ABSTRACT
Objective:To identify key genes and their potential biological mechanisms in the progression of non-alcoholic fatty liver disease (NAFLD) using bioinformatics technology.Methods:Genes differentially expressed in simple non-alcoholic fatty liver disease (NAFL) and non-alcoholic steatohepatitis (NASH) were analyzed by integrating NAFLD-related sequencing datasets GSE135251 and GSE167523 from the Gene Expression Omnibus (GEO) datebase. Gene Ontology (GO) functional enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome signaling pathway analysis were performed. Key genes were identified by STRING database and Cytoscape3.7.2 software, and the expression of key genes under different fibrosis grades and activity scores was observed. In addition, the expression of key genes in different cell clusters was observed based on the single-cell RNA-seq dataset of NAFLD mice.Results:Bioinformatics methods were used to obtain 97 common differential genes in NAFLD from two datasets. GO functional enrichment analysis was mainly performed in Extracellular Matrix (ECM) tissues. The main signaling pathway is ECM-receptor interaction. Five key genes were identified based on PPI network and Cytoscape software: COL1A1, THBS2, CXCL8, THY1 and LOXL1. The expression of key genes was significantly positively correlated with fibrosis grade and activity score, indicating that they were closely related to the progression of NAFLD. These key genes are highly expressed in hepatic stellate cells (HSCs) and natural killer/T cells (NK/T cells).Conclusion:In this study, bioinformatics technology was used to identify five key genes that may be involved in the NAFL-NASH transformation, suggesting that the ECM-receptor interaction signaling pathway may be a key molecular mechanism of NAFLD disease progression.
ABSTRACT
Currently, commercial devices for electrical neural stimulations can only provide fixed stimulation paradigms with preset constant parameters, while the development of new stimulation paradigms with time-varying parameters has emerged as one of the important research directions for expanding clinical applications. To facilitate the performance of electrical stimulation paradigms with time-varying parameters in animal experiments, the present study developed a well-integrated stimulation system to output various pulse sequences by designing a LabVIEW software to control a general data acquisition card and an electrical stimulus isolator. The system was able to generate pulse sequences with inter-pulse-intervals (IPI) randomly varying in real time with specific distributions such as uniform distribution, normal distribution, gamma distribution and Poisson distribution. It was also able to generate pulse sequences with arbitrary time-varying IPIs. In addition, the pulse parameters, including pulse amplitude, pulse width, interphase delay of biphasic pulse and duration of pulse sequence, were adjustable. The results of performance tests of the stimulation system showed that the errors of the parameters of pulse sequences output by the system were all less than 1%. By utilizing the stimulation system, pulse sequences with IPI randomly varying in the range of 5~10 ms were generated and applied in rat hippocampal regions for animal experiments. The experimental results showed that, even with a same mean pulse frequency of ~130 Hz, for neuronal populations, the excitatory effect of stimulations with randomly varying IPIs was significantly greater than the effect of stimulations with fixed IPIs. In conclusion, the stimulation system designed here may provide a useful tool for the researches and the development of new paradigms of neural electrical stimulations.
Subject(s)
Animals , Rats , Electric Stimulation , NeuronsABSTRACT
Deep brain stimulation (DBS), which usually utilizes high frequency stimulation (HFS) of electrical pulses, is effective for treating many brain disorders in clinic. Studying the dynamic response of downstream neurons to HFS and its time relationship with stimulus pulses can reveal important mechanisms of DBS and advance the development of new stimulation modes (e.g., closed-loop DBS). To exhibit the dynamic neuronal firing and its relationship with stimuli, we designed a two-dimensional raster plot to visualize neuronal activity during HFS (especially in the initial stage of HFS). Additionally, the influence of plot resolution on the visualization effect was investigated. The method was then validated by investigating the neuronal responses to the axonal HFS in the hippocampal CA1 region of rats. Results show that the new design of raster plot is able to illustrate the dynamics of indexes (such as phase-locked relationship and latency) of single unit activity (i.e., spikes) during periodic pulse stimulations. Furthermore, the plots can intuitively show changes of neuronal firing from the baseline before stimulation to the onset dynamics during stimulation, as well as other information including the silent period of spikes immediately following the end of HFS. In addition, by adjusting resolution, the raster plot can be adapted to a large range of firing rates for clear illustration of neuronal activity. The new raster plot can illustrate more information with a clearer image than a regular raster plot, and thereby provides a useful tool for studying neuronal behaviors during high-frequency stimulations in brain.
Subject(s)
Animals , Rats , Action Potentials , Axons , Physiology , CA1 Region, Hippocampal , Physiology , Deep Brain Stimulation , Neurons , PhysiologyABSTRACT
Deep brain stimulation (DBS) has been successfully used to treat a variety of brain diseases in clinic. Recent investigations have suggested that high frequency stimulation (HFS) of electrical pulses used by DBS might change pathological rhythms in action potential firing of neurons, which may be one of the important mechanisms of DBS therapy. However, experimental data are required to confirm the hypothesis. In the present study, 1 min of 100 Hz HFS was applied to the Schaffer collaterals of hippocampal CA1 region in anaesthetized rats. The changes of the rhythmic firing of action potentials from pyramidal cells and interneurons were investigated in the downstream CA1 region. The results showed that obvious θ rhythms were present in the field potential of CA1 region of the anesthetized rats. The θ rhythms were especially pronounced in the stratum radiatum. In addition, there was a phase-locking relationship between neuronal spikes and the θ rhythms. However, HFS trains significantly decreased the phase-locking values between the spikes of pyramidal cells and the θ rhythms in stratum radiatum from 0.36 ± 0.12 to 0.06 ± 0.04 ( < 0.001, paired -test, = 8). The phase-locking values of interneuron spikes were also decreased significantly from 0.27 ± 0.08 to 0.09 ± 0.05 ( < 0.01, paired -test, = 8). Similar changes were obtained in the phase-locking values between neuronal spikes and the θ rhythms in the pyramidal layer. These results suggested that axonal HFS could eliminate the phase-locking relationship between action potentials of neurons and θ rhythms thereby changing the rhythmic firing of downstream neurons. HFS induced conduction block in the axons might be one of the underlying mechanisms. The finding is important for further understanding the mechanisms of DBS.