Galanin-containing-neurons, in the gastrointestinal tract of the lizard Podarcis s. sicula, as components of anally projecting nerve pathway

The distribution of galanin immunoreactive (Gal/IR) neurons was investigate d in the gastrointestinal (GI) tract of the lizard Podarcis s. sicula. The indirect immunofluorescence method, image analysis and confocal analysis we re applied to cryostat sections and whole mount preparations. Gal/IR nerve fibers and cell bodies were found throughout the lizard GI tract in the mye nteric plexus, circular muscle layer and mucosa. These nerve structures dec reased caudally. The stomach revealed a denser reactive nerve population th an elsewhere. The projections of Gal/IR neurons were detected in the myente ric plexus of lizard gut using a confocal microscope which analyzed the imm unoreactive material on the proximal and distal sides of muscle myotomies. An accumulation of Gal/IR material on the oral side of the myotomies demons trated the oral-to-anal projection of Gal containing nerve structures. Base d on our results, it can be hypothesized that Gal/IR neurons of the lizard digestive tract belong to the inhibitory descending pathway, which in most vertebrates is responsible for gut peristalsis regulation. (C) 1999 Publish ed by Elsevier Science Ireland Ltd. All rights reserved.