Abstract
Histochemical studies have shown the existence of afferent fibers in the salivary glands, that is, the fibers around the small ducts which contain both substance P and CGRP are considered to be sensory fibers. In the present study, we injected WGA-HRP into the sympathetic and parasympathetic routes of rat submandibular gland, and observed the HRP-labeled cells in sensory ganglia. The following results were obtained: 1) When the tracer was injected into the parasympathetic route, the labeled cells were found mainly in the trigeminal ganglion and sparsely in the dorsal root ganglia (C2-C5); 2) When the tracer was injected into the sympathetic route, the labeled cells were found mainly in the dorsal root ganglia (C2-C5 and T2); 3) No labeled cells were found in the geniculate, superior, and inferior ganglia; 4) The labeled cells in the trigeminal ganglion are composed of various size of neurons, whereas those in the dorsal root ganglia are smaller size of neurons as compared with non-labeled cells. These results suggest that the afferent nerves from the submandibular gland travel in the sympathetic and parasympathetic routes and their cell bodies are dominantly located in the dorsal root ganglia and trigeminal ganglion, respectively. On the basis of cell size analyzed in the present study and the peripheral distribution reported by the previous studies, it is also suggested that the afferents do not conduct only pain but also pressure of the duct system. [Jpn J Physiol 55 Suppl:S190 (2005)]
