It is well known that acupoints have an intricate connection with the nervous system. The specific mechanism of acupuncture in regulating the nervous system and exerting the therapeutic effect is one of the hottest and most difficult aspects in the field of acupuncture research. The regulation of acupuncture on the nervous system involves multi-target and multi-link neurofeedback, and how to find the critical effector neurons in this process is the primary concern. In the present article, we introduce some modern paradigms and methodologies for screening acupuncture-responsive effector neurons starting from elucidation of structural and functional connectivity between acupoints and neurons, for example, 1) neurovirus tracing techniques for studying the neuronal structural connections, and immediate early gene labeling for identifying functionally connected neuronal ensembles activated by acupuncture stimulation, 2) neuroimaging techniques for observing the impact of acupuncture on brain functional connections from a macroscopic perspective in real-time, 3) in vitro and in vivo electrophysiological recordings, as well as in vivo fiber-optics recording or two-photon calcium imaging for revealing the activity characteristics of activated neuronal ensembles, 4) analysis of the causal relationship between the key effect neurons, their neural circuit connections and the therapeutic effect of acupuncture by using multiple measures such as optogenetics and chemogenetics, etc. We should further strengthen the connection between the experimental research, basic theory exploration and clinical practice of acupuncture, accelerate the process of revealing the scientific connotations and promote the modernization and internationalization of acupuncture therapy.
- Article type
- Year
Open Access
Issue
Open Access
Issue
To investigate the mechanisms by which the hypoglossal nucleus (12N) modulates swallowing-related activities and mediates the therapeutic effects of electroacupuncture (EA) at “Lianquan” (CV23) in alleviating post-stroke dysphagia (PSD).
Tracer viruses were used to investigate the brain regions that directly project to CV23. C57BL/6J mice were divided into 7 groups: control, model, model+EA, normal+12N inhibition control, normal+12N inhibition, model+EA+12N inhibition control, and model+EA+12N inhibition groups (7 mice/group). Three additional C57BL/6J mice were used for the virus tracing experiment. A photochemical thrombosis model was established in C57BL/6J mice to simulate PSD, by intraperitoneally injecting 0.2 mL of 1.5% rose bengal solution combined with laser irradiation to induce ischemic pathological changes in the primary motor cortex; EA at CV23 (2 Hz, 1 mA, for 15 minutes, once in total) to study the effect of electroacupuncture on swallowing function in PSD mice. Chemogenetic viral inhibition was applied to suppress neuronal activity in the 12N, and changes in vocal fold movements and swallowing electromyography were observed under physiological conditions, by laryngoscopy and electrophysiological recorder respectively. After PSD model establishment, EA combined with chemogenetic inhibition of 12N was followed to observe the effect of chemogenetic inhibition of 12N on EA at CV23 in improving PSD. Tracer viruses were used to trace the upper brain region of the 12N.
The 12N directly projected to the surrounding tissues of CV23. Compared with the control group, in the model group, food residues were observed in the pharyngeal cavity and piriform recesses, along with prolonged vocal cord movement cycle time, a reduced number of vocal cord movement cycles within 10 seconds (P<0.01), and decreased electromyographic area under the curve as well as reduced number of swallows (P<0.001, P<0.01). Compared with the model group, the model+EA group showed shortened vocal cord movement cycle time, an increased number of vocal cord movement cycles within 10 seconds (P<0.01), and an enlarged electromyographic area under the curve (P<0.001). Physiologically, compared with the normal+12N inhibition control group, the normal+12N inhibition group showed a reduction in the area under the swallowing electromyography curve and a decrease in the number of swallows (P<0.05). Pathologically, laryngoscopy showed that compared with the model+EA+12N inhibition control group, the vocal fold movement cycle time of the model+EA+12N inhibition group was prolonged, and the number of movement cycles within 10 seconds was reduced (P<0.01), the area under the swallowing electromyography curve was decreased (P<0.05). The upstream brain regions of the 12N projecting to the surrounding tissues of CV23 were mainly identified in the nucleus tractus solitarii (NTS), intermediate reticular nucleus (IRt), spinal trigeminal nucleus caudalis (SP5C) and lateral paragigantocellular nucleus (LPGi), etc.
The 12N directly projects to the surrounding tissues of CV23 and contributes to EA-mediated improvement in PSD.
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