Distinct localization and target specificity of galanin-immunoreactive sympathetic preganglionic neurons of a teleost, the filefish Stephanolepis cirrhifer

Immunoreactivity for galanin was examined in the sympathetic preganglionic neurons in the spinal cord, adrenal glands, sympathetic ganglia, and some s ensory ganglia of the filefish Stephanolepis cirrhifer. Galanin-immunoreact ive neurons were found only in the rostral parr, but not in the caudal part of the central autonomic nucleus (a column of sympathetic preganglionic ne urons of teleosts). Many galanin-immunoreactive nerve terminals were found in contact with neurons in the celiac ganglia and the cranial sympathetic g anglia on bath sides of the body. Most neurons encircled by galanin-immunor eactive nerve fibers were negative for tyrosine hydroxylase. Galanin-immuno reactive nerve fibers were very sparse in the spinal sympathetic paraverteb ral ganglia. No galanin-immunoreactive nerve fibers were found in the adren al glands. No sensory neurons of the trigeminal, vagal, or spinal dorsal ro ot ganglia were positive for galanin-immunoreactivity. These results sugges t that galanin-immunoreactive sympathetic preganglionic neurons have distin ct segmental localization and might project specifically to a population of non-adrenergic sympathetic postganglionic neurons in the celiac and crania l sympathetic ganglia. (C) 2000 Elsevier Science B.V. All rights reserved.