title: Histochemical and immunohistochemical study on endocrine cells (5HT, GAS, and SST) of the gastrointestinal tract of a teleost, the characin Astyanax bimaculatus.
abstract: Endocrine cells secrete hormones through the mucosa of the gastrointestinal tract (GIT) and act on the overall regulation of digestive processes such as nutrient absorption, gut motility and intestinal blood flow. This study aimed to determine regional distribution and frequency of endocrine cells secretory of serotonin (5-HT), somatostatin (SST) and gastrin (GAS) in the GIT of a small-bodied widespread characin Astyanax bimaculatus using histological, histochemical and immunohistochemical techniques. Fragments of the stomach and gut fixed for 8h in Bouin liquid were subjected to histological processing and immunohistochemical routine. For the histological analyses, the technique of staining with hematoxylin and eosin (HE) was used, whereas for the histochemical analyses Gomori's trichrome, periodic acid+Schiff (PAS) and Alcian blue pH 2.5 (AB) were used to further immunohistochemical processing. The stomach has a mucosa lined with a simple columnar epithelium with mucus-secreting cells; the glandular region (proximal and distal portions) has folds and pits, whereas the non-glandular region has pits only. The intestinal epithelium is simple with plain cylindrical grooved and goblet cells. The anterior region has thin folds with few goblet cells, and the posterior region with thick folds and many goblet cells. The regional distribution and frequency of endocrine cells varied across regions of the GIT with the stomach showing the highest amount of immunoreactive (IR) cells. Only the 5-HT was found in the stomach (epithelia and glands) and gut regions, with comparatively higher frequency in the stomach. SST-IR cells were found in the stomach (epithelia and gastric glands) with higher frequency in the glandular region, whereas GAS-IR were found in the gastric glands only. The stomach was the only organ to have all the three types of endocrine cells, indicating that this organ is the main site of digestion of food in this species.
authors.affiliation: Laboratory of Histology and Embryology, Institute of Biology, University Federal Rural of Rio de Janeiro, BR 465, Km 7, 23.870-000 Seropédica, RJ, Brazil.
authors.forename: Nathália das Neves
authors.initials: Nd
authors.lastname: Cardoso
authors.affiliation: Laboratory of Histology and Embryology, Institute of Biology, University Federal Rural of Rio de Janeiro, BR 465, Km 7, 23.870-000 Seropédica, RJ, Brazil.
authors.forename: Enely Maris da Silveira
authors.initials: EM
authors.lastname: Firmiano
authors.affiliation: Laboratory of Fish Ecology, Institute of Biology, University Federal Rural of Rio de Janeiro, BR 465, Km 7, 23.870-000 Seropédica, RJ, Brazil.
authors.forename: Iracema D
authors.initials: ID
authors.lastname: Gomes
authors.affiliation: Laboratory of Histology and Embryology, Institute of Biology, University Federal Rural of Rio de Janeiro, BR 465, Km 7, 23.870-000 Seropédica, RJ, Brazil.
authors.forename: Aparecida A
authors.initials: AA
authors.lastname: do Nascimento
authors.affiliation: Laboratory of Histology and Embryology, Institute of Biology, University Federal Rural of Rio de Janeiro, BR 465, Km 7, 23.870-000 Seropédica, RJ, Brazil.
authors.forename: Armando
authors.initials: A
authors.lastname: Sales
authors.affiliation: Laboratory of Fish Ecology, Institute of Biology, University Federal Rural of Rio de Janeiro, BR 465, Km 7, 23.870-000 Seropédica, RJ, Brazil. Electronic address: gerson@ufrrj.br.
authors.forename: Francisco G
authors.initials: FG
authors.lastname: Araújo
mesh_terms: D000818:Animals; D060126:Characidae / Q000378:metabolism*; D055098:Endocrine Cells / Q000378:metabolism*; D005755:Gastrins / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000166:cytology* / Q000378:metabolism*; D007150:Immunohistochemistry; D012701:Serotonin / Q000378:metabolism*; D013004:Somatostatin / Q000378:metabolism*
chemical_list: D005755:Gastrins; D012701:Serotonin; D013004:Somatostatin
keywords: Fishes; Histology; Immunoreactive cells; Stomach