Basic morphological studies on the tooth pain transmission.

将HRP注入小鼠下切牙髓内，追踪三叉神经感觉神经元。用戊巴比妥麻醉两只成年ICR小鼠。然后在下颌骨的牙齿萌出区域用牙盘切割一侧的下切牙。用微量注射器将10微升溶于生理盐水的5% WGA-HRP注入髓腔。48小时后再次麻醉动物，先用生理盐水经左心室灌注，然后用200 ml 1%戊二醛-0.5%多聚甲醛磷酸盐缓冲液（pH7.4）灌注。将同侧三叉神经节和脑干解剖出来，在相同的固定剂中于4 ℃重新固定2小时，并在4 ℃下储存在缓冲的10%蔗糖溶液中。用Cryostat将冷冻切片切成30 μ m，并在3，3 '，5，5'-四甲基联苯胺和0.3%H_2O_2的溶液中冲洗。用目镜测微计测量了两只动物三叉神经节神经元（共917个细胞）的大直径。小鼠三叉神经节神经元的大小在直径上从7到40 μ m变化，在20和25 μ m之间具有峰值。HRP标记的神经元大，直径为20- 35 μ m。在脑干，尤其是中脑核，未见HRP阳性神经元。这些结果直接或间接地表明，较大的感觉神经元可能产生无髓纤维。最近，由于NO被认为是一种感觉神经递质，我们研究了NADPH-黄递酶（NADPH-d，NO合成酶）在大鼠下切牙和磨牙牙髓中的分布。结果显示，在Rushkow神经丛和牙本质小管中可见大量NADPH-d阳性神经纤维，贯穿成牙本质细胞层。提示牙髓和牙本质的痛觉与NO阳性神经纤维密切相关。

We traced the trigeminal sensory neurons with HRP injected into the pulp of mouse lower incisors. Two adult ICR mice were anesthetized with Nembutal. The lower incisor on one side was then cut with a dental disk in the region of tooth eruption from the mandible. Ten microliter of 5% WGA-HRP dissolved in saline was injected into the pulp cavity by microsyringe. The animals were reanesthetized 48 hours later and perfused through the left cardiac ventricle first with saline and then with 200ml of 1% glutaraldehyde-0.5% paraformaldehyde in phosphate buffer(pH7.4). The ipsilateral trigeminal ganglion and brain stem were dissected out, re-fixed in the same fixative for 2 hours at 4ﾟC,and stored in buffered 10% sucrose solution at 4ﾟC.Frozen sections were cut at 30 mum with a Cryostat and rinsed in a solution of 3,3', 5,5'-tetramethylbenzidine and 0.3% H_2O_2. Large diameter of trigeminal ganglion neurons (total : 917 cells) from two animals were measured with ocular micrometer. The size of the mouse trigeminal ganglion neurons varied from 7 to 40 mum in diameter, having a peak between 20 and 25 mum. The HRP-labelled neurons were large, being 20-35mum in diameter. No HRP-incorporated neurons were seen in the brain stem, especially in the mesencephalic nucleus. These results directly or indirectly indicate that larger sensory neurons may give rise to unmyelinated fibers.Recently, since NO is thought of as a sensory neurotransmitter, we studied the distribution of the ANDPH-diaphorase (NADPH-d, NO synthetic enzyme) in the pulps of lower incisor and molar of the rat. As a result, many NADPH-d positive nerve fibers were seen in the plexus of Rushkow and dentinal tubules, running through the odontoblastic layr. Thus, the results suggest that the pain perception in the dentin and pulp is closlely related to NO-positive nerve fibers.