IMMUNOHISTOCHEMICAL STUDIES ON THE COEXISTENCE OF CATECHOLAMINE-SYNTHESIZING ENZYMES AND NEUROPEPTIDE-Y IN NERVE-FIBERS OF THE PORCINE PINEAL-GLAND

The distribution of nerve fibers immunoreactive (IR) to catecholamine- synthesizing enzymes, tyrosine hydroxylase (TH), dopamine-beta-hydroxy lase (D beta H), and phenylethanolamine-N-methyltransferase (PNMT) as well as neuropeptide Y (NPY), in the pineal gland of adult sows was in vestigated by the use of double-labeling immunohistochemistry. The por cine pineal gland was found to be supplied by TH-IR nerve fibers, the vast majority of which were also D beta H-positive. TH- and TH/D beta H-IR nerves were located mostly in the capsula and connective septa of the pineal gland, and their fine varicose branches terminated in the adherent parenchyma. NPY-IR fibers formed a loose network overlapping that was observed in the case of TH- and D beta H-IR fibers. Most of N PY-IR fibers were also positive for TH. The density of the fiber netwo rks depended on the region of the gland. No PNMT-IR structures were ob served.