Effect of dental malocclusion on cerebellar neuron activation via the dorsomedial part of the principal sensory trigeminal nucleus

Abstract

Occlusion has been proposed to play a role for body posture and balance, both of which are mediated mainly by the cerebellum. The dorsomedial part of the principal sensory trigeminal nucleus (Vpdm) has direct projection to the cerebellum. The experimental unilateral anterior crossbite (UAC) has an impact on the motor nuclei in the brain stem via trigeminal mesencephalic nucleus (Vme). The current aim was to explore whether UAC has an impact on Vpdm‐cerebellum circuit. The inferior alveolar nerve was injected into cholera toxin B subunit (CTb), the cerebellum was injected into fluoro‐gold (FG), and the Vpdm was injected into biotinylated dextran amine (BDA) to identify the activation of Vpdm‐cerebellum circuit by UAC. Data indicated that there were more neuronal nuclei (NeuN)/CTb/FG triple‐labelled neurons and NeuN/CTb/vesicular glutamate transporter 1(VGLUT1) triple‐labelled neurons in the Vpdm, and more NeuN/BDA/ VGLUT1 triple‐labelled neurons in the cerebellum of rats with UAC than in control rats. The VGLUT1 expression in the Vpdm and cerebellum in the UAC group was higher than that in control rats. These findings indicate an excitatory impact of UAC on the Vpdm‐cerebellum pathway and support the role of occlusion for body posture and balance.

Activation of the VpdmVGLUT1-VPM pathway contributes to anxiety-like behaviors induced by malocclusion

“…Moreover, in the trigeminal pathway, the Vme and Vpdm have both been shown to transmit proprioception and the Vme express only VGLUT1-mRNA ( Pang et al, 2006 ; Liu et al, 2018 ; Shi et al, 2021 ). In our previous studies, the expression of VGLUT1 in the Vme and Vpdm was upregulated under UAC conditions ( Liu et al, 2017 , 2018 ; Shi et al, 2021 ).…”

“…Moreover, in the trigeminal pathway, the Vme and Vpdm have both been shown to transmit proprioception and the Vme express only VGLUT1-mRNA ( Pang et al, 2006 ; Liu et al, 2018 ; Shi et al, 2021 ). In our previous studies, the expression of VGLUT1 in the Vme and Vpdm was upregulated under UAC conditions ( Liu et al, 2017 , 2018 ; Shi et al, 2021 ). Based on the above studies, we proposed that the hyperactivity of VGLUT1-ir neurons in the Vme-Vpdm pathway might play a pivotal role in the anxiety comorbidity induced by dental malocclusion.…”

“…Previous studies have reported elevated VGLUT1 expression in the Vpdm of animals with orofacial disorders and malocclusion-induced negative emotions (Liu et al, 2019;Shi et al, 2021). To determine whether VGLUT1-ir neurons in the Vpdm (Vpdm VGLUT1 ) participate in malocclusioninduced anxiety comorbidity, we employed designer receptors exclusively activated by designer drugs (DREADDs) to explore the effect of Vpdm VGLUT1 in modulating UAC-induced anxiety-like behaviors (Figure 2A).…”

“…Our previous studies indicated that UAC stimulated the expression of VGLUT1 in the Vme and Vpdm ( Liu et al, 2017 ; Shi et al, 2021 ). Thus, we aimed to determine whether there exists a putative Vme-Vpdm-VPM-SI glutamatergic neural pathway that dominates the emergence and regulation of anxiety-like behaviors stimulated by aberrant dental biomechanical stress.…”

The Osteopath’s Imprint: Osteopathic Medicine Under the Nanoscopic Lens

“…OMT administered to patients with Parkinson's improves some neuromotor parameters; an explanation highlighted by the authors is that of having improved some cranial dysfunctions [ 3 ]. Probably, by manually working the skull tissues, the surface receptors of the trigeminal system are stimulated, which can send afferents to the cerebellar and vestibular area, positively influencing postural balance [ 12 , 13 ]. The osteopathic approach for patients with COPD, combined with rehabilitation and pharmacological treatments, could demonstrate a greater benefit for this clinical setting.…”