Department of Animal Science, Shandong Agricultural University, Taian, Shandong, People's Republic of China.
PLoS One. 2012;7(5):e36663. doi: 10.1371/journal.pone.0036663. Epub 2012 May 18.
Glucocorticoid has an important effect on lipid metabolism in muscles, and the type of fatty acid likely affects mitochondrial utilization. Therefore, we hypothesize that the different fatty acid types treatment may affect the glucocorticoid induction of intramuscular lipid accumulation.
METHODOLOGY/PRINCIPAL FINDINGS: The effect of dexamethasone (DEX) on fatty acid metabolism and storage in skeletal muscle of broiler chickens (Gallus gallus domesticus) was investigated with and without fatty acid treatments. Male Arbor Acres chickens (31 d old) were treated with either palmitic acid (PA) or oleic acid (OA) for 7 days, followed by DEX administration for 3 days (35-37 d old). The DEX-induced lipid uptake and oxidation imbalance, which was estimated by increased fatty acid transport protein 1 (FATP1) expression and decreased carnitine palmitoyl transferase 1 activity, contributed to skeletal muscle lipid accumulation. More sensitive than glycolytic muscle, the oxidative muscle in DEX-treated chickens showed a decrease in the AMP to ATP ratio, a decrease in AMP-activated protein kinase (AMPK) alpha phosphorylation and its activity, as well as an increase in the phosphorylation of mammalian target of rapamycin (mTOR) and ribosomal p70S6 kinase, without Akt activation. DEX-stimulated lipid deposition was augmented by PA, but alleviated by OA, in response to pathways that were regulated differently, including AMPK, mTOR and FATP1.
DEX-induced intramuscular lipid accumulation was aggravated by SFA but alleviated by unsaturated fatty acid. The suppressed AMPK and augmented mTOR signaling pathways were involved in glucocortcoid-mediated enhanced intramuscular fat accumulation.
糖皮质激素对肌肉中的脂质代谢有重要影响，而脂肪酸的类型可能影响线粒体的利用。因此，我们假设不同类型的脂肪酸处理可能会影响糖皮质激素诱导的肌肉内脂质积累。
方法/主要发现：研究了地塞米松（DEX）在肉鸡（Gallus gallus domesticus）骨骼肌中对脂肪酸代谢和储存的影响，有无脂肪酸处理。雄性阿伯丁-阿科克斯鸡（31 日龄）用棕榈酸（PA）或油酸（OA）处理 7 天，然后用 DEX 处理 3 天（35-37 日龄）。DEX 诱导的脂质摄取和氧化失衡，通过增加脂肪酸转运蛋白 1（FATP1）的表达和降低肉碱棕榈酰转移酶 1 活性来估计，导致骨骼肌脂质积累。与糖酵解肌肉相比，DEX 处理的鸡的氧化肌肉表现出 AMP 与 ATP 比值降低，AMP 激活蛋白激酶（AMPK）α磷酸化及其活性降低，以及雷帕霉素（mTOR）和核糖体 p70S6 激酶的磷酸化增加，而 Akt 未被激活。PA 增强了 DEX 刺激的脂质沉积，但 OA 减轻了 DEX 刺激的脂质沉积，这与受不同途径调节的脂质沉积有关，包括 AMPK、mTOR 和 FATP1。
DEX 诱导的肌肉内脂质积累被 SFA 加剧，但被不饱和脂肪酸减轻。被抑制的 AMPK 和被增强的 mTOR 信号通路参与了糖皮质激素介导的增强的肌肉内脂肪积累。
