title: Mechanisms involved in the beta-cell mass increase induced by chronic sucrose feeding to normal rats.
abstract: The aim of the present study was to clarify the mechanisms by which a sucrose-rich diet (SRD) produces an increase in the pancreatic beta-cell mass in the rat. Normal Wistar rats were fed for 30 weeks either an SRD (SRD rats; 63% wt/wt), or the same diet but with starch instead of sucrose in the same proportion (CD rats). We studied body weight, serum glucose and triacylglycerol levels, endocrine tissue and beta-cell mass, beta-cell replication rate (proliferating cell nuclear antigen; PCNA), islet neogenesis (cytokeratin immunostaining) and beta-cell apoptosis (propidium iodide). Body weight (g) recorded in the SRD rats was significantly (P<0.05) larger than that of the CD group (556.0+/-8.3 vs 470.0+/-13.1). Both serum glucose and triacylglycerol levels (mmol/l) were also significantly higher (P<0.05) in SRD than in CD rats (serum glucose, 8.11+/-0.14 vs 6.62+/-0.17; triacylglycerol, 1.57+/-0.18 vs 0.47+/-0.04). The number of pancreatic islets per unit area increased significantly (P<0.05) in SRD rats (3.29+/-0.1 vs 2.01+/-0.2). A significant increment (2.6 times) in the mass of endocrine tissue was detected in SRD animals, mainly due to an increase in the beta-cell mass (P=0.0025). The islet cell replication rate, measured as the percentage of PCNA-labelled beta cells increased 6.8 times in SRD rats (P<0.03). The number of apoptotic cells in the endocrine pancreas decreased significantly (three times) in the SRD animals (P=0.03). The cytokeratin-positive area did not show significant differences between CD and SRD rats. The increase of beta-cell mass induced by SRD was accomplished by an enhanced replication of beta cells together with a decrease in the rate of beta-cell apoptosis, without any evident participation of islet neogenesis. This pancreatic reaction was unable to maintain serum glucose levels of these rats at the level measured in CD animals.
authors.affiliation: CENEXA, Centre of Experimental and Applied Endocrinology (UNLP-CONICET), University of La Plata School of Medicine, La Plata, Argentina.
authors.forename: H
authors.initials: H
authors.lastname: Del Zotto
authors.forename: C L
authors.initials: CL
authors.lastname: Gómez Dumm
authors.forename: S
authors.initials: S
authors.lastname: Drago
authors.forename: A
authors.initials: A
authors.lastname: Fortino
authors.forename: G C
authors.initials: GC
authors.lastname: Luna
authors.forename: J J
authors.initials: JJ
authors.lastname: Gagliardino
mesh_terms: D000818:Animals; D017209:Apoptosis; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D002452:Cell Count; D002455:Cell Division; D048429:Cell Size; D004032:Diet; D005934:Glucagon / Q000032:analysis; D007515:Islets of Langerhans / Q000473:pathology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013213:Starch / Q000008:administration & dosage; D013395:Sucrose / Q000008:administration & dosage*; D014280:Triglycerides / Q000097:blood
chemical_list: D001786:Blood Glucose; D014280:Triglycerides; D013395:Sucrose; D013213:Starch; D005934:Glucagon