Participation of the nucleus tractus solitarius in the therapeutic effect of electroacupuncture on post-stroke dysphagia through the primary motor cortex.

BACKGROUND: Post-stroke dysphagia (PSD), a common and serious disease, affects the quality of life of many patients and their families. Electroacupuncture (EA) has been commonly used effectively in the treatment of PSD, but the therapeutic mechanism is still under exploration at present. We aim to investigate the effect of the nucleus tractus solitarus (NTS) on the treatment of PSD by EA at Lianquan (CV23) through the primary motor cortex (M1). METHODS: C57 male mice were used to construct a PSD mouse model using photothrombotic technique, and the swallowing function was evaluated by electromyography (EMG) recording. C-Fos-positive neurons and types of neurons in the NTS were detected by immunofluorescence. Optogenetics and chemical genetics were used to regulate the NTS, and the firing rate of neurons was recorded via multichannel recording. RESULTS: The results showed that most of the activated neurons in the NTS were excitatory neurons, and multichannel recording indicated that the activity levels of both pyramidal neurons and interneurons in the NTS were regulated by M1. This process was involved in the EA treatment. Furthermore, while chemogenetic inhibition of the NTS reduced the EMG signal associated with the swallowing response induced by activation of M1 in PSD mice, EA rescued this signal. CONCLUSION: Overall, the NTS was shown to participate in the regulation of PSD by EA at CV23 through M1.

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

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

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.

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.

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

The aim of this study was to determine the optimum frequency of electroacupuncture (EA) for the treatment of dysphagia after stroke. Male C57BL/6 J mice were randomly divided into five groups: normal, model, 2 Hz, 50 Hz, and 100 Hz groups. All mice received a photochemical ischemia, except the normal group. The EA parameters were 1 mA for 15 min, with different frequencies (2, 50, and 100 Hz) applied. After a three day treatment, neuronal activation was detected by the expression of c-Fos. A multi-channel electrophysiological technique was used to assess the discharge of contralateral neurons and the neuron types in each group. The concentration of brain-derived neurotrophic factor (BDNF) in the contralateral neurons was also examined. In addition, the dysfunction of swallowing in mice was calculated according to the lick counts and the lick-lick interval within a certain period of time. The number of c-Fos neurons (P < 0.05) and the expression of BDNF (P < 0.05) increased after the 2 Hz EA treatment. The total frequency of neuron discharge in the 2 Hz group increased compared with the model group (P < 0.05). The pattern of sorted neuron populations was similar between the normal and 2 Hz groups. Consistent with these results, the lick counts increased (P < 0.05) and the lick-lick interval decreased after the 2 Hz EA treatment, which indicated a functional improvement in swallowing. These results indicated that the 2 Hz EA treatment had a good effect on dysphagia after stroke.

Effect of electro-acupuncture on regulating the swallowing by activating the interneuron in ventrolateral medulla (VLM).

Ventrolateral medulla(VLM) was one of the essential part of central pattern generator(CPG) in swallowing and electro-acupuncture(EA) was an important intervention in swallowing disorder. But the effect and mechanism of EA at acupoints on swallowing were unknown. The present aim to detect the effect of EA at Lianquan (CV23) on swallowing and swallowing-related(SR) interneuron in VLM. Thirty-six Sprague-Dawley rats were operated and the swallowing reflex was induced through Double distilled water (DDW) infusion. Simultaneously, the numbers of swallowing were recorded. Then EA was given at Lianquan and Neiguan (PC6) and the neuron discharges in VLM were detected. A total of 72 neurons were recorded, 60 of which were correctly recorded after histology identification. Two types of SR neurons were found and the numbers of swallowing increased after EA at CV23 and PC6 compared with no EA group. The neuron response rates were 78.3% and 50% for EA at CV23 and PC6 respectively with significant difference (P < 0.05). Meanwhile, the neuron spike patterns were changed after EA at CV23 and PC6. In addition, twenty-four rats were used for immunofluorescence after EA at CV23 and PC6. The results showed that c-fos positive cells in CV23 group were 20.63±2.35, while PC6 group was 14.13±1.78 and 6.88±1.42 in control group. There were significant difference between them (P < 0.05). These results indicated that EA could regulate the swallowing function via activating the SR interneurons in VLM under the physiological condition.

EA promotes swallowing via activating swallowing-related motor neurons in the nucleus ambiguus.

To observe the effect of electroacupuncture (EA) on swallowing and its underlying mechanism, 32 Sprague-Dawley (SD) rats were chose and the electrophysiology was used to detect the discharge of nucleus ambiguus (NA) after EA at CV23 (Lianquan), GV16 (Fengfu), and other acupoints. The swallowing-related motor neuron was identified by antidromic stimulation through recurrent laryngeal nerve. Meanwhile, the swallowing numbers were induced by Double-distilled water (DDW) and the neuron discharges were recorded before and after EA. Beside, 50 SD rats were used for testing the c-fos expressions in NA after EA at different acupoints and the other 80 SD rats were used for chemical damage through the microinjection to bilateral NA. 58 neurons provided complete data after histological identification. And two types of swallowing-related (SR) motor neurons were identified, named spontaneous and silent neurons. We found that the onset latency of the first swallow was shorter and the swallowing numbers were increased after EA at CV23 than the other acupoints (P < 0.01). The excitatory neuron response rates were 66.67%, 71.11%, 42.22% and 35.56% for CV23, GV16, PC6 (Neiguan), and ST36 (Zusanli), respectively. The c-fos expressions on CV23 and GV16 groups were significantly higher than the other groups (P < 0.05). After chemical damage, the swallowing numbers could not be regulated by EA, but could be regulated by EA after fake damage. The results of the present study demonstrate that EA at CV23 and GV16 could regulate swallowing function via activating swallowing-related motor neurons in NA.

Role of 5-HT1A in the nucleus of the solitary tract in the regulation of swallowing activities evoked by electroacupuncture in anesthetized rats.

Somatic stimulation therapy, such as electroacupuncture (EA), has been widely applied in the clinic to treat dysphagia. However, its underlying mechanism has remained unknown. In the present study, the effect of EA at acupoints Fengfu (DU16) and Lianquan (RN23) on swallowing activities and the involvement of 5-HT1A in the nucleus of the solitary tract (NTS) were examined in anesthetized rats. EA at DU16 and RN23 significantly evoked myoelectric activity of the mylohyoid muscle, which was attenuated by injection of 10 nmol 5-HT1A antagonist (WAY-100635) into the NTS. Meanwhile, 5-HT1A expression in the NTS increased following EA. The results suggested that EA at DU16 and RN23 promotes swallowing activity, and 5-HT1A in the NTS may play an important role in the excitatory effects.

Systematic Review on Acupuncture for Treatment of Dysphagia after Stroke.

OBJECTIVE: To assess the therapeutic efficacy of acupuncture for dysphagia after stroke. METHODS: Seven electronic databases were searched from their inception until 31 September 2016. All randomized controlled trials (RCTs) incorporating acupuncture or acupuncture combined with other interventions for treatment of dysphagia after stroke were enrolled. Then they were extracted and assessed by two independent evaluators. Direct comparisons were conducted in RevMan 5.3.0 software. RESULTS: 6010 patients of 71 papers were included. The pooled analysis of efficacy rate of 58 studies indicated that acupuncture group was superior to the control group with moderate heterogeneity (RR = 1.17, 95% CI: 1.13 1.21, Z = 9.08, and P < 0.00001); meta-analysis of the studies using blind method showed that the efficacy rate of acupuncture group was 3.01 times that of control group with no heterogeneity (RR = 3.01, 95% CI: 1.95 4.65, Z = 4.97, and P < 0.00001). Only 13 studies mentioned the safety evaluation. CONCLUSION: The result showed that the acupuncture group was better than control group in terms of efficacy rate of dysphagia after stroke. And the combining result of those researches using blind method was more strong in proof. Strict evaluation standard and high-quality RCT design are necessary for further exploration.

Effect of Subcritical Fluid Extraction on the High Quality of Headspace Oil from Jasminum sambac (L.) Aiton.

Subcritical fluid extraction (SFE), as a novel method, was applied to investigate the yield, quality, and sensory evaluation of headspace oil from Jasminum sambac (L.) Aiton in comparison with petroleum ether extraction (PEE). The results indicated that the yield of the headspace oil using SFE was significantly higher (P < 0.05) than when using PEE. SFE contributed to obtaining alcohols and ethers, prevented the thermal reaction of terpenes, and reduced α-caryophyllene and ß-caryophyllene in the headspace oil. The contents of linalool (21.90%) and benzyl acetate (16.31%) were higher via SFE than PEE. In addition, the sensory evaluation of SFE was superior to PEE, indicating a fresh, jasmine-like odor and green-yellow color. Thus, SFE is an improved method for obtaining natural headspace oil from jasmine flowers.

An Efficient Extraction Method for Fragrant Volatiles from Jasminum sambac (L.) Ait.

The sweet smell of aroma of Jasminum sambac (L.) Ait. is releasing while the flowers are blooming. Although components of volatile oil have been extensively studied, there are problematic issues, such as low efficiency of yield, flavour distortion. Here, the subcritical fluid extraction (SFE) was performed to extract fragrant volatiles from activated carbon that had absorbed the aroma of jasmine flowers. This novel method could effectively obtain main aromatic compounds with quality significantly better than solvent extraction (SE). Based on the analysis data with response surface methodology (RSM), we optimized the extraction conditions which consisted of a temperature of 44°C, a solvent-to-material ratio of 3.5:1, and an extraction time of 53 min. Under these conditions, the extraction yield was 4.91%. Furthermore, the key jasmine essence oil components, benzyl acetate and linalool, increase 7 fold and 2 fold respectively which lead to strong typical smell of the jasmine oil. The new method can reduce spicy components which lead to the essential oils smelling sweeter. Thus, the quality of the jasmine essence oil was dramatically improved and yields based on the key component increased dramatically. Our results provide a new effective technique for extracting fragrant volatiles from jasmine flowers.