Morphological and functional studies on NO producing neurons in the brainstem involved in pral sensori-motor functions

NADPH-黄递酶(NADPH-d)组织化学染色显示大鼠下脑干有一个明显的神经群。NADPH-d染色显示三叉神经背内侧背侧口侧核(Vo)和吻侧孤束核(Sn)有高尔基体样网络。另一组神经元分布在三叉神经旁核、三叉神经脊束核内侧核与尾侧核之间的间隙区、三叉神经脊束核浅层，而在三叉神经脊束核大细胞区染色较少。NADPH-d阳性神经元在Vo和Sn区的分布大多与支配口内结构的神经的WGA-HRP跨神经节标记的中央终末区重叠。NADPH-d阳性神经元在Vi和Vc的分布与支配口内外结构的神经的中央终末区域重叠。支配口内结构的神经切断后1~2周，Vo/Sn区标记神经元数量减少。这些结果表明，下脑干的NADPH-d阳性神经元可能受到口内结构初级传入的跨突触调节。胚胎第12天(EI2)，脑内无神经元NADPH-d染色，血管染色。E15时，Vo和Sn区出现标记神经元。出生后第4天(P4)，Vc的大细胞区出现标记。P10时，在副V区和Vc浅层出现标记。NADPH-d在各核首次表达后，标记增强或维持至成年期。NADPH-d标记最早出现在Vo和Sn区，早于脑干其他部位的NADPH-d标记，提示一氧化氮/环鸟苷一磷酸系统在原始口面部感觉运动反射功能中具有重要作用。

NADPH-diaphorase (NADPH-d) histochemical staining demonstrated a distinct neural group in the lower brainstem of rats. The NADPH-d stain revealed a Golgi-like network in the dorsomedial spinal trigeminal nucleus oralis (Vo) and rostrolateral solitary tract nucleus (Sn). Another neural group was stained in the paratrigeminal nucleus (paraV), gap region between spinal trigerninal nuclei interpolaris (Vi) and caudalis (Vc), superficial zone of Vc, and much less in the magnocellular zone of Vc. The distribution of NADPH-d-positive neurons in Vo and Sn overlapped mostly with the central terminal area labeled transganglionically with WGA-HRP from nerves innervating the intraoral structures. The distribution of NADPH-d-posibve neurons in Vi and Vc overlapped with the central terminal area from nerves innervating intra- and extra-oral structures. The number of labeled neurons in Vo/Sn decreased one to two weeks after transection of nerves innervating intraoral structures. These results show that NADPH-d-positive neurons in the lower brainstem could be regulated trans-synaptically by primary afferents from the intraoral structures. On embryonic day 12 (EI2), no neurons in the brain were stained for NADPH-d, while blood vessels were stained. On E15, labeled neurons appeared in Vo and Sn. On postnatal day 4 (P4), labeling appeared in the magnocellular zone of Vc. On P10, labeling appeared in paraV and the superficial zone of Vc. After the first expression of NADPH-d in each nuclei, the labeling increased or maintained to the adulthood. The very early appearance of NADPH-d labeling in Vo and Sn, which precedes the appearance of NADPH-d elsewhere in the brainstem, suggests that the nitric oxide/cyclic guanosine monophosphate system has an important role for primitive orofacial sensorimotor reflexive functions.