Effect of Different Frequencies of Electroacupuncture on Post-Stroke Dysphagia in Mice

Screening for optimal parameters for modified pharyngeal electrical stimulation for the treatment of dysphagia after stroke in rats

Pharyngeal electrical stimulation (PES), a novel noninvasive peripheral nerve stimulation technique, can effectively improve neurogenic dysphagia and increase the safety and effectiveness of swallowing in the clinic. However, the lack of animal models for dysphagia has limited the mechanistic research on PES, which affects its wide application. Therefore, determining optimal parameters for PES in rats is needed to enable mechanistic studies. Modified PES (mPES), which has different waves and pulse widths from PES, was used; in previous studies mPES was found to have a neurological mechanism like that of PES. A poststroke dysphagia (PSD) model was established, and rats with dysphagia were grouped into three different intensities (0.1 mA, 0.5 mA, and 1 mA) for the selection of optimal intensity and three different frequencies (1 Hz, 2 Hz, and 5 Hz) for the selection of optimal frequency based on a stimulation duration of 10 min in the clinic. A Videofluroscopic Swallow Screen (VFSS) was used to assess swallowing function in rats before and after mPES treatment. The results showed that the 1 mA group had better swallowing function (p < 0.05) than the model group. Compared with the model group, the 1 Hz and 5 Hz groups had the same improvement in swallowing function (p < 0.05). However, the increase in excitatory signals in the sensorimotor cortex was more pronounced in the 5 Hz group than in the other frequency stimulation groups (p < 0.05). Combining the clinical findings with the above results, we concluded that the optimal stimulation parameter for mPES in rats is "frequency: 5 Hz, current intensity: 1 mA for 10 min/day", which provides a basis for future basic experimental studies of mPES in animals.

Increased sensitivity in detection of deficits following two commonly used animal models of stroke

Stroke is a leading cause of death and disability in the United States. Most strokes are ischemic, resulting in both cognitive and motor impairments. Animal models of ischemic stroke such as the distal middle cerebral artery occlusion (dMCAO) and photothrombotic stroke (PTS) procedures have become invaluable tools, with their own advantages and disadvantages. The dMCAO model is clinically relevant as it occludes the artery most affected in humans, but yields variability in the infarct location as well as the behavioral and cognitive phenotypes disrupted. The PTS model has the advantage of allowing for targeted location of infarct, but is less clinically relevant. The present study evaluates phenotype disruption over time in mice subjected to either dMCAO, PTS, or a sham surgery. Post-surgery, animals were tested over 28 days on standard motor tasks (grid walk, cylinder, tapered beam, and rotating beam), as well as a novel odor-based operant task; the 5:1 Odor Discrimination Task (ODT). Results demonstrate a significantly greater disturbance of motor control with PTS as compared with Sham and dMCAO. Disruption of the PTS group was detected up to 28 days post-stroke on the grid walk, and up to 7 days on the rotating and tapered beam tasks. PTS also led to significant short-term disruption of ODT performance (1-day post-surgery), exclusively in males, which appeared to be driven by motoric disruption of the lick response. Together, this data provides critical insights into the selection and optimization of animal models for ischemic stroke research. Notably, the PTS procedure was best suited for producing disruptions of motor behavior that can be detected with common behavioral assays and are relatively enduring, as is observed in human stroke.

Role of TRPV1 in electroacupuncture-mediated signal to the primary sensory cortex during regulation of the swallowing function

AIMS

Electroacupuncture (EA) at the Lianquan (CV23) could alleviate swallowing dysfunction. However, current knowledge of its neural modulation focused on the brain, with little evidence from the periphery. Transient receptor potential channel vanilloid subfamily 1 (TRPV1) is an ion channel predominantly expressed in sensory neurons, and acupuncture can trigger calcium ion (Ca2+ ) wave propagation through active TRPV1 to deliver signals. The present study aimed to investigate whether TRPV1 mediated the signal of EA to the primary sensory cortex (S1) during regulation of swallowing function.

METHODS

Blood perfusion was evaluated by laser speckle contrast imaging (LSCI), and neuronal activity was evaluated by fiber calcium recording and c-Fos staining. The expression of TRPV1 was detected by RNA-seq analysis, immunofluorescence, and ELISA. In addition, the swallowing function was assessed by in vivo EMG recording and water consumption test.

RESULTS

EA treatment potentiated blood perfusion and neuronal activity in the S1, and this potentiation was absent after injecting lidocaine near CV23. TRPV1 near CV23 was upregulated by EA-CV23. The blood perfusion at CV23 was decreased in the TRPV1 hypofunction mice, while the blood perfusion and the neuronal activity of the S1 showed no obvious change. These findings were also present in post-stroke dysphagia (PSD) mice.

CONCLUSION

The TRPV1 at CV23 after EA treatment might play a key role in mediating local blood perfusion but was not involved in transferring EA signals to the central nervous system (CNS). These findings collectively suggested that TRPV1 may be one of the important regulators involved in the mechanism of EA treatment for improving swallowing function in PSD.

Electroacupuncture Attenuates Ventilator-Induced Lung Injury by Modulating the Nrf2/HO-1 Pathway

INTRODUCTION

Ventilator-induced lung injury (VILI) is the most common complication associated with mechanical ventilation. Electroacupuncture (EA) has shown potent anti-inflammatory effects. This study aimed to investigate the effects of EA on VILI and explore the underlying mechanisms.

METHODS

Male C57BL/6 mice were subjected to high tidal volume ventilation to induce VILI. Prior to mechanical ventilation, mice received treatment with EA, nonacupoint EA, or EA combined with zinc protoporphyrin.

RESULTS

EA treatment significantly improved oxygenation, as indicated by increased PaO2 levels in VILI mice. Moreover, EA reduced lung injury score, lung wet/dry weight ratio, and protein concentration in bronchoalveolar lavage fluid. EA also decreased the expression of pro-inflammatory cytokines including interleukin (IL)-1β, IL-6, tumor necrosis factor-α, IL-18, chemokine keratinocyte chemoattractant, macrophage inflammatory protein 2, and malondialdehyde. Furthermore, EA increased the activities of antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase in VILI mice. At the molecular level, EA upregulated the expression of Nrf2 (nucleus) and heme oxygenase -1, while down-regulating the expression of p-NF-κB p65, NLR Family Pyrin Domain Containing 3, Cleaved Caspase-1, and ASC in VILI mice. Notably, the effects of EA were reversed by zinc protoporphyrin treatment, nonacupoint EA did not affect the aforementioned indicators of VILI.

CONCLUSIONS

EA alleviates VILI by inhibiting the NLR Family Pyrin Domain Containing three inflammasome through activation of the Nrf2/HO-1 pathway.

The Role of Perineuronal Nets in the Contralateral Hemisphere in the Electroacupuncture-Mediated Rehabilitation of Poststroke Dysphagia Mice

Acupuncture at Lianquan (CV23) acupoint has been shown to improve swallowing function in poststroke dysphagia (PSD). This improvement is supposed to be associated with the regulation of neuronal activity in the contralateral primary motor cortex (M1), while the underlying mechanism still needs to be elucidated. Perineuronal nets (PNNs) are well-known to be involved in the regulation of neuronal activity. Thus, we here aimed to detect the role of PNNs in the contralateral M1 hemisphere in the electroacupuncture (EA)-mediated effect in male mice. The results were obtained from a combination of methods, including in vitro slice electrophysiological recording, in vivo electrophysiological recording, and immunofluorescent staining in male mice. These results showed a decrease of the excitatory postsynaptic currents (sEPSCs) and no alteration of the inhibitory postsynaptic currents (sIPSCs) in the GABAergic neurons and the tonic inhibition in the excitatory neurons in the contralateral M1 after stroke induction, and EA recovered the impaired sEPSCs in the GABAergic neurons. We further found that the effect of EA-induced increase of c-Fos expression, enhancement of spike firing, potentiation of sEPSCs in the excitatory neurons, and improvement of swallowing function were all blocked by the removal of PNNs in the contralateral M1. In conclusion, the PNNs in the contralateral M1 was suggested to be participated in stroke pathogenesis and might be associated with the EA-mediated swallowing function rehabilitation of PSD in male mice. Our study provides insight into how PNNs might be involved in the mechanism of EA treatment for stroke rehabilitation.

Electroacupuncture improves swallowing function in a post-stroke dysphagia mouse model by activating the motor cortex inputs to the nucleus tractus solitarii through the parabrachial nuclei

As a traditional medical therapy, stimulation at the Lianquan (CV23) acupoint, located at the depression superior to the hyoid bone, has been shown to be beneficial in dysphagia. However, little is known about the neurological mechanism by which this peripheral stimulation approach treats for dysphagia. Here, we first identified a cluster of excitatory neurons in layer 5 (L5) of the primary motor cortex (M1) that can regulate swallowing function in male mice by modulating mylohyoid activity. Moreover, we found that focal ischemia in the M1 mimicked the post-stroke dysphagia (PSD) pathology, as indicated by impaired water consumption and electromyographic responses in the mylohyoid. This dysfunction could be rescued by electroacupuncture (EA) stimulation at the CV23 acupoint (EA-CV23) in a manner dependent on the excitatory neurons in the contralateral M1 L5. Furthermore, neuronal activation in both the parabrachial nuclei (PBN) and nucleus tractus solitarii (NTS), which was modulated by the M1, was required for the ability of EA-CV23 treatment to improve swallowing function in male PSD model mice. Together, these results uncover the importance of the M1-PBN-NTS neural circuit in driving the protective effect of EA-CV23 against swallowing dysfunction and thus reveal a potential strategy for dysphagia intervention.

Manual acupuncture for neuromusculoskeletal disorders: The selection of stimulation parameters and corresponding effects

As a minimally invasive method of physical stimulation, manual acupuncture (MA) is used globally as a sort of therapy for neuromusculoskeletal disorders. In addition to selecting appropriate acupoints, acupuncturists should also determine the stimulation parameters of needling, such as the manipulation (lifting-thrusting or twirling), needling amplitude, velocity, and stimulation time. At present, most studies focus on acupoint combination and mechanism of MA, the relationship between stimulation parameters and their therapeutic effects, as well as the influence on mechanism of action are relatively scattered, and lack of systematic summary and analysis. This paper reviewed the three types of stimulation parameters of MA, their common options and values, corresponding effects and potential mechanisms of action. The purpose of such efforts is to provide a useful reference for the dose-effect relationship of MA and the quantification and standardization of its clinical treatment of neuromusculoskeletal disorders to further promote the application of acupuncture in the world.

Acupuncture at GV20 and ST36 Improves the Recovery of Behavioral Activity in Rats Subjected to Cerebral Ischemia/Reperfusion Injury

Traditional acupuncture and electroacupuncture (EA) have been widely performed to treat ischemic stroke. To provide experimental support for the clinical application of acupuncture to ameliorate post-stroke sequelae, in this study, we investigated the therapeutic effect of acupuncture and EA on CIRI following middle cerebral artery occlusion (MCAO) in rats. The animals were randomly divided into five groups: sham-operated (S), model (M), traditional acupuncture (A) treatment, electroacupuncture (EA) treatment, and drug (D; edaravone) therapies. Neurological behavioral characteristics (neurological deficit score, forelimb muscle strength, sensorimotor function, body symmetry, sucrose consumption, and mood) were examined in all the groups on days 1, 3, 5, and 7 after reperfusion. Expressions of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α) were detected by immunohistochemistry. Both acupuncture and EA significantly reduced neurological deficits and improved forelimb muscle strength, sensorimotor function, body symmetry recovery, and neurovascular regeneration in the rats after ischemia/reperfusion injury. The efficacies of both acupuncture and EA were comparable to that of edaravone, a commonly used medicine for stroke in the clinic. Thus, our data suggest that acupuncture and EA therapy at acupoints GV20 and ST36 might represent alternative or complementary treatments to the conventional management of ischemic stroke, providing additional support for the experimental evidence for acupuncture therapy in clinical settings. In summary, EA might provide alternative or complementary treatment strategies for treating patients with apoplexy in the clinic. However, potential mechanisms underlying the role of acupuncture require further investigation.

Excitatory neurons in paraventricular hypothalamus contributed to the mechanism underlying acupuncture regulating the swallowing function

Paraventricular hypothalamus (PVH) is demonstrated to regulate stress, feeding behaviors, and other related homeostatic processes. However, no direct evidence has been investigated for the role of PVH in swallowing function. Acupuncture therapy at Lianquan (CV23) acupoint has been reported to improve the swallowing function in clinical trials, but its underlying mechanism still needs to be uncovered. Thus, we aimed to explore whether PVH involved the acupuncture mediated regulating swallowing function. Chemogenetics, electromyography (EMG) recording, and immunofluorescence staining methods were combined to demonstrate that neurons in PVH could be activated by electroacupuncture (EA) stimulation at CV23, and this neuronal cluster was represented as excitatory neurons. Furthermore, we mapped both the inputs and outputs of PVH neurons using viral tracing. The neurons in PVH projected with the brain regions, including parabrachial nucleus (PBN) and the solitary tract nucleus (NTS), which both participated in the swallowing process. The EA function regulating the swallowing was attenuated after inhibiting the neurons in PVH in the post stroke dysphagia. In conclusion, this study suggested that EA at CV23 could regulate swallowing function involving the excitatory neurons in PVH.

Clinical Effects of Acupuncture for Stroke Patients Recovery

Stroke is assumed as one of the common cerebrovascular diseases that endangers human health and life. Its incidence and mortality rates are high, while survivors (50% to 70%) suffer from different degrees of disability. Hemiplegia is a common disability after stroke, mainly manifested as muscle weakness of the affected side, limb spasm, and limited activity, which severely impacts a patient's daily life. There are various rehabilitation methods for stroke hemiplegia, including modern rehabilitation medicine, motor therapy, acupuncture, and rehabilitation robot. The cost and effect of different rehabilitation methods are not the same. It is the focus to find an economical and effective rehabilitation method. In this paper, 128 stroke patients aged 41 to 73 hospitalized between January 2019 and January 2021 were analyzed. The intervention group used standard physical therapy and traditional acupuncture therapy, and the control group only used standard physical therapy. We used RStudio 1.1.419 (RStudio Corporation) for analysis. Experimental results show that the short-term efficacy of the intervention group is better than that of the control group. The intervention group was better than the control group in recovery from injury during rehabilitation, degree of muscle spasm, self-care ability in daily life, and overall degree of damage. In the long-term efficacy analysis, we can see that with the increase in the number of acupuncture, the efficacy of the intervention group is still better than that of the control group. Compared with physical rehabilitation alone, acupuncture has better short-term, and long-term clinical effects for stroke patients improves motor dysfunction and improves the quality of life and independence of stroke patients. With the increase in the number of acupuncture treatments, the patient's rehabilitation effect will be better.

Electroacupuncture Preconditioning Reduces Oxidative Stress in the Acute Phase of Cerebral Ischemia-Reperfusion in Rats by Regulating Iron Metabolism Pathways

Background

Oxidative stress is an important mechanism of cerebral ischemia-reperfusion injury. Ferroptosis caused by iron overload after cerebral ischemia-reperfusion is considered a common cause of oxidative stress. Many recent studies have shown that electroacupuncture (EA) can regulate the expression of inflammatory factors, and the use of electroacupuncture preconditioning can produce a protective effect, which can reduce injury after cerebral ischemia and reperfusion. We aimed to assess whether EA could be used to reduce oxidative stress.

Methods

The oxidative stress level of rats during the acute phase of cerebral ischemia and reperfusion was assessed with and without preconditioning with EA. Molecular biology methods were used to detect iron metabolism and oxidative stress-related proteins.

Results

Rats that had EA preconditioning had lower infarct volumes than rats in the control group. Furthermore, western blot analysis showed that the expression of iron metabolism-related protein FPN-1 was higher in the intervention group than in the model group after reperfusion. In this regard, further investigation also demonstrated higher expression of glutathione and glutathione peroxidase-4, and lower reactive oxygen species values in the brain tissue of the EA group were compared with those of the control group rats.

Conclusions

Electroacupuncture preconditioning can reduce oxidative stress after cerebral ischemia-reperfusion by regulating iron overload.

Contralateral S1 function is involved in electroacupuncture treatment-mediated recovery after focal unilateral M1 infarction

Acupuncture at acupoints Baihui (GV20) and Dazhui (GV14) has been shown to promote functional recovery after stroke. However, the contribution of the contralateral primary sensory cortex (S1) to recovery remains unclear. In this study, unilateral local ischemic infarction of the primary motor cortex (M1) was induced by photothrombosis in a mouse model. Electroacupuncture (EA) was subsequently performed at acupoints GV20 and GV14 and neuronal activity and functional connectivity of contralateral S1 and M1 were detected using in vivo and in vitro electrophysiological recording techniques. Our results showed that blood perfusion and neuronal interaction between contralateral M1 and S1 is impaired after unilateral M1 infarction. Intrinsic neuronal excitability and activity were also disturbed, which was rescued by EA. Furthermore, the effectiveness of EA treatment was inhibited after virus-mediated neuronal ablation of the contralateral S1. We conclude that neuronal activity of the contralateral S1 is important for EA-mediated recovery after focal M1 infarction. Our study provides insight into how the S1–M1 circuit might be involved in the mechanism of EA treatment of unilateral cerebral infarction. The animal experiments were approved by the Committee for Care and Use of Research Animals of Guangzhou University of Chinese Medicine (approval No. 20200407009) April 7, 2020.

Effect of opposing needling on motor cortex excitability in healthy participants and in patients with post-stroke hemiplegia: study protocol for a single-blind, randomised controlled trial

Background

Opposing needling has an obvious curative effect in the treatment of post-stroke hemiplegia; however, the mechanism of the opposing needling in the treatment of post-stroke hemiplegia is still not clear. The purpose of this study is to investigate the effect of opposing needling on the excitability of primary motor cortex (M1) of healthy participants and patients with post-stroke hemiplegia, which may provide insight into the mechanisms of opposing needling in treating post-stroke hemiplegia.

Methods

This will be a single-blind, randomised, sham-controlled trial in which 80 healthy participants and 40 patients with post-stroke hemiplegia will be recruited. Healthy participants will be randomised 1:1:1:1 to the 2-Hz, 50-Hz, 100-Hz, and sham electroacupuncture groups. Patients with post-stroke hemiplegia will be randomised 1:1 to the opposing needling or conventional treatment groups. The M1 will be located in all groups by using neuroimaging-based navigation. The stimulator coil of transcranial magnetic stimulation (TMS) will be moved over the left and right M1 in order to identify the TMS hotspot, followed by a recording of resting motor thresholds (RMTs) and motor-evoked potentials (MEPs) of the thenar muscles induced by TMS before and after the intervention. The primary outcome measure will be the percent change in the RMTs of the thenar muscles at baseline and after the intervention. The secondary outcome measures will be the amplitude (μV) and latency (ms) of the MEPs of the thenar muscles at baseline and after the intervention.

Discussion

The aim of this trial is to explore the effect of opposing needling on the excitability of M1 of healthy participants and patients with post-stroke hemiplegia.

Trial registration

Chinese Clinical Trial Registry ChiCTR1900028138. Registered on 13 December 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05443-x.