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ORIGINAL RESEARCH article

Front. Cell. Neurosci.
Sec. Cellular Neurophysiology
Volume 18 - 2024 | doi: 10.3389/fncel.2024.1509020

Regulation of CeA -Vme Projection in Masseter Hyperactivity Caused by Restraint Stress

Provisionally accepted
Yajuan Zhao Yajuan Zhao 1*Ji Chen Ji Chen 1Yang Liu Yang Liu 1*Lv-La Pan Lv-La Pan 2*Yan-Xia Guo Yan-Xia Guo 1*Zhou-Ming Zhang Zhou-Ming Zhang 1*Qiang Li Qiang Li 1*Yong-Jin Chen Yong-Jin Chen 1*
  • 1 Air Force Medical University, Xi'an, Shaanxi Province, China
  • 2 Zhengzhou University, Zhengzhou, Henan Province, China

The final, formatted version of the article will be published soon.

    The overactivity of the masticatory muscles (bruxism or teeth clenching) is associated with stress exposure, and often leading to consistent muscle pain. However, the neural mechanism underlining it is not fully understood. The central amygdala (CeA), which is linked to stress-induced behaviors and physical reactions, projects directly to the mesencephalic trigeminal nucleus (Vme), which is crucial for oral-motor coordination. Thus, we hypothesized that the projections from the CeA to the Vme could be linked to stress-induced anxiety and overactivity of the jaw muscles. After establishing an animal model of restraint stress, we found that chronic stress could lead to noticeable anxiety-related behavior, increased masseter muscle activity, activation of GABAergic neurons in the CeA, and opposite changes in the excitability of multipolar GABAergic interneurons and pseudounipolar excitatory neurons in the Vme. Subsequently, through the utilization of anterograde and transsynaptic tracing in conjunction with immunofluorescence staining, we discovered that the neural projections from the CeA to the Vme were mainly GABAergic and that the projections from the CeA terminated on GABAergic interneurons within the Vme. Moreover, chemogenetically suppressing the function of GABAergic neurons in the CeA could effectively reduce anxiety levels and reverse the increase in the activity of the masseter muscles induced by stress. And, specifically inhibiting GABAergic projections from the CeA to the Vme via optogenetics could reduce the hyperactivity of the masseter muscles but not stress-induced anxiety. In conclusion, our findings indicate that GABAergic projections from the CeA to the Vme may play an important role in the masseter overactivity in response to chronic stress.

    Keywords: central amygdala, Mesencephalic trigeminal nucleus, restraint stress, Anxiety, masticatory muscle, overactivity CeA-Vme Projection in Masseter Overactivity

    Received: 10 Oct 2024; Accepted: 08 Nov 2024.

    Copyright: © 2024 Zhao, Chen, Liu, Pan, Guo, Zhang, Li and Chen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Yajuan Zhao, Air Force Medical University, Xi'an, 710032, Shaanxi Province, China
    Yang Liu, Air Force Medical University, Xi'an, 710032, Shaanxi Province, China
    Lv-La Pan, Zhengzhou University, Zhengzhou, 450001, Henan Province, China
    Yan-Xia Guo, Air Force Medical University, Xi'an, 710032, Shaanxi Province, China
    Zhou-Ming Zhang, Air Force Medical University, Xi'an, 710032, Shaanxi Province, China
    Qiang Li, Air Force Medical University, Xi'an, 710032, Shaanxi Province, China
    Yong-Jin Chen, Air Force Medical University, Xi'an, 710032, Shaanxi Province, China

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