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

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.

Acupuncture for swallowing disorder after recovery from COVID-19: A protocol for systematic review and meta analysis

BACKGROUND

Swallowing disorder is a common sequela after recovery from COVID-19. Acupuncture is an important traditional therapy for treating swallowing disorder. However, the efficacy of acupuncture for swallowing disorder after recovery from COVID-19 lacks evidence-based medicine.

METHODS

All randomized controlled trials of acupuncture for swallowing disorder after recovery from COVID-19 will be retrieved and collected from December 2019 to November 2022 with no language restrictions. PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure Database, Chinese Biomedical Database, Chinese Science and Technology Journal Database (VIP), and the Wanfang Database will be searched. Two researchers will independently select studies, extract data, and evaluate study quality. The Cochrane risk of bias tool for randomized trials will be used to assess the risk of bias in the included studies. Statistical analyses will be performed using Review Manager version 5.3.

RESULTS

This study will provide a high-quality and convincing assessment of the efficacy and safety of acupuncture for swallowing disorder after recovery from COVID-19 and will be published in peer-reviewed journals.

CONCLUSION

Our findings will provide a reference for future clinical decisions and guidance development.

Press needle for aspiration pneumonia prevention in older adults: Study protocol for a randomized double-blind placebo-controlled trial

BACKGROUND

Pneumonia is the fifth most common cause of death among the Japanese population, with 97% of the deaths occurring among older adults aged ≥65 years. The incidence ratio of aspiration pneumonia is high among the older adults. Therefore, its prophylaxis is important in geriatric medicine. In our previous studies, we reported that stimulation of acupoints at stomach meridian 36 and kidney meridian 3 of the lower limbs with a press needle improved the swallowing function of patients with dysphagia. Improvements in swallowing function may prevent aspiration pneumonia. This study aims to investigate the protective efficacy of press needle stimulation in the lower limbs for aspiration pneumonia.

METHODS/DESIGN

This is a multicenter, randomized, double-blind, placebo-controlled trial. A total of 140 patients with cerebrovascular disorder and a history of aspiration pneumonia will be recruited from 6 centers and randomly assigned to either the real or sham press needle group in a 1:1 ratio. The press needle will be replaced twice a week. The treatment will be administered bilaterally at acupoints stomach meridian 36 and kidney meridian 3. The primary outcome is the frequency of aspiration pneumonia onset. The secondary outcome is the improvement of the latent time of the swallowing reflex. The study period is of 12-month. The primary outcome will be evaluated throughout the study period, while the secondary outcomes will be assessed at baseline, 1st month, 6th month, and at the end of the investigation period.

DISCUSSION

This study will evaluate the effects of press needle on the prevention of aspiration pneumonia and the improvement of swallowing function in patients. The results of this study will help support the prophylaxis of aspiration pneumonia.

Electroacupuncture Involved in Motor Cortex and Hypoglossal Neural Control to Improve Voluntary Swallowing of Poststroke Dysphagia Mice

The descending motor nerve conduction of voluntary swallowing is mainly launched by primary motor cortex (M1). M1 can activate and regulate peripheral nerves (hypoglossal) to control the swallowing. Acupuncture at “Lianquan” acupoint (CV23) has a positive effect against poststroke dysphagia (PSD). In previous work, we have demonstrated that electroacupuncture (EA) could regulate swallowing-related motor neurons and promote swallowing activity in the essential part of central pattern generator (CPG), containing nucleus ambiguus (NA), nucleus of the solitary tract (NTS), and ventrolateral medulla (VLM) under the physiological condition. In the present work, we have investigated the effects of EA on the PSD mice in vivo and sought evidence for PSD improvement by electrophysiology recording and laser speckle contrast imaging (LSCI). Four main conclusions can be drawn from our study: (i) EA may enhance the local field potential in noninfarction area of M1, activate the swallowing-related neurons (pyramidal cells), and increase the motor conduction of noninfarction area in voluntary swallowing; (ii) EA may improve the blood flow in both M1 on the healthy side and deglutition muscles and relieve PSD symptoms; (iii) EA could increase the motor conduction velocity (MCV) in hypoglossal nerve, enhance the EMG of mylohyoid muscle, alleviate the paralysis of swallowing muscles, release the substance P, and restore the ability to drink water; and (iv) EA can boost the functional compensation of M1 in the noninfarction side, strengthen the excitatory of hypoglossal nerve, and be involved in the voluntary swallowing neural control to improve PSD. This research provides a timely and necessary experimental evidence of the motor neural regulation in dysphagia after stroke by acupuncture in clinic.

Connection Input Mapping and 3D Reconstruction of the Brainstem and Spinal Cord Projections to the CSF-Contacting Nucleus

Objective

To investigate whether the CSF-contacting nucleus receives brainstem and spinal cord projections and to understand the functional significance of these connections.

Methods

The retrograde tracer cholera toxin B subunit (CB) was injected into the CSF-contacting nucleus in Sprague-Dawley rats according the previously reported stereotaxic coordinates. After 7–10 days, these rats were perfused and their brainstem and spinal cord were sliced (thickness, 40 μm) using a freezing microtome. All the sections were subjected to CB immunofluorescence staining. The distribution of CB-positive neuron in different brainstem and spinal cord areas was observed under fluorescence microscope.

Results

The retrograde labeled CB-positive neurons were found in the midbrain, pons, medulla oblongata, and spinal cord. Four functional areas including one hundred and twelve sub-regions have projections to the CSF-contacting nucleus. However, the density of CB-positive neuron distribution ranged from sparse to dense.

Conclusion

Based on the connectivity patterns of the CSF-contacting nucleus receives anatomical inputs from the brainstem and spinal cord, we preliminarily conclude and summarize that the CSF-contacting nucleus participates in pain, visceral activity, sleep and arousal, emotion, and drug addiction. The present study firstly illustrates the broad projections of the CSF-contacting nucleus from the brainstem and spinal cord, which implies the complicated functions of the nucleus especially for the unique roles of coordination in neural and body fluids regulation.