Establishment of a study model for the recovery of oral functions in patients suffering from somatosensory disfunction

本研究旨在建立躯体感觉功能障碍患者口腔功能恢复的研究模型。我们使用大鼠视交叉上核（SCN）神经元的分离细胞培养，因为SCN作为昼夜节律起搏器的功能在体内和体外都得到了积极的研究。通过使用多电极皿，我们连续2周以上测量了单个SCN神经元的昼夜节律。自发动作电位的互相关分析表明，当它们的昼夜节律同步时，神经元对在功能上通过突触连接。在昼夜节律不同步的成对神经元之间没有发现相关性。河豚毒素长期阻断神经通讯后，放电节律的去同步性和相互关系的消失表明突触传递与节律同步性之间存在因果关系。利用c-fos基因编码蛋白（Fos）作为标记物，研究了发育和成年大鼠延髓中与喂食相关的神经元激活。在出生后第3、7和14天，将新生儿与母亲分离12小时，进行强化母乳喂养或进一步分离3小时，然后处死。成年大鼠禁食24小时，献祭前给予食物和水或献祭时不进食。在母乳喂养的幼鼠中，fos免疫反应（FI）神经元主要分布在孤立束核（NST）和背髓网状结构（dRF）。饱腹的成年大鼠在NST和dRF中都表现出相似的Fos表达模式。相比之下，禁食幼鼠和成年鼠的NST和dRF中观察到的FI细胞要少得多。在幼鼠和成年鼠中Fos的明显定位表明NST和dRF在摄食行为中的功能意义。

The present study was carried out to establish a study model for the recovery of oral functions in patients suffering from somatosensory disfunction.We used dissociated cell culture of rat suprachiasmatic nucleus (SCN) neurons because the function of the SCN as a circadian pacemaker has been investigated enthusiastically in both in vivo and in vitro. By using a multi-electrode dish, we measured circadian firing rhythms in individual SCN neurons for more than 2 weeks continuously. Cross-correlation analysis of spontaneous action potentials revealed that a neuron pair was functionally connected by synapses when their circadian rhythms were synchronized. No correlation was found between the paired neurons whose circadian rhythms were not synchronized. Desynchronization of the firing rhythms and the disappearance of the cross-correlation after a chronic blockade of neural communication by tetrodotoxin demonstrate a causal relationship between synaptic transmission and rhythm synchrony.Feeding-associated activation of neurons in the medulla oblongata was examined in both developing and adult rats, using the c-fos gene-encoded protein (Fos) as a marker. Neonates were isolated from mothers for 12h on postnatal day 3,7 and 14, and either breast-fed intensively or further isolated for another 3h, and sacrificed. Adult rats were fasted for 24 hours and either given food and water before sacrifice or sacrificed without food intake. In the breast-fed pups, Fos-immunoreactive (FI) neurons were predominantly localized in the nucleus of the solitary tract (NST) and dorsal medullary reticular formation (dRF). Satiated adult rats with food showed similar patterns of Fos expression in both NST and dRF.In contrast, much fewer FI cells were observed in the NST and dRF in the fasted pups and adults. The distinct localization of Fos in fed pups and adults indicates functional significance of the NST and dRF in the feeding behavior.