Ex-vivo isolated perfusion of the pancreas in the Syrian golden hamster

GLP-1 receptors in golden Syrian hamster islets: identification and functional characterization

This study aims at the identification and functional characterization of glucagon-like peptide 1 (7-36) amide (GLP-1) receptor in islets from Golden Syrian hamsters. Using a polyclonal antibody against rat GLP-1 receptors, Western blotting of the islet proteins revealed two major bands of 44 and 70 kDa, similar to those found in rat islets, RINm5F cells, and HIT-T15 cells. In Northern blots, transcripts of 2.7, 3.6 and 3.7 kb were observed in rat islets and RINm5F cells after hybridization with rat GLP-1 receptor cDNA probes of either 21 9 bp or 1.5 kb. Such was not the case in either hamster islets or HIT-T15 cells. However, a single 3.6-kb transcript was observed in the latter two cases when a human GLP-1 receptor cDNA probe of 1.6 kb was used for hybridization. In the isolated perfused pancreas of Golden Syrian hamsters, a rise in D-glucose concentration from 3.3 to 8.3 mM caused a biphasic stimulation of insulin release, which was further increased by either GLP-1 or glucagon (10(-9)M each). The enhancing action of GLP-1 on glucose-stimulated insulin secretion was much more marked than that of glucagon. The rise in D-glucose concentration decreased by 46+/-4% the release of glucagon, but GLP-1 failed to exert any obvious effect on glucagon secretion in the presence of 8.3 mM D-glucose. These results indicate that GLP-1 receptors are expressed in islets of Golden Syrian hamsters with an extracellular part possessing the same immunoreactivity as the rat islet GLP-1 receptors. The expression of the mRNA for the GLP-1 receptor differs, however, from that found in rat or human islets.

Cell differentiation during pancreatic carcinogenesis

In many tissues, carcinogenesis mimics embryonic development. This is true for the pancreas. The first alteration seen during pancreatic tumor induction in the hamster model is proliferation of poorly differentiated ductular (tubular) structures intermingled with endocrine cells, a pattern consistent with findings in the embryonic and fetal pancreas. However, unlike the fetal tissue, various cell types of intestinal epithelium appear in the advance stages of pancreatic carcinogenesis. Moreover, contrary to the situation in the fetal and adult hamster pancreas, the induced pancreatic lesion expresses antigens with human blood group type specificities, including A, B, H, Leb, Lex, and Ley, antigens that are expressed, however, by fetal and adult duodenal epithelium. Considering the origin of the pancreas from the duodenal mucosa, the overall findings indicate that during pancreatic carcinogenesis some genes, acquired from the progenitor (duodenal) cells, which are inactive in embryonic and normal pancreatic cells, are activated, possibly as a function of some oncogenes. Comparative studies in human tissue lead to the same conclusion.