Study on a network of gut signals and development of diabetes

点击翻译按钮获取中文摘要

Secretion of gastric inhibitory polypeptide (GIP), a duodenal hormone, is primarily induced by absorption of ingested fat.. Our studies revealed that GIP receptor knockout mice have higher blood glucose levels with impaired initial insulin response after oral glucose load., that GIP receptor knockout mice fed a high-fat diet were clearly protected from both the obesity and the insulin resistance, that the insulin response was almost completely lost in Kir6.2 and GIP receptor double knockout mice, and that bone formation parameters in the GIP receptor knockout mice were significantly lower and the GIP receptor knockout mice had thinner trabeculae. These results and the in vitro studies that GIP directly acts not onlypancreatic b-cells but also adipocytes and osteoblasts indicated that early insulin secretion mediated by GIP determines glucose tolerance after oral glucose load, that GIP directly links overnutrition to obesity, that GIP is the major insulinotropic factor in the secretion of insulin in response to glucose load in KATP channel-deficient mice, and that GIP directly links calcium contained in meal to calcium deposition on bone.Therefore, GIP signaling should be activated by GIP receptor agonists or DPPIV inhibitors in diabetes with impaired insulin secretion, such as predominantly observed in Japan, and should be inhibited by GIP receptor antagonists in diabetes with insulin resistance, such as predominantly observed in western countries.