Department of Animal Science, Michigan State University, East Lansing, MI, USA.
Proc Nutr Soc. 2012 Aug;71(3):401-9. doi: 10.1017/S0029665112000572. Epub 2012 Jun 18.
Research with laboratory species suggests that meals can be terminated by peripheral signals carried to brain feeding centres via hepatic vagal afferents, and that these signals are affected by oxidation of fuels. Pre-gastric fermentation in ruminants greatly alters fuels, allowing mechanisms conserved across species to be studied with different types and temporal absorption of fuels. These fuels include SCFA, glucose, lactate, amino acids and long-chain fatty acid (FA) isomers, all of which are absorbed and metabolised by different tissues at different rates. Propionate is produced by rumen microbes, absorbed within the timeframe of meals, and quickly cleared by the liver. Its hypophagic effects are variable, likely due to its fate; propionate is utilised for gluconeogenesis or oxidised and also stimulates oxidation of acetyl-CoA by anapleurosis. In contrast, acetate has little effect on food intake, likely because its uptake by the ruminant liver is negligible. Glucose is hypophagic in non-ruminants but not ruminants and unlike non-ruminant species, uptake of glucose by ruminant liver is negligible, consistent with the differences in hypophagic effects between them. Inhibition of FA oxidation increases food intake, whereas promotion of FA oxidation suppresses food intake. Hypophagic effects of fuel oxidation also vary with changes in metabolic state. The objective of this paper is to compare the type and utilisation of fuels and their effects on feeding across species. We believe that the hepatic oxidation theory allows insight into mechanisms controlling feeding behaviour that can be used to formulate diets to optimise energy balance in multiple species.
研究实验室动物表明，食物可以通过肝迷走传入纤维向大脑摄食中枢传递的外周信号终止，而这些信号受到燃料氧化的影响。反刍动物的胃前发酵极大地改变了燃料，使得不同类型和时间吸收燃料的物种间保守机制能够得到研究。这些燃料包括 SCFA、葡萄糖、乳酸、氨基酸和长链脂肪酸（FA）异构体，它们通过不同的组织以不同的速度吸收和代谢。丙酸是由瘤胃微生物产生的，在进食时间内被吸收，并迅速被肝脏清除。其抑制摄食的作用是可变的，可能是由于其命运；丙酸用于糖异生或氧化，也刺激旁路氧化乙酰辅酶 A。相比之下，乙酸对食物摄入的影响很小，可能是因为它被反刍动物肝脏的吸收可以忽略不计。葡萄糖在非反刍动物中具有抑制摄食作用，但在反刍动物中没有，并且与非反刍动物不同，葡萄糖被反刍动物肝脏的摄取可以忽略不计，这与它们之间的抑制摄食作用的差异一致。抑制 FA 氧化增加食物摄入，而促进 FA 氧化抑制食物摄入。燃料氧化的抑制摄食作用也随着代谢状态的变化而变化。本文的目的是比较不同物种中燃料的类型和利用及其对摄食的影响。我们相信，肝脏氧化理论可以深入了解控制摄食行为的机制，这些机制可以用于制定饮食方案，以优化多种物种的能量平衡。
