Acta histochemica 107 (2005) 3—9 Presence and distribution of ghrelin- immunopositive cells in the chicken gastrointestinal tract Simona Neglia, Nadia Arcamone, Vincenzo Esposito, Giuliana Gargiulo, Paolo de Girolamo à Department of Biological Structures, Functions and Technologies, University of Naples ‘‘Federico II’’, Via Veterinaria 1, I-80137 Naples, Italy Received 16 June 2004; received in revised form 15 October 2004; accepted 17 December 2004 Summary The presence and distribution patterns of ghrelin, a gastric acylated peptide, were studied in the entire gastrointestinal tract of the chicken (Gallus domesticus) using the peroxidase–antiperoxidase immunohistochemical method, western blot analysis and a specific antibody against the C-terminal region of rat ghrelin. Ghrelin- immunopositive cells were observed in the mucosal layer of all segments examined. The largest numbers of ghrelin-positive cells were located at the base of lobuli of the proventriculus gland, along villi of the intestines and in crypts of the duodenum. Lower numbers of ghrelin-immunostained cells were located in crypts of jejunum and ileum and only few ghrelin-immunostained cells were detected at the base of crypts of the large intestine. Closed and open types of cells were observed in all segments. Western blot analysis confirmed the presence of ghrelin-like protein in the entire chicken gastrointestinal tract. The anatomical distribution patterns and the morphological characteristics of chicken ghrelin-positive cells suggest that they are endocrine cells. Furthermore, it is concluded that ghrelin shows a high degree of preservation during evolution from non-mammalian vertebrates to mammals. & 2005 Elsevier GmbH. All rights reserved. Introduction Growth-hormone secretagogues (GHSs) are small synthetic peptides and non-peptidyl molecules that stimulate growth hormone (GH) release both in vivo and in vitro from the anterior pitituary gland via a G-protein-coupled receptor (GHS-R; Bowers, 1998). Recently, a novel GHS-R ligand was isolated and ARTICLE IN PRESS www.elsevier.de/acthis KEYWORDS Ghrelin; Chicken; Gastrointestinal tract; Immunohistochemis- try; Western blot 0065-1281/$ - see front matter & 2005 Elsevier GmbH. All rights reserved. doi:10.1016/j.acthis.2004.12.001 à Corresponding author. Tel.: +39081 2536114; fax: +39081 2536097. E-mail address: degirola@unina.it (P. de Girolamo).