RESUMO
BACKGROUND: Gastrointestinal (GI) endocrine cells produce many GI hormones that perform various physiological functions of the digestive system. AIMS: We aimed to investigate the presence and distribution of immunoreactive (IR) endocrine cells to glucagon, somatostatin, cholecystokinin-8 (CCK-8), serotonin, secretin and histamine in the stomach of adult male New Zealand White rabbit (Oryctolagus cuniculus). METHODS: For immunohistochemical staining, peroxidase anti-peroxidase (PAP) method was applied to stomach samples. RESULTS: Glucagon-IR cells of closed- and open type were found throughout all the stomach parts examined. Somatostatin-IR cells of closed- and open type in the cardiac and oxyntic glands were localized to deep portions of foveola gastrica. CCK-8 IR cells that were not observed in the cardia and fundus were mostly localized to the glands and lamina epithelialis in the pyloric part near the duodenum. Oval-shaped open and closed type serotonin-IR cells were mostly dispersed throughout the fundic and pyloric glands. Secretin-IR cells were rare in the pyloric and cardiac region although they were not observed in the fundic glands. Histamine-IR cells were rarely found in the cardia, fundus and pylorus. CONCLUSION: Our findings show that glucagon, histamine, somatostatin, secretin and serotonin might be produced by all the stomach regions while pyloric region had only CCK-8 IR. These distribution patterns also provide further evidence of species-specific differences, which might be important from the evolutionary aspect of the digestive tract in relation to evolutional niches and nutrient resources.
RESUMO
Natriuretic peptides are structurally similar, but genetically distinct, hormones that participate in cardiovascular homeostasis by regulating blood and extracellular fluid volume and blood pressure. We investigated the distribution of natriuretic peptides and their receptors in goat (Capra hircus) heart tissue using the peroxidase-anti-peroxidase (PAP) immunohistochemical method. Strong staining of atrial natriuretic peptide (ANP) was observed in atrial cardiomyocytes, while strong staining for brain natriuretic peptide (BNP) was observed in ventricular cardiomyocytes. Slightly stronger cytoplasmic C-type natriuretic peptide (CNP) immunostaining was detected in the ventricles compared to the atria. Natriuretic peptide receptor-A (NPR-A) immunoreactivity was more prominent in the atria, while natriuretic peptide receptor-B (NPR-B) immunoreactivity was stronger in the ventricles. Cytoplasmic natriuretic peptide receptor-C (NPR-C) immunoreactivity was observed in both the atria and ventricles, although staining was more prominent in the ventricles. ANP immunoreactivity ranged from weak to strong in endothelial and vascular smooth muscle cells. Endothelial cells exhibited moderate to strong BNP immunoreactivity, while vascular smooth cells displayed weak to strong staining. Endothelial cells exhibited weak to strong cytoplasmic CNP immunoreactivity. Vascular smooth muscle cells were labeled moderately to strongly for CNP. Weak to strong cytoplasmic NPR-A immunoreactivity was found in the endothelial cells and vascular smooth muscle cells stained weakly to moderately for NPR-A. Endothelial and vascular smooth cells exhibited weak to strong cytoplasmic NPR-B immunoreactivity. Moderate to strong NPR-C immunoreactivity was observed in the endothelial and smooth muscle cells. Small gender differences in the immunohistochemical distribution of natriuretic peptides and receptors were observed. Our findings suggest that endothelial cells, vascular smooth cells and cardiomyocytes express both natriuretic peptides and their receptors.