Proprioceptive mechanisms in occlusion-stimulated masseter hypercontraction.
Neurons in the trigeminal mesencephalic nucleus (Vme) have an axon that branches peripherally to innervate the orofacial region and projects centrally to the trigeminal motor nucleus (Vmo). They function as the primary neurons conveying proprioceptive messages. The present study aimed to demonstrate the presence of a periodontal-Vme-Vmo circuit and to provide evidence for its involvement in an experimental unilateral anterior crossbite (UAC) model, which can induce osteoarthritis in the temporomandibular joint. Cholera toxin B subunit (CTb) was injected into the inferior alveolar nerve of rats to help identify the central axon terminals of Vme neurons in the Vmo. The levels of vesicular glutamate transporter 1 (VGLUT1) expressed in the periodontal region, Vme, Vmo, and masseter, and the level of acetylcholinesterase (AChE) expressed in the masseter, were assessed in UAC rats and controls. In CTb-treated rats, many CTb-labeled cell bodies and endings were identified in the Vme and in the Vmo, respectively. In UAC rats, VGLUT1 was expressed at a statistically significantly higher level in the periodontal ligament, Vme, Vmo, and masseter than it was in control rats. The level of AChE protein was 1.97 times higher in UAC rat masseter compared with control rat masseter. These findings reveal a trigeminal mechanism underlying masseter hyperactivity induced by an altered occlusion.
State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of Oral Anatomy and Physiology, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
Xin
X
Liu
Department of Anatomy, Histology and Embryology and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, China.
Chunkui
C
Zhang
School of Stomatology, The Third Affiliated Hospital of Xinxiang Medical University, Xinxiang, China.
Dongmei
D
Wang
State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of Oral Anatomy and Physiology, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
Hongyun
H
Zhang
State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of Oral Anatomy and Physiology, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
Xiaodong
X
Liu
Department of Anatomy, Histology and Embryology and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, China.
Jinlian
J
Li
State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of Oral Anatomy and Physiology, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
Meiqing
M
Wang
D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002772:Cholera Toxin / Q000494:pharmacology; D005260:Female; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008310:Malocclusion / Q000503:physiopathology*; D008406:Masseter Muscle / Q000294:innervation*; D009119:Muscle Contraction / Q000502:physiology; D011434:Proprioception / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism
C493466:Slc17a7 protein, rat; D050598:Vesicular Glutamate Transport Protein 1; D002772:Cholera Toxin; D000110:Acetylcholinesterase
VGLUT1; acetylcholinesterase; mastication; proprioception; unilateral anterior crossbite