Peptide YY-like immunoreactivity in sympathetic neurons of the rat.

The occurrence of peptide YY-like peptides in parts of the sympathetic nervous system of the rat was studied by immunocytochemistry and immunochemistry plus analysis by high performance liquid chromatography. Peptide YY-immunoreactive neurons and nerve fibers were detected in the superior cervical ganglion. Co-localization studies indicated that peptide YY and neuropeptide Y immunoreactivities co-exist in a subpopulation of neurons of the superior cervical ganglion. Immunochemical analysis revealed peptide YY-immunoreactive material, distinct from neuropeptide Y, in extracts of the superior cervical ganglion. On reverse-phase high performance liquid chromatography, extracts of superior cervical ganglion revealed several peaks of peptide YY-like immunoreactive material, one of which eluted close to the position of authentic porcine peptide YY. Peptide YY-immunoreactive nerve fibers were also present in sympathetic target tissues including the auricula and atria of the heart, carotid body, submandibular salivary gland and the adrenal cortex. It is suggested that peptide YY and/or peptide YY-like peptides are present not only in endocrine cells, but also in a subpopulation of cell bodies and fibers of the peripheral sympathetic nervous system.