Integrated Excitatory/Inhibitory Imbalance and Transcriptomic Analysis Reveals the Association between Dysregulated Synaptic Genes and Anesthetic-Induced Cognitive Dysfunction

The changing of α5-GABAA receptors expression and distribution participate in sevoflurane-induced learning and memory impairment in young mice

BACKGROUND

Sevoflurane is a superior agent for maintaining anesthesia during surgical procedures. However, the neurotoxic mechanisms of clinical concentration remain poorly understood. Sevoflurane can interfere with the normal function of neurons and synapses and impair cognitive function by acting on α5-GABAAR.

METHODS

Using MWM test, we evaluated cognitive abilities in mice following 1 h of anesthesia with 2.7%-3% sevoflurane. Based on hippocampal transcriptome analysis, we analyzed the differential genes and IL-6 24 h post-anesthesia. Western blot and RT-PCR were performed to measure the levels of α5-GABAAR, Radixin, P-ERM, P-Radixin, Gephyrin, IL-6, and ROCK. The spatial distribution and expression of α5-GABAAR on neuronal somata were analyzed using histological and three-dimensional imaging techniques.

RESULTS

MWM test indicated that partial long-term learning and memory impairment. Combining molecular biology and histological analysis, our studies have demonstrated that sevoflurane induces immunosuppression, characterized by reduced IL-6 expression levels, and that enhanced Radixin dephosphorylation undermines the microstructural stability of α5-GABAAR, leading to its dissociation from synaptic exterior and resulting in a disordered distribution in α5-GABAAR expression within neuronal cell bodies. On the synaptic cleft, the expression level of α5-GABAAR remained unchanged, the spatial distribution became more compact, with an increased fluorescence intensity per voxel. On the extra-synaptic space, the expression level of α5-GABAAR decreased within unchanged spatial distribution, accompanied by an increased fluorescence intensity per voxel.

CONCLUSION

Dysregulated α5-GABAAR expression and distribution contributes to sevoflurane-induced partial long-term learning and memory impairment, which lays the foundation for elucidating the underlying mechanisms in future studies.

Screening of potential biomarkers in propofol-induced neurotoxicity via bioinformatics prediction and experimental verification

OBJECTIVES

To identify hub genes and biological processes of propofol-induced neurotoxicity and promote the development of pediatric anesthesiology.

METHODS

We downloaded the GSE106799 dataset from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened, then Kyoto Encyclopedia of Genes and Genomes, Gene Ontology and Gene Set Enrichment analyses were performed on all DEGs. We identified potential ferroptosis genes in the pathogenesis of propofol-induced neurotoxicity. A key module was obtained after performing weighted gene co-expression network analysis (WGCNA) on the GSE106799 dataset. Hub genes were identified after the least absolute shrinkage and selection operator (LASSO) regression analysis of the intersection of DEGs and genes from the key module. We established a competing endogenous RNA network and predicted potential drugs according to the hub genes. Total RNA and proteins were extracted for real-time quantitative polymerase chain reaction and Western blotting, respectively.

RESULTS

A total of 112 DEGs, including 76 upregulated and 36 downregulated ones were screened out. Propofol-induced neurotoxicity involved processes such as nervous system development, activation of JAK/STAT and MAPK signaling pathways, vascular regeneration, and oxidative stress. The results of WGCNA suggested that the tan module was the most strongly associated with propofol-induced neurotoxicity. We identified 4 hub genes (EGR4, HAO1, ITK and GM14446) after LASSO regression analysis. Animal experiments demonstrated that propofol caused overexpression of the protein levels of HAO1, ITK and inflammatory factors in the brain, as well as the mRNA levels of HAO1, ITK and GM14446. Propofol inhibited expression of EGR4 at mRNA and protein levels.

CONCLUSIONS

Previous studies have demonstrated that EGR4, HAO1, ITK and GM14446 play a role in intellectual development, neuroinflammation and neuronal differentiation. These hub genes may help us to find new preventive and therapeutic targets for propofol-induced neurotoxicity.

Synaptic and mitochondrial mechanisms behind alcohol-induced imbalance of excitatory/inhibitory synaptic activity and associated cognitive and behavioral abnormalities

Alcohol consumption during pregnancy can significantly impact the brain development of the fetus, leading to long-term cognitive and behavioral problems. However, the underlying mechanisms are not well understood. In this study, we investigated the acute and chronic effects of binge-like alcohol exposure during the third trimester equivalent in postnatal day 7 (P7) mice on brain cell viability, synapse activity, cognitive and behavioral performance, and gene expression profiles at P60. Our results showed that alcohol exposure caused neuroapoptosis in P7 mouse brains immediately after a 6-hour exposure. In addition, P60 mice exposed to alcohol during P7 displayed impaired learning and memory abilities and anxiety-like behaviors. Electrophysiological analysis of hippocampal neurons revealed an excitatory/inhibitory imbalance in alcohol-treated P60 mice compared to controls, with decreased excitation and increased inhibition. Furthermore, our bioinformatic analysis of 376 dysregulated genes in P60 mouse brains following alcohol exposure identified 50 synapse-related and 23 mitochondria-related genes. These genes encoded proteins located in various parts of the synapse, synaptic cleft, extra-synaptic space, synaptic membranes, or mitochondria, and were associated with different biological processes and functions, including the regulation of synaptic transmission, transport, synaptic vesicle cycle, metabolism, synaptogenesis, mitochondrial activity, cognition, and behavior. The dysregulated synapse and mitochondrial genes were predicted to interact in overlapping networks. Our findings suggest that altered synaptic activities and signaling networks may contribute to alcohol-induced long-term cognitive and behavioral impairments in mice, providing new insights into the underlying synaptic and mitochondrial molecular mechanisms and potential neuroprotective strategies.