ABSTRACT
OBJECTIVES: To observe the analgesic effects of different levels and intensities of electrical stimulation on the local acupoints in the pain source area and their impact on wide dynamic range (WDR) neurons in the spinal dorsal horn, in order to provide a basis for selecting appropriate parameters for electroacupuncture (EA) stimulation. METHODS: Wistar rats were used in 3 parts of the experiment. Complete Freund's adjuvant was used to establish a model of inflammation-induced pain in the gastrocnemius muscle. After modeling, 6 rats were randomly selected for multi-channel extracellular electrophysiological recording of the electrical activity of WDR neurons, to determine the threshold for activating the A-component (Ta) and the C-component (Tc), which were used as the intervention intensities for skin transcutaneous electrical acupoint stimulation (TEAS) or EA. Thirty-six rats were randomly divided into normal , model , TEAS-Ta , TEAS-Tc, EA-Ta , and EA-Tc groups, with 6 rats in each group. In the pain source area , Ta or Tc intensity of TEAS or EA intervention at"Chengshan"(BL57) was performed for 30 min each time, once a day, for 3 consecutive days. A small animal pressure pain measurement instrument was used to measure the mechanical pressure pain threshold of the gastrocnemius muscle in rats, and the Von Frey filament was used to measure the mechanical pain threshold of the footpad. Thirteen rats were randomly selected to observe the immediate responsiveness of WDR neurons to Ta/Tc intensity of EA or TEAS in BL57. RESULTS: The thresholds of TEAS to activate WDR neuron A-component or C-component were (2.43±0.57) mA and (7.00±1.34) mA, respectively, while the thresholds for EA to activate muscle WDR neuron A-component or C-component were (0.72±0.34) mA and (1.58±0.35) mA, respectively. After injection of CFA into the gastrocnemius muscle, compared with the normal group both the mechanical pressure pain threshold of the gastrocnemius muscle and the mechanical pain threshold of the footpad of rats in the model group were significantly decreased (P<0.001). After TEAS-Ta, TEAS-Tc or EA-Ta intervention in the BL57, both the mechanical pressure pain threshold of the gastrocnemius muscle and the mechanical pain threshold of the footpad were significantly higher than those in the model group (P<0.05, P<0.001). Compared with the normal group, the electrical threshold for evoking WDR neuron C-component discharge was significantly decreased (P<0.001) in the model group, while increased after TEAS-Ta, TEAS-Tc, or EA-Ta intervention (P<0.01) compared with the model group. The evoked discharge frequency of muscle WDR neurons decreased significantly after immediate intervention with TEAS-Ta, TEAS-Tc, or EA-Ta (P<0.01, P<0.05). EA-Tc had no significant improvement on the evoked electrical activity of WDR neurons or pain behavior. CONCLUSIONS: TEAS-Ta, TEAS-Tc, or EA-Ta can all alleviate the local and footpad mechanical pain in rats with muscle inflammation and inhibit the responsiveness of WDR neurons, indicating that different intensities are required for analgesic effects at different levels of acupoints in the pain source area.
Subject(s)
Acupuncture Points , Electroacupuncture , Rats , Animals , Rats, Sprague-Dawley , Rats, Wistar , Pain , Neurons , Inflammation/therapy , Analgesics/adverse effects , Spinal CordABSTRACT
In the past 20 years, the acupuncture-moxibustion discipline has made a great progress in clinical research, method construction, standard formulation, guideline promotion, basic theory and key scientific issue research. Internationally, the development of acupuncture and moxibustion has gradually begun to pay more attention to the basic issues of the discipline itself from focusing on clinical evidence. The National Institute of Health of USA pays close attention to the construction of acupoint knowledge base and database and to the transformation of peripheral nerve stimulation techniques, which brings forth opportunities and challenges for the development of acupuncture-moxibustion discipline. In the present paper, we analyze the shortcomings of the current development of acupuncture and moxibustion, put forward some strategies for high-quality development in the future, and sort out the basic scientific issues to form an academic consensus. We should employ modern scientific language to express the scientific connotations of the basic theory of acupuncture and moxibustion, and build an open and self-consistent modern theoretical system. In addition, we also should attract more multidisciplinary talents to harmoniously and assiduously work together, insist on continuous innovation to open up a new situation in the transformation of basic scientific research achievements, and establish a new theoretical system of "somato-medicine" represented by acupuncture and moxibustion. In this way, we will guide the acupuncture-moxibustion discipline to make an original contribution to the modern life science and future medicine.
Subject(s)
Acupuncture Therapy , Acupuncture , Moxibustion , Medicine, Chinese Traditional , Acupuncture PointsABSTRACT
ABSTRACT: The efficacy of acupuncture in treating pain diseases has been recognized in clinical practice, and its mechanism of action has been a hot topic in academic acupuncture research. Previous basic research on acupuncture analgesia has focused mostly on the nervous system, with few studies addressing the immune system as a potential pathway of acupuncture analgesia. In this study, we investigated the effect of electroacupuncture (EA) on the ß-endorphins (ß-END) content, END-containing leukocyte type and number, sympathetic neurotransmitter norepinephrine (NE), and chemokine gene expression in inflamed tissues. To induce inflammatory pain, about 200 µL of complete Frester adjuvant (CFA) was injected into the unilateral medial femoral muscle of adult Wistar rats. Electroacupuncture treatment was performed for 3 days beginning on day 4 after CFA injection, with parameters of 2/100 Hz, 2 mA, and 30 minutes per treatment. The weight-bearing experiment and enzyme-linked immunosorbent assay showed that EA treatment significantly relieved spontaneous pain-like behaviors and increased the level of ß-END in inflamed tissue. Injection of anti-END antibody in inflamed tissue blocked this analgesic effect. Flow cytometry and immunofluorescence staining revealed that the EA-induced increase in ß-END was derived from opioid-containing ICAM-1 + /CD11b + immune cells in inflamed tissue. In addition, EA treatment increased the NE content and expression of ß2 adrenergic receptor (ADR-ß2) in inflammatory tissues and upregulated Cxcl1 and Cxcl6 gene expression levels. These findings provide new evidence for the peripheral analgesic effect of acupuncture treatment by recruiting ß-END-containing ICAM-1 + /CD11b + immune cells and increasing the ß-END content at the site of inflammation.
Subject(s)
Acupuncture Analgesia , Electroacupuncture , Rats , Animals , beta-Endorphin/metabolism , Intercellular Adhesion Molecule-1/adverse effects , Neutrophils/metabolism , Rats, Wistar , Pain/metabolism , Analgesics/adverse effectsABSTRACT
Introduction: Recent research has focused on the local control of articular inflammation through neuronal stimulation to avoid the systemic side effects of conventional pharmacological therapies. Electroacupuncture (EA) has been proven to be useful for inflammation suppressing and pain reduction in knee osteoarthritis (KOA) patients, yet its mechanism remains unclear. Methods: In the present study, the KOA model was established using the intra-articular injection of sodium monoiodoacetate (MIA) (1 mg/50 µL) into the knee cavity. EA was delivered at the ipsilateral ST36-GB34 acupoints. Hind paw weight-bearing and withdrawl thresholds were measured. On day 9, the histology, dep enrichment proteins, cytokines contents, immune cell population of the synovial membrane of the affected limbs were measured using HE staining, Masson staining, DIA quantitative proteomic analysis, flow cytometry, immunofluorescence staining, ELISA, and Western Blot. The ultrastructure of the saphenous nerve of the affected limb was observed using transmission electron microscopy on the 14th day after modeling. Results: The result demonstrated that EA intervention during the midterm phase of the articular inflammation alleviated inflammatory pain behaviors and cartilage damage, but not during the early phase. Mid-term EA suppressed the levels of proinflammatory cytokines TNF-α, IL-1ß, and IL-6 in the synovium on day 9 after MIA by elevating the level of sympathetic neurotransmitters Norepinephrine (NE) in the synovium but not systemic NE or systemic adrenaline. Selective blocking of the sympathetic function (6-OHDA) and ß2-adrenergic receptor (ICI 118,551) prevented the anti-inflammatory effects of EA. EA-induced increment of the NE in the synovium inhibited the CXCL1-CXCR2 dependent overexpression of IL-6 in the synovial macrophages in a ß2-adrenergic receptor (AR)-mediated manner. Discussion: These results revealed that EA activated sympathetic noradrenergic signaling to control local inflammation in KOA rats and contributed to the development of novel therapeutic neurostimulation strategies for inflammatory diseases.
ABSTRACT
Purpose: Spinal wide dynamic range (WDR) neurons are well studied in pain models and they play critical roles in regulating nociception. Evidence has started to accumulate that acupuncture produces a good analgesic effect via activating different primary fibers with distinct intensities. The purpose of the present study was to compare the distinct intensities of pre-electroacupuncture (pre-EA) at local muscular receptive fields (RFs), adjacent or contralateral non-RFs regulating the nociceptive discharges of spinal WDR neurons evoked by hypertonic saline (HS). Materials and Methods: Spinal segments of electrophysiological recording were identified by neural tracers applied at the left gastrocnemius muscle. The thresholds of Aß (TAß), Aδ (TAδ) and C (TC) components of WDR neurons were measured to determine the intensity of pre-EA by extracellular recording. The discharges of WDR neurons induced by distinct intensities of pre-EA and 200 µL HS (6%) injection in left gastrocnemius muscle of rats were observed by extracellular recording. Results: The spinal segments of WDR neurons were confirmed in lumbar (L)5-6 area according to the projective segments of dorsal root ganglion. TAß, TAδ and TC of WDR neurons was determined to be 0.5, 1, and 2 mA, respectively. The pre-EA with intensities of TAß (P < 0.05), TAδ (P < 0.05), TC (P < 0.05) or 2TC (P < 0.01) at ipsilateral adjacent non-RFs significantly reduced the discharges of WDR neurons, while at local RFs only pre-EA of TAδ (P < 0.05), TC (P < 0.05) and 2TC (P < 0.01) could inhibit the nociceptive discharges. In addition, intensity of pre-EA at contralateral non-RFs should reach at least TC to effectively inhibit the firing rates of WDR neurons (P < 0.01). Conclusion: Pre-EA could suppress nociceptive discharges of WDR neurons and the inhibitory effects were dependent on the distinct intensities and locations of stimulation.
ABSTRACT
For more than half a centuryï¼the modern bioresearch in acupuncture has made remarkable advancements, proving scientific basis underlying the traditional, intuitive treatment, as well as leading to some new discoveries with the potential to enhance the effectiveness of acupuncture as we know it. Meanwhile, the clinical researches have started to shift its paradigm from traditional individual observation to modern evidence-based medicine. However, there is little interaction between basic and clinic researches, which are like two separate worlds, not benefiting each other. Also the education and training of acupuncture are still traditional style, little combining with modern studies. To bridging the large gap, we need translational science involving in. In this article, with a critical reviews of the limitations of the traditional methods of acupuncture, the challenges faced by clinic practices and placebo-control studies, and the advantages and disadvantages of basic research, we propose a methodological paradigm of the translational research, Translational Acupuncture Research Spectrum, that meets the current situation of acupuncture researches, hoping to give insights into this field and to promote modern acupuncture to move towards a new stage.
Subject(s)
Acupuncture Therapy , Acupuncture , Translational Research, Biomedical , Translational Science, Biomedical , Acupuncture/education , Medicine, Chinese TraditionalABSTRACT
The latest guideline about ulcerative colitis (UC) clinical practice stresses that mucosal healing, rather than anti-inflammation, is the main target in UC clinical management. Current mucosal dysfunction mainly closely relates to the endoscopic intestinal wall (mechanical barrier) injury with the imbalance between intestinal epithelial cells (IECs) regeneration and death, as well as tight junction (TJ) dysfunction. It is suggested that biological barrier (gut microbiota), chemical barrier (mucus protein layer, MUC) and immune barrier (immune cells) all take part in the imbalance, leading to mechanical barrier injury. Lots of experimental studies reported that acupuncture and moxibustion on UC recovery by adjusting the gut microbiota, MUC and immune cells on multiple targets and pathways, which contributes to the balance of IEC regeneration and death, as well as TJ structure recovery in animals. Moreover, the validity and superiority of acupuncture and moxibustion were also demonstrated in clinic. This study aims to review the achievements of acupuncture and moxibustion on mucosal healing and analyse the underlying mechanisms.
Subject(s)
Acupuncture Therapy , Acupuncture , Colitis, Ulcerative , Moxibustion , Rats , Animals , Colitis, Ulcerative/therapy , Colitis, Ulcerative/metabolism , Rats, Sprague-DawleyABSTRACT
OBJECTIVE: To observe the pressure pain threshold (PPT), skin conductance (SC) and blood perfusion (BP) of the sensitized acupoints in patients with knee osteoarthritis (KOA), and explore the mechanism of acupuncture at the sensitized acupoints for treating diseases. METHODS: Eleven healthy subjects and 11 unilateral KOA patients were recruited from July 2020 to March 2021 in this study. The PPT, SC and BP of control acupoints in healthy controls, and non-sensitized and sensitized acupoints in KOA patients were measured and compared between baseline and after manual acupuncture (MA) treatment. RESULTS: Before MA treatment, lower PPT was observed at the sensitized acupoints compared with non-sensitized and control acupoints (P<0.05). After MA treatment, PPT at the sensitized acupoints increased significantly in KOA patients (P<0.05). Before MA treatment, there was no statistical difference in SC and BP among control, non-sensitized and sensitized acupoints (P>0.05). Compared with the control and non-sensitized acupoints, there were significant increases of SC and BP in sensitized acupoints of KOA patients after MA treatment (P<0.05 or P<0.01). CONCLUSION: MA at sensitized acupoints could elevate PPT of KOA patients, which may be associated with the increment of SC and BP.
Subject(s)
Acupuncture Therapy , Acupuncture , Osteoarthritis, Knee , Humans , Acupuncture Points , Pain Threshold , Osteoarthritis, Knee/therapy , PainABSTRACT
OBJECTIVE: To investigate the mechanism of electroacupuncture (EA) "Zusanli" (ST36) in delaying colon "inflammation-cancer transformation" in mice by anti-inflammatory. METHODS: C57BL/6J mice were randomly divided into normal, model and EA groups, with 12 mice in each group. The mouse model of colorectal cancer (CRC) was established by intrape-ritoneal injection of azomethane (AOM) and feeding dextran sodium sulfate (DSS). At the beginning of the 2nd cycle, EA was applied to bilateral ST36 for 30 min once every other day for 12 times. The number of colon tumors in each group was observed, and the weight and length of colon were recorded. The contents of interleukin (IL)-1ß, IL-6, IL-17A, IL-23, tumor necrosis factor (TNF)-α and CXC chemokine ligand 1 (CXCL1) of serum and colon tissue were detected by MSD multifactorial assay.The apoptosis of local cells in colon tumor was observed by TUNEL staining. Cell proliferation in colon tumor was observed by immunohistochemistry. RESULTS: Compared with the normal group, the colon length was significantly shortened (P<0.05) and the colon mass was significantly increased (P<0.001) in the model group, the contents of IL-1ß, IL-6, TNF-α, IL-17A and CXCL1 of serum and colon tissue were significantly increased (P<0.05, P<0.01, P<0.001), and the content of IL-23 was increased in colon tissue (P<0.05) in the model group. Compared with the model group, the colon mass was decreased (P<0.05) and the contents of IL-1ß, IL-6, TNF-α and IL-17A in serum were decreased (P<0.05), while the contents of IL-17A, CXCL1 and IL-23 in colon tissue were decreased (P<0.05) in the EA group, the percentage of local apoptotic cells in the EA group was increased (P<0.001), the percentage of PCNA positive cells was decreased (P<0.001), the number of tumors and the tumor volume were significantly decreased (P<0.01, P<0.05). The contents of IL-6, TNF-α, IL-17A and IL-23 in serum of CRC mice were positively correlated with tumor burden (P<0.05).The contents of IL-1ß, TNF-α, CXCL1 and IL-23 in colon tissue of CRC mice were positively correlated with tumor burden (P<0.05). CONCLUSION: Electroacupuncture at ST36 can inhibit the inflammatory response of AOM/DSS inflammatory associated CRC mice and delay the "inflammation-cancer transformation" of colon.
Subject(s)
Colonic Neoplasms , Electroacupuncture , Animals , Mice , Colonic Neoplasms/genetics , Colonic Neoplasms/therapy , Inflammation/genetics , Inflammation/therapy , Interleukin-17 , Interleukin-23 , Interleukin-6 , Mice, Inbred C57BL , Tumor Necrosis Factor-alpha/geneticsABSTRACT
The therapeutic effects of electroacupuncture (EA) on the comorbidity of visceral pain and anxiety in patients with inflammatory bowel disease (IBD) is well known. It has been known that the ventral hippocampus (vHPC) and the cannabinoid type 1 receptors (CB1R) are involved in regulating anxiety and pain. Therefore, in this study, we determined whether EA reduces visceral pain and IBD-induced anxiety via CB1R in the vHPC. We found that EA alleviated visceral hyperalgesia and anxiety in TNBS-treated IBD mice. EA reversed over-expression of CB1R in IBD mice and decreased the percentage of CB1R-expressed GABAergic neurons in the vHPC. Ablating CB1R of GABAergic neurons in the vHPC alleviated anxiety in TNBS-treated mice and mimicked the anxiolytic effect of EA. While ablating CB1R in glutamatergic neurons in the vHPC induced severe anxiety in wild type mice and inhibited the anxiolytic effect of EA. However, ablating CB1R in either GABAergic or glutamatergic neurons in the vHPC did not alter visceral pain. In conclusion, we found CB1R in both GABAergic neurons and glutamatergic neurons are involved in the inhibitory effect of EA on anxiety but not visceral pain in IBD mice. EA may exert anxiolytic effect via downregulating CB1R in GABAergic neurons and activating CB1R in glutamatergic neurons in the vHPC, thus reducing the release of glutamate and inhibiting the anxiety circuit related to vHPC. Thus, our study provides new information about the cellular and molecular mechanisms of the therapeutic effect of EA on anxiety induced by IBD.
ABSTRACT
OBJECTIVE: To investigate the changes of skin temperature, blood infusion and inflammatory cytokines of cutaneous tissue in the sensitized area of colitis model rats, as well as the relationship between sensory and sympathetic nerves and the formation of sensitized area, and to initially reveal the partial physical-chemical characteristics of the sensitized area in the colitis model rats. METHODS: Thirty-five male SD rats were randomly divided into a control group (n=10), a model group (n=18) and a guanethidine group (n=7). 5% dextran sulfate sodium (DSS) was adopted for 6-day free drinking to establish colitis model in the model group and the guanethidine group. On day 6 and 7, in the guanethidine group, guanethidine solution (30 mg/kg) was injected intraperitoneally for sympathetic block. On day 7, after injection of evans blue (EB) solution, the EB extravasation areas on the body surface were observed to investigate the distribution and physical-chemical characteristics of the sensitized area. The control area was set up, 0.5 cm away from the sensitized area, and with the same nerve segment innervation. Disease activity index (DAI) score of rats was compared between the normal group and the model group, and the morphological changes in the colon tissue were investigated with HE method. Using infrared thermal imaging technology and laser speckle flow imaging technology, skin temperature and blood infusion were determined in the sensitized area and the control area of the rats in the model group. Immunofluorescence technique was adopted to observe the expression levels of the positive nerve fibers of substance P (SP), calcitonin gene-related peptide (CGRP) and tyrosine hydroxylase (TH), and the correlation with blood vessels; as well as the expression levels of SP positive nerve fibers/tryptase+ mast cells, and tryptase+ mast cells/5-hydroxytryptamine (5-HT) in skin tissue in the sensitized area and the control area of the rats in the model group. MSD multi-level factorial method and ELISA were applied to determine the contents of pro-inflammatory and anti-inflammatory cytokines (e.g. TNF-α, IL-1ß, IL-6, IL-4 and IL-10) and anti-inflammatory substance corticosterone (CORT). RESULTS: Sensitization occurred at the T12-S1 segments of the colitis model rats, especially at L2-L5 segments. Compared with the normal group, DAI score was increased in the rats of the model group (P<0.05), and the colonic mucosal damage was obvious, with the epithelial cells disordered, even disappeared, crypt destructed, submucosal edema and a large number of inflammatory cells infiltrated. In comparison with the control area, the skin temperature and blood infusion were increased in the sensitized area of the model group (P<0.05, P<0.01); as well as the expression levels of the positive nerve fibers of SP, CGRP and TH of skin tissue (P<0.05), which was specially distributed in peripheral vessels, the expression levels of SP positive nerve fibers/tryptase+ mast cells, and tryptase+ mast cells/5-HT of the skin tissue were all expanded (P<0.05) in the sensitized area of the model group. Compared with the model group, the number of sensitized areas was reduced in the guanethidine group (P<0.05). In comparison with the control area of the model group, in the sensitized area, the contents of pro-inflammatory cytokines, e.g. TNF-α, IL-1ß and IL-6, and the anti-inflammatory substance CORT of skin tissue were all increased (P<0.05); and the contents of IL-6 and TNF-α were negatively correlated with CORT (P<0.05). CONCLUSION: The sensitized areas on the body surface of colitis rats are mainly distributed in the L2-L5 segments. Sensory and sympathetic nerves are involved in the acupoint sensitization, and the sensitized areas may have the dynamic changes in pro-inflammatory and anti-inflammatory substances.
Subject(s)
Colitis , Skin Temperature , Animals , Anti-Inflammatory Agents , Calcitonin Gene-Related Peptide/metabolism , Colitis/chemically induced , Colitis/metabolism , Cytokines/metabolism , Guanethidine , Interleukin-6 , Male , Rats , Rats, Sprague-Dawley , Serotonin , Substance P/genetics , Tryptases , Tumor Necrosis Factor-alphaABSTRACT
Inflammatory bowel disease (IBD) results in chronic abdominal pain in patients due to the presence of inflammatory responses in the colon. Electroacupuncture (EA) is effective in alleviating visceral pain and colonic inflammation associated with IBD. Cannabinoid CB2 receptor agonists also reduce colonic inflammation in a mouse model of IBD. However, whether EA reduces visceral pain and colonic inflammation via the CB2 receptor remains unknown. Here, we determined the mechanism of the antinociceptive effect of EA in a mouse model of IBD induced by rectal perfusion of 2,4,6-trinitrobenzenesulfonic acid solution (TNBS). EA or sham EA was performed at the bilateral Dachangshu (BL25) point for seven consecutive days. The von Frey and colorectal distension tests were performed to measure mechanical referred pain and visceral pain. Western blotting and immunohistochemistry assays were carried out to determine the expression of IL-1ß and iNOS and activation of macrophages in the colon tissues. We found that EA, but not sham EA, attenuated visceral hypersensitivity and promoted activation of CB2 receptors, which in turn inhibited macrophage activation and the expression of IL-1ß and iNOS. The effects of EA were blocked by AM630, a specific CB2 receptor antagonist, and by CB2 receptor knockout. Our findings suggest that EA attenuates mechanical allodynia and visceral hypersensitivity associated with IBD by activating CB2 receptors and subsequent inhibition of macrophage activation and expression of IL-1ß and iNOS.
ABSTRACT
October 2021, Nature published an original research article entitled A neuroanatomical basis for electroacupuncture to drive the vagal-adrenal axis, which draws great attention and arouses extensive discussion in the acupuncture field. Based on previous findings, this study demonstrates that the abundant innervation of PROKR2-Cre neurons in deep fascia tissues mediates the anti-inflammatory effect induced by low-intensity electroacupuncture stimulation at "Zusanli"ï¼ST36ï¼ or "Shousanli"(LI10) via the "vagal-adrenal axis". This study is one of milestones in the field of acupuncture basic research and represents a great achievement generated by multi-discipline integration of acupuncture and neuro-immunology. It reveals partial contributing factors involved in acupuncture's effect and the relative specificity of the neuroanatomical basis of acupoints in the context of immune modulation. This study is both very informative and instructive for the innovation and clinical translation of future acupuncture research. Acupuncture researchers are recommended to attach great importance to this study in terms of its research strategy,methods and findings.
Subject(s)
Acupuncture Therapy , Acupuncture , Electroacupuncture , Acupuncture Points , Vagus NerveABSTRACT
OBJECTIVE: To determine whether electroacupuncture (EA) or moxibustion-like stimulation (MLS) can affect the cutaneous and/or systemic hypothalamic-pituitary-adrenal (HPA) axes. METHODS: Rats were divided into Control, EA, 37°C MLS and 43.5°C MLS groups. EA and MLS were performed at bilateral ST36 or LI4. The expression of corticotropin-releasing factor (CRF), adrenocorticotropic hormone (ACTH) and the glucocorticoid receptor (GR) was detected in local cutaneous tissues at the site of ST36 and LI4 by immunohistochemical staining. In addition, levels of CRF, ACTH and corticosterone (CORT) in cutaneous tissue and plasma were determined. RESULTS: Cutaneous expression of CRF, ACTH and GR significantly increased after EA at ST36, while only GR increased after 43.5°C MLS at ST36. The results of EA and MLS at LI4 were in parallel with those at ST36. In plasma, compared with the control group, the level of CORT increased after EA at ST36, while both ACTH and CORT were markedly increased after 43.5°C MLS. For LI4, plasma CRF and CORT increased after EA, while the levels of all three hormones increased following 43.5°C MLS. Notably, compared with the effect of EA, 43.5°C MLS at ST36 produced a more substantial increase in plasma CORT, and 43.5°C MLS at LI4 induced a more dramatic increase in plasma CRF and CORT. CONCLUSION: Both EA and 43.5°C MLS can activate the cutaneous and systemic HPA axes of the rat. EA tended to activate the local cutaneous HPA, while 43.5°C MLS was more likely to activate the systemic HPA axis.
Subject(s)
Electroacupuncture , Moxibustion , Acupuncture Points , Adrenocorticotropic Hormone/metabolism , Adrenocorticotropic Hormone/pharmacology , Animals , Corticosterone , Corticotropin-Releasing Hormone/metabolism , Electroacupuncture/methods , Hypothalamo-Hypophyseal System/metabolism , Pituitary-Adrenal System/metabolism , Rats , Rats, Sprague-Dawley , Receptors, Glucocorticoid/metabolismABSTRACT
Somatosensory autonomic reflexes allow electroacupuncture stimulation (ES) to modulate body physiology at distant sites1-6 (for example, suppressing severe systemic inflammation6-9). Since the 1970s, an emerging organizational rule about these reflexes has been the presence of body-region specificity1-6. For example, ES at the hindlimb ST36 acupoint but not the abdominal ST25 acupoint can drive the vagal-adrenal anti-inflammatory axis in mice10,11. The neuroanatomical basis of this somatotopic organization is, however, unknown. Here we show that PROKR2Cre-marked sensory neurons, which innervate the deep hindlimb fascia (for example, the periosteum) but not abdominal fascia (for example, the peritoneum), are crucial for driving the vagal-adrenal axis. Low-intensity ES at the ST36 site in mice with ablated PROKR2Cre-marked sensory neurons failed to activate hindbrain vagal efferent neurons or to drive catecholamine release from adrenal glands. As a result, ES no longer suppressed systemic inflammation induced by bacterial endotoxins. By contrast, spinal sympathetic reflexes evoked by high-intensity ES at both ST25 and ST36 sites were unaffected. We also show that optogenetic stimulation of PROKR2Cre-marked nerve terminals through the ST36 site is sufficient to drive the vagal-adrenal axis but not sympathetic reflexes. Furthermore, the distribution patterns of PROKR2Cre nerve fibres can retrospectively predict body regions at which low-intensity ES will or will not effectively produce anti-inflammatory effects. Our studies provide a neuroanatomical basis for the selectivity and specificity of acupoints in driving specific autonomic pathways.
Subject(s)
Adrenal Glands/physiology , Autonomic Nervous System , Electroacupuncture , Vagus Nerve/physiology , Acupuncture Points , Animals , Hindlimb/innervation , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , ReflexABSTRACT
Recent studies have shown that both superficial and deep acupuncture produced clinically relevant and persistent effect on chronic pain, and several subtypes of somatic primary afferents played critical roles in acupuncture and moxibustion analgesia. However, which kind of primary afferents in the superficial and deep tissue of the acupoint is activated by acupuncture or moxibustion to relieve pain persistently remains unclear. The aim of this study is to investigate the roles of distinct peripheral afferents in different layers of the tissue (muscle or skin) in the acupoint for pain relief. Muscular A-fibers activated by deep electroacupuncture (dEA) with lower intensity (approximately 1 mA) persistently alleviated inflammatory muscle pain. Meanwhile, cutaneous C-nociceptors excited by noxious moxibustion-like stimulation (MS) and topical application of capsaicin (CAP) on local acupoint area produced durable analgesic effect. Additionally, spontaneous activity of C-fibers caused by muscular inflammation was also inhibited by dEA and CAP. Furthermore, decreases in pain behavior induced by dEA disappeared after deep A-fibers were demyelinated by cobra venom, whereas CAP failed to relieve pain following cutaneous denervation. Collectively, these results indicate that dEA and MS ameliorate inflammatory muscle pain through distinct primary afferents in different layers of somatic tissue; the former is achieved by activating muscular A-fibers, while the latter is mediated by activating cutaneous C-fibers.
ABSTRACT
Acupuncture is an effective alternative therapy for pain management. Evidence suggests that acupuncture relieves pain by exciting somatic afferent nerve fibers. However, the mechanism underlying the interaction between neurons in different layers of the spinal dorsal horn induced by electroacupuncture (EA) remains unclear. The aim of this study was to explore the mechanism of EA relieving inflammatory muscle pain, which was associated with activation of the spontaneous firing of low-threshold mechanoreceptor (LTM) neurons and inhibition of wide dynamic range (WDR) neuronal activities in the spinal dorsal horn of rats. Inflammatory muscle pain was induced by injecting complete Freund's adjuvant into the right biceps femoris muscle. EA with intensity of threshold of A fibers (Ta) in Liangqiu (ST34) muscle considerably inhibited the abnormal spontaneous activities of electromyography (EMG) due to muscle inflammation. While EA with intensity of C-fiber threshold (Tc) increased the abnormal activities of EMG. EA with Ta also ameliorated the imbalance of weight-bearing behavior. A microelectrode array with 750-µm depth covering 32 channels was used to record the neuronal activities of WDR and LTM in different layers of the spinal dorsal horn. The spontaneous firing of LTM neurons was enhanced by EA-Ta, while the spontaneous firing of WDR neurons was inhibited. Moreover, EA-Ta led to a significant inverse correlation between changes in the frequency of WDR and LTM neurons (r = -0.64, p < 0.05). In conclusion, the results indicated that EA could alleviate inflammatory muscle pain, which was associated with facilitation of the spontaneous firing of LTM neurons and inhibition of WDR neuronal activities. This provides a promising evidence that EA-Ta could be applied to relieve muscular inflammatory pain in clinical practice.
ABSTRACT
OBJECTIVE: To compare the effect of electroacupuncture (EA) and transcutaneous electrical acupoint stimulation (TEAS) of skin and muscle layers of "Liangqiu" (ST34) area on inflammatory muscular pain in rats, so as to study the role of different-layer afferent nerve fibers in acupuncture analgesia. METHODS: A total of 120 male SD rats were used in the present study, including 8 rats used for determining the excitatory threshold of Aδ(Ta) and C (Tc) afferent nerve fibers, 48 employed for comparing the analgesic effect of EA and TEAS at intensities of Ta and Tc, and 64 for observing the effect of EA and TAES stimulation of ipsilateral (Ipsi), contralateral (Contra) ST34 and ipsilateral LI4 at Ta and Tc intensities. Inflammatory muscle pain was induced by injection of complete Freund's adjuvant (CFA) into the right biceps femoris muscle. In the second part of the present study, 48 rats were randomly and equally divided into control, model, TEAS-Ta, TEAS-Tc, EA-Ta and EA-Tc groups, while in the 3rd part, 64 rats were randomly and equally divided into control, model, Ipsi-ST34-TEAS, Contra-ST34-TEAS, Ipsi-ST34-EA, Contra-ST34-EA, Ipsi-LI4-TEAS and Ipsi-LI4-EA groups. TEAS or EA was applied to the skin and muscle layers, respectively. Before and after modeling, the animal was forced to stand on a bipedal equilibrator, the difference in body mass distribution of both feet (bearing difference) was used to assess the pain severity. The frequency of myoelectrical discharges of the right bicep femoris muscle in responding to electrical stimulation of the spot between the 4th and 5th toes of the ipsilateral hindlimb at an intensity of two-folds of C-fiber excitatory threshold was recorded. RESULTS: 1) The bearing difference between the bilateral hindlimbs was markedly higher in the model group than in the control group (P<0.01), and significantly lower at the 2nd and 3rd day in the EA-Ta and EA-Tc, and TEAS-Tc groups relevant to the model group (P<0.05, P<0.01). 2) The frequency of C-fiber reflex induced electromyogram (EMG) activities were significantly decreased at 0 and 1 min after TEAS of both ipsilateral ST34 at Tc, and 0 min after TEAS of the contralateral ST34 at Tc (rather than at Ta and not LI4 even at Tc) in comparison with pre-TEAS, and 0, 1 and 2 min after TEAS of ipsilateral ST34 at Tc, and 0 min after TEAS of contra-ST34 at Tc compared with the model group, respectively (P<0.01, P<0.05). In comparison with pre-EA, the frequency of C-fiber reflex induced EMG activities were significantly decreased at 0 and 1 min after EA of the ipsilateral ST34 at Ta, and 0 min after EA of the contra-ST34 at Ta. In addition, the frequency of C-fiber reflex induced EMG activities were decreased at 0, 1 and 2 min after EA of the ipsilateral ST34 at Tc, and 0 and 1 min after EA of the contra-ST34 at Tc, as well as 0 min after EA of LI4 at Tc (P<0.01, P<0.05).In comparison with the model group, the frequency of C-fiber reflex induced EMG activities are significantly decreased at 0, and 1 min after EA of the ipsilateral ST34 at Ta, and 0 min after EA of the contra-ST34 at Ta. In addition, the frequency of C-fiber reflex induced EMG activities were decreased at 0, 1 ,2,and 3 min after EA of the ipsilateral ST34 at Tc, and 0 and 1 min after EA of the contra-ST34 at Tc, as well as 0 min after EA of LI4 at Tc, respectively (P<0.01, P<0.05). CONCLUSION: TEAS-ST34 at Tc and EA-ST34 at both Ta and Tc can alleviate pain behavior in inflammatory pain rats, which may be related to its effect in activating the afferent nerve fiber in different layers of ST34 area.