Glucagon-like peptide 1 (GLP-1) in the gastrointestinal tract of the pheasant (Phasianus colchicus).

The distribution of Glucagon-like peptide 1 (GLP-1) was investigated in the gastrointestinal tract of the pheasant using immunohistochemistry. GLP-1 immunoreactive cells were common in the small intestine, in the proventriculus and in the pancreas. Immunostained cells were not seen in the crop, in the gizzard and in the large intestine. Double labelling demonstrated that GLP-1 and pituitary adenylate cyclase-activating polypeptide (PACAP) were occasionally co-localized only in the duodenal villi. In contrast to what was previously described in the chicken and ostrich, we noted GLP-1 positive cells in the duodenum. These data were consistent with the presence of proglucagon mRNA in the chicken duodenum. Our findings indicate that GLP-1 might have an inhibitory effect on gastric and crop emptying and on acid secretion also in the pheasant. Moreover, the results of the present research regarding the initial region of the small intestine suggest a further direct mechanism of the GLP-1 release during the early digestion phase and an enhancement of its incretin role.

Histochemical features of the Muscovy duck small intestine during development.

We demonstrated for the first time the distribution and morphology of argyrophil and of goblet cells in the mucosa of the small intestine of the Muscovy duck during development using the Grimelius silver staining and alcian blue/periodic acid-Schiff (AB/PAS) staining technique. The argyrophil cells distribution was variable over the length of the small intestine from embryonic day 24 (24E) to post-hatching day 13 (13d). In the villi most argyrophil cells belonged to the open-type, while in the crypts they belonged to the closed-type. In the duodenum the density of argyrophil cells was highest at hatching, while in the jejunum and in the ileum the highest density value was at hatching and 13d. AB/PAS-positive goblet cells appeared on the villi and crypts of the duodenum and jejunum at 30E, and in the ileum at hatching. The density of AB/PAS-positive cells was the highest in the three segments at hatching. The AB-positive cells, compared with the PAS-positive cells, predominated in villi and crypts of the three segments, moreover the rate of AB-positive cells to PAS-positive cells significantly decreased from 30E to 9d. An increase in argyrophil and goblet cells number during the later incubation and at hatching, could indicate the small intestine in that period is being prepared to face a new diet.