Co-localization of neuroendocrine hormones in the human fetal pancreas

Abstract

Objective and Design: Co-localization of the four major pancreatic hormones, and also of islet amyloid polypeptide (IAPP), peptide tyrosine tyrosine (PYY), secretin and neurotensin, has been studied in the endocrine pancreas of human fetuses at 16, 18 and 22 weeks of gestation. Methods: Double and triple immunofluorescence stainings have been used. Results: All three fetal pancreata contained cells that showed insulin, glucagon, somatostatin, pancreatic polypeptide (PP), IAPP, secretin and PYY immunoreactivity. Neurotensin cells were found in the youngest fetus and gastric inhibitory polypeptide (GIP) in the two older fetuses. Colocalization of two hormones occurred in most of the endocrine cell types in the three fetuses examined, but three hormones occurred in only a few cells and especially in the youngest fetus. Somatostatin cells were the only cell type which was largely monohormonal. Our findings showed that there are two different co-localization patterns: insulin was co-localized mainly with IAPP and glucagon, while secretin and PYY occurred together with glucagon and PP. Conclusions: These data are the first to describe secretin and neurotensin in the fetal pancreas. Two different co-localization patterns could be distinguished: insulin, IAPP and glucagon, and glucagon, secretin, PP and PYY.

Immunocytochemical staining for islet amyloid polypeptide in pancreatic endocrine tumors

“…Both Portela-Gomez et al with fetal islets and Iki and Pour with adult islets reported about 50% of insulin cells positive for IAPP, 5,6 and our results showed about 15-20% of anuclear insulin cells were strongly and densely positive for IAPP and about 50-60% of islet cells including the majority of insulin cells and a few non-β-cells were at least moderately and granularly positive for IAPP (Table 1 and Fig. 1).…”

“…11 There is a disagreement on immunopositive staining for IAPP in non-β-cells. In fetal islets, Portela-Gomez et al reported that glucagon and SRIF cells were positive for IAPP at 1.4 and 2.6%, respectively, 5 whereas with normal adult islets Iki and Pour reported none of the glucagon cells were positive for IAPP, but in type 2 diabetics, some islets in the atrophic islets were positive for both SRIF and IAPP. 6 Our current results also support that at least a few non-β-cells are positive for IAPP at weaker than insulin cells (Fig.…”

“…3 In fetal islets, IAPP is co-localized in insulin-cells at 50% frequency whereas glucagon and somatostatin (SRIF) cells were co-localized with IAPP at 1.4 and 2.6%, respectively, by immuofluorescence study. 5 By double immunocytochemical staining, Iki and Pour reported 50% of insulin cells positive for IAPP and none of the glucagon cells were co-stained for IAPP in non-diabetic islets; whereas there were some islet cells co-expressing both SRIF and IAPP in atrophic type 2 diabetic islets. 6 We had previously immunostained pancreatic endocrine tumors (PETs) consisting of insulinomas, glucagonomas, pancreatic polypetidoma (PPomas), gastrinomas and non-functioning tumors, revealing all insulinomas and at least some non-β-cell tumors weakly positive for IAPP, suggesting that some neoplastic Aims/hypothesis: Islet amyloid polypeptide is originally identified as the chief constituent of amyloid in insulinomas and type 2 diabetic islets.…”

Islet amyloid polypeptide in pancreatic islets from type 1 diabetic subjects

“…6 Glucagon and SRIF cells have been co-localized with IAPP in fetal islets 5 and the other authors also co-localized SRIF cells with IAPP in fetal rat islets 7 and in mouse gastric mucosa, 8 respectively. Despite co-secretion of insulin and IAPP in the blood stream, IAPP is co-localized with β-cells at 50% 5,6 with less densely immunocytochemical staining than that of insulin staining in control islets (Fig. 1).…”

“…3 In fetal islets, IAPP is co-localized with insulin-cells at 50% frequency whereas glucagon and somatostatin (SRIF) cells were co-localized at 1.4 and 2.6%, respectively, by immunofluorescence study. 5 By double immuncocytochemical staining, Iki and Pour reported 50% of insulin cells positive for IAPP and none of glucagon cells were co-stained for IAPP in non-diabetic islets whereas there were some islets cells co-expressing both IAPP and SRIF cells in atrophic type 2 diabetic islets. 6 A synthetic IAPP, Pranlintide 25,28,29 (Pro-hIAPP) has been used for treating type 1 diabetics with insulin for a better glycemic control as type 1 diabetics presented with IAPP hyposecretion, and IAPP Aims/hypothesis: Islet amyloid polypeptide is originally isolated as the chief constituent of amyloid deposits in type 2 diabetic islets.…”