Jambor de Sousa Ulrike L, Benthem Lambertus, Arsenijevic Denis, Scheurink Anton J W, Langhans Wolfgang, Geary Nori, Leonhardt Monika
Institute of Animal Sciences, ETH Zurich, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland.
Physiol Behav. 2006 Oct 30;89(3):329-34. doi: 10.1016/j.physbeh.2006.06.020. Epub 2006 Aug 7.
In several human and animal studies, medium-chain triglycerides decreased food intake more than did long-chain triglycerides. It is possible that faster uptake and metabolism of medium-chain fatty acids in the liver is responsible for this difference. To test this hypothesis we compared the feeding effects of hepatic portal vein (HPV) infusion of the medium-chain fatty acid caprylic acid (CA) with those of the long-chain fatty acid oleic acid (OA). Contrary to our expectation, six-h HPV infusion of 14 microg/min (50 nmol/min) OA robustly inhibited feeding, whereas infusion of 22 or 220 microg/min (150 and 1500 nmol/min) CA failed to have any effect on feeding. Only a much larger dose of CA, 1100 microg/min (7500 nmol/min) inhibited feeding similarly to 14 microg/min OA. The increased feeding-inhibitory potency of OA did not appear to be due to differences in stimulation of hepatic fatty acid oxidation because equimolar (50 nmol/min) doses of OA (14 microg/min) and CA (7 microg/min) did not differentially affect post-infusion levels of beta-hydroxybutyrate. Stress, inflammation, acute hepatotoxicity or oxidative stress also do not appear to account for the increased feeding-inhibitory potency of HPV OA because plasma concentrations of the stress hormones corticosterone and epinephrine, the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha, the liver enzymes gamma-glutamyl transferase and alanine aminotransferase and as well as hepatic levels of malondialdehyde and glutathione were all similar after HPV infusion of saline or of 50 nmol/min OA or CA.
在多项人体和动物研究中，中链甘油三酯比长链甘油三酯更能减少食物摄入量。肝脏中中链脂肪酸更快的摄取和代谢可能是造成这种差异的原因。为了验证这一假设，我们比较了肝门静脉（HPV）输注中链脂肪酸辛酸（CA）和长链脂肪酸油酸（OA）对进食的影响。与我们的预期相反，以14微克/分钟（50纳摩尔/分钟）的速度进行6小时的HPV输注OA能强烈抑制进食，而以22或220微克/分钟（150和1500纳摩尔/分钟）的速度输注CA对进食没有任何影响。只有剂量大得多的CA，即1100微克/分钟（7500纳摩尔/分钟），才能像14微克/分钟的OA一样抑制进食。OA增强的抑制进食效力似乎并非由于对肝脏脂肪酸氧化刺激的差异，因为等摩尔（50纳摩尔/分钟）剂量的OA（14微克/分钟）和CA（7微克/分钟）对输注后β-羟基丁酸水平没有差异影响。应激、炎症、急性肝毒性或氧化应激似乎也不能解释HPV输注OA增强的抑制进食效力，因为在HPV输注生理盐水、50纳摩尔/分钟的OA或CA后，应激激素皮质酮和肾上腺素、促炎细胞因子白细胞介素-6和肿瘤坏死因子-α、肝脏酶γ-谷氨酰转移酶和丙氨酸转氨酶的血浆浓度，以及丙二醛和谷胱甘肽的肝脏水平都相似。
