TRPA1 Ion Channel Mediates the Analgesic Effects of Acupuncture at the ST36 Acupoint in Mice Suffering from Arthritis.

Purpose: Acupuncture (ACU) has been demonstrated to alleviate inflammatory pain. Mechanoreceptors are present in acupuncture points. When acupuncture exerts mechanical force, these ion channels open and convert the mechanical signals into biochemical signals. TRPA1 (T ransient receptor potential ankyrin 1) is capable of sensing various physical and chemical stimuli and serves as a sensor for inflammation and pain. This protein is expressed in immune cells and contributes to local defense mechanisms during early tissue damage and inflammation. In this study, we investigated the role of TRPA1 in acupuncture analgesia. Patients and Methods: We injected complete Freund's adjuvant (CFA) into the mouse plantars to establish a hyperalgesia model. Immunohistochemistry and immunofluorescence analyses were performed to determine the effect of acupuncture on the TRPA1 expression in the Zusanli (ST36). We used TRPA1-/- mouse and pharmacological methods to antagonize TRPA1 to observe the effect on acupuncture analgesia. On this basis, collagenase was used to destroy collagen fibers at ST36 to observe the effect on TRPA1. Results: We found that the ACU group vs the CFA group, the number of TRPA1-positive mast cells, macrophages, and fibroblasts at the ST36 increased significantly. In CFA- inflammatory pain models, the TRPA1-/- ACU vs TRPA1+/+ ACU groups, the paw withdrawal latency (PWL) and paw withdrawal threshold (PWT) downregulated significantly. In the ACU + high-, ACU + medium-, ACU + low-dose HC-030031 vs ACU groups, the PWL and PWT were downregulated, and in carrageenan-induced inflammatory pain models were consistent with these results. We further found the ACU + collagenase vs ACU groups, the numbers of TRPA1-positive mast cells, macrophages, and fibroblasts at the ST36 were downregulated. Conclusion: These findings together imply that TRPA1 plays a significant role in the analgesic effects produced via acupuncture at the ST36. This provides new evidence for acupuncture treatment of painful diseases.

Molecular mechanisms of quetiapine bidirectional regulation of bipolar depression and mania based on network pharmacology and molecular docking: Evidence from computational biology.

BACKGROUND: Quetiapine monotherapy is recommended as the first-line option for acute mania and acute bipolar depression. However, the mechanism of action of quetiapine is unclear. Network pharmacology and molecular docking were employed to determine the molecular mechanisms of quetiapine bidirectional regulation of bipolar depression and mania. METHODS: Putative target genes for quetiapine were collected from the GeneCard, SwissTargetPrediction, and DrugBank databases. Targets for bipolar depression and bipolar mania were identified from the DisGeNET and GeneCards databases. A protein-protein interaction (PPI) network was generated using the String database and imported into Cytoscape. DAVID and the Bioinformatics platform were employed to perform the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of the top 15 core targets. The drug-pathway-target-disease network was constructed using Cytoscape. Finally, molecular docking was performed to evaluate the interactions between quetiapine and potential targets. RESULTS: Targets for quetiapine actions against bipolar depression (126 targets) and bipolar mania (81 targets) were identified. Based on PPI and KEGG pathway analyses, quetiapine may affect bipolar depression by targeting the MAPK and PI3K/AKT insulin signaling pathways via BDNF, INS, EGFR, IGF1, and NGF, and it may affect bipolar mania by targeting the neuroactive ligand-receptor interaction signaling pathway via HTR1A, HTR1B, HTR2A, DRD2, and GRIN2B. Molecular docking revealed good binding affinity between quetiapine and potential targets. LIMITATIONS: Pharmacological experiments should be conducted to verify and further explore these results. CONCLUSIONS: Our findings suggest that quetiapine affects bipolar depression and bipolar mania through distinct biological core targets, and thus through different mechanisms. Furthermore, our results provide a theoretical basis for the clinical use of quetiapine and possible directions for new drug development.

Effects and mechanisms of acupuncture analgesia mediated by afferent nerves in acupoint microenvironments.

In the past few decades, the use of acupuncture analgesia in clinical practice has increased worldwide. This is due to its various benefits, including natural alleviation of pain without causing various adverse effects associated with non-steroidal anti-inflammatory drugs (NSAID) and opioids. The acupoint represents the initial site of acupuncture stimulation, where diverse types of nerve fibers located at the acupoint hold significant roles in the generation and transmission of acupuncture-related information. In this study, we analyzed the patterns and mechanisms of acupuncture analgesic mediated by acupoint afferent fibers, and found that acupuncture stimulates acupoints which rapidly and directly induces activation of high-density primary afferent fibers under the acupoints, including myelinated A fibers and unmyelinated C fibers. During acupuncture stimulation at the muscle layer, the analgesic effects can be induced by stimulation of A fiber threshold intensity. At the skin layer, the analgesic effects can only be produced by stimulation of C fiber threshold intensity. Electroacupuncture (EA) activates A fibers, while manual acupuncture (MA) activates both A and C fibers. Furthermore, acupuncture alters acupoint microenvironments, which positively modulates afferent fibers, enhancing the transmission of analgesic signals. In addition to local activation and conduction at acupoints, nerve fibers mediate the transmission of acupuncture information to pain centers. In the spinal cord, acupuncture activates neurons by inducing afferent fiber depolarization, modulating pain gating, inhibiting long-term potentiation (LTP) of the spinal dorsal horn and wide dynamic range (WDR) neuronal activities. At higher nerve centers, acupuncture inhibits neuronal activation in pain-related brain regions. In summary, acupuncture inhibits pain signal transmission at peripheral and central systems by activating different patterns of afferent fibers located on various layers of acupoints. This study provides ideas for enhancing the precise application and clinical translation of acupuncture.

[Acupoit is the "transducer" in the physiochemical information coupling response of acupuncture].

Acupoint is the initial response site of acupuncture stimulus and also the source link of the effect onset of acupuncture. Acupuncture is a mechanical physical stimulus. How is the mechanical force of acupuncture transduced into neuroelectrical and biochemical signals at acupoint? How does the physiochemical information of acupoint launch acupuncture effect? All of these remain the common and crucial questions in the study of acupuncture effect mechanism. Physical changes are induced in the local tissue of acupoint by needling techniques, such as the deformation and displacement of muscle fibers, which may act on the nerve ending receptors and produce electroneurographic signals. Besides, these changes may activate the mechanosensitive ion channels of the cytomembrane in acupoint site. Through cellular signal transduction, the physical signals may be transformed into chemical ones to trigger the physiochemical coupling response of acupoint microenvironment. Eventually, acupuncture effect is generated via nerves and body fluids. "The mechanical force of acupuncture", through "the physiochemical transduction", promotes the body's perception and transmits acupuncture signals. It suggests that acupoint is the "transducer" in the physiochemical information coupling response of acupuncture.

The Anti-Inflammatory Actions and Mechanisms of Acupuncture from Acupoint to Target Organs via Neuro-Immune Regulation.

Inflammation plays a significant role in the occurrence and development of multiple diseases. This study comprehensively reviews and presents literature from the last five years, showing that acupuncture indeed exerts strong anti-inflammatory effects in multiple biological systems, namely, the immune, digestive, respiratory, nervous, locomotory, circulatory, endocrine, and genitourinary systems. It is well known that localized acupuncture-mediated anti-inflammatory effects involve the regulation of multiple populations and functions of immune cells, including macrophages, granulocytes, mast cells, and T cells. In acupuncture stimulation, macrophages transform from the M1 to the M2 phenotype and the negative TLR4 regulator PPARγ is activated to inhibit the intracellular TLR/MyD88 and NOD signaling pathways. The downstream IκBα/NF-κB and P38 MAPK pathways are subsequently inhibited by acupuncture, followed by suppressed production of inflammasome and proinflammatory mediators. Acupuncture also modulates the balance of helper T cell populations. Furthermore, it inhibits oxidative stress by enhancing SOD activity via the Nrf2/HO-1 pathway and eliminates the generation of oxygen free radicals, thereby preventing inflammatory cell infiltration. The anti-inflammatory effects of acupuncture on different biological systems are also specific to individual organ microenvironments. As part of its anti-inflammatory action, acupuncture deforms connective tissue and upregulates the secretion of various molecules in acupoints, further activating the NF-κB, MAPK, and ERK pathways in mast cells, fibroblasts, keratinocytes, and monocytes/macrophages. The somatic afferents present in acupuncture-activated acupoints also convey sensory signals to the spinal cord, brainstem, and hypothalamic neurons. Upon information integration in the brain, acupuncture further stimulates multiple neuro-immune pathways, including the cholinergic anti-inflammatory, vagus-adrenal medulla-dopamine, and sympathetic pathways, as well as the hypothalamus-pituitary-adrenal axis, ultimately acting immune cells via the release of crucial neurotransmitters and hormones. This review provides a scientific and reliable basis and viewpoints for the clinical application of acupuncture in various inflammatory conditions.