Brief isoflurane anaesthesia affects differential gene expression, gene ontology and gene networks in rat brain

Transcriptome analysis identifies an ASD-Like phenotype in oligodendrocytes and microglia from C58/J amygdala that is dependent on sex and sociability

BACKGROUND

Autism Spectrum Disorder (ASD) is a group of neurodevelopmental disorders with higher incidence in males and is characterized by atypical verbal/nonverbal communication, restricted interests that can be accompanied by repetitive behavior, and disturbances in social behavior. This study investigated brain mechanisms that contribute to sociability deficits and sex differences in an ASD animal model.

METHODS

Sociability was measured in C58/J and C57BL/6J mice using the 3-chamber social choice test. Bulk RNA-Seq and snRNA-Seq identified transcriptional changes in C58/J and C57BL/6J amygdala within which DMRseq was used to measure differentially methylated regions in amygdala.

RESULTS

C58/J mice displayed divergent social strata in the 3-chamber test. Transcriptional and pathway signatures revealed immune-related biological processes differ between C58/J and C57BL/6J amygdala. Hypermethylated and hypomethylated genes were identified in C58/J versus C57BL/6J amygdala. snRNA-Seq data in C58/J amygdala identified differential transcriptional signatures within oligodendrocytes and microglia characterized by increased ASD risk gene expression and predicted impaired myelination that was dependent on sex and sociability. RNA velocity, gene regulatory network, and cell communication analysis showed diminished oligodendrocyte/microglia differentiation. Findings were verified using Bulk RNA-Seq and demonstrated oxytocin's beneficial effects on myelin gene expression.

LIMITATIONS

Our findings are significant. However, limitations can be noted. The cellular mechanisms linking reduced oligodendrocyte differentiation and reduced myelination to an ASD phenotype in C58/J mice need further investigation. Additional snRNA-Seq and spatial studies would determine if effects in oligodendrocytes/microglia are unique to amygdala or if this occurs in other brain regions. Oxytocin's effects need further examination to understand its' potential as an ASD therapeutic.

CONCLUSIONS

Our work demonstrates the C58/J mouse model's utility in evaluating the influence of sex and sociability on the transcriptome in concomitant brain regions involved in ASD. Our single-nucleus transcriptome analysis elucidates potential pathological roles of oligodendrocytes and microglia in ASD. This investigation provides details regarding regulatory features disrupted in these cell types, including transcriptional gene dysregulation, aberrant cell differentiation, altered gene regulatory networks, and changes to key pathways that promote microglia/oligodendrocyte differentiation. Our studies provide insight into interactions between genetic risk and epigenetic processes associated with divergent affiliative behavior and lack of positive sociability.

Drug target genes and molecular mechanism investigation in isoflurane-induced anesthesia based on WGCNA and machine learning methods

PURPOSE

This study sought to identify drug target genes and their associated molecular mechanisms during isoflurane-induced anesthesia in clinical applications.

METHODS

Microarray data (ID: GSE64617; isoflurane-treated vs. normal samples) were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened and hub genes were investigated using weighted correlation network analysis (WGCNA). Protein-protein interactions (PPIs) were constructed among the co-DEGs (common genes between DEGs and hub genes), followed by functional enrichment analyses. Then, three machine learning methods were used to reveal drug targets, followed by validation, nomogram analysis, and gene set enrichment analysis. Finally, an miRNA-target network was constructed.

RESULTS

A total of 686 DEGs were identified between the two groups-of which, 183 DEGs integrated with genes revealed by WCGNA were identified as co-genes. These genes, including contactin-associated protein 1 (CNTNAP1), are mainly involved in functions such as action potentials. PPI network analysis revealed three models, with the machine learning analysis exploring four drug target genes: A2H, FAM155B, SCARF2, and SDR16C5. ROC and nomogram analyses demonstrated the ideal diagnostic value of these target genes. Finally, miRNA-mRNA pairs were constructed based on the four mRNAs and associated 174 miRNAs.

CONCLUSION

FA2H, FAM155B, SCARF2, and SDR16C5 may be novel drug target genes for isoflurane-induced anesthesia. CNTNAP1 may participate in the progression of isoflurane-induced anesthesia via its action potential function.

Isoflurane affects brain functional connectivity in rats 1 month after exposure

Isoflurane, the most commonly used preclinical anesthetic, induces brain plasticity and long-term cellular and molecular changes leading to behavioral and/or cognitive consequences. These changes are most likely associated with network-level changes in brain function. To elucidate the mechanisms underlying long-term effects of isoflurane, we investigated the influence of a single isoflurane exposure on functional connectivity, brain electrical activity, and gene expression. Male Wistar rats (n = 22) were exposed to 1.8% isoflurane for 3 h. Control rats (n = 22) spent 3 h in the same room without exposure to anesthesia. After 1 month, functional connectivity was evaluated with resting-state functional magnetic resonance imaging (fMRI; n = 6 + 6) and local field potential measurements (n = 6 + 6) in anesthetized animals. A whole genome expression analysis (n = 10+10) was also conducted with mRNA-sequencing from cortical and hippocampal tissue samples. Isoflurane treatment strengthened thalamo-cortical and hippocampal-cortical functional connectivity. Cortical low-frequency fMRI power was also significantly increased in response to the isoflurane treatment. The local field potential results indicating strengthened hippocampal-cortical alpha and beta coherence were in good agreement with the fMRI findings. Furthermore, altered expression was found in 20 cortical genes, several of which are involved in neuronal signal transmission, but no gene expression changes were noted in the hippocampus. Isoflurane induced prolonged changes in thalamo-cortical and hippocampal-cortical function and expression of genes contributing to signal transmission in the cortex. Further studies are required to investigate whether these changes are associated with the postoperative behavioral and cognitive symptoms commonly observed in patients and animals.

Prediction and analysis of weighted genes in isoflurane induced general anesthesia based on network analysis

Purpose: Isoflurane is still wildly used in the developing countries and isoflurane-induced general anesthesia gives rise to serious side effects. The aim of the present study was to investigate the molecular mechanism on isoflurane-induced general anesthesia.Materials and methods: The microarray data of GSE64617 dataset was downloaded from Gene Expression Omnibus (GEO) database. A total of 755 DEGs were identified using the limma package in the R programming language. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes, and Genomes (KEGG) pathways enrichment were conducted for DEGs. A protein-protein interaction (PPI) network was constructed for DEGs and sensory perception related genes. A global miRNA-mRNA regulatory network was constructed to reveal the interactions in miRNA and mRNA in isoflurane treated samples. Degree was used to evaluate the importance of a gene in the PPI network and miRNA-mRNA regulatory network.Results and conclusions: HMBOX1, CSNK2A1, PNN, SRRM1, PRPF40A, APCNTRK1, MAPK1, hsa-miR-16-5p, hsa-miR-424-5p, hsa-miR-497-5p and hsa-miR-17-5p were selected as weighted genes. The expression changes were further vitrificated in the rat models by performing quantitative real-time PCR (qPCR) analysis. In conclusion, we find several weighted mRNAs and miRNAs involved in isoflurane induced general anesthesia through bioinformatics analysis.

Effect of different anaesthetic techniques on gene expression profiles in patients who underwent hip arthroplasty

Objectives

To investigate the modulation of genes whose expression level is indicative of stress and toxicity following exposure to three anaesthesia techniques, general anaesthesia (GA), regional anaesthesia (RA), or integrated anaesthesia (IA).

Methods

Patients scheduled for hip arthroplasty receiving GA, RA and IA were enrolled at Rizzoli Orthopaedic Institute of Bologna, Italy and the expression of genes involved in toxicology were evaluated in peripheral blood mononuclear cells (PBMCs) collected before (T0), immediately after surgery (T1), and on the third day (T2) after surgery in association with biochemical parameters.

Results

All three anaesthesia methods proved safe and reliable in terms of pain relief and patient recovery. Gene ontology analysis revealed that GA and mainly IA were associated with deregulation of DNA repair system and stress-responsive genes, which was observed even after 3-days from anaesthesia. Conversely, RA was not associated with substantial changes in gene expression.

Conclusions

Based on the gene expression analysis, RA technique showed the smallest toxicological effect in hip arthroplasty.

Trial registration

ClinicalTrials.gov number NCT03585647.

Nicotine withdrawal-induced inattention is absent in alpha7 nAChR knockout mice

RATIONALE

Smoking is the leading cause of preventable death in the USA, but quit attempts result in withdrawal-induced cognitive dysfunction and predicts relapse. Greater understanding of the neural mechanism(s) underlying these cognitive deficits is required to develop targeted treatments to aid quit attempts.

OBJECTIVES

We examined nicotine withdrawal-induced inattention in mice lacking the α7 nicotinic acetylcholine receptor (nAChR) using the five-choice continuous performance test (5C-CPT).

METHODS

Mice were trained in the 5C-CPT prior to osmotic minipump implantation containing saline or nicotine. Experiment 1 used 40 mg kg-1 day-1 nicotine treatment and tested C57BL/6 mice 4, 28, and 52 h after pump removal. Experiment 2 used 14 and 40 mg kg-1 day-1 nicotine treatment in α7 nAChR knockout (KO) and wildtype (WT) littermates tested 4 h after pump removal. Subsets of WT mice were killed before and after pump removal to assess changes in receptor expression associated with nicotine administration and withdrawal.

RESULTS

Nicotine withdrawal impaired attention in the 5C-CPT, driven by response inhibition and target detection deficits. The overall attentional deficit was absent in α7 nAChR KO mice despite response disinhibition in these mice. Synaptosomal glutamate mGluR5 and dopamine D4 receptor expression were reduced during chronic nicotine but increased during withdrawal, potentially contributing to cognitive deficits.

CONCLUSIONS

The α7 nAChR may underlie nicotine withdrawal-induced deficits in target detection but is not required for response disinhibition deficits. Alterations to the glutamatergic and dopaminergic pathways may also contribute to withdrawal-induced attentional deficits, providing novel targets to alleviate the cognitive symptoms of withdrawal during quit attempts.