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Regional Differences of Pancreatic Islet Area and Beta Cell Density in Obese and Lean Zucker Rats
Author(s) -
Goudy Gabriel,
Asano Shinichi,
Hoskinson Hannah,
Dawson Mariah,
Breit Matthew,
Olfert Mark,
Frisbee Jefferson C,
Chantler Paul D,
Alway Stephan,
Bryner Randall
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.766.9
Subject(s) - islet , pancreas , medicine , endocrinology , beta (programming language) , beta cell , insulin , chemistry , biology , programming language , computer science
Several studies have characterized the density of beta‐cell mass in rodents reporting greater amounts in the body and tail (which is most proximal to the spleen) compared to the head of the pancreas (located in curved of the duodenum). Whether or not obesity alters the distributions within the pancreas is not known. PURPOSE The objective of this study was to evaluate islet area and beta‐cell density in a rat model of obesity and metabolic syndrome. METHODS Obese (OZR, n=8) and lean Zucker rats (LZR, n=8) were euthanized at 17‐weeks of age. Pancreases were harvested, sectioned into three regions (head, body, tail) and flash frozen in liquid N 2 cooled isopentane. Frozen 7μm thick sections of pancreas tissues were cut, mounted on glass slides, and incubated with an insulin antibody that was labeled with Alexa‐Fluor 546 to identify the beta cells. The tissue was covered in DAPI to label the cell nuclei. Digital images of the pancreas cells were obtained by a Zeiss LSM 510 Confocal microscope using Zenn 2009 software. The insulin positive area of the stained islets was measured using Image J. The images of stained cells and islets were merged and the number of beta cells per islet recorded. ANOVA was used to compare the insulin positive area (islet area), total beta cell number, and beta cell density (beta cell/μm 2 insulin positive area) between obese and lean rats with significance set at P<0.05. RESULTS There was a significant main effect of phenotype (obese vs lean) for all three dependent variables ( Table 1) with overall values lower in the OZR. There was also a significant interaction for phenotype and insulin positive area (islet area) as well as an interaction for phenotype and total beta cell number, but not for beta cell density. This suggests the biggest difference associated with obesity within the pancreas is in the tail region causing a reduced islet area. CONCLUSION These data indicate that obesity can significantly reduce islet area but that its affect is primarily in the tail region of the pancreas. The heterogeneity of islet area is consistent with previous findings among the different regions in the pancreas of the rat. Future research needs to examine what mechanisms are responsible for this regional difference. Support or Funding Information NIH AHA 1 Mean±SEGroup (n=8) Mean Islet Area (μm 2 ) Total Beta Cells Beta cell/μm 2 islet areaOZR LZR OZR LZR OZR LZRHead 6859 ±859 8266 ±266 82±26 115±15 0.0124 ± 0.0008 0.0144 ± 0.0008 Body 7831 ±831 7335 ±335 94±4 98±83 0.0123 ± 0.0010 0.0139 ± 0.0008 Tail 4749 ±651 * 9475 ±475 56 ±6 136 ±3 0.0118 ± 0.0007 0.0147 ± 0.0004