Glucagon stimulates insulin secretion in islets isolated from DEX rats.

<p><i>A</i>: Insulin secretion in response to incubation with 5.6 mmol/l glucose with or without glucagon or forskolin in islets isolated from DEX and CTL rats (<i>n</i> = 10 wells). <i>B</i>: Representative immunoblots for the glucagon receptor (GR) and β-actin and their quantification (bar graphs) for DEX and CTL islet lysates (<i>n</i> = 6 independent samples). Data are the mean ± SEM. * <i>p</i><0.05, *** <i>p</i><0.001 <i>vs.</i> CTL. ^†††<i>p</i><0.001 <i>vs.</i> 5.6 m glucose. ^‡‡‡<i>p</i><0.001 <i>vs.</i> 5.6 mmol/l glucose plus 1 µmol/l glucagon in <i>A. C</i>: Immunostaining of pancreas sections from DEX and CTL rats for the GR (green) and insulin or glucagon (red). Merged in orange. DAPI was used for nuclei staining (<i>n</i> = 3 pancreases). Scale bars = 7.5 µm.</p

The number of docked glucagon granules is increased in the α-cells of DEX rats.

<p><i>A</i>: Electron micrographs of α-cells from CTL and DEX rats. The images demonstrate an enlargement of the Golgi complex (GC) and the increase in glucagon granules docked to the plasma membrane in the DEX α-cells (*). N, Nucleus; Mi, mitochondria. <i>B</i>: Profile of glucagon granules per median section of α-cells. <i>C</i>: Proportion of granules docked to the plasma membrane of α-cells. Data are the mean ± SEM (<i>n</i> = 16 cells in each condition). ** <i>p</i><0.01 <i>vs.</i> CTL.</p

The inhibition of glucagon secretion by pancreatic α-cells in response to glucose is impaired in DEX rats.

<p><i>A</i>: Glucagon secretion in response to 0.5 mmol/l or 11.1 mmol/l glucose in isolated islets from DEX and CTL rats (<i>n</i> = 10 wells). <i>B</i>: Total islet glucagon content (<i>n</i> = 10). <i>C</i>: <i>In vitro</i> glucagon secretion in response to 0.5 mmol/l or 11.1 mmol/l glucose in isolated islets that were pre-incubated for 3 h with 8.3 mmol glucose with or without 1 µmol/l dexamethasone (<i>n</i> = 10 wells). <i>D</i>: Total islet glucagon content (<i>n</i> = 10). Data are the mean ± SEM. * <i>p</i><0.05 <i>vs.</i> CTL. ^†<i>p</i><0.05 <i>vs.</i> 0.5 mmol/l glucose. G, glucose.</p

11-Dehydrocorticosterone [11-DHC) stimulates insulin secretion under basal glucose conditions in islets isolated from DEX rats.

<p><i>A</i>: Insulin secretion in response to incubation with 5.6 mmol/l glucose with or without 11-DHC or carbenoxolone in islets isolated from DEX and CTL rats (<i>n</i> = 10 wells). <i>B</i>: Insulin secretion in response to incubation with 16.7 mmol/l glucose with or without 11-DHC or carbenoxolone in islets isolated from DEX and CTL rats (<i>n</i> = 10 wells). Data are the mean ± SEM. *** <i>p</i><0.001 <i>vs.</i> CTL. ^†<i>p</i><0.05 <i>vs.</i> 5.6 mmol/l glucose. ^‡<i>p</i><0.05 <i>vs.</i> 5.6 mmol/l glucose plus 100 nmol/l 11-DHC.</p

The pancreatic α-cell mass in DEX rats.

<p><i>A</i>: Panoramic and detailed view of DEX and CTL pancreas sections that were immunostained for glucagon. <i>B</i>: Relative, <i>C</i>: absolute, and <i>D</i>: normalized α-cell mass in DEX and CTL rats. Data are the mean ± SEM (<i>n</i> = 6). Scale bars = 200, 50, 20 and 10 µm from the top to bottom images in <i>A</i>.</p

Insulin secretion ratio in isolated islets from CTL and DEX rats.

<p>The medium containing 1 µmol/l glucagon or 5 µmol/l forskolin also contained 5.6 mmol/l glucose. Data are expressed as mean ± SEM (<i>n</i> = 10 wells).</p><p>* <i>p</i><0.05 <i>vs.</i> CTL.</p

Glucagon secretion (ng/l) per islet in response to low or high glucose in isolated islets.

<p>Data are expressed as mean ± SEM (<i>n</i> = 10 wells).</p><p>* <i>p</i><0.05 <i>vs.</i> CTL and</p>†<p><i>p</i><0.05 <i>vs.</i> 0.5 mmol/l glucose.</p

11β Hydroxysteroid dehydrogenase type 1 [11βHSD-1) content and cellular distribution in the pancreas in DEX rats.

<p><i>A</i>: Representative immunoblots for 11βHSD-1 and β-actin and their quantification (bar graphs) in DEX and CTL islet lysates (<i>n</i> = 6 independent samples). Data are the mean ± SEM. <i>C</i>: Immunostaining of pancreas sections from DEX and CTL rats for glucagon (red) and 11βHSD-1 (green). Merged in orange. <i>n</i> = 3 pancreases. Scale bars = 7.5 µm.</p