Bing Zhu

Background: Mas-related G-protein-coupled receptor b4 (Mrgprb4)-lineage neurons in the peripheral nervous system are a type of C fibers in hairy skin. Our prior work demonstrated that these neurons respond to both noxious and innocuous mechanical and thermal stimuli. Ablating them eliminates the pleasant sensation elicited by gentle pressure on a mouse’s nape. However, their potential role in mitigating pain and pain-related negative emotions in response to somatic stimuli remains unclear. Methods: A CFA-induced chronic pain and anxiety comorbidity model was established in C57BL/6J mice. In vivo calcium imaging of dorsal root ganglia (DRG) neurons in Mrgprb4-GCaMP6s transgenic mice characterized neuronal responses to transcutaneous electrical nerve stimulation (TENS) at the Zusanli (ST36) acupoint. Optogenetic activation (Mrgprb4-ChR2 mice) and viral ablation of Mrgprb4-lineage neurons were employed to evaluate their role in mediating TENS effects on mechanical pain thresholds and anxiety-like behaviors. Results: In vivo calcium imaging revealed that 0.5 mA TENS preferentially activated Mrgprb4-lineage neurons compared to 2.0 mA TENS. In CFA model mice, 0.5 mA TENS at ST36 significantly increased mechanical pain thresholds and reduced anxiety-like behaviors in the open-field test. Optogenetic activation of Mrgprb4-lineage neurons at ST36 replicated these analgesic and anxiolytic effects, demonstrating the sufficiency of these neurons for therapeutic outcomes. Conversely, viral ablation of L3–L5 Mrgprb4-lineage neurons substantially attenuated the therapeutic effects of 0.5 mA TENS for both pain relief and anxiety reduction, indicating their necessity in mediating TENS efficacy. Conclusions: Mrgprb4-lineage neurons serve as critical peripheral mediators of TENS-induced analgesia and anxiolysis. These findings identify a specific neuronal population underlying the therapeutic effects of somatic stimulation at ST36, providing mechanistic insights that may guide optimization of TENS parameters for treating chronic pain and comorbid anxiety in clinical settings.

Background :Mas-related G-protein-coupled receptor b4 (Mrgprb4)-lineage neurons in the peripheral nervous system, were a type of C fibers in the hairy skin. Our prior work demonstrated that these neurons respond to both noxious and innocuous mechanical and thermal stimuli. Ablating them eliminates the pleasant sensation elicited by gentle pressure on the mouse nape. However, their potential role in mitigating pain and pain-related negative emotions in response to somatic stimuli remains unclear. Methods:Animal experiments investigated the pivotal role of Mrgprb4-lineage neurons in mediating the analgesic and anxiolytic effects of transcutaneous electrical nerve stimulation (TENS) applied to the Zusanli (ST36) acupoint. In vivo calcium imaging of lumbar 4 dorsal root ganglia (DRG) neurons in Mrgprb4-GCaMP6s transgenic mice characterized neuronal encode of distinct TENS intensities. Mechanical pain thresholds and anxiety-like behaviors were assessed in a CFA-induced mouse model of comorbid chronic pain and anxiety. To simulate TENS, optogenetic stimulation was applied to the ST36 acupoint in Mrgprb4-ChR2 mice; intrathecal viral injection specifically ablated L3-L5 Mrgprb4-lineage neurons, and TENS effects were evaluated with their gain- or loss-of-function manipulation. Results: 0.5 mA TENS on ST36 ameliorated pain and anxiety-like behaviors in model mice and activated Mrgprb4-lineage neurons. Photostimulation on ST36 induced analgesic and anxiolytic effect in comorbidity of chronic pain and anxiety model of Mrgprb4-ChR2 mice. Ablating these neurons attenuated the therapeutic effects of 0.5 mA TENS in model mice. Conclusion:These genetic engineering-assisted findings may deepen our understanding of the analgesic and anxiolytic effect and mechanism of somatic stimulation and further improve the clinical efficacy.

Neuroinflammation represents the central pathological process in neurological disorders. Effectively regulating neuroinflammation to restore immune homeostasis and alleviate neuronal damage has emerged as a critical strategy in the prevention and treatment of these diseases. In recent years, the role of acupuncture in neuroimmune regulation, along with its anti-inflammatory and analgesic effects, has attracted considerable attention. Its potential to modulate immune homeostasis and inflammatory responses through various targets and pathways has been gradually elucidated, offering new research directions for the regulation of neuroinflammation. A series of studies have emphasized that acupuncture has significant clinical applications by regulating the immunoinflammatory pathway mediated by the brain’s TRPV1 channel. This discovery not only enhances the scientific understanding of the mechanisms underlying acupuncture but also offers new potential targets for the prevention and treatment of neuroinflammation-related diseases. The immunomodulatory properties of brain TRPV1 channels in inflammation associated with the nervous system have been emphasized. Furthermore, this study explores the immunomodulatory benefits of acupuncture in treating neuroinflammation, focusing on the potential mechanisms of TRPV1 channels at the brain level, as well as the criteria for selecting acupoints, intensity, frequency, and other relevant parameters in these studies. A deeper understanding of the neuroimmune regulatory mechanisms mediated by brain TRPV1 channels may offer new strategies and approaches for developing treatments or preventing neuropathological diseases.

This protocol describes a technique for optogenetic manipulation of specific types of neurons and real-time recording of the effects of electroacupuncture at Zusanli (ST36) on nuclear calcium signals and gastric motility in mice under anesthesia in vivo. The exploration of the central mechanisms underlying the efficacy of acupuncture has been limited by technological constraints. However, the advancement of optogenetic and optical imaging technology has propelled the development of neuroscience. Fiber photometry recording, initially leveraging genetically encoded calcium indicators to visualize changes in calcium dynamics indicative of neuronal activity, stands out as a key technology for characterizing brain-behavior correlations in vivo. The application of optogenetics enables the genetic encoding of neurons, enabling their activation or inhibition in response to light stimulation. This capability facilitates the establishment of causal links between neural circuitry function and behavioral outcomes. Simultaneous fiber photometry, calcium recording, and optogenetic stimulation provide a method for real-time recording and manipulation of neuronal activity, serving as an effective approach to investigate the central mechanisms of acupuncture. Nonetheless, there remains a scarcity of studies documenting the concurrent utilization of fiber photometry calcium recording, optogenetics, and visceral function monitoring in acupuncture research. The results of this experiment show that EA-ST36 might regulate gastric motility related to PBNGlu-NTSGlu-DMVChAT circuit. Optogenetic stimulation of this circuit produces the same effect. After the superposition of the two, the changes in calcium signal and gastric motility reach their maximum. This study established a novel approach for the simultaneous integration of optogenetic, intracerebral calcium signal recording, and gastric motility monitoring, offering a novel paradigm for real-time monitoring of the relationship between somatic stimulation and neural circuit-visceral function interactions.

This protocol describes a technique for optogenetic manipulation of specific types of neurons and real-time recording of the effects of electroacupuncture at Zusanli (ST36) on nuclear calcium signals and gastric motility in mice under anesthesia in vivo. The exploration of the central mechanisms underlying the efficacy of acupuncture has been limited by technological constraints. However, the advancement of optogenetic and optical imaging technology has propelled the development of neuroscience. Fiber photometry recording, initially leveraging genetically encoded calcium indicators to visualize changes in calcium dynamics indicative of neuronal activity, stands out as a key technology for characterizing brain-behavior correlations in vivo. The application of optogenetics enables the genetic encoding of neurons, enabling their activation or inhibition in response to light stimulation. This capability facilitates the establishment of causal links between neural circuitry function and behavioral outcomes. Simultaneous fiber photometry, calcium recording, and optogenetic stimulation provide a method for real-time recording and manipulation of neuronal activity, serving as an effective approach to investigate the central mechanisms of acupuncture. Nonetheless, there remains a scarcity of studies documenting the concurrent utilization of fiber photometry calcium recording, optogenetics, and visceral function monitoring in acupuncture research. The results of this experiment show that EA-ST36 might regulate gastric motility related to PBNGlu-NTSGlu-DMVChAT circuit. Optogenetic stimulation of this circuit produces the same effect. After the superposition of the two, the changes in calcium signal and gastric motility reach their maximum. This study established a novel approach for the simultaneous integration of optogenetic, intracerebral calcium signal recording, and gastric motility monitoring, offering a novel paradigm for real-time monitoring of the relationship between somatic stimulation and neural circuit-visceral function interactions.

The wisdom of Chinese medicine in maintaining health is "Yin Ping Yang Mi" (balance between yin and yang). Obviously, the maintenance of "homeostasis" contains dual factors of "excessiveness" and "falling short". The life process must be protected by the stability-maintaining mechanism of the "bidirectional regulation" system. Therefore, the two-way regulation of the "homeostasis" maintaining involves the relatively independent potential energy of the "spear" and "shield", and also depends on two sets of relatively independent regulatory systems to complete. Acupuncture is an excellent performer of the "bidirectional regulation effect" of living organisms, but can this effect be caused by a single acupoint stimulation?This issue, which was not a problem, has become a big problem in acupuncture-moxibustion discipline. The concept of "two-way regulation" of acupuncture is over-expanded, which is difficult for the theory of Chinese medicine to take into account. It is only a broad expansion of the boundary of theoretical extension arbitrarily. From the perspective of life science, the present paper expounds that the "bidirectional regulation effect" of acupuncture is obtained from the activation of the "integration center" (not necessarily limited to the brain) by the stimulated acupoints at different somatic parts of the body, and through two sets of relatively independent regulation systems, so as to maintain the life's "homeostasis".

Background: The global prevalence of stroke has been increasing. Motor dysfunction is observed in approximately 55 to 75% of stroke patients, with upper limb impairment affecting around 85% of them. Following upper limb dysfunction, the body’s recovery time is not only slower compared to the lower limbs, but the restoration of its fine motor skills is significantly more challenging, greatly impacting the daily lives of patients. Consequently, there is an increasing urgency for study on the upper limb function in stroke.Methods: A search was conducted in the Web of Science Core Collection: Science Citation Index Expanded (SCI-Expanded) database for material published from January 1, 2004 to December 31, 2023. We included all relevant literature reports and conducted an analysis of annual publications, countries/regions, institutions, journals, co-cited references, and keywords using the software packages CiteSpace, VOSviewer, and Bibliometrix R. Next, we succinctly outlined the research trends and hotspots in post-stroke upper limb dysfunction.Results: This analysis comprised 1,938 articles from 1,897 institutions, 354 journals, and 53 countries or regions. A yearly rise in the production of publications was noted. The United States is the foremost nation on the issue. Northwestern University has the most amounts of papers compared to all other institutions. The journal Neurorehabilitation and Neural Repair is a highly significant publication in this field, with Catherine E. Lang serving as the principal author. The majority of the most-cited references focus on subjects such as the reliability and validity of assessment instruments, RCT of therapies, systematic reviews, and meta-analyses. The intervention measures primarily comprise three types of high-frequency phrases that are related, as determined by keyword analysis: intelligent rehabilitation, physical factor therapy, and occupational therapy. Current areas of focus in research include randomized clinical trials, neurorehabilitation, and robot-assisted therapy.Conclusion: Current research has shown a growing interest in studying upper limb function assessment, occupational therapy, physical therapy, robot-assisted therapy, virtual reality, brain-computer interface, telerehabilitation, cortical reorganisation, and neural plasticity. These topics have become popular and are expected to be the focus of future research.

To explore the neural mechanism of visceral pain and related somatic (acupoints) sensitization by using in vivo calcium imaging of dorsal root ganglia (DRG) neurons. Eight BALB/c mice were randomly divided into control and model groups, with 4 mice in each group. The colitis model was induced by colorectal perfusion of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) once daily for 7 days. Mice of the control group received colorectal perfusion of normal saline once daily for 7 days. The location and area of the somatic neurogenic inflammation (cutaneous exudation of Evans blue ［EB］) of the 2 groups of mice were observed after intravenous injection of EB. For pain behavioral tests, sixteen C57BL/6J mice were randomly divided into control and model groups, with 8 mice in each group, and a Von Frey filament was used to stimulate the referred somatic reactive regions in colitis mice, and the number of avoidance and paw withdraw reaction within 10 tests was recorded. For in vivo DRG calcium imaging tests, 24 Pirt-GCaMP6s transgenic mice were randomly and equally divided into control group and colitis model group. The responses of the neurons in L6 or L4 DRG to colorectal distension (CRD), lower back brushing, or mechanical stimulation at the hindpaw were observed using confocal fluorescence microscope. Compared with the control group, the area of EB exudation spot in the hindpaw and lower back regions was increased in the colitis model group (PPPPPPirt-GCaMP6s transgenic mice, following brushing the skin of the receptive field (lower back) of L6 DRG neurons, the fluorescence intensity of the brushing-activated DRG neurons and small, medium and large-sized neurons were significantly higher in the colitis model group than those in the control group (PPPPP<0.05), while there were no significant changes in the proportion of small, medium and large-sized neurons between the control and colitis model groups. Colitis may lead to body surface sensitization at the same and adjacent neuro-segments as well as to an increase of the number and activity of the responsive lumbar DRG neurons, among which the L6 DRG neurons at the same neuro-segment as the rectum colon showed an increase in the number of responders and intensity of calcium fluorescence signal while L4 DRG neurons at the level adjacent to the rectum colon showed an increase in the number of responders, suggesting that there may be different mechanisms of peripheral neural sensitization.

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