Electroacupuncture alleviates the relapse of pain-related aversive memory by activating KOR and inhibiting GABAergic neurons in the insular cortex.

Pain-related aversive memory is common in chronic pain patients. Electroacupuncture has been demonstrated to block pain-related aversive memory. The insular cortex is a key region closely related to aversive behaviors. In our study, a potential mechanism underlying the effect of electroacupuncture treatment on pain-related aversive memory behaviors relative to the insular cortex was investigated. Our study used the chemogenetic method, pharmacological method, electroacupuncture intervention, and behavioral detection. Our study showed that both inhibition of gamma-aminobutyric acidergic neurons and activation of the kappa opioid receptor in the insular cortex blocked the pain-related aversive memory behaviors induced by 2 crossover injections of carrageenan in mice; conversely, both the activation of gamma-aminobutyric acidergic neurons and inhibition of kappa opioid receptor in the insular cortex play similar roles in inducing pain-related aversive memory behaviors following 2 crossover injections of carrageenan. In addition, activation of gamma-aminobutyric acidergic neurons in the insular cortex reversed the effect of kappa opioid receptor activation in the insular cortex. Moreover, electroacupuncture effectively blocked pain-related aversive memory behaviors in model mice, which was reversed by both activation of gamma-aminobutyric acidergic neurons and inhibition of kappa opioid receptor in the insular cortex. The effect of electroacupuncture on blocking pain-related aversive memory behaviors may be related to the activation of the kappa opioid receptor and inhibition of gamma-aminobutyric acidergic neurons in the insular cortex.

Serum lipidomics-based study of electroacupuncture for skin wound repair in rats.

Lipid metabolism plays an important role in the repair of skin wounds. Studies have shown that acupuncture is very effective in skin wound repair. However, there is little knowledge about the mechanism of electroacupuncture. Thirty-six SD rats were divided into three groups: sham-operated group, model group and electroacupuncture group, with six rats in each group. After the intervention, orbital venous blood was collected for lipid metabolomics analysis, wound perfusion was detected and finally the effect of electroacupuncture on skin wound repair was comprehensively evaluated by combining wound healing rate and histology. Lipid metabolomics analysis revealed 11 differential metabolites in the model versus sham-operated group. There were 115 differential metabolites in the model versus electro-acupuncture group. 117 differential metabolites in the electro-acupuncture versus sham-operated group. There were two differential metabolites common to all three groups. Mainly cholesteryl esters and sphingolipids were elevated after electroacupuncture and triglycerides were largely decreased after electroacupuncture. The electroacupuncture group recovered faster than the model group in terms of blood perfusion and wound healing (p < 0.05). Electroacupuncture may promote rat skin wound repair by improving lipid metabolism and improving local perfusion.

Electroacupuncture promotes skin wound repair by improving lipid metabolism and inhibiting ferroptosis.

Lipid metabolism plays an important role in the repair of skin wounds. Studies have shown that acupuncture is very effective in skin wound repair. However, there is little knowledge about the mechanism of electroacupuncture. Thirty-six SD rats were divided into three groups: sham-operated group, model group and electroacupuncture group, with 12 rats in each group. After the intervention, local skin tissues were collected for lipid metabolomics analysis, wound perfusion and ferroptosis-related indexes were detected and finally the effect of electroacupuncture on skin wound repair was comprehensively evaluated by combining wound healing rate and histology. Lipid metabolomics analysis revealed 37 differential metabolites shared by the three groups, mainly phospholipids, lysophospholipids, glycerides, acylcarnitine, sphingolipids and fatty acids, and they could be back-regulated after electroacupuncture. The recovery of blood perfusion and wound healing was faster in the electroacupuncture group than in the model group (p < 0.05). The levels of GPX4, FTH1, SOD and GSH-PX, which are related to ferroptosis, were higher in the electroacupuncture group than in the model group (p < 0.05). The levels of ACSL4 and MDA were lower in the electroacupuncture group than in the model group (p < 0.05). Electroacupuncture may promote skin wound repair by improving lipid metabolism and inhibiting ferroptosis in local tissues.

Inhibition of phosphorylated calcium/calmodulin-dependent protein kinase IIα relieves streptozotocin-induced diabetic neuropathic pain through regulation of P2X3 receptor in dorsal root ganglia.

Diabetic neuropathic pain (DNP) is frequent among patients with diabetes. We previously showed that P2X3 upregulation in dorsal root ganglia (DRG) plays a role in streptozotocin (STZ)-induced DNP but the underlying mechanism is unclear. Here, a rat model of DNP was established by a single injection of STZ (65 mg/kg). Fasting blood glucose was significantly elevated from the 1st to 3rd week. Paw withdrawal thresholds (PWTs) and paw withdrawal latencies (PWLs) in diabetic rats significantly reduced from the 2nd to 3rd week. Western blot analysis revealed that elevated p-CaMKIIα levels in the DRG of DNP rats were accompanied by pain-associated behaviors while CaMKIIα levels were unchanged. Immunofluorescence revealed significant increase in the proportion of p-CaMKIIα immune positive DRG neurons (stained with NeuN) in the 2nd and 3rd week and p-CaMKIIα was co-expressed with P2X3 in DNP rats. KN93, a CaMKII antagonist, significantly reduce mechanical hyperalgesia and thermal hyperalgesia and these effects varied dose-dependently, and suppressed p-CaMKIIα and P2X3 upregulation in the DRGs of DNP rats. These results revealed that the p-CaMKIIα upregulation in DRG is involved in DNP, which possibly mediated P2X3 upregulation, indicating CaMKIIα may be an effective pharmacological target for DNP management.

Dorsal root ganglia P2X4 and P2X7 receptors contribute to diabetes-induced hyperalgesia and the downregulation of electroacupuncture on P2X4 and P2X7.

Diabetic neuropathic pain (DNP) is highly common in diabetes patients. P2X receptors play critical roles in pain sensitization. We previously showed that elevated P2X3 expression in dorsal root ganglion (DRG) contributes to DNP. However, the role of other P2X receptors in DNP is unclear. Here, we established the DNP model using a single high-dose streptozotocin (STZ) injection and investigated the expression of P2X genes in the DRG. Our data revealed elevated P2X2, P2X4, and P2X7 mRNA levels in DRG of DNP rats. The protein levels of P2X4 and P2X7 in DNP rats increased, but the P2X2 did not change significantly. To study the role of P2X4 and P2X7 in diabetes-induced hyperalgesia, we treated the DNP rats with TNP-ATP (2',3'-O-(2,4,6-trinitrophenyl)-adenosine 5'-triphosphate), a nonspecific P2X1-7 antagonist, and found that TNP-ATP alleviated thermal hyperalgesia in DNP rats. 2 Hz electroacupuncture is analgesic against DNP and could downregulate P2X4 and P2X7 expression in DRG. Our findings indicate that P2X4 and P2X7 in L4-L6 DRGs contribute to diabetes-induced hyperalgesia, and that EA reduces thermal hyperalgesia and the expression of P2X4 and P2X7.

Analgesic effect of electroacupuncture on bone cancer pain in rat model: the role of peripheral P2X3 receptor.

Upregulation of P2X3 receptor (P2X3R) has been strongly implicated in nociceptive signaling including bone cancer pain (BCP). The present study, using rat bone cancer model, aimed to explore the role of P2X3R in regulating rat pain behavior under the intervention of electroacupuncture (EA). The BCP model was successfully established by injection with MRMT-1 breast cancer cell into the medullary cavity of left tibia for 3 × 104 cells/3 µL PBS in rats as revealed by obvious bone destruction, decreased paw withdrawal thresholds (PWTs), and reduced paw withdrawal latencies (PWLs). Western blot analyses showed that P2X3R expression was significantly upregulated in ipsilateral lumbar 4-6 (L4-6) dorsal root ganglia (DRG), but the difference not seen in spinal cord dorsal horn (SCDH). With the in-depth study of P2X3R activation, we observed that intrathecal injection of P2X3R agonist α,ß-meATP aggravated MRMT-1 induced BCP, while injection of P2X3R inhibitor A-317491 alleviated pain. Subsequently, we demonstrated that BCP induced mechanical allodynia and thermal hyperalgesia were attenuated after EA treatment. Under EA treatment, total P2X3R protein expression in ipsilateral DRGs was decreased, and it is worth mentioning that decreased expression of P2X3R membrane protein, which indicated that both the expression and membrane trafficking of P2X3R were inhibited by EA. The immunofluorescence assay showed that EA stimulation exerted functions by reducing the expression of P2X3R-positive cells in ipsilateral DRGs of BCP rats. Ca2+ imaging analysis revealed that the EA stimulation decreased the percentage of α,ß-meATP responsive neurons in DRGs and inhibited calcium influx. Notably, the inhibitory effect of EA on mechanical allodynia and nociceptive flinches was abolished by intrathecal injection of α,ß-meATP. These findings demonstrated EA stimulation ameliorated mechanical allodynia and thermal hyperalgesia in rat model of MRMT-1-induced BCP. EA exerts analgesic effect on BCP by reducing the overexpression and functional activity of P2X3R in ipsilateral DRGs of BCP rats. Our work first demonstrates the critical and overall role of P2X3R in EA's analgesia against peripheral sensitization of MRMT-1-induced BCP and further supports EA as a potential therapeutic option for cancer pain in clinic.

Electroacupuncture may alleviate diabetic neuropathic pain by inhibiting the microglia P2X4R and neuroinflammation.

Diabetic neuropathic pain (DNP) is a common and destructive complication of diabetes mellitus. The discovery of effective therapeutic methods for DNP is vitally imperative because of the lack of effective treatments. Although 2 Hz electroacupuncture (EA) was a successful approach for relieving DNP, the mechanism underlying the effect of EA on DNP is still poorly understood. Here, we established a rat model of DNP that was induced by streptozotocin (STZ) injection. P2X4R was upregulated in the spinal cord after STZ-injection. The upregulation of P2X4R was mainly expressed on activated microglia. Intrathecal injection of a P2X4R antagonist or microglia inhibitor attenuated STZ-induced nociceptive thermal hyperalgesia and reduced the overexpression of brain-derived neurotrophic factor (BDNF), interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) in the spinal cord. We also assessed the effects of EA treatment on the pain hypersensitivities of DNP rats, and further investigated the possible mechanism underlying the analgesic effect of EA. EA relieved the hyperalgesia of DNP. In terms of mechanism, EA reduced the upregulation of P2X4R on activated microglia and decreased BDNF, IL-1ß and TNF-α in the spinal cord. Mechanistic research of EA's analgesic impact would be beneficial in ensuring its prospective therapeutic effect on DNP as well as in extending EA's applicability.

Transcriptome profiling of long noncoding RNAs and mRNAs in spinal cord of a rat model of paclitaxel-induced peripheral neuropathy identifies potential mechanisms mediating neuroinflammation and pain.

BACKGROUND: Paclitaxel is a widely prescribed chemotherapy drug for treating solid tumors. However, paclitaxel-induced peripheral neuropathy (PIPN) is a common adverse effect during paclitaxel treatment, which results in sensory abnormalities and neuropathic pain among patients. Unfortunately, the mechanisms underlying PIPN still remain poorly understood. Long noncoding RNAs (lncRNAs) are novel and promising targets for chronic pain treatment, but their involvement in PIPN still remains unexplored. METHODS: We established a rat PIPN model by repetitive paclitaxel application. Immunostaining, RNA sequencing (RNA-Seq) and bioinformatics analysis were performed to study glia cell activation and explore lncRNA/mRNA expression profiles in spinal cord dorsal horn (SCDH) of PIPN model rats. qPCR and protein assay were used for further validation. RESULTS: PIPN model rats developed long-lasting mechanical and thermal pain hypersensitivities in hind paws, accompanied with astrocyte and microglia activation in SCDH. RNA-Seq identified a total of 814 differentially expressed mRNAs (DEmRNA) (including 467 upregulated and 347 downregulated) and 412 DElncRNAs (including 145 upregulated and 267 downregulated) in SCDH of PIPN model rats vs. control rats. Functional analysis of DEmRNAs and DElncRNAs identified that the most significantly enriched pathways include immune/inflammatory responses and neurotrophin signaling pathways, which are all important mechanisms mediating neuroinflammation, central sensitization, and chronic pain. We further compared our dataset with other published datasets of neuropathic pain and identified a core set of immune response-related genes extensively involved in PIPN and other neuropathic pain conditions. Lastly, a competing RNA network analysis of DElncRNAs and DEmRNAs was performed to identify potential regulatory networks of lncRNAs on mRNA through miRNA sponging. CONCLUSIONS: Our study provided the transcriptome profiling of DElncRNAs and DEmRNAs and uncovered immune and inflammatory responses were predominant biological events in SCDH of the rat PIPN model. Thus, our study may help to identify promising genes or signaling pathways for PIPN therapeutics.

Electroacupuncture alleviates diabetic neuropathic pain in rats by suppressing P2X3 receptor expression in dorsal root ganglia.

Diabetic neuropathic pain (DNP) is a troublesome diabetes complication all over the world. P2X3 receptor (P2X3R), a purinergic receptor from dorsal root ganglion (DRG), has important roles in neuropathic pain pathology and nociceptive sensations. Here, we investigated the involvement of DRG P2X3R and the effect of 2 Hz electroacupuncture (EA) on DNP. We monitored the rats' body weight, fasting blood glucose level, paw withdrawal thresholds, and paw withdrawal latency, and evaluated P2X3R expression in DRG. We found that P2X3R expression is upregulated on DNP, while 2 Hz EA is analgesic against DNP and suppresses P2X3R expression in DRG. To evaluate P2X3R involvement in pain modulation, we then treated the animals with A317491, a P2X3R specific antagonist, or α ß-me ATP, a P2X3R agonist. We found that A317491 alleviates hyperalgesia, while α ß-me ATP blocks EA's analgesic effects. Our findings indicated that 2 Hz EA alleviates DNP, possibly by suppressing P2X3R upregulation in DRG.

Effects of Electroacupuncture on Pain Memory-Related Behaviors and Synchronous Neural Oscillations in the Rostral Anterior Cingulate Cortex in Freely Moving Rats.

Our previous studies have confirmed that electroacupuncture (EA) can effectively intervene in pain memory, but the neural mechanism involved remains unclear. In this study, we observed the effects of EA in regulating pain memory-related behaviors and synchronous neural oscillations in the rostral anterior cingulate cortex (rACC). During nociceptive behavioral testing, pain memory induced a nonpain stimulus that spurred a neural oscillatory reaction similar to that caused by pain stimuli in the rACC. After EA, nonpain stimuli did not induce decreased neural oscillatory activity in the rACC until the presentation of pain stimuli. During aversive behavioral testing, EA, through the downregulation of theta power, inhibited the retrieval of aversive memory and relieved pain memory-induced aversive behaviors. These changes of oscillatory activity may be the hallmarks of EA therapy for pain memory.

Suppressing PKC-dependent membrane P2X3 receptor upregulation in dorsal root ganglia mediated electroacupuncture analgesia in rat painful diabetic neuropathy.

Painful diabetic neuropathy (PDN) is a common and troublesome diabetes complication. Protein kinase C (PKC)-mediated dorsal root ganglia (DRG) P2X3 receptor upregulation is one important mechanism underlying PDN. Accumulating evidence demonstrated that electroacupuncture (EA) at low frequency could effectively attenuate neuropathic pain. Our previous study showed that 2-Hz EA could relieve pain well in PDN. The study aimed to investigate whether 2-Hz EA relieves pain in PDN through suppressing PKC-mediated DRG P2X3 receptor upregulation. A 7-week feeding of high-fat and high-sugar diet plus a single injection of streptozotocin (STZ) in a dose of 35 mg/kg after a 5-week feeding of the diet successfully induced type 2 PDN in rats as revealed by the elevated body weight, fasting blood glucose, fasting insulin and insulin resistance, and the reduced paw withdrawal threshold (PWT), as well as the destructive ultrastructural change of sciatic nerve. DRG plasma membrane P2X3 receptor level and DRG PKC expression were elevated. Two-hertz EA failed to improve peripheral neuropathy; however, it reduced PWT, DRG plasma membrane P2X3 receptor level, and DRG PKC expression in PDN rats. Intraperitoneal administration of P2X3 receptor agonist αß-meATP or PKC activator phorbol 12-myristate 13-acetate (PMA) blocked 2-Hz EA analgesia. Furthermore, PMA administration increased DRG plasma membrane P2X3 receptor level in PDN rats subject to 2-Hz EA treatment. These findings together indicated that the analgesic effect of EA in PDN is mediated by suppressing PKC-dependent membrane P2X3 upregulation in DRG. EA at low frequency is a valuable approach for PDN control.

Electroacupuncture Alleviates Hyperalgesia and Anxiety-Like Behaviors in Pain Memory Model Rats Through Activation of GABAergic Neurons and GABA Receptor in the Rostral Anterior Cingulate Cortex.

Recent studies have confirmed that pain memory is often accompanied by negative emotions. Electroacupuncture (EA) can block the retrieval of painful memories, thereby alleviating the associated negative behaviors. However, the underlying mechanism is poorly understood. This study revealed that the effect of EA on pain memory-induced negative behaviors is related to the mediation of GABAergic neuron activity and GABA receptor expression in the rostral anterior cingulate cortex (rACC). Previous studies have shown that the rACC is a crucial area for regulating nociceptive behaviors and negative emotions in pain memory models. The GABAergic neurons and receptors in the rACC are largely involved in pain sensation and related effects. However, the relationships among pain memory, GABAergic neurons and receptors in the rACC have not been investigated. In this study, we established a pain memory model via secondary plantar cross-injection of carrageenan and EA treatment. Using chemogenetic methods and behavioral assessments of pain and negative emotion, we found that early excitation of GABAergic neurons in the rACC blocked the recall of pain memories and reduced anxiety-like behaviors in pain memory model rats. Furthermore, pharmacological methods revealed that excitation of GABAA and GABAB receptors in the rACC blocks hyperpathia associated with pain memory and pain-induced anxiety-like behaviors, while inhibition of GABAA and GABAB receptors reverses these effects. These results suggest that EA may alleviate pain and associated anxiety-like behaviors related to pain memories through the activation of GABAergic neurons and excitation of GABAA and GABAB receptors in the rACC.

Electroacupuncture alleviates diabetes-induced mechanical allodynia and downregulates bradykinin B1 receptor expression in spinal cord dorsal horn.

OBJECTIVE: Diabetic neuropathic pain (DNP) is one of the most prevalent symptoms of diabetes. The alteration of proteins in the spinal cord dorsal horn (SCDH) plays a significant role in the genesis and the development of DNP. Our previous study has shown electroacupuncture could effectively relieve DNP. However, the potential mechanism inducing DNP's genesis and development remains unclear and needs further research. METHODS: This study established DNP model rats by intraperitoneally injecting a single high-dose streptozotocin; 2 Hz electroacupuncture was used to stimulate Zusanli (ST36) and Kunlun (BL60) of DNP rats daily from day 15 to day 21 after streptozotocin injection. Behavioral assay, quantitative PCR, immunofluorescence staining, and western blotting were used to study the analgesic mechanism of electroacupuncture. RESULTS: The bradykinin B1 receptor (B1R) mRNA, nuclear factor-κB p65 (p65), substance P, and calcitonin gene-related peptide (CGRP) protein expression were significantly enhanced in SCDH of DNP rats. The paw withdrawal threshold was increased while body weight and fasting blood glucose did not change in DNP rats after the electroacupuncture treatment. The expression of B1R, p65, substance P, and CGRP in SCDH of DNP rats was also inhibited after the electroacupuncture treatment. CONCLUSION: This work suggests that the potential mechanisms inducing the allodynia of DNP rats were possibly related to the increased expression of B1R, p65, substance P, and CGRP in SCDH. Downregulating B1R, p65, substance P, and CGRP expression levels in SCDH may achieve the analgesic effect of 2 Hz electroacupuncture treatment.

A neural circuit associated with anxiety-like behaviors induced by chronic inflammatory pain and the anxiolytic effects of electroacupuncture.

AIMS: Negative emotions induced by chronic pain are a serious clinical problem. Electroacupuncture (EA) is a clinically proven safe and effective method to manage pain-related negative emotions. However, the circuit mechanisms underlying the effect of EA treatment on negative emotions remain unclear. METHODS: Plantar injection of complete Freund's adjuvant (CFA) was performed to establish a rat model of chronic inflammatory pain-induced anxiety-like behaviors. Adeno-associated virus (AAV) tracing was used to identify excitatory synaptic transmission from the rostral anterior cingulate cortex (rACC) to the dorsal raphe nucleus (DRN). Employing chemogenetic approaches, we examined the role of the rACC-DRN circuit in chronic pain-induced anxiety-like behaviors and investigated whether EA could reverse chronic pain-induced dysfunctions of the rACC-DRN circuit and anxiety-like behaviors. RESULTS: We found that chemogenetic activation of the rACC-DRN circuit alleviated CFA-induced anxiety-like behaviors, while chemogenetic inhibition of the rACC-DRN circuit resulted in short-term CFA-induced anxiety-like behaviors. Further research revealed that the development of CFA-induced anxiety-like behaviors was attributed to the dysfunction of rACC CaMKII neurons projecting to DRN serotonergic neurons (rACCCaMKII-DRN5-HT neurons) but not rACC CaMKII neurons projecting to DRN GABAergic neurons (rACCCaMKII-DRNGABA neurons). This is supported by the findings that chemogenetic activation of the rACCCaMKII-DRN5-HT circuit alleviates anxiety-like behaviors in rats with chronic pain, whereas neither chemogenetic inhibition nor chemogenetic activation of the rACCCaMKII-DRNGABA circuit altered CFA chronic pain-evoked anxiety-like behaviors in rats. More importantly, we found that EA could reverse chronic pain-induced changes in the activity of rACC CaMKII neurons and DRN 5-HTergic neurons and that chemogenetic inhibition of the rACCCaMKII-DRN5-HT circuit blocked the therapeutic effects of EA on chronic pain-induced anxiety-like behaviors. CONCLUSIONS: Our data suggest that the reversal of rACCCaMKII-DRN5-HT circuit dysfunction may be a mechanism underlying the therapeutic effect of EA on chronic pain-induced anxiety-like behaviors.

Electroacupuncture alleviates streptozotocin-induced diabetic neuropathic pain via suppressing phosphorylated CaMKIIα in rats.

Diabetic neuropathic pain (DNP) is a frequent complication of diabetes. Calcium/calmodulin-dependent protein kinase II α (CaMKIIα), a multi-functional serine/threonine kinase subunit, is mainly located in the surface layer of the spinal cord dorsal horn (SCDH) and the primary sensory neurons in dorsal root ganglion (DRG). Numerous studies have indicated electroacupuncture (EA) takes effect in various kinds of pain. In this research, we explored whether CaMKIIα on rats' SCDH and DRG participated in DNP and further explored the mechanisms underlying the analgesic effects of EA. The DNP model in rats was successfully established by intraperitoneal injection of streptozotocin. Certain DNP rats were treated with intrathecal injections of KN93, a CaMKII antagonist, and some of the DNP rats received EA intervention. The general conditions, behaviors, the expressions of CaMKIIα and phosphorylated CaMKIIα (p-CaMKIIα) were evaluated. DNP rats' paw withdrawal threshold was reduced and the expressions of p-CaMKIIα in SCDH and DRG were upregulated compared with the Normal group, while the level of CaMKIIα showed no significance. KN93 attenuated DNP rats' hyperalgesia and reduced the expressions of p-CaMKIIα. We also found EA attenuated the hyperalgesia of DNP rats and reduced the expressions of p-CaMKIIα. The above findings suggest that p-CaMKIIα in SCDH and DRG is involved in DNP. The analgesic effect of EA in DNP might be related to the downregulation of p-CaMKIIα expression level. Our study further supports that EA can be an effective clinical treatment for DNP.

Neutrophil-derived oxidative stress contributes to skin inflammation and scratching in a mouse model of allergic contact dermatitis via triggering pro-inflammatory cytokine and pruritogen production in skin.

Allergic contact dermatitis (ACD) is a common skin disease featured with skin inflammation and a mixed itch/pain sensation. The itch/pain causes the desire to scratch, affecting both physical and psychological aspects of patients. Nevertheless, the mechanisms underlying itch/pain sensation of ACD still remain elusive. Here, we found that oxidative stress and oxidation-related injury were remarkably increased in the inflamed skin of a mouse model of ACD. Reducing oxidative stress significantly attenuated itch/pain-related scratching, allokonesis and skin inflammation. RNA-Sequencing reveals oxidative stress contributes to a series of skin biological processes, including inflammation and immune response. Attenuating oxidative stress reduces overproduction of IL-1ß and IL-33, two critical cytokines involved in inflammation and pain/itch, in the inflamed skin of model mice. Exogenously injecting H2O2 into the neck skin of naïve mice triggered IL-33 overproduction in skin keratinocytes and induced scratching, which was reduced in mice deficient in IL-33 receptor ST2. ACD model mice showed remarkable neutrophil infiltration in the inflamed skin. Blocking neutrophil infiltration reduced oxidative stress and attenuated scratching and skin inflammation. Therefore, our study reveals a critical contribution of neutrophil-derived oxidative stress to skin inflammation and itch/pain-related scratching of ACD model mice via mechanisms involving the triggering of IL-33 overproduction in skin keratinocytes. Targeting skin oxidative stress may represent an effective therapy for ameliorating ACD.

Research Trends on Acupuncture for Shoulder Pain Treatment Over the Past 15 Years: A Bibliometric Analysis.

Objective: Currently, acupuncture for shoulder pain has been widely used in clinical and scientific research worldwide, but the bibliometric literature on acupuncture for shoulder pain is still scarce. This study reviews the application of acupuncture in the treatment of shoulder pain over the past 15 years, to analyze the current state of research, research hotspots, and trends. The article can also provide a reference for future research. Methods: This paper searches the core collection of the Web of Science database for publications related to acupuncture therapy for shoulder pain between 2008 and 2022. And the data were visualized and analyzed using VOSviewer and CiteSpace for annual publications, countries, institutions, journals and co-cited journals, authors and co-cited authors, keywords, and emergent keywords. Results: A total of 135 papers were included, with an overall increasing trend in the number of annual publications. The country with the highest centrality in publishing articles is the United States (0.28). In terms of research institutions, Kyung Hee University has the highest number of publications (18). In terms of authors, Lewith George, Lind Klaus, MacPherson Hugh, Sherman Karen J, and Vickers Andrew J are the five most published authors. Vickers, Andrew J. is the most co-cited author (50 times). In terms of journals, PAIN has the highest number of publications (82) and co-cited frequency (232), while the highest impact factor was BMJ-BRIT MED J (96.216). "Acupuncture" was the most frequently mentioned keyword (65 times), with the keyword "protocol" appearing the most recently. Emerging keywords that are still in vogue are "stroke", "systematic review" and "stimulation". Conclusion: This study provides statistics on current research on the treatment of shoulder pain with acupuncture, which may be able to inform future research directions for all researchers and physicians, as well as facilitate closer communication and collaboration.

Electroacupuncture improves gout arthritis pain via attenuating ROS-mediated NLRP3 inflammasome overactivation.

BACKGROUND: Gout results from disturbed uric acid metabolism, which causes urate crystal deposition in joints and surrounding tissues. Gout pain management is largely limited to colchicine and nonsteroidal anti-inflammatory drugs. Constant usage of these medications leads to severe side effects. We previously showed electroacupuncture (EA) is effective for relieving pain in animal model of gout arthritis. Here we continued to study the mechanisms underlying how EA alleviates gout pain. METHODS: Monosodium urate was injected into ankle joint to establish gout arthritis model in mice. EA or sham EA was applied at ST36 and BL60 acupoints of model animals. Biochemical assays, immunostaining, live cell Ca2+ imaging and behavioral assays were applied. RESULTS: Model mice displayed obvious mechanical allodynia, accompanied with gait impairments. EA attenuated mechanical hypersensitivities and improved gait impairments. EA reduced the overexpression of NLRP3 inflammasome signaling molecules in ankle joints of model animals. EA-induced anti-allodynia, as well as inhibition on NLRP3 inflammasome, were mimicked by antagonizing but abolished by activating NLRP3 inflammasome via pharmacological methods. EA attenuated oxidative stress, an upstream signaling of NLRP3 inflammasome in ankle joints of model mice. Exogenously increasing oxidative stress abolished EA's inhibitory effect on NLRP3 inflammasome and further reversed EA's anti-allodynic effect. EA reduced neutrophil infiltrations in ankle joint synovium, a major mechanism contributing to oxidative stress in gout. Pharmacological blocking NLRP3 inflammasome or EA reduced TRPV1 channel overexpression in dorsal root ganglion (DRG) neurons. Ca2+ imaging confirmed that EA could reduce functional enhancement in TRPV1 channel in DRG neurons during gout. CONCLUSIONS: Our results demonstrate that EA reduces gout pain possibly through suppressing ROS-mediated NLRP3 inflammasome activation in inflamed ankle joints and TRPV1 upregulation in sensory neurons, supporting EA as a treatment option for gout pain.

Specificity for the correlation between the body surface and viscera in the pathological state of COPD: A prospective, controlled, and assessor-blinded trial.

Background: The association between the body surface and viscera remains obscure, but a better understanding of the body surface-viscera correlation will maximize its diagnostic and therapeutic values in clinical practice. Therefore, this study aimed to investigate the specificity of body surface-viscera correlation in the pathological state. Methods: The study subjects included 40 participants with chronic obstructive pulmonary disease (COPD) in the COPD group and 40 age-matched healthy participants in the healthy control group. Laser Doppler flowmetry, infrared thermography, and functional near-infrared spectroscopy were respectively adopted to measure 1) the perfusion unit (PU), 2) temperature, and 3) regional oxygen saturation (rSO2) of four specific sites distributed in the heart and lung meridians. These three outcome measures reflected the microcirculatory, thermal, and metabolic characteristics, respectively. Results: Regarding the microcirculatory and thermal characteristics of the body surface, the PU and temperature of specific sites on the body surface [i.e., Taiyuan (LU9) and Chize (LU5) in the lung meridian] in the COPD group were significantly increased compared with healthy controls (p < 0.05), whereas PU and temperature of other sites in the heart meridian [i.e., Shenmen (HT7) and Shaohai (HT3)] did not change significantly (p > 0.05). Regarding the metabolic characteristics, rSO2 of specific sites in the lung meridian [i.e., Taiyuan (LU9) and Chize (LU5)] and Shaohai (HT3) of the heart meridian in the COPD group was significantly decreased compared with healthy controls (p < 0.01), whereas rSO2 of Shenmen (HT7) in the heart meridian did not change significantly (p > 0.05). Conclusion: In the disease state of COPD, the microcirculatory, thermal, and metabolic characteristics of specific sites on the body surface in the lung meridian generally manifest more significant changes than those in the heart meridian, thereby supporting relative specificity for the body surface-viscera correlation in the pathological state.

Characterization of pain-related behaviors and gene expression profiling of peripheral sensory ganglia in a mouse model of acute ankle sprain.

Introduction: Lateral ankle sprain (LAS) is a very common type of joint injury. It occurred with high incidence among general population and especially among individuals participating sports and outdoor activities. A certain proportion of individuals who once developed LAS may suffer persistent ankle pain that affects daily activities. However, the mechanisms underlying LAS-induced pain still remained largely unknown. Methods: We established a LAS mouse model and systematically evaluated the pain-related behaviors in this mouse model. RNA sequencing (RNA-Seq), combined with bioinformatics analysis, was undertaken to explore gene expression profiles. Immunostaining was used to study glial cell and neuron activation in ipsilateral spinal cord dorsal horn (SCDH) of LAS model mice. Ibuprofen was used to treat LAS model mice. Results: The LAS model mice developed obvious signs of mechanical and heat hypersensitivities as well as gait impairments in ipsilateral hind paws. Besides, LAS model mice developed signs of pain-related emotional disorder, including pain-induced aversion. By RNA-Seq, we were able to identify certain differentially expressed genes and signaling pathways that might contribute to pain mechanisms of LAS mouse model. In addition, LAS model mice showed increased c-Fos and p-ERK immunoreactivity as well as astrocyte and microglia overactivation in ipsilateral spinal cord dorsal horn, indicating central sensitization might occur. Finally, LAS model mice respond to ibuprofen, a drug clinically used to treat ankle sprain pain. Conclusion: Our study found LAS model mice may be used as a preclinical animal model for screening novel targets or therapies for ankle sprain. Thus, the study may further help to understand molecular mechanisms contributing to ankle sprain-induced pain.