Immunolocalization of histamine H3 receptors on endocrine cells in the rat gastrointestinal tract
Daniela Grandi1, Fiona C. Shenton2, Paul L. Chazot2 and Giuseppina Morini1
1Department of Human Anatomy, Pharmacology and Forensic Medicine, University of Parma, Parma, Italy and 2Centre for Integrative Neuroscience, School of Biological and Biomedical Sciences, Durham University, Durham, UK.
Offprint requests to: Giuseppina Morini, Department of Human Anatomy, Pharmacology and Forensic Medicine, University of Parma, Via Volturno 39, 43100, Parma, Italy. e-mail: giuseppina.morini@unipr.it
Summary. The histamine H3 receptor (H3R) has been identified in the gastrointestinal tract of the rat by immunohistochemistry, using the first validated anti-H3 receptor antibody. Immunoreactivity to H3R was exclusively localized to the endocrine cells scattered in the gastrointestinal mucosa, with positive cells being prominently abundant in the gastric fundus, while they were rarely found in the other regions. In the fundus, positive cells were distributed in the lower half of the mucosa and their number significantly decreased after a 24 h-fasting period. Double-labeling studies were undertaken to identify the H3R-immunoreactive cell types in the fundic and antral mucosa. The H3R-immunoreactive cells were positive for chromogranin A. In the fundus, approximately 90% of cells positive to H3R were also positive to the histamine-forming enzyme, histidine decarboxylase. None of the cells expressing H3R displayed immunoreactivity for gastrin, somatostatin or ghrelin. Location, the influence of food deprivation and colocalization with histidine decarboxylase indicate that H3R positive cells correspond to the enterochromaffin-like cells (ECL). Histol Histopathol 23, 789-798 (2008)
Key words: Histamine H3 receptor, Gastric fundus, Histidine decarboxylase, Enterochromaffin-like cells, Food deprivation
DOI: 10.14670/HH-23.789