We have determined whether
brain-derived neurotrophic factor immunoreactive (
BDNF-ir) neurons in the vagal ganglia innervate the gastrointestinal tract. Many
BDNF-ir neurons were medium in size and located throughout the jugular and nodose ganglia. When
Fluorogold was injected into the wall of the cervical esophagus, many retrogradely
Fluorogold-labeled neurons were found in both the jugular
ganglion and the nodose ganglion. When
Fluorogold was injected into the body of the stomach or applied to the cut end of the subdiaphragmatic vagus nerve, numerous
Fluorogold-labeled neurons were found mostly in the nodose ganglion. Double-labeling combining immunohistochemistry for
BDNF and retrograde tracing with
Fluorogold showed that more than 90% of the neurons in the jugular
ganglion and the nodose ganglion projecting to the cervical esophagus contained
BDNF-like immunoreactivity. In the cases of both
Fluorogold injection into the stomach and
Fluorogold application to the subdiaphragmatic vagus nerve, almost all
Fluorogold-labeled neurons in the nodose ganglion contained
BDNF-like immunoreactivity. These results indicated that almost all vagal sensory neurons located in either the jugular
ganglion or the nodose ganglion that innervate the gastrointestinal tract are
BDNF-ir neurons.