Genomewide analysis of rat periaqueductal gray-dorsal horn reveals time-, region- and frequency-specific mRNA expression changes in response to electroacupuncture stimulation

Network based analysis of microarray gene expression profiles in response to electroacupuncture

Electroacupuncture (EA) has been extensively considered as a tool for treating diseases and relieving various pains. However, understanding the molecular mechanisms underlying its effect is of high importance. In this study, we performed a weighted gene co-expression network analysis (WGCNA) on data collected from a microarray experiment to investigate the relationship underlying EA within three factors, time, frequency and tissue regions (periaqueductal grey (PAG) and spinal dorsal horn (DH)) as well as the biological implication of gene expression changes. Gene expression on rats in PAG-DH regions induced by EA with 2 Hz and 100 Hz at l h and 24 h were measured using microarray technology. The WGCNA was performed to identify distinct network modules related to EA effects. To find the biological function of genes and pathways, the gene ontology (GO) Consortium was applied and the gene-gene interaction network of top genes in important modules was visualized. We identified one network module (466 genes) which is significantly associated with time, another module (402 genes) significantly related to frequency, and three modules each consisting of 1144, 402 and 3148 genes that are significantly associated with tissue regions. Furthermore, meaningful biological pathways were enriched in association with each of the experimental factors during EA stimulation.

Our analysis showed the robustness of WGCNA and revealed important genes within specific modules and pathways which might be activated in response to EA analgesia. The findings may help to clarify the underlying mechanisms of EA and provide references for future verification of this study.

Cardioprotective effect of electroacupuncture in cardiopulmonary bypass through apelin/APJ signaling

Aim Acupuncture, particularly electroacupuncture (EA), can improve the clinical outcomes of cardiopulmonary bypass (CPB) patients; however, the mechanisms remain unclear. This study aimed to examine the effects of EA pre-treatment on myocardial injury after CPB and investigate its potential mechanisms.

MAIN METHODS

Male Sprague-Dawley rats were subjected to CPB and divided into Control (sham-operated), CPB, and EA (CPB + EA) groups. In the EA group, rats were treated with EA at the "PC6" acupoint for 30 min before being subjected to CPB. At 0.5, 1, and 2 h after CPB, the expression levels of plasma cardiac troponin I (cTnI) and lactate dehydrogenase (LDH), and myeloperoxidase (MPO) activity, TNFα, IL-1β, reduced glutathione (GSH), oxidized glutathione (GSSH), and the ratio of GSH/GSSH in the myocardial tissue were measured. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining. The expression of cleaved caspase-3 was detected by immunofluorescence. The expression of apelin, APJ, AKT, p-Akt, ERK1/2, and p-ERK1/2 was determined using western blotting.

KEY FINDINGS

Decreased myocardial injury marker levels, myocardial apoptosis, oxidative stress, and the inflammatory response were found in the EA group compared with the CPB group. The expression levels of apelin, APJ, and p-Akt/AKT were increased in the EA group, and the p-ERK1/2/ERK1/2 level was decreased.

SIGNIFICANCE

This study showed that EA pre-treatment can protect the heart from damage following CPB, which might be mainly mediated by restoring the apelin/APJ signaling pathway.

Electroacupuncture Inhibits Visceral Nociception via Somatovisceral Interaction at Subnucleus Reticularis Dorsalis Neurons in the Rat Medulla

Electroacupuncture (EA) is an efficacious treatment for alleviating visceral pain, but the underlining mechanisms are not fully understood. This study investigated the role of medullary subnucleus reticularis dorsalis (SRD) neurons in the effects of EA on visceral pain. We recorded the discharges of SRD neurons extracellularly by glass micropipettes on anesthetized rats. The responses characteristics of SRD neurons to different intensities of EA (0.5, 1, 2, 4, 6, and 8 mA, 0.5 ms, and 2 Hz) on acupoints “Zusanli” (ST 36) and “Shangjuxu” (ST 37) before and during noxious colorectal distension (CRD) were analyzed. Our results indicated that SRD neurons responded to either a noxious EA stimulation ranging from 2 to 8 mA or to noxious CRD at 30 and 60 mmHg by increasing their discharge frequency at an intensity-dependent manner. However, during the stimulation of both CRD and EA, the increasing discharges of SRD neurons induced by CRD were significantly inhibited by 2–8 mA of EA. Furthermore, SRD neurons can encode the strength of EA, where a positive correlation between current intensity and the magnitude of neuronal responses to EA was observed within 2–6 mA. Yet, the responses of SRD neurons to EA stimulation reached a plateau when EA exceeded 6 mA. In addition, 0.5–1 mA of EA had no effect on CRD-induced nociceptive responses of SRD neurons. In conclusion, EA produced an inhibiting effect on visceral nociception in an intensity-dependent manner, which probably is due to the somatovisceral interaction at SRD neurons.

Exploring the Mechanisms of Electroacupuncture-Induced Analgesia through RNA Sequencing of the Periaqueductal Gray

Electroacupuncture (EA) can relieve various pains. However, its mechanism in terms of the transcriptome is still not well-known. To explore the full profile of EA-induced molecular modification in the central nerve system, three twins of goats were selected for a match-paired experiment: EA stimulation (60 Hz, 30 min) and none-EA (control). Goats in the EA group showed an increased (p < 0.05) nociceptive threshold compared with the control goats. Experimental goats were sacrificed at 4 h of the experiment, and the periaqueductal grays were harvested for RNA sequencing. As a result, 2651 differentially expressed genes (1803 up-regulated and 848 down-regulated genes) were found and enriched in 30 Kyoto Encyclopedia of Genes and Genomes pathways and 149 gene ontology terms. EA-regulated five neuropeptide genes (proenkephalin, proopiomelanocortin, preprodynorphin, diazepam-binding inhibitor and proprotein convertase 1 inhibitor) were validated with quantitative PCR. Furthermore, up-regulated glutamate receptors, glutamate transporters, γ-aminobutyric acid (GABA) receptors, GABA transporters, synaptotagmins or mitogen-activated protein kinase (MAPK) genes might contribute to EA-induced analgesia through regulating the glutamatergic synapse, GABAergic synapse, MAPKs, ribosome or ubiquitin-proteasome pathways. Our findings reveal a full profile of molecular modification in response to EA and provide a solid experimental framework for exploring the mechanisms underlying EA-induced analgesia.

Comprehensive evaluation of gene expression signatures in response to electroacupuncture stimulation at Zusanli (ST36) acupoint by transcriptomic analysis

Background

Electroacupuncture (EA) has been applied to treat and prevent diseases for years. However, molecular events happened in both the acupunctured site and the internal organs after EA stimulation have not been clarified.

Methods

Here we applied transcriptomic analysis to explore the gene expression signatures after EA stimulation. Mice were applied EA stimulation at ST36 for 15 min and nine tissues were collected three hours later for microarray analysis.

Results

We found that EA affected the expression of genes not only in the acupunctured site but also in the internal organs. EA commonly affected biological networks involved in cytoskeleton and cell adhesion, and also regulated unique process networks in specific organs, such as γ-aminobutyric acid-ergic neurotransmission in brain and inflammation process in lung. In addition, EA affected the expression of genes related to various diseases, such as neurodegenerative diseases in brain and obstructive pulmonary diseases in lung.

Conclusions

This report applied, for the first time, a global comprehensive genome-wide approach to analyze the gene expression profiling of acupunctured site and internal organs after EA stimulation. The connection between gene expression signatures, biological processes, and diseases might provide a basis for prediction and explanation on the therapeutic potentials of acupuncture in organs.

Role of capsaicin- and heat-sensitive afferents in stimulation of acupoint-induced pain and analgesia in humans

We investigated role of capsaicin-sensitive afferents within and without the areas of Zusanli (ST36)/Shangjuxu (ST37) acupoints along the stomach (ST) meridian in the perception and modulation of pain assessed by visual analog scale of pain and its distribution rated by subjects, pressure pain threshold (PPT), and heat pain threshold (HPT) in humans. Compared with the treatment of non-acupoint area, capsaicin (100µg/50µl) administered into either ST36 or ST37 acupoint caused the strongest pain intensity and the most extensive pain distribution, followed by rapid onset, bilateral, long-lasting secondary mechanical hyperalgesia and slower onset secondary heat hypoalgesia (1day after the capsaicin treatment). Between treatments of different acupoints, capsaicin administrated into the ST36 acupoint exhibited the stronger pain intensity and more widespread pain distribution compared with the treatment of ST37 acupoint. A period of 30- to 45-min, but not 15-min, 43°C heating-needle stimulation applied to the ST36 acupoint significantly enhanced the HPT, and had no effect on PPT. Upon trapezius muscle pain elicited by the i.m. injection of 5.8% saline, pre-emptive treatment of the contralateral ST36 acupoint with 43°C heating-needle stimulation alleviated the ongoing muscle pain, reduced painful area, and reversed the decrease in HPT. It is suggested that (1) pain elicited from the acupoint and non-acupoint areas differs significantly, which are supposed to be dependent on the different distributions and contributions of capsaicin-sensitive afferents. (2) Non-painful heat stimulation is a valid approach in prevention of ongoing muscle pain with associated post-effects of peripheral and central sensitization.

Amblyopia: Can Laser Acupuncture be an Option?

This paper describes the results of the treatment of amblyopia in young patients using an unconventional laser-acupuncture technique. After obtaining satisfactory results in the treatment of a 14-year-old amblyopic girl, the treatment was applied to 13 amblyopic children aged 3-11 years, with an encouraging outcome. An ultralow-light-intensity laser with a square-wave modulated emission was applied over a sequence of acupuncture points. Each session lasted < 15 minutes, and the treatment was performed once a week in 6-week cycles. Patients were followed for several years to evaluate the long-term results and/or to extend the treatment. All except two of the treated patients showed a rapid increase in visual acuity after several treatment sessions. Some required retreatment for regressions in visual acuity. The need for medium-term treatment cycles seems, however, to suggest that results may not be stable for all individuals. Although acupuncture has already been proved to be effective in the treatment of amblyopia, the results reported in this paper suggest that laser acupuncture at ultra-low-light-intensity levels can provide similar, if not better, results to conventional acupuncture stimulation, but with higher patient compliance.

Analgesic Neural Circuits Are Activated by Electroacupuncture at Two Sets of Acupoints

To investigate analgesic neural circuits activated by electroacupuncture (EA) at different sets of acupoints in the brain, goats were stimulated by EA at set of Baihui-Santai acupoints or set of Housanli acupoints for 30 min. The pain threshold was measured using the potassium iontophoresis method. The levels of c-Fos were determined with Streptavidin-Biotin Complex immunohistochemistry. The results showed pain threshold induced by EA at set of Baihui-Santai acupoints was 44.74% ± 4.56% higher than that by EA at set of Housanli acupoints (32.64% ± 5.04%). Compared with blank control, EA at two sets of acupoints increased c-Fos expression in the medial septal nucleus (MSN), the arcuate nucleus (ARC), the nucleus amygdala basalis (AB), the lateral habenula nucleus (HL), the ventrolateral periaqueductal grey (vlPAG), the locus coeruleus (LC), the nucleus raphe magnus (NRM), the pituitary gland, and spinal cord dorsal horn (SDH). Compared with EA at set of Housanli points, EA at set of Baihui-Santai points induced increased c-Fos expression in AB but decrease in MSN, the paraventricular nucleus of the hypothalamus, HL, and SDH. It suggests that ARC-PAG-NRM/LC-SDH and the hypothalamus-pituitary may be the common activated neural pathways taking part in EA-induced analgesia at the two sets of acupoints.