Neurochemical features of feline superior mesenteric ganglion.

The distribution of various neuronal peptides: substances P (SP), somatostatin (SOM), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) was studied by means of immunofluorescence in the superior mesenteric ganglion of the cat. Several populations of neurons can be characterized by their contents of neurotransmitters. All of the neuropeptides were seen in the ganglion cells in different proportions but the majority of the cells were NPY-immunopositive and immunoreactivity for CGRP, SOM and SP was restricted to rather small subpopulations. Only a few ganglionic cells were VIP-immunoreactive. The neuronal fibres expressed different peptide immunoreactivity as well; the most widespread ones were VIP-containing fibres. The neuronal filaments immunoreactive to the rest of neuropeptides were seen more rarely, usually surrounding immunonegative cell bodies and blood vessels.