Increased intake of dietary carbohydrate that is fermented in the colon by the microbiota has been reported to decrease body weight, although the mechanism remains unclear. Here we use in vivo11C-acetate and PET-CT scanning to show that colonic acetate crosses the blood–brain barrier and is taken up by the brain. Intraperitoneal acetate results in appetite suppression and hypothalamic neuronal activation patterning. We also show that acetate administration is associated with activation of acetyl-CoA carboxylase and changes in the expression profiles of regulatory neuropeptides that favour appetite suppression. Furthermore, we demonstrate through 13C high-resolution magic-angle-spinning that 13C acetate from fermentation of 13C-labelled carbohydrate in the colon increases hypothalamic 13C acetate above baseline levels. Hypothalamic 13C acetate regionally increases the 13C labelling of the glutamate–glutamine and GABA neuroglial cycles, with hypothalamic 13C lactate reaching higher levels than the ‘remaining brain’. These observations suggest that acetate has a direct role in central appetite regulation.

参考译文：
科学家发现，食物中的膳食纤维在肠道中经一些微生物发酵后能产生一种“抗食欲”分子——醋酸，这对于节食者来说将是个好消息。
多吃膳食纤维有助于减肥，这点已为人们所知。最近，研究者们使用同位素示踪的方法发现：有些糖类膳食纤维在小鼠的大肠中经微生物发酵产生醋酸，醋酸根进入血液并到达脑部透过血脑屏障。下丘脑醋酸根浓度的升高使小鼠的食欲受到抑制。给小鼠的腹腔内注射醋酸盐也能起到类似抑制食欲的作用，这也为这个新发现提供了证据。
不过，易发酵的膳食纤维才有这个作用，不易发酵的如纤维素则没有。
 
原始来源：http://www.nature.com/ncomms/2014/140429/ncomms4611/full/ncomms4611.html