Byrd K E, Stein S T, Sokoloff A J, Shankar K
Department of Basic Sciences, University of Southern California School of Dentistry, Los Angeles 90089.
Am J Anat. 1990 Oct;189(2):93-110. doi: 10.1002/aja.1001890202.
The objective of this study was to define further the role of the trigeminal motor nucleus (TMNu) in the postnatal ontogeny of the mammalian craniofacial skeleton. To that end, 42 male Sprague-Dawley rats underwent stereotaxic surgery at 40 days of age; 21 received small electrolytic lesions to their left-side TMNu (lesioned group) while 21 had TMNu stimulation with no actual electrolytic lesion produced (sham group). Seven rats from each group were killed at 28, 56, and 84 days postoperative to analyze trigeminal motoneuron (TMNe) count, masticatory muscle weight, and osteological growth vector data. At all three time periods, lesioned animals showed significant differences 1) between the surgery and nonsurgery sides, and 2) from sham animals. However, sham animals also demonstrated significant between-side differences for medial pterygoid muscle weight (56 days), mandibular height (28 and 56 days), and mandibular length data (84 days); these data suggested that even relatively slight damage to TMNe can create morphological changes within the craniofacial complex. Snout deviation in a lesioned rat towards the opposite side from all other lesioned animals was correlated with unique damage to its pontine reticular formation; this suggested that the observed morphological alterations of the craniofacial complex may have been due not only to TMNu damage, but also to changed expressions of the masticatory central pattern generator (CPG). Morphological alterations of the craniofacial skeleton resulting from lesions to the TMNu were likely due to changed neuromuscular activity patterns of the masticatory muscles and their biomechanical effects upon bone.
本研究的目的是进一步明确三叉神经运动核（TMNu）在哺乳动物颅面骨骼出生后个体发育中的作用。为此，42只雄性Sprague-Dawley大鼠在40日龄时接受了立体定向手术；21只大鼠左侧TMNu接受了微小电解损伤（损伤组），而另外21只大鼠接受了TMNu刺激但未产生实际电解损伤（假手术组）。术后28天、56天和84天，每组处死7只大鼠，以分析三叉神经运动神经元（TMNe）计数、咀嚼肌重量和骨生长向量数据。在所有三个时间段，损伤动物均表现出显著差异：1）手术侧与非手术侧之间；2）与假手术动物之间。然而，假手术动物的翼内肌重量（56天）、下颌高度（28天和56天）和下颌长度数据（84天）在两侧之间也表现出显著差异；这些数据表明，即使是对TMNe相对轻微的损伤也会在颅面复合体中产生形态学变化。一只损伤大鼠的吻部向与所有其他损伤动物相反的一侧偏斜，这与其脑桥网状结构的独特损伤有关；这表明观察到的颅面复合体形态学改变可能不仅是由于TMNu损伤，还可能是由于咀嚼中枢模式发生器（CPG）表达的改变。TMNu损伤导致的颅面骨骼形态学改变可能是由于咀嚼肌神经肌肉活动模式的改变及其对骨骼的生物力学作用。
