Expression of somatostatin receptor subtypes 1-5 in pancreatic islets of normoglycaemic and diabetic NOD mice.
OBJECTIVE
Somatostatin acts on five specific receptors (sst1-5) to elicit different biological functions. The non-obese diabetic (NOD) mouse is an experimental model of type 1 diabetes. The aim of this study was to investigate whether the islet expression of sst1-5 is affected during the development of diabetes in NOD mice, with insulitis accompanied by spontaneous hyperglycaemia.


METHODS
By immunostaining for sst1-5 the expression and co-expression together with the four major islet hormones in pancreatic islets were investigated in female and male NOD mice at different stages of disease. The NOD related non-diabetic ICR mouse was also examined.


RESULTS
The islet cells of diabetic NOD mice showed an increased islet cell expression of sst2-5 compared with normoglycaemic female NOD mice. This correlated to increasing age and extent of insulitis. Major findings from the co-expression investigations were that sst2 was expressed in a majority of beta-cells in the normoglycaemic NOD mice, but absent in the beta-cells in the diabetic NOD mice. A majority of the alpha-cells expressed sst2 and 5 in normoglycaemic and diabetic NOD mice. About 60% of delta-cells showed co-expression of sst4 and 5 in both normoglycaemic and diabetic NOD mice. 60% of pancreatic polypeptide (PP)-cells expressed sst4 in both groups. Insulitis was found to be accompanied by a down-regulation of sst in normoglycaemic animals.


CONCLUSIONS
The difference in sst expression in the islets cells of diabetic mice may suggest either a contributing factor in the process leading to diabetes, or a defence response against ongoing beta-cell destruction.
Ludvigsen
E
E
Department of Medical Cell Biology, Uppsala, Sweden. Eva.Ludvigsen@medcellbiol.uu.se
Stridsberg
M
M
Janson
E T
ET
Sandler
S
S
D000367:Age Factors; D000818:Animals; D002452:Cell Count; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D007150:Immunohistochemistry; D007515:Islets of Langerhans / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D016688:Mice, Inbred NOD; D008856:Microscopy, Fluorescence; D010191:Pancreatic Polypeptide / Q000276:immunology; D017481:Receptors, Somatostatin / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics / Q000276:immunology; D012737:Sex Factors; D013997:Time Factors
D017481:Receptors, Somatostatin; D010191:Pancreatic Polypeptide