THE DISTRIBUTION AND ORIGIN OF NERVE-FIBERS IMMUNOREACTIVE FOR SUBSTANCE-P AND NEUROKININ-A IN THE ANTERIOR BUCCAL GLAND OF THE RAT

The distribution and origin of substance P (SP) and neurokinin A (NKA) were studied in rat in the anterior buccal glands, which are minor mu cous salivary glands. Indirect immunofluorescence staining showed mode rate SP and NKA innervation of salivary acini and interlobular ducts, whereas blood vessels were more sparsely innervated, and there were fe w nerve fibers in the stroma and around the intralobular ducts. About 10%-20% of the trigeminal ganglion cells showed equally strong immunor eactivity to both SP and NKA. Unilateral denervation of the branches o f the trigeminal nerve caused complete disappearance of the stromal fi bers and greatly reduced the number of all other SP-immunoreactive and NKA-immunoreactive nerve fibers. In the superior cervical ganglia, SP and NKA immunoreactivity was restricted to small intensely fluorescen t cells; SP and NKA immunoreactivity was absent from principal ganglio nic cells, and thus sympathectomy had no any effect on the number or d istribution of fibers immunoreactive for SP and NKA in the anterior bu ccal glands. The fibers remaining after sensory denervation could have been of parasympathetic origin, indicating a dual origin of nerves im munoreactive for SP and NKA in these glands. The present data demonstr ate that the major part of the glandular SP and NKA innervation in the minor salivary glands derives from the trigeminal ganglia. The distri bution of the peripheral nerve fibers indicates that they may play a r ole in the delivery of potent neuropeptides involved in the vascular, secretory, and motor (myoepithelial cells) functions of salivary gland s.