DEHYDROEPIANDROSTERONE SULFATE AND INSULIN SECRETION

这项研究的长期目标是开发一种 了解DHEAS在血糖调节中的作用及其潜力 糖尿病的治疗作用。许多作者都展示了一种 脱氢表雄酮对不同类型啮齿动物糖尿病的有益作用 然而，从病因上讲，这种影响的机制尚不清楚。预赛 研究表明，DHEAS强烈增强了葡萄糖的促胰岛素作用， 暗示DHEAS对胰岛β细胞的影响是其 抗糖尿病作用。此外，研究人员还表明，DHEAS会改变 乙酰辅酶A合成酶-2(ACS-2)和乙酰辅酶A合成酶-2(acyl CoA synthetase-2，ACS-2)基因的β细胞表达 辅酶A氧化酶(ACO)，参与细胞内脂肪酸的代谢。 β细胞脂肪储存和游离脂肪酸(FFA)浓度强烈 调节葡萄糖刺激的胰岛素分泌和胞浆长链脂肪 酰辅酶A(LC CoA)被认为是胰岛素的重要信号 分泌物。有人建议检验DHEAS增强 葡萄糖通过最初刺激ACS-2活性来刺激胰岛素的分泌， 导致细胞质LC-CoA水平升高。除了增强 葡萄糖刺激的胰岛素分泌，研究人员假设 升高的LC-CoA或LC-CoA的产物激活β细胞过氧化物酶 增殖物激活受体(PPAR)，从而增加 脂肪氧化酶ACO的活性。以下是具体目标 已解决：(1)确定改变ACS-2表达是否会改变 葡萄糖刺激的胰岛素切片，ACS活性，胞浆LC-CoA水平， PPARpha激活和ACO表达，方式类似于与 德赫斯。实验将包括评估：i)DHEAS对ACS-2mRNA的影响 表达，以及II)过表达的ACS-2对葡萄糖刺激的影响 胰岛素分泌。(2)确定LC-CoA水平的调制是否改变 葡萄糖刺激的胰岛素分泌、PPARpha激活或ACO表达。 LC-CoA水平的调节将通过β细胞与FFA的孵育实现， 依托莫昔尔(肉碱棕榈酰转移酶-1的抑制剂)和Triacsin C(AN 急性冠脉综合征的抑制剂)。(3)确定PPARpha基因敲除是否会改变效果 DHEAS对葡萄糖刺激的胰岛素分泌、血管紧张素转换酶活性和ACO mRNA的影响 表情。(4)观察DHEAS对糖刺激的ACS活性的影响。 人胰岛分泌胰岛素和ACO基因表达的研究

The long-term objective of this research is to develop an understanding of the role of DHEAS in glucose regulation and its potential therapeutic role in diabetes mellitus. Many authors have demonstrated a beneficial effect of DHEA administration in rodent diabetes of various etiologies, however, the mechanism of this effect is unclear. The preliminary studies show that DHEAS strongly enhances the insulinotropic effect of glucose, implicating an effect of DHEAS at the pancreatic beta-cell as a basis for its anti-diabetic effects. Furthermore, the investigators show that DHEAS alters beta-cell expression of specific genes, acyl CoA synthetase-2 (ACS-2) and acyl CoA oxidase (ACO), involved in the intracellular metabolism of fatty acids. Beta cell lipid stores and free fatty acid (FFA) concentrations strongly modulate glucose-stimulated insulin secretion and cytoplasmic long-chain fatty acyl CoA (LC CoA) has been postulated to be an important signal for insulin secretion. It is proposed to test the hypothesis that DHEAS enhances glucose-stimulated insulin secretion by initially stimulating ACS-2 activity, resulting in increased cytoplasmic LC-CoA levels. In addition to enhancing glucose-stimulated insulin secretion, the investigators postulate that the elevated LC-CoA, or a product of LC-CoA, activates beta-cell peroxisome proliferator-activated receptors (PPARs) and consequently increases the activity of the lipid oxidation enzyme ACO. The following Specific Aims will be addressed: (1) Determine whether changing ACS-2 expression alters glucose-stimulated insulin section, ACS activity, cytoplasmic LC-CoA levels, PPARalpha activation and ACO expression, in a similar manner to incubation with DHEAS. Experiments will include assessing: i) the effect of DHEAS on ACS-2 mRNA expression, and ii) the effect of ACS-2 over-expression on glucose-stimulated insulin secretion. (2) Determine whether modulation of LC-CoA levels alters glucose-stimulated insulin secretion, PPARalpha activation or ACO expression. Modulation of LC-CoA levels will be achieved by beta-cell incubation with FFA, etomoxir (an inhibitor of carnitine palmitoyl transferase-1) and Triacsin C (an inhibitor of ACS). (3) Determine whether PPARalpha knockout alters the effect of DHEAS on glucose-stimulated insulin secretion, ACS activity and ACO mRNA expression. (4) Assess the effects of DHEAS on ACS activity, glucose-stimulated insulin secretion and ACO mRNA expression in human pancreatic islets.