Acupuncture Analgesia Research Articles

Recent advances in acupuncture for pain relief.

Acupuncture therapy has achieved global expansion and shown promise for health promotion and treatment of acute/chronic pain. To present an update on the existing evidence base for research and clinical practice supporting acupuncture analgesia. This Clinical Update elaborates on the 2023 International Association for the Study of Pain Global Year for Integrative Pain Care "Factsheet Acupuncture for Pain Relief" and reviews best evidence and practice. Acupuncture is supported by a large research evidence base and growing utilization. Mechanisms of acupuncture analgesia include local physiological response at the needling site, suppression of nociceptive signaling at spinal and supraspinal levels, and peripheral/central release of endogenous opioids and other biochemical mediators. Acupuncture also produces pain relief by modulating specific brain networks, integral for sensory, affective, and cognitive processing, as demonstrated by neuroimaging research. Importantly, acupuncture does not just manage pain symptoms but may target the sources that drive pain, such as inflammation, partially by modulating autonomic pathways. Contextual factors are important for acupuncture analgesia, which is a complex multifaceted intervention. In clinical practice, historical records and many providers believe that acupuncture efficacy depends on specific acupoints used, the technique of needle placement and stimulation, and the person who delivers the procedure. Clinical research has supported the safety and effectiveness of acupuncture for various pain disorders, including acupuncture as a complementary/integrative therapy with other pain interventions. Although the quality of supportive evidence is heterogeneous, acupuncture's potential cost-effectiveness and low risk profile under standardized techniques suggest consideration as a neuromodulatory and practical nonpharmacological pain therapy.

Astrocytic P2X7 receptor in retrosplenial cortex drives electroacupuncture analgesia.

P2X7 receptor (P2X7R) has been found to contribute to the peripheral mechanism of acupuncture analgesia (AA). However, whether it plays an important role in central mechanism remains unknown. In this study, we aimed to reveal the role of astrocytic P2X7R in retrosplenial cortex (RSC) in AA and provide new evidence for underlying the central mechanism of AA. We applied the chemogenetic receptors hM3Dq to stimulate or hM4Di to inhibit astrocytes ligand clozapine-N-oxide (CNO) following injection of adeno-associated virus (AAV) into the bilateral RSC, or pharmacologically intervened in the activity of the purinergic receptor P2X7R. Current data indicated that chemogenetic inhibition of astrocytes or injection of P2X7R agonist Bz-ATP in the bilateral RSC significantly reverses the analgesic effect of electroacupuncture (EA) in formalin tests while the bilateral injection of the P2X7R antagonist A438079 alleviated formalin-induced nociceptive behavior. Additionally, chemogenetic suppression of astrocytic P2X7R by injection of AAV in the bilateral RSC decreased hind paw flinches induced by formalin in the mice. These findings indicate the participation of both astrocytes and P2X7R in the RSC in EA analgesic. Moreover, P2X7R on astrocytes in the RSC appears to play a critical role in the ability of EA to attenuate formalin-induced pain responses in mice.

Keratinocyte Piezo1 and CD39 initiated the acupuncture analgesic signals via Co-regulating extracellular ATP mobilization at acupoints

Acupoints are the initiation sites for acupuncture analgesic signals, where adenosine signaling plays a crucial role. A comprehensive understanding of this matter will guide clinicians to optimize acupuncture manipulations to improve acupuncture effectiveness. Recently, keratinocyte Piezo1 channels and cascade ATP release are independently unveiled to be essential for the skin tactile sensation. Thus, we aimed to investigate whether keratinocyte Piezo1-mediated ATP release, in orchestration with CD39, contributed to this initiation mechanism via producing adenosine. 20-min needling was administered at the unilateral ST36 acupoint on the acute ankle arthritis rats. The pain thresholds in the affected hindpaws were determined. Interstitial ATP and adenosine were extracted with microdialysis and assessed by luciferase-luciferin and HPLC, respectively. To simulate needling stimulation, keratinocyte HaCaT cells were subjected to hypotonic shock. ATP release and live calcium imaging were conducted. Immunofluorescence labeling showed the presence of Piezo1 and CD39 on keratinocytes. Acupuncture led to a prompt analgesic effect, as well as a temporary accumulation of ATP and adenosine. Activating adenosine A1 receptors, promoting ATP release by activating Piezo1, or facilitating ATP hydrolysis by potentiating CD39 achieved anti-nociceptive effects. Conversely, altering these modulations in the opposite direction reversed the subsequent effects of acupuncture. Needling-induced accumulation of interstitial ATP parallelly changed with these modulations. Hypotonic shock led to ATP release and [Ca2+]i rise in HaCaT, which were impeded by introducing siRNA-Piezo1, or replicated by agonism at Piezo1. These findings suggest that keratinocyte Piezo1 and CD39 co-mediated ATP mobilization at acupoints contributes to the initiation signals of acupuncture analgesia via triggering adenosine signaling. SectionPhysical/Mental practices (acupuncture) Taxonomy (classification by evise)pain and analgesia.

Peripheral Rho-associated protein kinase activation mediates acupuncture analgesia

BackgroundAcupuncture has been proven effective for various types of pain, and peripheral molecular signals around acupuncture-treated areas have been suggested to contribute to the analgesic effects of acupuncture. However, the underlying mechanism from these peripheral molecular signals to central ones remains unclear. The purpose of this study was to investigate whether peripheral Rho-associated protein kinase (ROCK) activation induced by acupuncture treatment mediates acupuncture analgesia, and also to investigate the relationship between ROCK activation and extracellular signal-regulated kinase (ERK), which has previously been proven to mediate acupuncture analgesia and other related molecular changes during acupuncture. MethodsAcupuncture was treated at the bilateral GB34 acupoints of C57BL/6 mice, after which changes in ROCK activation and the location of its expression in the skin were analyzed. To verify the role of ROCK in acupuncture analgesia, we administrated ROCK inhibitor Y-27632 (0.3 μg/ul) into the skin before acupuncture treatment with formalin and complete Freund adjuvant (CFA) induced pain models, then the nociceptive responses were analyzed. ResultsAcupuncture treatment produced ROCK2 activation in the skin after 30 and 60 min, and the histological analyses revealed that ROCK2 was activated in the fibroblast of the dermis. The acupuncture-induced ROCK2 expression was significantly attenuated by the ERK inhibitor, whereas phospho-ERK expression was not inhibited by ROCK inhibitor. In both the formalin- and CFA-induced mouse pain models, acupuncture analgesia was blocked by ROCK inhibitor administration. ConclusionAcupuncture treatment-induced ROCK2 expression is a downstream effector of phospho-ERK in the skin and plays a crucial role in acupuncture analgesia.

Effect of electroacupuncture at "Neiguan" (PC6) on pain and brain orexin 1 receptor in mice with inflammatory pain.

To observe the effect of electroacupuncture (EA) at "Neiguan" (PC6) on pain response in mice injected with complete Freund's adjuvant (CFA) in the hind paw, so as to investigate the mechanism of orexin 1 receptor (OX1R) -endogenous cannabinoid 1 receptor (CB1R) pathway in acupuncture analgesia. A total of 48 male C57BL/6 mice were used in the present study. In the first part of this study, 18 mice were randomized into control, model and EA groups, with 6 mice in each group. In the second part of this study, 30 mice were randomized into control, model, EA, EA+Naloxone, EA+OX1R antagonist (SB33486) groups, with 6 mice in each group. Inflammatory pain model was established by subcutaneous injection of 20 μL CFA solution in the left hind paw. EA (2 Hz, 2 mA ) was applied to bilateral PC6 for 20 min, once a day for 5 consecutive days. The mice in the EA+Naloxone and EA+SB33486 groups were intraperitoneally injected with naloxone (10 mg/kg) or SB33486 (15 mg/kg) 15 min before EA intervention on day 5, respectively. Tail-flick method and Von Frey method were used to detect the thermal pain threshold and mechanical pain threshold of mice. Quantitative real-time PCR was used to detect the expression level of β-endorphin mRNA in periaqueductal gray (PAG) of mice. The expression of OX1R positive cells in the lateral hypothalamic area (LH) and CB1R positive cells in the ventrolateral periaqueductal gray (vlPAG) were detected by immunofluorescence. Compared with the control group, the thermal pain threshold and mechanical pain threshold of the model group were decreased (P<0.001), the expression level of β-endorphin mRNA in PAG was decreased (P<0.001), and the numbers of OX1R positive cells in LH and CB1R positive cells in vlPAG were decreased (P<0.05, P<0.001). Compared with the model group, the thermal pain threshold and mechanical pain threshold of the EA group were significantly increased (P<0.001), and the numbers of OX1R positive cells in LH and CB1R positive cells in vlPAG were increased (P<0.01, P<0.001). Compared with the EA group, the mechanical pain threshold in the EA+SB33486 group was significantly decreased (P<0.01), but there was no significant difference in the mechanical pain threshold between the EA+Naloxone group and EA group, and the numbers of OX1R positive neurons in LH and CB1R positive neurons in vlPAG were decreased in the EA+SB33486 group (P<0.001). EA at PC6 can achieve analgesic effect on CFA mice by activating the OX1R-CB1R pathway in the brain, and this effect is opioid-independent.

Effect of "needle sensation" and the real-time changes in autonomic nervous system activity during acupuncture analgesia.

Acupuncture analgesia (AA) is widely used in clinical practice. The autonomic nervous system (ANS) may be an important pathway for acupuncture signal transduction. However, real-time changes in autonomic function during AA and the effect of "needle sensation" remain unclear. We established a human pain model in healthy adults and randomly assigned 128 participants to the model, sham acupuncture, and acupuncture groups in a 1:1:2 ratio. Heart rate variability (HRV), including total power (TP), low-frequency power (LF), high-frequency power (HF), ratio of LF to HF (LF/HF), standard deviation of the normal-normal intervals (SDNN), and root mean square of successive interval differences (RMSSD), were used to assess autonomic function. The visual analog scale (VAS) and efficiency were used to assess the analgesic effect of acupuncture. The Massachusetts General Hospital acupuncture sensation scale (MASS) was used to indicate the intensity of the needle sensation. Anxiety levels were also measured. Finally, the correlation of MASS with HRV, VAS, and anxiety levels was analyzed. VAS decreased after 10 min of needling and 5 min after needle withdrawal in the acupuncture group compared with those in the model group (p = 0.038, p = 0.020). The efficacy rates were 82.0, 50.0, and 61.3% in the acupuncture, model, and sham groups, respectively. These represent significant differences between the acupuncture group and the model and sham acupuncture groups (p < 0.001 in each case). No differences were observed between the model and sham acupuncture groups. HF, TP, SDNN, and RMSSD were all increased in the acupuncture group compared with those in the model group (p = 0.045, p = 0.041, p = 0.002, p = 0.006, respectively). No differences were observed in the sham acupuncture group compared to the model group (p = 0.632, p = 0.542, p = 0.093, p = 0.222, respectively). The LF and LF/HF did not differ among all three groups. A positive correlation was observed between MASS and RMSSD2, LF2, RMSSD4, TP4, VAS5, and anxiety levels. AA was associated with enhanced vagal activity. The intensity of needle sensation was positively correlated with vagal and sympathetic nerve activities. Acupuncture is an effective means of regulating autonomic function, and needle sensation may be an important modulator.

TRPA1 Ion Channel Mediates the Analgesic Effects of Acupuncture at the ST36 Acupoint in Mice Suffering from Arthritis.

Acupuncture (ACU) has been demonstrated to alleviate inflammatory pain. Mechanoreceptors are present in acupuncture points. When acupuncture exerts mechanical force, these ion channels open and convert the mechanical signals into biochemical signals. TRPA1 (T ransient receptor potential ankyrin 1) is capable of sensing various physical and chemical stimuli and serves as a sensor for inflammation and pain. This protein is expressed in immune cells and contributes to local defense mechanisms during early tissue damage and inflammation. In this study, we investigated the role of TRPA1 in acupuncture analgesia. We injected complete Freund's adjuvant (CFA) into the mouse plantars to establish a hyperalgesia model. Immunohistochemistry and immunofluorescence analyses were performed to determine the effect of acupuncture on the TRPA1 expression in the Zusanli (ST36). We used TRPA1-/- mouse and pharmacological methods to antagonize TRPA1 to observe the effect on acupuncture analgesia. On this basis, collagenase was used to destroy collagen fibers at ST36 to observe the effect on TRPA1. We found that the ACU group vs the CFA group, the number of TRPA1-positive mast cells, macrophages, and fibroblasts at the ST36 increased significantly. In CFA- inflammatory pain models, the TRPA1-/- ACU vs TRPA1+/+ ACU groups, the paw withdrawal latency (PWL) and paw withdrawal threshold (PWT) downregulated significantly. In the ACU + high-, ACU + medium-, ACU + low-dose HC-030031 vs ACU groups, the PWL and PWT were downregulated, and in carrageenan-induced inflammatory pain models were consistent with these results. We further found the ACU + collagenase vs ACU groups, the numbers of TRPA1-positive mast cells, macrophages, and fibroblasts at the ST36 were downregulated. These findings together imply that TRPA1 plays a significant role in the analgesic effects produced via acupuncture at the ST36. This provides new evidence for acupuncture treatment of painful diseases.

In Vivo Calcium Imaging of Dorsal Root Ganglia Neurons' Response to Somatic and Visceral Stimuli.

A technique is described for surgically exposing the dorsal root ganglion (DRG) of the lumbar-6 in a live, anesthetized laboratory mouse, along with the protocol for in vivo calcium imaging of the exposed DRG in response to various visceral and somatic stimuli. Pirt-GCaMP6s mice or C57BL6 mice intrathecally injected with AAV viruses packaged with GCaMP6s were utilized to capture Ca2+ transients. The amplitude of these transients indicates sensitivity to specific sensory modalities. Afferent fibers originate from internal organs, with primary neuronal cell bodies in spinal or vagal ganglia. Studies on visceral nociception and acupuncture analgesia can potentially be conducted on primary sensory neurons using advanced imaging technologies like in vivo calcium imaging, allowing for the recording of neuronal activity ensembles in the intact animal during stimulation or intervention. The responses of DRG neuron ensembles to somatic and visceral stimuli applied to their corresponding receptive fields were recorded. This technique illustrates how neuronal populations react to various types of somatic and visceral stimuli. It is possible to comprehensively compare neuronal ensemble responses to different stimuli, which is a particularly valuable approach in research on visceral pain and segmental mechanisms of somatic stimulation, such as acupuncture.

NTPDase1-ATP-P2Y2Rs axis in the sciatic nerve contributes to acupuncture at “Zusanli” (ST36)-induced analgesia in ankle arthritis rats

BackgroundThe efficacy of acupuncture at Zusanli (ST36) in alleviating lower-limb pain is widely acknowledged in clinical practice, while its underlying mechanism remains incompletely elucidated. Our previous research had revealed that the prompt analgesia induced by needling-ST36 was accompanied by expression alterations in certain exco-nucleotidases within the sciatic nerve. Building upon this finding, the current work focused on NTPDase1, the primary ecto-nucleotidase in the human body, which converts ATP into AMP. MethodsA 20-min acupuncture was administered unilaterally at the ST36 on rats with acute ankle arthritis. The pain thresholds of the injured hind paws were determined. Pharmacological interference was carried out by introducing the corresponding reagents to the sciatic nerve. ATP levels around the excised nerve were measured using a luciferase-luciferin assay. Live calcium imaging, utilizing the Fura 2-related-F340/F380 ratio, was conducted on Schwann cells in excised nerves and cultured rat SCs line, RSC96 cells. ResultsThe analgesic effect induced by needling-ST36 was impaired when preventing ATP degradation via inhibiting NTPDase1 activities with ARL67156 or Ticlopidine. Conversely, increasing NTPDase1 activities with Apyrase duplicated the acupuncture effect. Similarly, preventing the conversion of AMP to adenosine via suppression of NT5E with AMP-CP hindered the acupuncture effect. Unexpectedly, impeded ATP hydrolysis ability and diminished NTPDase1 expression were observed in the treated group. Agonism at P2Y2Rs with ATP, UTP, or INS365 resulted in anti-nociception. Contrarily, antagonism at P2Y2Rs with Suramin or AR-C 118925xx prevented acupuncture analgesia. Immunofluorescent labeling demonstrated that the treated rats expressed more P2Y2Rs that were predominant in Schwann cells. Suppression of Schwann cells by inhibiting ErbB receptors also prevented acupuncture analgesia. Finally, living imaging on the excised nerves or RSC96 cells showed that agonism at P2Y2Rs indeed led to [Ca2+]i rise. ConclusionThese findings strongly suggest that the analgesic mechanism of needling-ST36 on the hypersensation in the lower limb partially relies on NTPDase1 activities in the sciatic nerve. In addition to facilitating adenosine signaling in conjunction with NT5E, most importantly, NTPDase1 may provide an appropriate low-level ATP milieu for the activation of P2Y2R in the sciatic nerve, particularly in Schwann cells.

Effects and mechanisms of acupuncture analgesia mediated by afferent nerves in acupoint microenvironments.

In the past few decades, the use of acupuncture analgesia in clinical practice has increased worldwide. This is due to its various benefits, including natural alleviation of pain without causing various adverse effects associated with non-steroidal anti-inflammatory drugs (NSAID) and opioids. The acupoint represents the initial site of acupuncture stimulation, where diverse types of nerve fibers located at the acupoint hold significant roles in the generation and transmission of acupuncture-related information. In this study, we analyzed the patterns and mechanisms of acupuncture analgesic mediated by acupoint afferent fibers, and found that acupuncture stimulates acupoints which rapidly and directly induces activation of high-density primary afferent fibers under the acupoints, including myelinated A fibers and unmyelinated C fibers. During acupuncture stimulation at the muscle layer, the analgesic effects can be induced by stimulation of A fiber threshold intensity. At the skin layer, the analgesic effects can only be produced by stimulation of C fiber threshold intensity. Electroacupuncture (EA) activates A fibers, while manual acupuncture (MA) activates both A and C fibers. Furthermore, acupuncture alters acupoint microenvironments, which positively modulates afferent fibers, enhancing the transmission of analgesic signals. In addition to local activation and conduction at acupoints, nerve fibers mediate the transmission of acupuncture information to pain centers. In the spinal cord, acupuncture activates neurons by inducing afferent fiber depolarization, modulating pain gating, inhibiting long-term potentiation (LTP) of the spinal dorsal horn and wide dynamic range (WDR) neuronal activities. At higher nerve centers, acupuncture inhibits neuronal activation in pain-related brain regions. In summary, acupuncture inhibits pain signal transmission at peripheral and central systems by activating different patterns of afferent fibers located on various layers of acupoints. This study provides ideas for enhancing the precise application and clinical translation of acupuncture.

The role of purinergic signaling in acupuncture-mediated relief of neuropathic and inflammatory pain.

Acupuncture is a traditional medicinal practice in China that has been increasingly recognized in other countries in recent decades. Notably, several reports have demonstrated that acupuncture can effectively aid in pain management. However, the analgesic mechanisms through which acupuncture provides such benefits remain poorly understood. Purinergic signaling, which is mediated by purine nucleotides and purinergic receptors, has been proposed to play a central role in acupuncture analgesia. On the one hand, acupuncture affects the transmission of nociception by increasing adenosine triphosphate dephosphorylation and thereby decreasing downstream P2X3, P2X4, and P2X7 receptors signaling activity, regulating the levels of inflammatory factors, neurotrophic factors, and synapsin I. On the other hand, acupuncture exerts analgesic effects by promoting the production of adenosine, enhancing the expression of downstream adenosine A1 and A2A receptors, and regulating downstream inflammatory factors or synaptic plasticity. Together, this systematic overview of the field provides a sound, evidence-based foundation for future research focused on the application of acupuncture as a means of relieving pain.

Understanding of Spinal Wide Dynamic Range Neurons and Their Modulation on Pathological Pain.

The spinal dorsal horn (SDH) transmits sensory information from the periphery to the brain. Wide dynamic range (WDR) neurons within this relay site play a critical role in modulating and integrating peripheral sensory inputs, as well as the process of central sensitization during pathological pain. This group of spinal multi-receptive neurons has attracted considerable attention in pain research due to their capabilities for encoding the location and intensity of nociception. Meanwhile, transmission, processing, and modulation of incoming afferent information in WDR neurons also establish the underlying basis for investigating the integration of acupuncture and pain signals. This review aims to provide a comprehensive examination of the distinctive features of WDR neurons and their involvement in pain. Specifically, we will examine the regulation of diverse supraspinal nuclei on these neurons and analyze their potential in elucidating the mechanisms of acupuncture analgesia.

Advances in the study of endocannabinoid receptors in experimental acupuncture analgesia.

The endocannabinoid system, an important biological network for maintaining and balancing various functions of the human body, is involved in many physiological functions such as pain, emotion, learning and memory, etc. Among which the endocannabinoid receptors ［including type I (CB1) and type II (CB2) receptors］ play an important role in the regulation of pain and have become an important target in the mechanism research of acupuncture analgesia. CB1 is mainly distributed in the central nervous system, including the spinal cord, cerebral cortex, amygdala, insular cortex, and basal ganglia, etc. CB2 is mainly distributed in peripheral immune tissues, such as spleen, bone, skin, etc. In the central and peripheral nervous systems, acupuncture can activate CB1 and CB2 receptors respectively, which is involved in the transmission of central nociceptive signals and related transmitters as well as the peri-pheral pro-nociceptive inflammatory response, thereby alleviating the nociceptive hypersensitivity in animal models. In this paper, we systematically summarize the roles of the above mechanisms in different types of animal models (inflammatory pain, neuropathological pain, visceral pain, etc.), so as to provide new ideas for the study of the underlying mechanisms of acupuncture analgesia.

Acupuncture Analgesia in Total Thyroidectomy for Graves’ Disease: A Case Report

Acupuncture Analgesia in Total Thyroidectomy for Graves’ Disease: A Case Report

Electroacupuncture Exerts Analgesic Effects by Restoring Hyperactivity via Cannabinoid Type 1 Receptors in the Anterior Cingulate Cortex in Chronic Inflammatory Pain.

As one of the commonly used therapies for pain-related diseases in clinical practice, electroacupuncture (EA) has been proven to be effective. In chronic pain, neurons in the anterior cingulate cortex (ACC) have been reported to be hyperactive, while the mechanism by which cannabinoid type 1 receptors (CB1Rs) in the ACC are involved in EA-mediated analgesic mechanisms remains to be elucidated. In this study, we investigated the potential central mechanism of EA analgesia. A combination of techniques was used to detect the expression and function of CB1R, including quantitative real-time PCR (q-PCR), western blot (WB), immunofluorescence (IF), enzyme-linked immunosorbent assay (ELISA), and in vivo multichannel optical fibre recording, and neuronal activity was examined by in vivo two-photon imaging and in vivo electrophysiological recording. We found that the hyperactivity of pyramidal neurons in the ACC during chronic inflammatory pain is associated with impairment of the endocannabinoid system. EA at the Zusanli acupoint (ST36) can reduce the hyperactivity of pyramidal neurons and exert analgesic effects by increasing the endocannabinoid ligands anandamide (AEA), 2-arachidonoylglycerol (2-AG) and CB1R. More importantly, CB1R in the ACC is one of the necessary conditions for the EA-mediated analgesia effect, which may be related to the negative regulation of the N-methyl-D-aspartate receptor (NMDAR) by the activation of CB1R downregulating NR1 subunits of NMDAR (NR1) via histidine triad nucleotide-binding protein 1 (HINT1). Our study suggested that the endocannabinoid system in the ACC plays an important role in acupuncture analgesia and provides evidence for a central mechanism of EA-mediated analgesia.

Research Progress of Acupuncture Analgesia Based on Autonomic Nerve Regulation Pathway

The autonomic nervous system (ANS) includes the sympathetic, parasympathetic, and enteric nervous systems, and its senior regulatory center includes the brainstem, cingulate gyrus, and hypothalamus. Acupuncture can affect visceral, vascular, and glandular functions via the autonomic nervous regulatory pathway. In this paper, the relationship between pain and autonomic nervous function, the application of acupuncture guided by the autonomic nervous system, and the basis and clinical research on acupuncture analgesia are reviewed.

Caffeine Impaired Acupuncture Analgesia in Inflammatory Pain by Blocking Adenosine A1 Receptor

Caffeine consumption inhibits acupuncture analgesic effects by blocking adenosine signaling. However, existing evidence remains controversial. Hence, this study aimed to examine the adenosine A1 receptor (A1R) role in moderate-dose caffeine-induced abolishing effect on acupuncture analgesia using A1R knockout mice (A1R−/−). We assessed the role of A1R in physiological sensory perception and its interaction with caffeine by measuring mechanical and thermal pain thresholds and administering A1R and adenosine 2A receptor antagonists in wild-type (WT) and A1R−/− mice. Formalin- and complete Freund's adjuvant (CFA)-induced inflammatory pain models were recruited to explore moderate-dose caffeine effect on pain perception and acupuncture analgesia in WT and A1R−/− mice. Moreover, a C-fiber reflex electromyogram in the biceps femoris was conducted to validate the role of A1R in the caffeine-induced blockade of acupuncture analgesia. We found that A1R was dispensable for physiological sensory perception and formalin- and CFA-induced hypersensitivity. However, genetic deletion of A1R impaired the antinociceptive effect of acupuncture in A1R−/− mice under physiological or inflammatory pain conditions. Acute moderate-dose caffeine administration induced mechanical and thermal hyperalgesia under physiological conditions but not in formalin- and CFA-induced inflammatory pain. Moreover, caffeine significantly inhibited electroacupuncture (EA) analgesia in physiological and inflammatory pain in WT mice, comparable to that of A1R antagonists. Conversely, A1R deletion impaired the EA analgesic effect and decreased the caffeine-induced inhibitory effect on EA analgesia in physiological conditions and inflammatory pain. Moderate-dose caffeine administration diminished the EA-induced antinociceptive effect by blocking A1R. Overall, our study suggested that caffeine consumption should be avoided during acupuncture treatment. PerspectiveModerate-dose caffeine injection attenuated EA-induced antinociceptive effect in formalin- and CFA-induced inflammatory pain mice models by blocking A1R. This highlights the importance of monitoring caffeine intake during acupuncture treatment.

Revealing the Wave (Quantum) Nature of Acupuncture and Acupuncture Analgesia

The acupuncture points are electrically conducting ellipses aligned with their long axes along a line called acupuncture meridian and they are imbedded in the semi-conducting tissue of the body. Since the media is electrically inhomogeneous, to describe mathematically one acupuncture meridian I needed nonlinear equation. Nonlinear equations have more than one solution and my nonlinear equation had two types of solutions – electric impulse and wave. Chinese scientists had already measured electric impulse running from the treated acupuncture point in the direction of the acupuncture meridian (determined by DC potential gradient at rest). However, nobody has measured waves. The nonlinear mathematical model predicted waves must run from the treated acupuncture point in the direction of the acupuncture meridian. Only a year later, the waves were experimentally found. Pain is the cry of the body for help – the pain signal is a wave signal sent to the brain along the acupuncture meridian asking for help. If an acupuncture treatment creates wave, it can block the propagation of the pain-impulse wave and provide analgesia (pain relief). Pain blockage with acupuncture is also the basis of the acupuncture used for anesthesia, which allows painless surgery with much faster recovery.

Conditioned pain modulation and analgesia of local acupuncture for chronic musculoskeletal pain: An exploratory study

ObjectiveConditioned pain modulation (CPM) has been found to be inefficient in patients with chronic pain. Animal and human studies showed that CPM is involved in acupuncture analgesia. This study explored the relationship between the potency of CPM and the extent of acupuncture analgesia. Materials and methodsThirty-five (35) participants with chronic non-specific low back pain or knee osteoarthritis were given sessions of acupuncture treatment at the pain sites twice per week for four weeks. Participants were asked to complete a diary, before and after the treatment, to monitor changes in clinical pain intensity, daily pain duration and analgesic intake. The potency of CPM was assessed before and after the treatment course. Correlation between potency of CPM and extent of acupuncture analgesia was analysed. ResultsClinical average pain intensity (0.79 ± 1.09, p < 0.01), daily pain duration (1.45 ± 3.77 hr, p = 0.03) and analgesic intake (1.41 ± 3.96, p = 0.04) decreased significantly after treatment, while potency of CPM increased significantly (18.21 ± 49.94%, p = 0.04). Pearson correlations showed those with less efficient baseline CPM presented with better pain reduction after treatment. Those with less efficient baseline CPM were associated with greater improvement in potency of CPM after treatment (r = 0.60, p < 0.01). There was no association between the change in potency of CPM and the change in clinical pain intensity. ConclusionsIndividuals have varied acupuncture analgesia. People with less efficient baseline CPM would likely benefit from local acupuncture with greater pain relief and improved potency of CPM. Larger studies with a control arm are needed to confirm these results.

Research progress of acupuncture mediated analgesia via regulating the function of endocannabinoid system

Endocannabinoid system (ECS), which composed of its ligands and receptors, widely distributes in peripheral tissues and nerve system. Through complex regulating mechanisms, ECS exerts a variety of biological functions including analgesia. Its utility in analgesic regulation has attracted extensive attention, and the related achievements have also been transformed into clinical practice. With the deepened understanding of the essence of pain, as well as the advances in research techniques, quantity of research evidences showed that ECS could be regulated by acupuncture treatment and exerted analgesic effect in inflammatory pain, neuropathic pain and other related diseases, and the mechanism had also been revealed gradually. By reviewing literatures related to acupuncture analgesia and ECS, we summarized the effect and mechanism of acupuncture analgesia involved with regulation of ECS, pointed out cannabinoid (CB) 1 receptor and CB2 receptor exerted analgesic effect in central and peripheral neural system through mechanisms of inhibiting neural activation and anti-inflammation, respectively. Therefore, we hope to provide reference and inspiration for relevant research and clinical practice in the future.