Response of Local Nitric Oxide Release to Manual Acupuncture and Electrical Heat in Humans: Effects of Reinforcement Methods

Stimuli-evoked NOergic molecules and neuropeptides at acupuncture points and the gracile nucleus contribute to signal transduction of propagated sensation along the meridian through the dorsal medulla-thalamic pathways

Numerous studies from different international groups have demonstrated that sensations can be propagated along acupuncture channel pathways. The propagated sensation along the channel pathway (PSCP) can be elicited by electroacupuncture (EA), transcutaneous electrical nerve stimulation (TENS), manual acupuncture (MA), and heat applied to distal acupuncture points (acupoints). Nitric oxide (NO) levels were reported to be elevated in the gracile nucleus and skin regions near to the EA sites, with higher levels at acupoints associated with an enhanced expression of NO synthase and transient receptor potential vanilloid type 1. The stimuli, EA, MA, TENS, and heat, have been used to elicit axonal reflexes, which increase local release of NO and neuropeptides such as calcitonin gene related peptide. Furthermore, the sensation of PSCP along the body surface occurs only ipsilaterally to the stimulated acupoints in various human studies, which does not support the involvement of the spinal-thalamic pathway, which would involve cross over transmission of the signals. The gracile nucleus receives ascending input from the sciatic nerve and responds to somatosensory stimulation mainly on the ipsilateral side via the dorsal column pathway. EA at Zusanli (ST36) increases NO release and expression of NO synthase mainly in the ipsilateral side of the gracile nucleus, while the cardiovascular effects and analgesic responses to EA at ST36 are changed by influences of l-arginine-derived NO synthesis in the ipsilateral gracile nucleus in rats. The stimuli-induced release of NOergic molecules and neuropeptides exist high levels in the acupoints, which contain rich neuronal components and blood vessels. Enhanced NOergic molecules at acupoints cause axon reflexes during the stimuli, which elevate cutaneous blood flow. Elevated NOergic molecules and local blood flow may spread over acupoints one after another along the meridian lines differing from nerve pathways following the stimuli to induce PSCP. The same types of stimulation also elicit NO release in the gracile nucleus, which contributes to the somatosensory signal transduction of PSCP through the dorsal medulla-thalamic pathways. Other substances such as serotonin and catecholamines are proposed to mediate responses and certain effects of acupuncture-like stimulation but their mechanisms are poorly-understood. In this review we summarize the current understanding of the neurobiological processes of PSCP research with an emphasis on recent developments of NO mediating stimulation-evoked axon reflexes and somatosensory signal transduction for PSCP perceptions through the dorsal medulla-thalamic pathways. Please cite this article as: Ma SX. Stimuli-evoked NOergic molecules and neuropeptides at acupuncture points and gracile nucleus contribute to signal transduction of propagated sensation along the meridian through the dorsal medulla-thalamic pathways. J Integr Med. 2024; 22(5): 515-522.

Stimuli-induced NOergic Molecules and Neuropeptides Mediated Axon Reflexes Contribute to Tracers along Meridian Pathways

An abundance of studies from different international groups have demonstrated tracers along linear pathways resembling meridians over the body surface of humans. All experiments of the studies have been conducted by injection of a radiotracer solution or tracer dyes in a volume of solution into acupuncture points (acupoints). The solution injected into acupoints produces much stronger mechanical stimuli than acupuncture, which causes axon reflex. Anatomical studies have demonstrated that acupoints/meridians exist higher number of small nerve fibers and blood vessels with rich nitric oxide (NO) and neuropeptides in the cutaneous tissues as structures for the biomolecules mediated axon reflexes. Recent advances have determined that NO and calcitonin generelated peptides play crucial roles in the comprehension of the axon reflex. The stimuli-evoked axon reflex and NOergic biomolecules/neuropeptides increase local blood flow with higher levels in acupoints/meridians, which move radioactive substances or tracer dyes in the skin and subcutaneous tissue under a linear path resembling acupoints and meridians, the important phenomena of meridians induced by the stimuli. The evidence and understanding of the biomolecular processes of the tracers along linear pathways resembling meridians have been summarized with an emphasis on recent developments of NO and neuropeptides mediating stimuli-evoked axon reflexes to increase local blood flow with higher levels in acupoints/meridians, which move radioactive substances or tracer dyes in the skin and subcutaneous tissue contributing to tracers along linear pathways resembling meridians in this mini-review.

Acupoint stimulation for long COVID: A promising intervention:

"Long COVID" is a sustained symptom following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). According to recent statistics, at least 65 million people have long COVID, which poses a long-term threat to human health. The pathogenic mechanisms of coronavirus disease 2019 (COVID-19) are complex and affect multiple organs and systems. Common symptoms include palpitations, breathing difficulties, attention and memory deficits, fatigue, anxiety, and depression. It is difficult to achieve satisfactory treatment effect with a single intervention. Currently, treatment strategies for long COVID are still in the exploratory stage, and there is an urgent need to find appropriate and effective methods for long COVID treatment. Traditional Chinese medicine is effective in treating the various phases of COVID-19. Previous studies have shown that acupoint stimulation therapy is effective in improving palpitations, dyspnea, cognitive impairment, anxiety, depression, and other symptoms in patients. According to previous studies, acupoint stimulation may improve various symptoms related to long COVID. This paper discusses the potential application value of acupoint stimulation in the treatment of long COVID-related symptoms, based on the common sequelae of various systems involved in long COVID, and the effect of acupoint stimulation in the treatment of similar symptoms and diseases in recent years.

Kininogen-Nitric Oxide Signaling at Nearby Nonexcited Acupoints after Long-Term Stimulation

Acupuncture treatment is based on acupoint stimulation; however, the biological basis is not understood. We stimulated one acupoint with catgut embedding for 8 weeks and then used isobaric tags for relative and absolute quantitation to screen proteins with altered expression in adjacent acupoints of Sprague Dawley rats. We found that kininogen expression was significantly upregulated in the stimulated and the nonstimulated adjacent acupoints along the same meridian. The enhanced kininogen expression was meridian dependent and was most apparent among small vessels in the subcutaneous layer. Enhanced signals of nitric oxide synthases, cGMP-dependent protein kinase, and myosin light chain were also observed at the nonstimulated adjacent acupoints along the same meridian. These findings uncover biological changes at acupoints and suggest the critical role of the kininogen–nitric oxide signaling pathway in acupoint activation.

Nitric Oxide on Pathophysiology of SARS-CoV 19: Toward Possible Role of Acupuncture Treatment

The ongoing outbreak of COVID-19 has quickly become a daunting challenge to global health. In the absence of satisfied therapy, effective treatment interventions are urgently needed. Previous studies have demonstrated that acupuncture is effective at relieving common symptoms of COVID-19 including breathlessness, nausea, insomnia, leukopenia, fatigue, vomiting, and abdominal pain. Experiments have shown that nitric oxide (NO) inhibits the replication cycle of severe acute respiratory syndrome (SARS) coronavirus with similar structures of COVID-19. Increase in level of NO by using NO gas inhalation has been shown to restore lung function by reducing airway resistance and improving virus-induced lung infections in SARS patients. Recent case report showed that a medical acupuncturist with symptoms consistent with severe COVID pneumonia achieved full recovery by self-administered medical acupuncture and cupping therapy at home. Clinical features and pathophysiology demonstrated that NO deficiency and endothelial dysfunction contribute to the development of COVID-19. Several studies from different groups consistently demonstrated that acupuncture increases NO synthase expression and induces an elevation of NO production and release in plasma and the local skin regions in both animals and humans. It is suggested that exogenous NO supplies or interventions that induce increasing levels of NO can play an important role in protective effects against inflammation and acute lung injury. This article reviews the rationale for mechanisms of NO induction induced by acupuncture in the possible treatment of COVID-19 and highlights its potential for contributing to better clinical outcomes and improving future clinical studies of acupuncture on treatment of COVID-19.

Can Traditional Chinese Medicine Diagnosis Be Parameterized and Standardized? A Narrative Review

The integration of Traditional Chinese Medicine (TCM) in Western health systems and research requires a rational communicable theory, scientific proof of efficacy and safety, and quality control measures. The existence of clear definitions and the diagnosis standardization are critical factors to establish the patient's vegetative functional status accurately and, therefore, systematically apply TCM therapeutics such as the stimulation of reflex skin areas known as acupoints. This science-based conceptualization entails using validated methods, or even developing new systems able to parameterize the diagnosis and assess TCM related effects by objective measurements. Traditionally, tongue and pulse diagnosis and the functional evaluation of action points by pressure sensitivity and physical examination may be regarded as essential diagnostic tools. Parameterizing these techniques is a future key point in the objectification of TCM diagnosis, such as by electronic digital image analysis, mechanical pulse diagnostic systems, or the systematic evaluation of acupoints' electrophysiology. This review aims to demonstrate and critically analyze some achievements and limitations in the clinical application of device-assisted TCM diagnosis systems to evaluate functional physiological patterns. Despite some limitations, tongue, pulse, and electrophysiological diagnosis devices have been reported as a useful tool while establishing a person's functional status.

Benefits of Adding Gluteal Dry Needling to a Four-Week Physical Exercise Program in a Chronic Low Back Pain Population. A Randomized Clinical Trial

OBJECTIVE

To determine if adding dry needling to a four-week exercise program has an additional benefit compared with adding sham dry needling to the same exercise program in subjects with chronic low back pain.

DESIGN

Randomized clinical trial.

SETTING

Physiotherapy and Pain Clinic of Alcala University.

SUBJECTS

Forty-six patients with chronic low back pain.

METHODS

Subjects were randomized to two groups: the dry needling group (N = 23) or sham dry needling group (N = 23). Both groups received a four-week exercise program and before the exercise started a session of dry needling or sham dry needling. Pain (visual analog scale), disability (Roland-Morris Questionnaire), and fear avoidance beliefs (Fear Avoidance Beliefs Questionnaire) were assessed at baseline, after treatment, and at three-month follow-up. Pressure pain thresholds (algometer) were measured at baseline, after the dry needling or the sham dry needling, and after treatment.

RESULTS

Both groups showed significant improvements for all variables. In the between-group comparison, the dry needling group improved significantly in pain at three-month follow-up and pressure pain thresholds at the end of treatment for all measures, and at three-month follow-up there was no improvement in gluteus medium.

CONCLUSIONS

In chronic low back patients, adding dry needling to a four-week exercise program has an additional benefit in pain and sensitivity compared with adding sham dry needling to the same exercise program.

Establishing an adequate dose of acupuncture is essential for clinical trial studies

IMPORTANCE

A number of recent clinical trials have demonstrated that acupuncture is more effective for treating chronic pain conditions compared to sham and no acupuncture, but some research questions have remained unaddressed and are standing in the way of further progress.

OBSERVATIONS AND ADVANCES

The effectiveness of acupuncture for pain conditions compared to usual care have been demonstrated, which has significantly enhanced the position of acupuncture in multiple pain guidelines following these studies. However, the studies also generated some conflicting results with difficulty in comparing each other. Research examining an adequate dose of acupuncture therapy with optimal intervention parameters and time table has also long been neglected and is now urgent. The dose of acupuncture depends on stimulation parameters: force/intensity and speed/frequency of manual acupuncture (MA) or electroacupuncture (EA) and time table (number of treatment sessions and duration). Various frequencies and intensities of MA and EA stimulation have been utilized in individual research. Different acupuncture treatment sessions (once, twice, three to five times per week) and periods (4, 6, 8, and 12 weeks) have been used in these clinical trials. One clinical trial using one session of needle acupuncture and laser at 12 weeks (8 to 12 treated sessions) did not improve pain in patients with chronic knee pain but similar trials of osteoarthritis knee have significant effects of pain improvement after biweekly sessions of needle acupuncture for 8 weeks of treatment.

CONCLUSIONS AND RELEVANCE

Determining a right treatment regimen on correct acupuncture point(s) for acupuncture is a critical first step for acupuncture clinical trials. Appropriate acupuncture parameters such as acupuncture stimulation technique, treatment sessions, and treatment duration must be considered in acupuncture clinical trials. An adequate dose of acupuncture for clinical trials should be established following dose finding workshops for acupuncture before the studies, which not only improve the therapeutic effects of the therapies but also allow the comparisons between trials and between the acupuncture community/practice and trial studies.

Short-term effects of two deep dry needling techniques on pressure pain thresholds and electromyographic amplitude of the lumbosacral multifidus in patients with low back pain - a randomized clinical trial

Objectives: The purpose of this study was to compare the effects of deep dry needling (DN) with and without needle manipulation on pressure pain thresholds (PPTs) and electromyographic (EMG) amplitude of the lumbosacral multifidus (LM) in adults with low back pain (LBP). Methods: Participants were randomized into two treatment groups: with needle manipulation (n = 21) and without needle manipulation (n = 21). All participants received a single session of the assigned DN intervention. PPTs and EMG amplitude of the LM muscle were collected three times: before DN, immediately after DN, and one week after DN. Results: The needle manipulation group had a significantly greater increase in PPT immediately after the intervention and at the one-week follow-up as compared to the no needle manipulation group. The increase of PPT in the needle manipulation group was significant immediately after the intervention, and the increase remained significant at the one-week follow-up. However, there was no significant difference in EMG amplitude of the LM muscle between groups across the three time points. Discussion: Deep DN with needle manipulation appeared to reduce mechanical pressure sensitivity more than DN without manipulation for patients with LBP. Although a single session of DN could reduce pressure pain sensitivity, it may not be sufficient to improve LM muscle function. Level of Evidence: 1b. Trial registration numbers: NCT03970486.

Therapeutic Effect of Superficial Acupuncture in Treating Myofascial Pain of the Upper Trapezius Muscle: A Randomized Controlled Trial

The aim of this study was to compare the treatment efficacies of superficial acupuncture and traditional acupuncture on trigger points of the upper trapezius muscle. Forty people were recruited and randomly allocated to the traditional and superficial acupuncture groups. Each subject received two treatments per week in a four-week period. Outcomes were measured by visual analogue scale (VAS), the Northwick Park neck pain questionnaire scores (NPQ), and pressure pain threshold (PPT) assessments of trigger points. Data collected before the interventions were considered as baseline. Assessments were performed after the first treatment and at the end of the second and fourth weeks of treatment. Patients reported significant (p<0.05) and immediate improvements in VAS and PPT for both superficial acupuncture and traditional acupuncture after the first treatment and after two and four weeks. Significant improvements (p<0.05) in NPQ were attained after two weeks of treatments in both groups. Because superficial acupuncture is associated with less pain while producing immediate pain relief, we recommend it for treating myofascial pain syndrome in the upper trapezius muscle.

Nitric oxide signaling molecules in acupoints: Toward mechanisms of acupuncture

Recent clinical trial studies have demonstrated that the effects of acupuncture on pain improvement are small and no difference between acupoints and non-points. Whether acupuncture needles must be inserted in specific points depends on whether acupoint specificity exists that is still not resolved, and is now urgent. Previous anatomical studies have demonstrated that acupoints exist higher number of nerve fibers/trunks, blood vessels, hair follicles, and sweat glands as well as density of the gap junction. Recent evidence shows that nitric oxide (NO) level is elevated in the acupoints/ meridians and is associated with an enhanced expression of NO synthase endowed with transient receptor potential vanilloid type-1. There is growing evidence from international groups showing that acupuncture induces NO-mediated vasodilatation, which increases local blood flow and allows for a flush of algesic or sensitizing substances, leading to pain relief. Previous studies, using a novel biocapture system, have demonstrated that NOx- (total nitrite and nitrate) and cyclic guanosine monophosphate (cGMP) concentrations are consistently increased over skin acupoints compared to non-meridian control regions (NMCR) in humans. Dermal microdialysis in humans showed that NO-cGMP releases in the subcutaneous tissue of acupoint are higher than those in NMCR and increased by electroacupuncture (EA). Recent studies have demonstrated that low-frequency electrical stimulation and manual acupuncture with low stimulating force and rate produce an elevation of NO release predominantly over acupoints. In contrast, NO levels over the areas of the skin regions are moderately reduced by high-frequency EA stimulation. The results from anatomical and biochemical studies consistently show that acupoints exist higher levels of NO signaling molecules, and stimulus-evoked NO release is also with a higher level at acupoints. Results suggest that NO signaling molecules contribute to the specificity of acupoints, and selecting well-trained acupuncturetists for using correct acupoints and appropriate parameters should improve acupuncture clinical trial studies.

Effects of Combined Far-Infrared Radiation and Acupuncture at ST36 on Peripheral Blood Perfusion and Autonomic Activities

Using four-channel photoplethysmography (PPG) for acquiring peripheral arterial waveforms, this study investigated vascular and autonomic impacts of combined acupuncture-far infrared radiation (FIR) in improving peripheral circulation. Twenty healthy young adults aged 25.5 ± 4.6 were enrolled for 30-minute measurement. Each subject underwent four treatment strategies, including acupuncture at ST36 (Zusanli), pseudoacupuncture, FIR, and combined acupuncture-FIR at different time points. Response was assessed at 5-minute intervals. Area under arterial waveform at baseline was defined as Area_Baseline, whereas Area_Stim referred to area at each 5-minute substage during and after treatment. Area_Stim/Area_Baseline was compared at different stages and among different strategies. Autonomic activity at different stages was assessed using low-to-high frequency power ratio (LHR). The results demonstrated increased perfusion for each therapeutic strategy from stage 1 to stage 2 (all p < 0.02). Elevated perfusion was noted for all treatment strategies at stage 3 compared to stage 1 except pseudoacupuncture. Increased LHR was noted only in subjects undergoing pseudoacupuncture at stage 3 compared to stage 1 (p = 0.045). Reduced LHR at stage 2 compared to stage 1 was found only in combined treatment group (p = 0.041). In conclusion, the results support clinical benefits of combined acupuncture-FIR treatment in enhancing peripheral perfusion and parasympathetic activity.