Location of sensory nerve cells that provide calbindin-containing laminar nerve endings in myenteric ganglia of the rat esophagus.

To determine the origin of the calbindin-containing laminar nerve endings in the myenteric ganglia of the rat esophagus, retrograde tracing experiments combined with immunohistochemistry using an antibody for calbindin were carried out. After Fast blue was injected into the cervical portion of the esophagus, labeled neurons were found bilaterally in the nodose ganglion and dorsal root ganglia of C1 to T3. 80% of the total neurons in the nodose ganglion and 20% of those in the dorsal root ganglia showed calbindin immunoreactivity. Moreover, 79% of Fast-blue-labeled neurons found in the nodose ganglion and 18% of those in the dorsal root ganglia were immunoreactive for calbindin. These results suggest that the calbindin antibody we used is useful as a marker for identifying esophageal vagal afferents derived from the nodose ganglion. The calbindin-immunoreactive nerve fibers forming the laminar endings in the myenteric ganglia of the rat cervical esophagus are mainly derived from sensory neurons in the nodose ganglion and partly derived from those in the cervical and upper thoracic dorsal root ganglia. Calbindin-containing laminar nerve endings may be related to mechanoreceptors in the esophagus.