Oh Young Taek, Oh Hyun Hee, Nguyen Anh-Khoi, Choi Cheol Soo, Youn Jang H
Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University School of Medicine, Incheon, Republic of Korea.
Physiol Behav. 2016 Dec 1;167:194-201. doi: 10.1016/j.physbeh.2016.09.015. Epub 2016 Sep 18.
Previous rodent studies showed that when injected into the brain, free fatty acids (FFAs) reduced food intake in an oleate-specific manner. The present study was performed to test whether food intake is regulated by circulating FFAs in an oleate-specific manner. Male Wistar rats received an intravenous infusion of olive, safflower, or coconut oil (100mg/h), together with heparin, to raise circulating oleate, linoleate, or palmitate, respectively, and their effects on overnight food intake were evaluated. Compared to other oils, olive oil infusion showed a significantly greater effect to reduce food intake (P<0.01). Total caloric intake, the sum of the calories from the diet and infused oil, was significantly reduced with olive oil (P<0.01) but not with coconut or safflower oil infusion, suggesting an oleate-specific effect on caloric intake. To further test this idea, different groups of rats received an intravenous infusion of oleate, linoleate, or octanoate (0.5mg/h). Oleate infusion decreased overnight food intake by 26% (P<0.001), but no significant effect was seen with linoleate, octanoate, or vehicle infusion (P>0.05). The effects of olive oil or oleate infusion could not be explained by changes in plasma glucose, insulin, leptin, or total FFA levels. The olive oil effect on food intake was not reduced in vagotomized rats, suggesting that oleate sensing may not involve peripheral sensors. In contrast, olive oil's effect was attenuated in high-fat-fed rats, suggesting that this effect is regulated (or impaired) under physiological (or pathological) conditions. Taken together, the present study provides evidence that circulating oleate is sensed by the brain differentially from other FFAs to control feeding in rats.
先前的啮齿动物研究表明，当游离脂肪酸（FFA）注入大脑时，会以油酸特异性的方式减少食物摄入量。本研究旨在测试食物摄入量是否以油酸特异性的方式受循环FFA调节。雄性Wistar大鼠接受静脉输注橄榄油、红花油或椰子油（100mg/h）以及肝素，以分别提高循环中的油酸、亚油酸或棕榈酸水平，并评估它们对过夜食物摄入量的影响。与其他油相比，输注橄榄油对减少食物摄入量的作用显著更大（P<0.01）。总热量摄入，即饮食和输注油中的热量总和，用橄榄油时显著降低（P<0.01），但输注椰子油或红花油时没有降低，这表明油酸对热量摄入有特异性影响。为了进一步验证这一观点，不同组的大鼠接受静脉输注油酸、亚油酸或辛酸（0.5mg/h）。输注油酸使过夜食物摄入量减少了26%（P<0.001），但输注亚油酸、辛酸或赋形剂时未观察到显著影响（P>0.05）。橄榄油或油酸输注的作用无法用血浆葡萄糖、胰岛素、瘦素或总FFA水平的变化来解释。在迷走神经切断的大鼠中，橄榄油对食物摄入量的影响并未降低，这表明油酸感知可能不涉及外周传感器。相比之下，在高脂喂养大鼠中，橄榄油的作用减弱，这表明这种作用在生理（或病理）条件下受到调节（或受损）。综上所述，本研究提供了证据表明，大脑对循环中的油酸与其他FFA的感知不同，从而控制大鼠的进食。
