Role of apoptosis and mitochondrial apoptotic pathway in glucolipotoxicity-induced islet beta-cell dysfunction / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the mechanism of beta-cell dysfunction induced by glucolipotoxicity in high fat-fed obese rats.</p><p><b>METHODS</b>Eighteen high-fat obese male Wistar rats were assigned into 3 groups and underwent 48-hour infusion through the jugular vein with normal saline (n=6), 20% intralipid + heparin (FFA group, n=6), or 25%glucose +20% intralipid + heparin (GS-FFA group, n=6). The plasma beta-hydroxybutyric acid (beta-HBA) was measured before and at the end of the infusion. After the infusion, the rats were sacrificed following an intravenous glucose tolerance test (IVGTT) to remove the tail of the pancreas for detection of apoptotic islet cells using TUNEL method. Immunohistochemical staining was performed to detect the expression of cytochrome c (cyt c), apoptosis-inducing factor (AIF), caspase-9 and caspase-3 in the islet cells.</p><p><b>RESULTS</b>At the end of the infusion, all the rats exhibited increased plasma beta-HBA levels, which was the highest in the GS-FFA group (P<0.05). IVGTT performed after the infusion showed a significantly lower insulinogenic index in GS-FFA group than that in NS and FFA groups. Greater number of apoptotic islet cells was found in the GS-FFA group than in the FFA and NS groups (P<0.05), and the islets had significantly higher levels of cyt c, AIF, caspase-9 and caspase-3 in the former group than in the latter two groups (P<0.05).</p><p><b>CONCLUSIONS</b>Hyperglycemia and high free fatty acid level synergistically impair insulin secretions to cause ketone overproduction in high fat-fed obese rats. The beta-cell dysfunction due to glucolipotoxicity is associated with increased beta-cell apoptosis and activation of mitochondrial apoptotic pathway.</p>

Establishment of perfusion technique for isolated rat pancreas / 中华内分泌代谢杂志

Objective To establish an isolated rat pancreas perfusion technique,a method for the precise measurement of insulin secretion in vitro.Methods An isolated rat pancreas perfusion technique was applied in the study of insulin secretion from?-cells in 10 high-fat diet-induced obese Wistar rats.Results For the assessment of the functional integrity of the perfused pancreas,the isolated pancreas of 6 rats met all the criteria: (1)The constancy of perfusion pressure was kept over the whole experiment time[(70?5)mm Hg,1 mm Hg= 0.133 kPa].(2)The duodenal peristaltic activity of isolated pancreas and duodenum block was present after perfusion experiment.(3)Total insulin response to arginine stimulation was significantly increased as compared with glucose stimulation[maximum insulin secretion rate:(987?100)?U/min vs(545?50)?U/min,P