Erman A, Baer P G, Nasjletti A
J Biol Chem. 1985 Apr 25;260(8):4679-83.
The present study was designed to investigate the effect of dexamethasone treatment for 2 weeks (2.5 mg/kg/week, subcutaneously) on the level of unesterified fatty acids, particularly arachidonic acid, in the renal medulla of rats, and to relate the observed effect to changes in the tissue concentration and the fatty acid composition of renal medulla phospholipids and triglycerides. Dexamethasone treatment caused an increase in the renal inner medulla level of unesterified fatty acids, including arachidonic acid, that was associated with a reduction of triglycerides and of arachidonic acid esterified into triglycerides, and with an increase in the rate of fatty acids esterification into triglycerides. In contrast, dexamethasone treatment did not affect the renal medulla concentration of phospholipids, the arachidonic acid content of renal medulla phospholipids, or the rate of esterification of fatty acids into renal medulla phospholipids. In the face of increased fatty acid esterification into triglycerides, the finding of reduced triglyceride levels in the renal medulla of dexamethasone-treated rats suggests excessive triglyceride breakdown. If so, fatty acids including arachidonic acid liberated from triglycerides may contribute to elevation of unesterified fatty acid levels in the renal medulla during dexamethasone treatment. The increased level of free arachidonic acid in the renal medulla of dexamethasone-treated rats may explain in part the reported effect of this steroid in increasing urinary prostaglandins.
本研究旨在探讨地塞米松皮下注射2周（2.5毫克/千克/周）对大鼠肾髓质中未酯化脂肪酸，特别是花生四烯酸水平的影响，并将观察到的效应与肾髓质磷脂和甘油三酯的组织浓度及脂肪酸组成的变化联系起来。地塞米松治疗导致肾内髓质中未酯化脂肪酸水平升高，包括花生四烯酸，这与甘油三酯及酯化到甘油三酯中的花生四烯酸减少有关，同时脂肪酸酯化到甘油三酯的速率增加。相比之下，地塞米松治疗不影响肾髓质磷脂的浓度、肾髓质磷脂中花生四烯酸的含量或脂肪酸酯化到肾髓质磷脂中的速率。面对脂肪酸酯化到甘油三酯增加的情况，地塞米松治疗的大鼠肾髓质中甘油三酯水平降低这一发现提示甘油三酯过度分解。如果是这样，从甘油三酯释放的包括花生四烯酸在内的脂肪酸可能导致地塞米松治疗期间肾髓质中未酯化脂肪酸水平升高。地塞米松治疗的大鼠肾髓质中游离花生四烯酸水平升高可能部分解释了该类固醇增加尿前列腺素的报道效应。
