Obesity and pancreatic islet hyperplasia in the Mongolian gerbil

Abstract

Summary. In a colony of Mongolian gerbils maintained on a standard laboratory diet, occasional obese animals were found. Obesity developed in animals of both sexes and was either transitory or permanent. The mean fasting blood glucose level in non-obese and obese gerbils was 83 and 105 rag/100 ml, respectively. Glucosuria and hyperglycemia were found only in a few obese animals, whereas the glucose tolerance was decreased in most obese gerbils. --The endocrine pancreas of the obese animals was morphologically either normal or more often hyperplastic, sometimes with the appearance of adenomatous islets. The fl-eells possessed prominent Golgi complex and endoplasmic reticulum, and sparse granulation. Large, granule-poor cells and mitotic figures were seen in the islets. Degenerative changes occurred in the fl-cells of diabetic animals. --It is suggested that the maintenance of the gerbils under laboratory conditions with free access to laboratory diet plays a majo r role in the development of obesity and that the endocrine pancreas of these animals has a good capacity for hyperplasia that often is sufficient to maintain normo-glycemia in obese animals, although the glucose tolerance is decreased. Obdsit@ et hyperplasie des ilots du panerdas chez la gerbille mongolienneRdsumd. Dans un 61evage de gerbilles mongoliennes soumises ~ un r@gime standard de laboratoire ont dr@ parfois trouvds des animaux ob@ses. L~ se dgveloppait chez les animaux des deux sexes et 6tait tantSt transitoire, tant6t permanente. Le taux moyen de glucose du sang, ~ jefin, ehez les animaux non ob@ses et ob~-ses 6tait respectivement de 83 et 105 mg/100 ml. La glyeosurie et l'hyperglycdmie n'dtaient trouvdes que ehez peu d'animaux ob6ses, tandis que la toldrance au glucose 6tait rdduite ehez la plupart des animaux ob@ses. --Le pancrdas endocrine des animaux ob@ses dtait, morphologiquement, normal ou plus souvent hyperplasique avec parfois l'apparition d'ilots adgnomateux. Les eellules /~ poss@daient un eomplexe de Golgi et un rdticulum endoplasmique pro@minents et une granulation faible. De grosses eellules pauvres en granules et des figures mitotiques se montraient dans les ilots. Des changements d@gdndratifs se produisaient dans les cellules fl des animaux diab6tiques. --On sugg~re que le maintien des animaux darts les conditions de laboratoire avec libre acc@s au r@gime de laboratoire joue un r61e prddominant darts le d@veloppement de I'ob@sit@ et que le pancr@as endocrine de ces animaux a une excellente eapaeit6 d'hyperplasie qu! suffit souvent ~ maintenir la normoglycdmie ehez les ammaux ob@ses, malgr6 la r6duction de la tol6rance au glucose. ~]bergewieht und Hyperplasie der Pankreasinseln bei der mongolischen RennmausZusammenfassung.

Increased pancreatic islet mass is accompanied by activation of the insulin receptor substrate‐2/serine‐threonine kinase pathway and augmented cyclin D2 protein levels in insulin‐resistant rats

“…No alterations are observed with regard to the distribution of exocrine and endocrine cells. These results correlate well with hyperinsulinaemia (Boquist 1972; Visser et al. 1979; Tomita et al.…”

“…Studies on the structure of pancreatic islets during insulin resistance induced by glucocorticoids have already been documented (Boquist 1972; Visser et al. 1979; Jonas et al.…”

“…Islets from these animals exhibited adaptive compensations, including increases in glucose‐ and other secretagogue‐induced insulin secretion. The structural and ultrastructural data on pancreatic islets, referring to glucocorticoid‐induced insulin resistance, are scarce; however, the majority of these studies only demonstrate islet hypertrophy as a compensatory adaptation to peripheral insulin resistance (Boquist 1972; Jonas et al. 1983; Tomita et al.…”

“…Islets from these animals exhibited adaptive compensations, including increases in glucose-and other secretagogue-induced insulin secretion. The structural and ultrastructural data on pancreatic islets, referring to glucocorticoid-induced insulin resistance, are scarce; however, the majority of these studies only demonstrate islet hypertrophy as a compensatory adaptation to peripheral insulin resistance (Boquist 1972;Jonas et al 1983;Tomita et al 1984). Unfortunately, other studies employing prolonged periods of treatment with glucocorticoids refer to pancreatic islet observations in relation to diabetic conditions (Visser et al 1979;Diani et al 1987;Zwicker & Eyster 1993;Momose et al 2006).…”

Histology and cytology of the islets of Langerhans in the Mongolian gerbil (<i>Meriones unguiculatus</i>)

“…It is naturally a de sert animal and under laboratory conditions of housing and diet spontaneously develops obesity, hyperglycaemia and islet hyperplasia [Boquist, 1972]. This ten dency is also shown by its close relative Psammomys obesus, though the latter has been more extensively studied from this point of view [Haines, et al, 1965).…”