Evidence of substance P immunoreactive neurons in dorsal root ganglia and vagal ganglia projecting to the guinea pig pylorus.

The origin of extrinsic substance P fibers in the guinea pig pyloric wall was investigated by combining retrograde axonal tracing and indirect immunofluorescence techniques. After injection of Fast Blue into the pyloric wall labeled cells were found in the T7-T9 dorsal root ganglia and the nodose and jugular ganglia. About 60% of the labeled cells in the dorsal root ganglia contained substance P-like immunoreactivity. After local application of colchicine, a few substance P positive cells were observed in the nodose and jugular ganglia, some of which also contained Fast Blue.