Spinal Serotonin 1A Receptor Contributes to the Analgesia of Acupoint Catgut Embedding by Inhibiting Phosphorylation of the N-Methyl-d-Aspartate Receptor GluN1 Subunit in Complete Freund's Adjuvant-Induced Inflammatory Pain in Rats

Natural product Kaji-ichigoside F1 exhibits rapid antidepression via activating the AMPA-BDNF-mTOR pathway and inhibiting the NMDAR-CaMKIIα pathway

BACKGROUND

Depression is a common and recurrent neuropsychiatric disorder. Recent studies have shown that the N-methyl-d-aspartate (NMDA) receptor (NMDAR) is involved in the pathophysiology of depression. Previous studies have found that Kaji-ichigoside F1 (KF1) has a protective effect against NMDA-induced neurotoxicity. However, the antidepressant mechanism of KF1 has not been confirmed yet.

PURPOSE

In the present study, we aimed to evaluate the rapid antidepressant activity of KF1 and explore the underlying mechanism.

STUDY DESIGN

First, we explored the effect of KF1 on NMDA-induced hippocampal neurons and the underlying mechanism. Second, depression was induced in C57BL/6 mice via chronic unpredictable mild stress (CUMS), and the immediate and persistent depression-like behavior was evaluated using the forced swimming test (FST) after a single administration of KF1. Third, the contributions of NMDA signaling to the antidepressant effect of KF1 were investigated using pharmacological interventions. Fourth, CUMS mice were treated with KF1 for 21 days, and then their depression-like behaviors and the underlying mechanism were further explored.

METHODS

The FST was used to evaluate immediate and persistent depression-like behavior after a single administration of KF1 with or without NMDA pretreatment. The effect of KF1 on depressive-like behavior was investigated in CUMS mice by treating them with KF1 once daily for 21 days through the sucrose preference test, FST, open field test, and tail suspension test. Then, the effects of KF1 on the morphology and molecular and functional phenotypes of primary neuronal cells and hippocampus of mice were investigated by hematoxylin-eosin staining, Nissl staining, propidium iodide staining, TUNEL staining, Ca2+ imaging, JC-1 staining, ELISA, immunofluorescence analysis, RT-PCR, and Western blot.

RESULTS

KF1 could effectively improve cellular viability, reduce apoptosis, inhibit the release of LDH and Ca2+, and increase the mitochondrial membrane potential and the number of dendritic spines numbers in hippocampal neurons. Moreover, behavioral tests showed that KF1 exerted acute and sustained antidepressant-like effects by reducing Glu-levels and ameliorating neuronal damage in the hippocampus. Additionally, in vivo and in vitro experiments revealed that PSD95, Syn1, α-amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and brain-derived neurotrophic factor (BDNF) were upregulated at the protein level, and BDNF and AMPA were upregulated at the mRNA level. NR1 and NR2A showed the opposite trend.

CONCLUSION

These results confirm that KF1 exerts rapid antidepressant effects mainly by activating the AMPA-BDNF-mTOR pathway and inhibiting the NMDAR-CaMKIIα pathway. This study serves as a new reference for discovering rapid antidepressants.

A study on the use of acupoint catgut embedding in the treatment of pre-diabetes: a meta-analysis and data mining approach

Objective

The efficacy of acupoint catgut embedding (ACE) for the treatment of pre-diabetes remains controversial. Therefore, this study investigated the clinical efficacy and acupoint selection in ACE for the treatment of pre-diabetes.

Methods

Eight common databases were searched for relevant literature on ACE for pre-diabetes. Meta-analysis was used to evaluate its efficacy and safety, and data mining was used to explore the protocol for acupoint selection.

Results

The meta-analysis revealed that compared with conventional treatment alone, conventional treatment combined with ACE reduced the levels of glycated hemoglobin A1c [mean difference (MD) -0.45, 95% confidence interval (CI) -0.67 to -0.24%, p < 0.001], fasting blood glucose (MD -0.61 mmol/L, 95% CI -0.87 to -0.36 mmol/L, p < 0.001), 2-h postprandial glucose (MD -0.77 mmol/L, 95% CI -0.98 to -0.55 mmol/L, p < 0.001), total cholesterol (MD -0.37 mmol/L, 95% CI -0.74 to 0.00 mmol/L, p = 0.049), triglyceride (MD -0.49 mmol/L, 95% CI -0.77 to -0.20 mmol/L, p < 0.001) and low-density lipoprotein cholesterol (MD -0.23 mmol/L, 95% CI -0.33 to -0.12 mmol/L, p < 0.001), and increased high-density lipoprotein cholesterol levels (MD 0.16 mmol/L, 95% CI 0.05 to 0.27 mmol/L, p = 0.004), whereas changes in the body mass index and the adverse event rates were comparable between groups. Data mining revealed that Pishu (BL20), Weiwanxiashu (EX-B3), Zusanli (ST36), Shenshu (BL23), Sanyinjiao (SP6), Weishu (BL21), and Taixi (KI3) were the core acupoints used in ACE for pre-diabetes.

Conclusion

ACE can effectively improve blood glucose and lipid levels in pre-diabetes patients and has a good safety profile. ACE consisting of Pishu (BL20), Weiwanxiashu (EX-B3), Zusanli (ST36), Shenshu (BL23), Sanyinjiao (SP6), Weishu (BL21), and Taixi (KI3), is a promising complementary strategy for the treatment of pre-diabetes.

Acupoint catgut embedding for chronic non-specific low back pain: A protocol of randomized controlled trial

Chronic non-specific low back pain (CNLBP) is one of the leading causes of disability worldwide. Acupoint embedding (ACE) is widely used in China for the treatment of chronic non-specific low back pain, but there are no rigorous randomized controlled trials (RCTs) to confirm the effectiveness and safety of ACE for chronic non-specific low back pain. In this study, we design a single-center, single-blind, prospective RCT, with the aim of evaluating the efficacy and safety of ACE for CNLBP. 82 participants with CNLBP will be randomized in a 1:1 ratio into an ACE group and a sham ACE group. Participants will receive either ACE treatment or sham ACE treatment at once every 2 weeks, for an 8-week period, and followed by 6 months of follow-up. The primary outcome will be the change in visual analog scale (VAS) scores before and after treatment. Secondary outcomes will include the Oswestry Disability Index (ODI), the Roland Morris Disability Questionnaire (RMDQ) and the Short Form 36-Health Survey (SF-36). Adverse events that occur during the course of the trial will be recorded. Data will be analyzed according to a predefined statistical analysis plan. This study was approved by the medical ethics committee of Guangzhou Panyu Hospital of Chinese Medicine (202230). Written informed consent from patients is required. This trial is registered in the Chinese Clinical Trial Registry (ChiCTR2200059245). Trial results will be published in a peer-reviewed academic journal.

Clinical trial registration

https://www.chictr.org.cn, identifier ChiCTR2200059245.

Electroacupuncture alleviates orofacial allodynia and anxiety-like behaviors by regulating synaptic plasticity of the CA1 hippocampal region in a mouse model of trigeminal neuralgia

Objective

Trigeminal neuralgia (TN), one of the most severe and debilitating chronic pain conditions, is often accompanied by mood disorders, such as anxiety and depression. Electroacupuncture (EA) is a characteristic therapy of Traditional Chinese Medicine with analgesic and anxiolytic effects. This study aimed to investigate whether EA ameliorates abnormal TN orofacial pain and anxiety-like behavior by altering synaptic plasticity in the hippocampus CA1.

Materials and methods

A mouse infraorbital nerve transection model (pT-ION) of neuropathic pain was established, and EA or sham EA was used to treat ipsilateral acupuncture points (GV20-Baihui and ST7-Xiaguan). Golgi-Cox staining and transmission electron microscopy (TEM) were administrated to observe the changes of synaptic plasticity in the hippocampus CA1.

Results

Stable and persistent orofacial allodynia and anxiety-like behaviors induced by pT-ION were related to changes in hippocampal synaptic plasticity. Golgi stainings showed a decrease in the density of dendritic spines, especially mushroom-type dendritic spines, in hippocampal CA1 neurons of pT-ION mice. TEM results showed that the density of synapses, membrane thickness of the postsynaptic density, and length of the synaptic active zone were decreased, whereas the width of the synaptic cleft was increased in pT-ION mice. EA attenuated pT-ION-induced orofacial allodynia and anxiety-like behaviors and effectively reversed the abnormal changes in dendritic spines and synapse of the hippocampal CA1 region.

Conclusion

EA modulates synaptic plasticity of hippocampal CA1 neurons, thereby reducing abnormal orofacial pain and anxiety-like behavior. This provides evidence for a TN treatment strategy.

Role of Neuroimmune Crosstalk in Mediating the Anti-inflammatory and Analgesic Effects of Acupuncture on Inflammatory Pain

Inflammatory pain is caused by peripheral tissue injury and inflammation. Inflammation leads to peripheral sensitization, which may further cause central sensitization, resulting in chronic pain and progressive functional disability. Neuroimmune crosstalk plays an essential role in the development and maintenance of inflammatory pain. Studies in recent years have shown that acupuncture can exert anti-inflammatory and analgesic effects by regulating peripheral (i.e., involving local acupoints and inflamed regions) and central neuroimmune interactions. At the local acupoints, acupuncture can activate the TRPV1 and TRPV2 channels of mast cells, thereby promoting degranulation and the release of histamine, adenosine, and other immune mediators, which interact with receptors on nerve endings and initiate neuroimmune regulation. At sites of inflammation, acupuncture enables the recruitment of immune cells, causing the release of opioid peptides, while also exerting direct analgesic effects via nerve endings. Furthermore, acupuncture promotes the balance of immune cells and regulates the release of inflammatory factors, thereby reducing the stimulation of nociceptive receptors in peripheral organs. Acupuncture also alleviates peripheral neurogenic inflammation by inhibiting the release of substance P (SP) and calcitonin gene-related peptide from the dorsal root ganglia. At the central nervous system level, acupuncture inhibits the crosstalk between glial cells and neurons by inhibiting the p38 MAPK, ERK, and JNK signaling pathways and regulating the release of inflammatory mediators. It also reduces the excitability of the pain pathway by reducing the release of excitatory neurotransmitters and promoting the release of inhibitory neurotransmitters from neurons and glial cells. In conclusion, the regulation of neuroimmune crosstalk at the peripheral and central levels mediates the anti-inflammatory and analgesic effects of acupuncture on inflammatory pain in an integrated manner. These findings provide novel insights enabling the clinical application of acupuncture in the treatment of inflammatory diseases.

Thread Embedded Acupuncture for Non-Specific Posterior Neck Pain: A PRISMA-Compliant Protocol for Systematic Review and Meta-Analysis

Purpose

The prevalence of non-specific posterior neck pain (NPNP) has been increasing yearly. There are several treatments for NPNP, but in this review, we will focus on thread-embedded acupuncture (TEA). TEA is used in the Republic of Korea, Taiwan, and China for managing musculoskeletal diseases, obesity, and sequelae of facial palsy. However, there is insufficient evidence on its effectiveness and safety. This study aims to assess the efficacy and safety of TEA for NPNP.

Methods

We will search the following nine electronic databases, from their inception to May 2020: MEDLINE, Embase, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, Citation Information by the National Information infrastructure, Korean Studies Information Service System, National Digital Science Library, Oriental Medicine Advanced Searching Integrated System, and Research Information Service System. Only randomized controlled trials of TEA for NPNP will be included. The methodological quality of the included trials will be assessed using the Cochrane risk-of bias tool. To conduct the meta-analysis, the risk ratio and mean difference with the 95% confidence interval will be used. Sensitivity analyses will be conducted based on this protocol.

Results

The results of this study will be submitted to a peer-reviewed journal for publication.

Conclusion

The results of this study would provide the evidence of whether TEA can be effective for treating NPNP.

Registration Number

PROSPERO CRD42020188346.

Determining 5HT7R's Involvement in Modifying the Antihyperalgesic Effects of Electroacupuncture on Rats With Recurrent Migraine

Electroacupuncture (EA) is widely used in clinical practice to relieve migraine pain. 5-HT₇ receptor (5-HT₇R) has been reported to play an excitatory role in neuronal systems and regulate hyperalgesic pain and neurogenic inflammation. 5-HT₇R could influence phosphorylation of protein kinase A (PKA)- or extracellular signal-regulated kinase_{1 / 2} (ERK_{1 / 2})-mediated signaling pathways, which mediate sensitization of nociceptive neurons via interacting with cyclic adenosine monophosphate (cAMP). In this study, we evaluated the role of 5-HT₇R in the antihyperalgesic effects of EA and the underlying mechanism through regulation of PKA and ERK_{1 / 2} in trigeminal ganglion (TG) and trigeminal nucleus caudalis (TNC). Hyperalgesia was induced in rats with dural injection of inflammatory soup (IS) to cause meningeal neurogenic inflammatory pain. Electroacupuncture was applied for 15 min every other day before IS injection. Von Frey filaments, tail-flick, hot-plate, and cold-plated tests were used to evaluate the mechanical and thermal hyperalgesia. Neuronal hyperexcitability in TNC was studied by an electrophysiological technique. The 5-HT₇R antagonist (SB269970) or 5-HT₇R agonist (AS19) was administered intrathecally before each IS application at 2-day intervals during the 7-day injection protocol. The changes in 5-HT₇R and 5-HT₇R-associated signaling pathway were examined by real-time polymerase chain reaction (RT-PCR), Western blot, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) analyses. When compared with IS group, mechanical and thermal pain thresholds of the IS + EA group were significantly increased. Furthermore, EA prevented the enhancement of both spontaneous activity and evoked responses of second-order trigeminovascular neurons in TNC. Remarkable decreases in 5-HT₇R mRNA expression and protein levels were detected in the IS + EA group. More importantly, 5-HT₇R agonist AS19 impaired the antihyperalgesic effects of EA on p-PKA and p-ERK_{1 / 2}. Injecting 5-HT₇R antagonist SB-269970 into the intrathecal space of IS rats mimicked the effects of EA antihyperalgesia and inhibited p-PKA and p-ERK_{1 / 2}. Our findings indicate that 5-HT₇R mediates the antihyperalgesic effects of EA on IS-induced migraine pain by regulating PKA and ERK_{1 / 2} in TG and TNC.

Leite L, da S. Tavares-Henriques M, Lopes LAF, Oliveira LGR, Silva-Filho SE, da Silveira APS, Cuman RKN, de S. Silva-Comar FM, Comar JF, do A. Brasileiro L, dos Santos JN, de Freitas WR, Leão KV, da Silva JG, Klein RC, Klein MHF, da S. Ramos BH, Fernandes CKC, de L. Ribas DG, Oesterreich SA. Modulation of the Serotonergic Receptosome in the Treatment of Anxiety and Depression: A Narrative Review of the Experimental Evidence

Serotonin (5-HT) receptors are found throughout central and peripheral nervous systems, mainly in brain regions involved in the neurobiology of anxiety and depression. 5-HT receptors are currently promising targets for discovering new drugs for treating disorders ranging from migraine to neuropsychiatric upsets, such as anxiety and depression. It is well described in the current literature that the brain expresses seven types of 5-HT receptors comprising eighteen distinct subtypes. In this article, we comprehensively reviewed 5-HT1-7 receptors. Of the eighteen 5-HT receptors known today, thirteen are G protein-coupled receptors (GPCRs) and represent targets for approximately 40% of drugs used in humans. Signaling pathways related to these receptors play a crucial role in neurodevelopment and can be modulated to develop effective therapies to treat anxiety and depression. This review presents the experimental evidence of the modulation of the “serotonergic receptosome” in the treatment of anxiety and depression, as well as demonstrating state-of-the-art research related to phytochemicals and these disorders. In addition, detailed aspects of the pharmacological mechanism of action of all currently known 5-HT receptor families were reviewed. From this review, it will be possible to direct the rational design of drugs towards new therapies that involve signaling via 5-HT receptors.

Effect of acupoint catgut embedding in chronic fatigue syndrome patients: A protocol for systematic review and meta-analysis

BACKGROUND

Chronic fatigue syndrome (CFS) is a relatively complex and disabling illness with a substantial economic burden and functional impairment. Until now, many CFS patients lack appropriate healthcare. Acupoint catgut embedding is an effective and emerging alternative therapy for CFE. With this research, we endeavor to investigate the effect and safety of ACE for CFS.

METHODS

Eight databases will be searched from inception to December 2020: PubMed, EMBASE, The Cochrane Library, Web of Science, China National Knowledge Infrastructure, Chinese Biomedical Literature Database, Chong-Qing VIP database, and Wan-fang database. We regard studies as eligible for inclusion if they were RCTs done in CFS patients, compare acupoint catgut embedding to another treatment strategy, and report fatigue changes at the end of the intervention period. Two independent reviewers complete the study selection, data extraction, and the risk of bias assessment. We assess pooled data using a random-effects model through Revman software (v.5.3) and Stata (version 15.0).

ETHICS AND DISSEMINATION

Ethics approval is not required because the individual patient data will not be involved, with no privacy concerns. This systematic review and meta-analysis will provide a reference for CFS patients and clinicians on the non-drug interventions. We will publish and disseminate the results of this review in a peer-reviewed journal or relevant conference.

OSF REGISTRATION NUMBER

10.17605/OSF.IO/7SHD9 (https://osf.io/7shd9).

Acupoint Catgut Embedding for Insomnia: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

A Meta-analysis was carried out to evaluate the efficacy and safety of acupoint catgut embedding (ACE), a procedure of embedding sutures made of absorbable materials into the skin tissue of acupoints, on insomnia.

METHODS

Relevant clinical randomized controlled trials (RCTs) were comprehensively searched from eleven electronic databases (up to 1 March 2020). Two authors independently screened literature, extracted data, and assessed the risk of bias of included studies. Stata 12 and RevMan 5.3.0 software were used for meta-analysis. PyCharm 2019 and Gephi software (version 0.9.2) were used for complex network analysis.

RESULTS

Thirty-four RCTs involving 2,655 patients were included. The meta-analysis suggested that ACE induced a better clinical efficacy compared with that in the estazolam tablets (EZ) group (RR = 1.22, 95% CI: 1.13, 1.31) or in the acupuncture (ACU) group (RR = 1.21, 95% CI: 1.14, 1.28) and could significantly reduce the score of Pittsburgh Sleep Quality Index (P < 0.05). ACE resulted in better long-term efficacy compared to that in the EZ group (RR = 1.87, 95% CI: 1.58, 2.22) and ACU group (RR = 1.30, 95% CI: 1.14, 1.48). ACE could significantly reduce the incidence of adverse events (RR = 0.30, 95% CI: 0.15, 0.60) compared with that in the EZ group. Complex network analysis indicated that acupoints of BL23, SP6, PC6, BL15, BL20, BL18, and HT7 were the core acupoints selected in ACE for insomnia.

CONCLUSION

The clinical efficacy of ACE for insomnia is better than that of other interventions (EZ and ACU) in both short-term and long-term observations. Considering the efficacy and reduced visits to the clinic by ACE, the present study provides a practical and convenient complementary and alternative therapy for insomnia. This trial is registered with PROSPERO CRD 42020169866.

Prolonged Use of NMDAR Antagonist Develops Analgesic Tolerance in Neuropathic Pain via Nitric Oxide Reduction-Induced GABAergic Disinhibition

Neuropathic pain is usually persistent due to maladaptive neuroplasticity-induced central sensitization and, therefore, necessitates long-term treatment. N-methyl-D-aspartate receptor (NMDAR)-mediated hypersensitivity in the spinal dorsal horn represents key mechanisms of central sensitization. Short-term use of NMDAR antagonists produces antinociceptive efficacy in animal pain models and in clinical practice by reducing central sensitization. However, how prolonged use of NMDAR antagonists affects central sensitization remains unknown. Surprisingly, we find that prolonged blockage of NMDARs does not prevent but aggravate nerve injury-induced central sensitization and produce analgesic tolerance, mainly due to reduced synaptic inhibition. The disinhibition that results from the continuous decrease in the production of nitric oxide from neuronal nitric oxide synthase, downstream signal of NMDARs, leads to the reduction of GABAergic inhibitory synaptic transmission by upregulating brain-derived neurotrophic factor expression and inhibiting the expression and function of potassium-chloride cotransporter. Together, our findings suggest that chronic blockage of NMDARs develops analgesic tolerance through the neuronal nitric oxide synthase-brain-derived neurotrophic factor-potassium-chloride cotransporter pathway. Thus, preventing the GABAergic disinhibition induced by nitric oxide reduction may be necessary for the long-term maintenance of the analgesic effect of NMDAR antagonists.

Acupuncture for Pain Management: Molecular Mechanisms of Action

Acupuncture reduces pain by activating specific areas called acupoints on the patient’s body. When these acupoints are fully activated, sensations of soreness, numbness, fullness, or heaviness called De qi or Te qi are felt by clinicians and patients. There are two kinds of acupuncture, manual acupuncture and electroacupuncture (EA). Compared with non-acupoints, acupoints are easily activated on the basis of their special composition of blood vessels, mast cells, and nerve fibers that mediate the acupuncture signals. In the spinal cord, EA can inhibit glial cell activation by down-regulating the chemokine CX3CL1 and increasing the anti-inflammatory cytokine interleukin-10. This inhibits P38 mitogen-activated protein kinase and extracellular signal-regulated kinase pathways, which are associated with microglial activation of the C-Jun N-terminal kinase signaling pathway and subsequent astrocyte activation. The inactivation of spinal microglia and astrocytes mediates the immediate and long-term analgesic effects of EA, respectively. A variety of pain-related substances released by glial cells such as the proinflammatory cytokines tumor necrosis factor [Formula: see text], interleukin-1[Formula: see text], interleukin-6, and prostaglandins such as prostaglandins E2 can also be reduced. The descending pain modulation system in the brain, including the anterior cingulated cortex, the periaqueductal gray, and the rostral ventromedial medulla, plays an important role in EA analgesia. Multiple transmitters and modulators, including endogenous opioids, cholecystokinin octapeptide, 5-hydroxytryptamine, glutamate, noradrenalin, dopamine, [Formula: see text]-aminobutyric acid, acetylcholine, and orexin A, are involved in acupuncture analgesia. Finally, the “Acupuncture [Formula: see text]” strategy is introduced to help clinicians achieve better analgesic effects, and a newly reported acupuncture method called acupoint catgut embedding, which injects sutures made of absorbable materials at acupoints to achieve long-term effects, is discussed.