Figure 1.
Islet structure and size, β-cell mass, and α-cell mass at twenty weeks of age.
A. Representative islets from B6 (left) and WSB (right) mice fed the chow diet. Insulin is stained red, glucagon green, and cell nuclei are marked by DAPI staining (blue). No alteration to islet structures was found in islets from the high fat-fed mice. B. The average cross-sectional areas of all islets found in each mouse were determined then averaged for each strain (average number of islets per mouse examined: B6 chow- 167, B6 HFD 187, WSB chow 129, WSB HFD 171). C. Distribution of islet sizes in B6 (black; chow-fed solid, high fat diet (HFD)-fed striped) and WSB mice (white; chow-fed solid, high fat diet (HFD)-fed striped). In the upper group, although there was substantial overlap in the sizes, B6 mice tended to have larger maximal islet sizes (both diets). D. Percent of pancreatic tissue area stained for insulin. E. Pancreatic weight of mice used in these experiments. F. Pancreatic weights normalized to total body weight in chow and high fat-fed WSB and B6 mice. G. β-cell mass, calculated as the % staining area multiplied by the pancreatic weight. H. Percent of pancreatic area stained for glucagon. I. α-cell mass calculated as for β-cell mass. (n = 5 mice per strain per diet). *p<0.05, **p<0.01, ***p<0.001 vs. B6 mice consuming the same diet. +p<0.05, +++p<0.001 vs. chow-fed of the same strain.
Figure 2.
Islet structure and size, β-cell mass, and α-cell mass in young WSB mice.
Studies were performed on mice at 4 weeks of age. A. Representative islets from B6 (left) and WSB (right) mice. Insulin (red), glucagon (green) and DNA (blue) are stained. B. Mean islet sizes (average number of islets per mouse examined: B6 chow- 166, B6 HFD 130, WSB chow 108, WSB HFD 115). C. Islet size distribution of B6 (black; chow solid, high fat diet (HFD) striped) and WSB (white; chow solid, high fat diet white striped) mice. The range of islet sizes observed was similar in all groups. D. Percent of pancreatic area stained for insulin. E. Pancreas weight for stained tissues. F. β-cell mass. G. Percent of pancreatic area stained for glucagon. H. α-cell mass. (n = 5 mice per strain per diet). **p<0.01 vs. B6 mice consuming the same diet.
Figure 3.
Whole pancreas insulin content.
These studies were performed in young mice between 6 and 7 weeks of age. A. Total pancreatic insulin content. B. Pancreas weight. C. Pancreatic insulin content per gram of pancreas. (n = 5–6 WSB per diet, n = 10 B6 per diet) *p<0.05, ***p<0.001 vs. B6 mice consuming the same diet. ++p<0.01 vs. chow-fed mice of the same strain.
Figure 4.
Insulin secretion in WSB mice.
A, Insulin secretion response of size-matched B6 and WSB islets in 3 mM basal glucose, 20 mM glucose, and 30 mM KCl for the times indicated. Thin line represents B6 islets, Thick line represents WSB islets. B, Area between insulin secretion curve and average basal glucose insulin response when incubated with 20 mM glucose. C, Area between insulin secretion curve and average basal glucose insulin response when incubated with 30 mM potassium chloride in basal glucose. Perifusions were performed in ∼6 week old mice (n = 10 per strain). **p<0.01, ***p<0.001 vs. B6.
Figure 5.
Islet vascularization at 4 weeks of age.
A. Islet vascularization of chow-fed C57BL/6J (top) and WSB/EiJ (bottom) mice. Vasculature (CD31) is stained in green, while insulin is stained red to demarcate islet areas. B. Percent of islet area stained for CD31. (n = 5 per strain).