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.

Electroacupuncture (EA) treatment has proved to significantly decrease nociception in inflammatory nociception model by suppressing the phosphorylation of p38 mitogen-activated protein kinase (p38MAPK). However, repeated EA treatment results in gradual attenuation of its analgesic effects, which was defined as "EA tolerance." Recent studies have shown that let-7b-5p microRNA (miRNA) contributes to the EA tolerance. The present study aimed to explore the function of let-7b-5p in p38MAPK pathway and the development of EA tolerance in the inflammatory nociception. Dual luciferase reporter gene experiments were used in cortical neurons to determine the target gene locus of let-7b-5p. The threshold of nociception was assessed by tail flick latency (TFL) and paw withdrawal threshold (PWT). Western blots were used to measure the expression of mitogen-activated protein kinase phosphatase 1 (MKP-1) and phosphorylation level of p38MAPK after intracerebroventricular (ICV) injections of let-7b-5p agomir, antagomir, and controls. In vitro dual luciferase experiments demonstrated that the MKP-1-3′ untranslated region (UTR) is a target of let-7b-5p. In vivo experiment, rat with repeated EA treatment exhibits gradual decrease in TFL and PWT, which showed formation of EA tolerance. This trend was delayed after IVC injection of let-7b-5p antagomir and facilitated after IVC injection of let-7b-5p agomir. The protein levels of MKP-1 in the EA+let-7b-5p antagomir group were significantly higher than in the EA + let-7b-5p agomir group. However, P-p38MAPK in the EA+let-7b-5p antagomir group was significantly lower than in the EA+let-7b-5p agomir group. By upregulating the p38MAPK pathway through the inactivation of the MKP-1 gene, let-7b-5p contributes to EA tolerance in complete Freund's adjuvant (CFA)-induced inflammatory nociception rats. Our work revealed the mechanism of EA tolerance and indicated that let-7b-5p could be targeted to improve the long-term effects of EA.

Background: Electroacupuncture (EA) tolerance, a negative therapeutic effect, is a gradual decline in antinociception because of its repeated or prolonged use. This study aims to explore the role of thymosin beta 4 (Tβ4), having neuro-protection properties, in EA tolerance (EAT). Methods: Rats were treated with EA once daily for eight consecutive days to establish EAT, effect of Tβ4 on the development of EAT was determined through microinjection of Tβ4 antibody and siRNA into the cerebroventricle. The mRNA and protein expression profiles of Tβ4, opioid peptides (enkephalin, dynorphin and endorphin), and anti-opioid peptides (cholecystokinin octapeptide, CCK-8 and orphanin FQ, OFQ), and mu opioid receptor (MOR) and CCK B receptor (CCKBR) in the brain areas (hypothalamus, thalamus, cortex, midbrain and medulla) were characterized after Tβ4 siRNA was administered. Results: Tβ4 levels were increased at day 1, 4, and 8 and negatively correlated with the changes of tail flick latency in all areas. Tβ4 antibody and siRNA postponed EAT. Tβ4 siRNA caused decreased Tβ4 levels in all areas, which resulted in increased enkephalin, dynorphin, endorphin and MOR levels in most measured areas during repeated EA, but unchanged OFQ, CCK-8, and CCKBR levels in most measured areas. Tβ4 levels were negatively correlated with enkephalin, dynorphin, endorphin, or MOR levels in all areas except medulla, while positively correlated with OFQ and CCK-8 levels in some areas. Conclusion: These results confirmed Tβ4 facilitates EAT probably through negatively changing endogenous opioid peptides and their receptors and positively influencing anti-opioid peptides in the central nervous system.

Electroacupuncture (EA) is an efficient treatment for visceral hypersensitivity (VH). However, the mechanism underlying VH remains obscure. This study aimed to examine the effect of EA at Housanli acupoint on PAR2 and PAR4 expression in the periaqueductal gray (PAG), rostral ventromedial medulla (RVM), and spinal cord dorsal horn (SCDH) axes, as well as on expression of the proinflammatory cytokines IL-1β and TNF-α, COX-2 enzyme, c-Fos, and the neuropeptides CGRP and SP in the same areas of the descending pain modulatory system. To induce VH in male goats, a 2,4,6-trinitrobenzene-sulfonic acid (TNBS)–ethanol solution was administered to the ileal wall. The visceromotor response (VMR) and nociceptive response at different colorectal distension pressures were measured to evaluate VH. Goats in the TNBS group displayed significantly increased VMR and nociceptive response scores, and elevated protein and mRNA levels of PAR2 and PAR4 in the descending pain modulatory system compared to those in the control group. EA alleviated VMR and nociceptive responses, decreased the protein and mRNA expression levels of PAR2, and elevated those of PAR4 in the descending pain modulatory system. EA may relieve VH by reducing PAR2 expression and increasing PAR4 expression in the descending pain modulatory system.

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