It was also found that the growth environment may impact neurodevelopment even more than narcotic drugs. Nonetheless, the current scientific literature available further highlights how more extensive clinical trials are absolutely required for corroborating the conclusion drawn here.

Propofol induces the apoptosis of neural stem cells via microRNA-9-5p / chemokine CXC receptor 4 signaling pathway

Recent studies suggested that propofol, one of the most widely used anesthetics, may cause neurotoxicity in the developing brain, leading to cognitive deficits in adults. However, the underlying mechanisms remain unclear. In this study, we aimed to evaluate the mechanisms of propofol neurotoxicity in the neural stem cells (NSCs). The mRNA and protein expression levels of microRNA-9-5p (miR-9-5p) and chemokine CXC receptor 4 (CXCR4) were determined by quantitative reverse transcription-polymerase chain reaction and Western blotting analyses. Cell viability and apoptosis were evaluated using the cell counting kit-8 and Hoechst staining kits. The levels of apoptosis-related proteins B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein, and caspase-3 were detected by Western blotting analysis. These results confirmed that propofol activated cell apoptosis in a dose-dependent manner. A significant increase in the miR-9-5p and CXCR4 expression was observed in the propofol-treated cells. The overexpression of miR-9-5p induced apoptosis in NSCs, accompanied by elevated apoptosis-related protein activity. Furthermore, mitigated CXCR4 expression reduced propofol-induced cell apoptosis. We conclude that propofol induces cell death in NSCs, and overexpression of miR-9-5p/CXCR4 contributes to propofol-induced cell apoptosis, which might be a target for developing novel strategies to treat propofol neurotoxicity.