Department of Physiology and Biophysics (Y.T.O., J.K., J.H.Y.), University of Southern California, Keck School of Medicine, Los Angeles, California 90089; and Department of Biochemistry and Molecular Biology (I.K., J.H.Y.), Kyung Hee University, School of Medicine, Seoul 130-701, Korea.
Endocrinology. 2014 Mar;155(3):923-31. doi: 10.1210/en.2013-1700. Epub 2013 Dec 11.
We previously showed that a fall in the plasma free fatty acid (FFA) level increases plasma corticosterone levels in rats by activating the hypothalamic-pituitary-adrenal axis. In the present study, we tested whether this regulation is mediated by specific or all species of FFAs. Nicotinic acid (NA) (30 μmol/h) was infused in rats to decrease plasma FFAs and increase plasma ACTH and corticosterone. The NA infusion was combined with an infusion of lipids with different FFA compositions to selectively prevent falls in individual FFA levels; coconut, olive, and safflower oils (n = 7 for each), which are predominantly (>70%) composed of saturated, monounsaturated (oleic acid), and polyunsaturated (linoleic acid) FFAs, respectively, were used. At an infusion rate (0.1 g/h) that only partially prevented a fall in the total FFA level, coconut oil, but not olive or safflower oil, completely prevented NA-induced increases in plasma ACTH or corticosterone, suggesting that these responses are mainly mediated by saturated FFAs. In addition, quantification of individual FFA species in the blood using FFA-specific fluorescent probes revealed that plasma corticosterone and ACTH correlated significantly with plasma palmitate but not with other FFAs, such as oleate, linoleate, or arachidonate. Taken together, our data suggest that the regulation of the hypothalamic-pituitary-adrenal axis by FFAs is mainly mediated by the saturated fatty acid palmitate, but not by unsaturated fatty acids, such as oleate and linoleate.
我们之前的研究表明，血浆游离脂肪酸（FFA）水平的下降通过激活下丘脑-垂体-肾上腺轴增加血浆皮质酮水平。在本研究中，我们测试了这种调节是否由特定或所有 FFA 介导。烟酸（NA）（30 μmol/h）输注以降低血浆 FFA 并增加血浆促肾上腺皮质激素和皮质酮。NA 输注与具有不同 FFA 组成的脂质输注相结合，以选择性地防止个体 FFA 水平下降；分别使用椰子油、橄榄油和红花油（每组 7 只），它们主要（>70%）由饱和、单不饱和（油酸）和多不饱和（亚油酸）FFA 组成。在仅部分防止总 FFA 水平下降的输注率（0.1 g/h）下，椰子油而不是橄榄油或红花油完全阻止了 NA 诱导的血浆促肾上腺皮质激素或皮质酮增加，表明这些反应主要由饱和 FFA 介导。此外，使用 FFA 特异性荧光探针定量血液中的个体 FFA 种类表明，血浆皮质酮和促肾上腺皮质激素与血浆棕榈酸显著相关，但与其他 FFA（如油酸、亚油酸或花生四烯酸）无关。综上所述，我们的数据表明，FFA 对下丘脑-垂体-肾上腺轴的调节主要由饱和脂肪酸棕榈酸介导，而不是由不饱和脂肪酸油酸和亚油酸介导。
