Department of Endocrinology, First Hospital of Harbin Medical University, Harbin 150001, Heilongjiang Province, China.
World J Gastroenterol. 2010 Dec 28;16(48):6111-8. doi: 10.3748/wjg.v16.i48.6111.
to determine whether mitochondrial dysfunction resulting from high-fat diet is related to impairment of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt, also known as PKB) pathway.
rat models of nonalcoholic fatty liver were established by high-fat diet feeding. The expression of total and phosphorylated P13K and Akt proteins in hepatocytes was determined by Western blotting. Degree of fat accumulation in liver was measured by hepatic triglyceride. Mitochondrial number and size were determined using quantitative morphometric analysis under transmission electron microscope. The permeability of the outer mitochondrial membrane was assessed by determining the potential gradient across this membrane.
after Wistar rats were fed with high-fat diet for 16 wk, their hepatocytes displayed an accumulation of fat (103.1 ± 12.6 vs 421.5 ± 19.7, P < 0.01), deformed mitochondria (9.0% ± 4.3% vs 83.0% ± 10.9%, P < 0.05), and a reduction in the mitochondrial membrane potential (389.385% ± 18.612% vs 249.121% ± 13.526%, P < 0.05). In addition, the expression of the phosphorylated P13K and Akt proteins in hepatocytes was reduced, as was the expression of the anti-apoptotic protein Bcl-2, while expression of the pro-apoptotic protein caspase-3 was increased. When animals were treated with pharmacological inhibitors of P13K or Akt, instead of high-fat diet, a similar pattern of hepatocellular fat accumulation, mitochondrial impairment, and change in the levels of PI3K, Akt, Bcl-2 was observed.
high-fat diet appears to inhibit the PI3K/Akt signaling pathway, which may lead to hepatocellular injury through activation of the mitochondrial membrane pathway of apoptosis.
确定高脂肪饮食引起的线粒体功能障碍是否与磷酸肌醇 3-激酶（PI3K）/蛋白激酶 B（Akt，也称为 PKB）途径的损害有关。
通过高脂肪饮食喂养建立非酒精性脂肪肝大鼠模型。用 Western blot 法测定肝细胞中总及磷酸化 P13K 和 Akt 蛋白的表达。肝组织甘油三酯测定肝内脂肪堆积程度。用定量形态计量分析在透射电镜下测定线粒体数量和大小。通过测定跨外膜的电位梯度来评估外膜的通透性。
Wistar 大鼠高脂喂养 16 周后，其肝细胞脂肪堆积（103.1±12.6 比 421.5±19.7，P＜0.01），线粒体变形（9.0%±4.3%比 83.0%±10.9%，P＜0.05），线粒体膜电位降低（389.385%±18.612%比 249.121%±13.526%，P＜0.05）。此外，肝细胞中磷酸化 P13K 和 Akt 蛋白的表达减少，抗凋亡蛋白 Bcl-2 的表达减少，而促凋亡蛋白 caspase-3 的表达增加。当用 P13K 或 Akt 的药理抑制剂处理动物而不是用高脂肪饮食处理时，观察到类似的肝细胞脂肪堆积、线粒体损伤以及 PI3K、Akt、Bcl-2 水平变化的模式。
高脂肪饮食似乎抑制了 PI3K/Akt 信号通路，通过激活线粒体膜凋亡途径可能导致肝细胞损伤。
