Effects triggered in the periphery by acupuncture

Attenuation of immobilization stress-induced hypertension by temperature-controllable warm needle acupuncture in rats and the peripheral neural mechanisms

Introduction

We and others have shown that electrical stimulation of the PC-6 acupoint over the wrist relieves hypertension by stimulating afferent sensory nerve fibers and activating the central endogenous opioid system. Warm needle acupuncture has long been utilized to treat various diseases in clinics.

Methods

Here, we developed a temperature-controllable warm needle acupuncture instrument (WAI) and investigated the peripheral mechanism underlying the effect of warm needle acupuncture at PC-6 on hypertension in a rat model of immobilization stress-induced hypertension.

Results

Stimulation with our newly developed WAI and traditional warm needle acupuncture attenuated hypertension development. Such effects were reproduced by capsaicin (a TRPV1 agonist) injection into PC-6 or WAI stimulation at 48°C. In contrast, PC-6 pretreatment with the TRPV1 antagonist capsazepine blocked the antihypertensive effect of WAI stimulation at PC-6. WAI stimulation at PC-6 increased the number of dorsal root ganglia double-stained with TRPV1 and CGRP. QX-314 and capsaicin perineural injection into the median nerve for chemical ablation of small afferent nerve fibers (C-fibers) prevented the antihypertensive effect of WAI stimulation at PC-6. Additionally, PC-6 pretreatment with RTX ablated the antihypertensive effect of WAI stimulation.

Conclusion

These findings suggest that warm needle acupuncture at PC-6 activates C-fiber of median nerve and the peripheral TRPV1 receptors to attenuate the development of immobilization stress-induced hypertension in rats.

Effects of acupuncture at acupoints with lower versus higher pain threshold for knee osteoarthritis: a multicenter randomized controlled trial

BACKGROUND

The acupoint selections impact the effects of acupuncture, and preliminary evidence showed potential connection between pain threshold (PT) and acupuncture response. This study examined whether acupuncture at acupoints with lower PT versus higher PT would yield different effects in patients with knee osteoarthritis (KOA).

METHODS

In this multicenter randomized clinical trial, patients were randomly assigned (1:1:1) to receive acupuncture at acupoints with lower PT (LPT group), acupuncture at acupoints with higher PT (HPT group), and no acupuncture (waiting-list group). PT was measured with electronic von Frey detector. The primary outcome was the change in WOMAC total score from baseline to 16 weeks, and the secondary outcomes were SF-12 score, and active knee range of motion (ROM). Intention-to-treat analysis was conducted with linear mixed-effect model.

RESULTS

Among 666 randomized patients, 625 (93.84%) completed the study. From baseline to 16 weeks, patients in the LPT group versus HPT group had similar effects in reducing WOMAC total score (adjusted mean difference (MD) 2.21, 95% confidence interval (CI) -2.51 to 6.92, P = 0.36), while a greater reduction in WOMAC total score was observed in LPT group (-9.77, 95% CI -14.47 to -5.07, P < 0.001) and HPT group (-11.97, 95% CI -16.71 to -7.24, P < 0.001) compared with waiting-list group. There were no differences in SF-12 score and knee ROM between LPT versus HPT groups.

CONCLUSION

Our findings found that the effects of acupuncture at acupoints with lower versus higher PT were similar, both were effective for patients with KOA.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03299439. Registered 3 October 2017, https://clinicaltrials.gov/ct2/show/NCT03299439.

Effect of Acupuncture on Time-Dependent of Muscle Endurance in Female Elbow Joint: A Randomized Controlled Trial

Immediate characteristics of acupuncture have been confirmed by relevant studies; however, the current study on the time effect of acupuncture in improving upper limb forearm muscle endurance is still limited. The aims of this study are to explore: (1) whether real acupuncture (RA) can improve female forearm muscle endurance compared to sham acupuncture (SA) and (2) whether the changes in forearm muscle endurance after RA are time-dependent. Thirty-six healthy female students were recruited to participate in isokinetic tests of elbow flexion/extension (Flex/Ext) from maximum flexion to maximum extension as much as possible using an isokinetic dynamometer at a speed rate of 60°/sec. Participants in the RA group were stimulated at Quchi (LI11), Shousanli (LI10), Hegu (LI4), Xiaohai (SI8), Tianjing (SJ10), and Waiguan (SJ5) acupoints for 20 min, while the SA group needling was near at these acupoints. The values of the isokinetic parameters and surface electromyography (sEMG) signals were recorded before and after acupuncture. After RA, the isokinetic parameters values (average torque, work, power, and speed), the sEMG values at four major muscles, and the joint stiffness of elbow Flex/Ext were significantly increased (p < 0.05). The enhancement of forearm muscle endurance lasted approximately 7–21 min (from post1 to post3/post4), indicating that the effect of RA to improve elbow Flex/Ext muscle endurance is time-dependent. Therefore, this study found that RA can immediately improve the forearm muscle endurance of healthy women compared with SA, and this effect can last approximately 7–21 min until the acupuncture efficacy decreased or disappeared.

Peripheral receptors and neuromediators involved in the antihyperalgesic effects of acupuncture: a state-of-the-art review

The present study aims to describe state-of-the-art of preclinical studies that have investigated peripheral receptors and neuromediators involved in the antihyperalgesic effects of acupuncture. The PubMed, Scopus, and Web of Science databases were searched using the integrative review method. Preclinical articles that involved the study of peripheral receptors and neuromediators on the pain control effects of acupuncture in rats or mice were selected using a predefined search strategy. From this search, 456 articles were found, and 29 of them met the inclusion criteria of the study. The selected articles addressed the following peripheral receptors: opioid (n = 9), adenosine (n = 5), cannabinoid (n = 5), transient receptor potential vanilloid (TRPV) (n = 3), histamine (n = 2), adrenergic (n = 1), muscarinic (n = 1), corticotrophin-releasing factor (CRF) (n = 2), IL-1 (n = 1), and endothelin (n = 1) receptors. The peripheral neuromediators correlated with the peripheral pain control effect were as follows: opioid peptides (n = 4), adenosine (n = 3), histamine (n = 1), substance P (n = 1) calcitonin gene-related peptide (CGRP) (n = 1), anandamide (n = 1), nitric oxide (n = 1), and norepinephrine (n = 1). This review summarizes the methods used to investigate the peripheral effects of acupuncture and discusses the main findings on each family of receptors and neuromediators. Ten families of peripheral receptors and 8 types of neuromediators were correlated with the antihyperalgesic effects of acupuncture in preclinical studies. Considering the benefits of a better understanding of the role of peripheral receptors and neuromediators in the context pain management, the findings of the present study highlight the importance of deepening the exploration of the peripheral mechanisms of acupuncture.

Dry needling strategies for musculoskeletal conditions: Do the number of needles and needle retention time matter? A narrative literature review

Acupuncture and dry needling are both minimally invasive procedures that use thin, filiform needles without injectate for the management of a variety of neuromusculoskeletal pain conditions. While the theoretical constructs underlying the use of acupuncture and dry needling are unique, both appear to have the ability to elicit biochemical, biomechanical, endocrinological and neurovascular changes associated with reductions in pain and disability. However, optimal treatment dosage has yet to be determined, and there is a lack of consistency in the literature on the number of needles that should be inserted and the needle retention time. Therefore, the purpose of this narrative review is to further explore the importance of these two variables. While trigger point dry needling advocates single needle insertions via repetitive, quick in-and-out pistoning, most acupuncture and dry needling clinical trials have incorporated multiple needles for five to 40 min. Notably and to date, using a single needle to repeatedly prick trigger points one at a time with fast-in and fast-out pistoning maneuvers has not yet been shown to produce significant and clinically meaningful long term improvements in pain and disability in a wide array of musculoskeletal conditions. Insertion of multiple needles for typically 20-30 min durations has been shown to produce larger treatment effect sizes and longer-lasting outcomes than brief, single-needle strategies. Moreover, the number of needles and needle retention time are two variables associated with treatment dosage and must be carefully matched with specific musculoskeletal conditions and the patient's goals.

Acupuncture Points and Perforating Cutaneous Vessels Identified Using Infrared Thermography: A Cross-Sectional Pilot Study

Aims

To evaluate the presence of perforating cutaneous vessels (PCV) in different lower limb acupuncture points (AP) using thermography.

Material and Methods

An analytical cross-sectional study was performed on the two lower limbs (n=6) of volunteer subjects. In total, 144 AP and 144 control points (CP) were analysed, one for each AP. First, the AP and CP were located on each individual. Subsequently, both the real and thermographic images were created. In the real images, the location of the AP and the established CP were highlighted with boxes. FLIR Tools Plus and Physio Thermal Imaging software were used to merge the real image with the AP and the CP and to merge the thermographic image with the PCV. By superimposing both images, we were able to verify the presence of PCV among the AP and CP.

Results

PCV were identified in 87.5% of the 144 AP examined and in 18.1% of the respective CP. All the AP had a higher percentage of PCV compared to their respective CP, with statistically significant differences in all points, except for ST33 and ST34. The probability of finding PCV in AP was 11 times higher than the probability of not finding it.

Discussion

Thermography may serve as a useful tool in the assessment and treatment of patients using acupuncture. The presence of PCV in the area of the acupuncture needle insertion could partially influence the effects generated by the acupuncture technique from the vascular autonomic point of view.

Conclusions

There is a high proportion of PCV in the AP area located in the lower limb.