Neurogastroenterol. Mot. zyxwvutsrqp (1996) 8,255-272 The dorsal vagal complex of the ferret: anatomical and immunohistochemical studies zyx F. M. BOISSONADE,' J. S. DAVISON,' R. EGIZII,' G. E. LUCIER' 8\ K. A. SHARKEYZ 'Department of Oral and Maxillofacial Surgery, School of Clinical Dentistry, University of Sheffield, Sheffield,UK ZNeuroacience and Gastrointestinal Research Groups, Department of Medical Physiology, Universityof Calgary, Calgary, Alberta, Canada Abstract zyxwvuts To zyxwvutsrqpo further the understanding zyxwvu of gastrointest- inal function in this species. and in particular to advance ow own work concerning central emetic path- ways, the cytoarchitecture and the distribution of eight neurochemicals were studied in the ferret dorsal vagal complex (DVC; area postrema, nucleus of the solitary tract [nTS] and dorsal motor nucleus of the vagus).The cytoarchitectural features of this region in the ferret were similar to those seen in other species; however, the ferret possesses a particularly large and distinct subnucleus gelatinosus zyxwvuts of the nTS. Dense calcitonin gene-related peptide-immunoreactivity was found in the gelatinous, interstitial and commissurd subnuclei of the nTS, with lesser amounts in other regions of the DVC. Enkephalin-immunoreactivity of varying densi- ties was found throughout the DVC. Moderate to dense galanin-immunoreactivity was observed throughout the DVC, with the exception of the subnucleus gelati- nosus of the nTS, from which it was virtually absent. Dense neuropeptide Y-immunoreactivity was observed in the subnucleus gelatinosus and interstitial subnu- cleus, with moderate staining in other regions of the DVC. Neurotensin immunoreactivity was very sparse or absent. Immunoreactivity forserotonin was sparsely dism'buted throughout the DVC. Moderate somatosta- tin-immunoreactivity was observed over a large portion of the DVC, but was virtually absent from the gelatinosus and interstitial subnuclei. Substance P immunoreactivity was observed throughout the DVC and was particularly dense in the dorsalldorsolateral subnucleus and the dorsal aspects of the medial and commissural subnuclei. In terms of its cytoarchitec- Address for correspondence Dr F. M. Soissonade, Department of Oral and Maxillofacial Surgery, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield zyxwvuts S10 2TA, UK. Received 30 June 1995 Accepted for publication: 10 April 1996 ture the DVC of the ferret is more similar to the cat than the rat, especially with regard to the area post- rema and the subnucleus gelatinosus of the nTS. The distribution of neuroactive substances was largely similar to other species; however, differences were present particularly in patterns of immunoreactivity for enkephalin, serotonin, neuropeptide Y and soma- tostatin. Keywords area postrema, brainstem, dorsal motor nucleus of the vagus, neuropeptides, nucleus of the solitary tract, serotonin. INTRODUCTION The dorsal vagal complex (DVC) comprises the nucleus of the solitary tract (nTS), the dorsal motor nucleus of the vagus (DMNXI and the area postrema (AP) {see ref. 60). The concept of the DVC has arisen because of the importance of these regions, at the caudal end of the medulla, in the integration of gastric, respiratory and cardiovascular functions, and in respiratory and gastrointestinal protective reflexes, including emesis.& Considerable attention has been paid to the connections of the nTS, since it was shown that subdivisions of the nTS received distinct topo- graphic visceral inputs and that neurons in the nTS projected to specific central and spinal loci (reviewed in ref. 66). In rat, cat, hamster, monkey and man, the z nTS demonstrates distinct cpoarchitectural features which have enabled investigators to divide it into a series of subnuclei, which can also be correlated with the topography of the afferent and efferent connec- tionS.2,8,34,3S,46,49-S 1,62,67,74,87,90,95', 104,107,111 Many of the neurochemical features of the DVC have also been investigated. Pioneering studies by Kalia and co- worker~~~ have demonstrated distinct patterns of neuropeptide immunoreactivity zyx in various subnuclei of the nTS and other regions of the medulla of the rat. f+ 1996 BIackwelI Science Ltd 255