19：第十八章 动物的采食量(1学时)

Long-term signals regulating food intake and energy

homeostasis. Insulin and leptin are the two most important long- term regulators of food intake and energy balance. Both insulin and leptin act in the CNS to inhibit food intake and to increase energy expenditure, most likely by activating the sympathetic nervous system (SNS). Insulin is secreted fromβ cells in the

endocrine pancreas in response to circulating nutrients (glucose and amino acids) and to the incretin hormones, glucose-

dependent insulinotropic polypeptide (GIP) and GLP-1, which are released during meal ingestion and absorption. Insulin can also act indirectly by stimulating leptin production from adipose tissue via increased glucose metabolism. In contrast, dietary fat and fructose do not stimulate insulin secretion and therefore do not increase leptin production. There is also evidence that leptin can inhibit insulin secretion from the pancreas. The gastric hormone ghrelin increases food intake and decreases fat

oxidation in rodents and may have an anabolic role in long-term food intake regulation. The long-term signals interact with the short-term signals in the regulation of energy homeostasis and appear to set sensitivity to the satiety-producing effects of short- term signal such as CCK.

CNS 色 香 饲料

食靡

养分 储备 时间

图 采食量的反馈调节

注：

表示随着采食饲料到养分