Immunohistochemical characterization of neurones in the hypoglossal nucleus of the pig.

In this study, the presence of several neurotransmitters and transmitter synthesizing enzymes was studied in hypoglossal nucleus (HN) of the juvenile (4 months old) female pigs (n = 3). Double-labeling immunofluorescence revealed neurones expressing cholinacetyltranspherase (ChAT), calcitonin gene-related peptide (CGRP), nitric oxide synthase (NOS), and somatostatin (SOM). Nerve fibers within HN were ChAT, CGRP, NOS, SOM, substance P (SP), Leu-5-enkephalin (Leu-5-Enk), ss-dopamine hydroxylase (DssH), neuropeptide Y (NPY) positive. Virtually all the perikarya contained ChAT, whereas CGRP was present in 47% of the neurones. Nerve cell bodies containing NOS or SOM were only occasionally observed. Immunoreactive nerve fibers were found in a close vicinity of the perikarya, often forming baskets around nerve cell bodies. The results obtained were compared with similar data obtained in other species. The presence of immunoreactive structures, origin of the nerve fibers, and functional significance of the findings are discussed.