[Change in trigeminal mesencephalic neurons after teeth extraction in guinea pig].
Trigeminal mesencephalic (Mes V) neurons innervating the periodontal mechanoreceptor (PMR) are known to play an important role in controlling the bite force and jaw-movements during mastication. After teeth loss, the PMR disappears due to loss of the periodontal membrane. The present work is a study on whether cell death is induced in the Mes V neurons in association with teeth loss. The upper and lower incisors were extracted on the right side in 5 guinea pigs (extraction group) and the other 5 guinea pigs were kept intact (control group). In the extraction group, the animals were kept alive for 58-119 days after teeth extraction. Serial coronal sections (50 microns thick) were made of the midbrain and pons and stained with cresyl violet. The Mes V neurons were counted on every other section. In the caudal half of the Mes V nucleus, where the neurons innervating the PMR are reported to be located, the number of neurons was less on the right side than on the left side (P < 0.01) in the extraction group, while there was no difference between the right and left sides in the control group. We conclude that teeth extraction can induce cell death in the Mes V neurons innervating the PMR and produce a significant change in the brainstem mechanisms controlling mastication.
Kimoto
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Department of Physiology, Faculty of Dentistry, Tokyo Medical and Dental University.
D000818:Animals; D016923:Cell Death; D006168:Guinea Pigs; D008465:Mechanoreceptors / Q000502:physiology; D008636:Mesencephalon / Q000473:pathology*; D009434:Neural Pathways / Q000473:pathology; D009474:Neurons / Q000473:pathology*; D010519:Periodontium / Q000294:innervation; D014081:Tooth Extraction; D014276:Trigeminal Nerve / Q000473:pathology*