Department of Anatomy, Cell Biology and Physiology and Biophysics, Institute of Biology, State University of Campinas, Brazil.
Pancreas. 2010 Aug;39(6):847-55. doi: 10.1097/MPA.0b013e3181d37210.
We investigated the influence of leucine supplementation on insulin secretion and on some proteins related to insulin secretion in malnourished mice.
Swiss mice (aged 21 days) received isocaloric normo-17% (NP) or 6% low-protein (LP) diet for 120 days. Half of the NP and LP mice received 1.5% leucine in the drinking water during the last 30 days (NPL and LPL, respectively).
The LP mice were hypoinsulinemic compared with the NP group, whereas LPL mice exhibited increased insulinemia in the fed state versus LP mice. The LP mouse islets were less responsive to 22.2 mM glucose, 100 microM carbachol (Cch), and 10 mM leucine than the NP group. However, LPL islets were more responsive to all these conditions compared with the LP group. The muscarinic type 3 receptor, (M3R) Cabeta2, and PKC-alpha protein contents were reduced in LP compared with NP islets but significantly higher in LPL than LP islets. The p-AKT/AKT ratio was higher in LPL compared with LP islets.
Leucine supplementation increases insulin secretion in response to glucose and leucine and to agents that potentiate secretion, such as Cch, in malnourished mice. The enhanced levels of M3R, Cabeta2, and PKC-alpha proteins, as well as of the p-AKT/AKT ratio, may play a role in this process.
我们研究了亮氨酸补充对营养不良小鼠胰岛素分泌和一些与胰岛素分泌相关蛋白的影响。
21 天大的瑞士小鼠接受等热量正常 17%（NP）或 6%低蛋白（LP）饮食 120 天。NP 和 LP 组的一半小鼠在最后 30 天饮用含 1.5%亮氨酸的水（分别为 NPL 和 LPL）。
与 NP 组相比，LP 组小鼠出现胰岛素血症，而 LPL 组小鼠在进食状态下胰岛素血症增加。与 NP 组相比，LP 组小鼠胰岛对 22.2mM 葡萄糖、100µM 卡巴胆碱（Cch）和 10mM 亮氨酸的反应性降低，但 LPL 胰岛对所有这些条件的反应性均高于 LP 组。与 NP 胰岛相比，LP 胰岛中的毒蕈碱型 3 受体（M3R）、Cabeta2 和 PKC-alpha 蛋白含量降低，但 LPL 胰岛中的含量明显高于 LP 胰岛。与 LP 胰岛相比，LPL 胰岛中的 p-AKT/AKT 比值更高。
亮氨酸补充可增加营养不良小鼠对葡萄糖和亮氨酸以及增强分泌的药物（如 Cch）的胰岛素分泌。M3R、Cabeta2 和 PKC-alpha 蛋白水平以及 p-AKT/AKT 比值的升高可能在这一过程中发挥作用。
