Distribution of Galaninergic Immunoreactivity in the Brain of the Mouse SILVIA E. PE ´ REZ, 1,4 DAVID WYNICK, 2 ROBERT A. STEINER, 3 AND ELLIOTT J. MUFSON 1 1 Department of Neurological Sciences, Rush-Presbyterian-St. Luke’s Medical Center, Chicago, Illinois 60612 2 Department of Medicine, Bristol University, Marlborough Street, Bristol BS2 8HW, United Kingdom 3 Departments of Obstetrics and Gynecology, Physiology and Biophysics, School of Medicine, University of Washington, Seattle, Washington 4 Department Cellular and Molecular Biology, Unversity of A Corun ˜ a, 15071 Corun ˜ a, Spain ABSTRACT The distribution of galaninergic immunoreactive (-ir) profiles was studied in the brain of colchicine-pretreated and non-pretreated mice. Galanin (GAL)-ir neurons and fibers were observed throughout all encephalic vesicles. Telencephalic GAL-ir neurons were found in the olfactory bulb, cerebral cortex, lateral and medial septum, diagonal band of Broca, nucleus basalis of Meynert, bed nucleus of stria terminalis, amygdala, and hippocampus. The thal- amus displayed GAL-ir neurons within the anterodorsal, paraventricular, central lateral, paracentral, and central medial nuclei. GAL-ir neurons were found in several regions of the hypothalamus. In the midbrain, GAL-ir neurons appeared in the pretectal olivary nucleus, oculomotor nucleus, the medial and lateral lemniscus, periaqueductal gray, and the interpe- duncular nucleus. The pons contained GAL-ir neurons within the dorsal subcoeruleus, locus coeruleus, and dorsal raphe. In the medulla oblongata, GAL-ir neurons appear in the anterodorsal and dorsal cochlear nuclei, salivatory nucleus, A5 noradrenergic cells, giganto- cellular nucleus, inferior olive, solitary tract nucleus, dorsal vagal motor and hypoglossal nuclei. Only GAL-ir fibers were seen in the lateral habenula nucleus, substantia nigra, parabrachial complex, cerebellum, spinal trigeminal tract, as well as the motor root of the trigeminal and facial nerves. GAL-ir was also observed in several circumventricular organs. The widespread distribution of galanin in the mouse brain suggests that this neuropeptide plays a role in the regulation of cognitive and homeostatic functions. J. Comp. Neurol. 434: 158 –185, 2001. © 2001 Wiley-Liss, Inc. Indexing terms: galanin; central nervous system; immunohistochemistry; mouse; neuropeptide Galanin (GAL) is a 29/30-amino acid neuropeptide, which is widely distributed throughout the central and peripheral nervous systems. It was discovered in extracts of porcine intestine by Tatemoto et al. (1983). GAL is synthesized as part of the precursor protein preprogalanin (123–124 amino acids in porcine and rat, respectively), which is cleaved in GAL and GAL message-associated peptide (Kaplan et al., 1988; Sillard et al., 1992). The study of galaninergic systems in the central nervous system (CNS) has attracted increas- ing interest due to its involvement in a variety of biological actions including feeding, reproduction, learning, memory, antinociception, and Alzheimer disease (AD; see Crawley, 1996; Wynick et al., 1998). GAL immunohistochemical studies have characterized the widespread distribution of the galaninergic profiles within the CNS of rat (Skofitsch and Jacobowitz, 1985; Grant sponsor: NIA; Grant number: AG10668; Grant sponsor: NSF; Grant number: 1BN97201; Grant sponsor: NICHD; Grant number: AD27142; Grant sponsor: NIH/NICHD; Grant number: 3U54-HD12629 (SCCPRR); Grant sponsor: Unversity of A Corun ˜ a. *Correspondence to: Elliott J. Mufson, Department of Neurological Sci- ences, Rush-Presbyterian-St. Luke’s Medical Center, Tech 2000, 2242 West Harrison, Suite 200, Chicago, IL 60612. E-mail: emufson@rush.edu Received 2 January 2001; Revised 21 February 2001; Accepted 23 Feb- ruary 2001 THE JOURNAL OF COMPARATIVE NEUROLOGY 434:158 –185 (2001) © 2001 WILEY-LISS, INC.