19：第十八章 动物的采食量（1学时） - 图文

二、调节采食量的其他途径

（1）血糖：与采食量负相关 “血糖稳衡理论”：

下丘脑存在葡萄糖受体，对血糖浓度变化敏感。动物采食 后，血糖浓度上升，触发葡萄糖受体，使动物食欲受到抑 制，采食停止。饱中枢和饿中枢通过胰岛素分泌参与血糖调 节。饱中枢对葡萄糖敏感，当动静脉葡萄糖差增加时，饱中 枢对饿中枢的抑制作用加强，从而使动物产生饱感。

1. Short term (hours) control of food intake involves many factors a. CCK, blood glucose,

stomach distention, etc. 1) Also,

emotional inputs (smell of food,

stress, etc.) b. Roles of vagus

nerve/satiety center in medulla.

Short-term signals regulating food intake. Signals from the GI tract and the liver are involved in short-term regulation of feeding. Afferent signals travel in vagal nerve fibers from stretch receptors, and chemoreceptors activated by the presence of nutrients in the stomach and proximal small intestine are involved in meal termination. Nutrients arriving via the portal vein may also trigger vagal afferent signals from the liver. Glucose can modulate food intake by acting on glucose-responsive neurons in the CNS. Ketones appear to decrease appetite. In response to nutrient stimulation, the proximal intestine releases cholecystokinin (CCK), which reaches the liver via the portal vein and the CNS via the systemic circulation; CCK may act on CCK-A receptors at both sites to inhibit food intake. Endocrine L cells in the terminal small intestine (ileum) release glucagon-like peptide-1 (GLP- 1), which inhibits feeding, most likely at a hepatic site or by inhibiting gastric emptying. The short-term signals by themselves do not produce sustained alterations in energy intake and body adiposity.

二、调节采食量的其他途径

（2）挥发性脂肪酸（VFA）

反刍动物血液挥发性脂肪酸参与采食量的调节； 乙酸和丙酸可直接或间接参与采食量的调节； VFA可影响瘤胃液的渗透压和pH，调节瘤胃运动和 血流速度,使采食行为终止和反刍开始。