Localization of Nerves Innervating Submandibular Gland in the Rat Brain Stem Using Cholera Toxin B Subunit

Han, Eui Hyeog; Ryu, Young Geun; Lee, Moo Sam

Abstract

The purpose of this study is to investigate the origin of neurons and afferent fibers projecting to submandibular gland by means of retrograde transport of Cholera Toxin B Subunit (CTB). CTB was injected into the both side submandibular gland or left side submandibular gland. In the rat brain stem, neurons were labeled with CTB in superior salivatory nucleus (SSN), facial nucleus, caudal region of hypoglossal nucleus, lateral horn of spinal cervical segment and their afferent fibers in nucleus tractus solitarius. At the most rostal level of SSN, the labeled cells were seen in lateral aspect of pontine reticular formation. At the level of facial nerve that traverse the dorsal part of the spinal trigeminal tract, the labeled cells of SSN extended to the anterolateral direction of lateral aspect of reticular formation. At the level of facial nucleus, the labeled cells of SSN were seen in the area of caudal prologation of the same region of rostral ones, but decreased in cell number. In the facial nucleus, the labeled cells were confined in central part of facial nucleus. In the first and second spinal cervical segment, the labeled cells were seen in the intermediomedial nucleus of lateral horn. The labeled nerve fibers in nucleus tractus solitarius were seen at the level of the 4th ventricle which the medial border of the nucleus tractus solitarius meets. Injection of CTB into the left submandibular gland labeled their neurons on the left and right superior salivatory nucleus (SSN), but other labeled cells and fibers were localized only on the left side.