Regulation of Ghrelin

生长素释放肽的调节

• 批准号: 6919536
• 负责人: RALF M NASS
• 金额: $ 13.13万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-22 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6919536
• 关键词: age difference; body composition; clinical research; ghrelin; glucose; glucose clamp technique; hormone regulation /control mechanism; human old age (65+); human subject; injection /infusion; insulin; insulin sensitivity /resistance; oral administration; patient oriented research; young adult human (21-34)

DESCRIPTION (provided by applicant): Ghrelin a peptide which is mainly derived from the stomach, is present in plasma in an active (acylated) and inactive (des-acylated) form. The major active form of ghrelin contains 28 amino acids with a unique post-translational modification: the hydroxyl group of ser3 is esterified by octanoic acid. The n-octanoyl group is essential for the GH (growth hormone) releasing activity. Plasma ghrelin plays a role in energy homeostasis, food intake, and possibly in GH release and obesity. To date it is unclear how circulating ghrelin levels are regulated. The overall hypothesis of this application is that glucose, insulin as well as insulin sensitivity play a role in the acute regulation of ghrelin. The influence of age and BMI on the response of circulating ghrelin to these factors will also be examined. Specific Aim 1. To determine to what extent the short-term regulation of ghrelin is mediated through glucose (peripheral or luminal) and/or peripheral insulin. In man, circulating ghrelin levels decrease after glucose administration. It is unclear to what extent the route of glucose administration plays a role in its effects on circulating ghrelin. Studies of insulin effects on ghrelin levels under euglycemic conditions have yielded inconsistent results, i.e., a decrease in circulating ghrelin vs. no change. It is also unclear to what extent the route of glucose administration plays a role in its effects on circulating ghrelin and whether differences in insulin resistance have an impact on the effects of insulin and/or glucose on circulating ghrelin. In two groups of BMI matched young adults with different insulin resistance, we will examine the effects of insulin under euglycemic conditions on peripheral ghrelin and compare them with the effects of oral and IV glucose. We will also compare the effects of oral and IV glucose on peripheral ghrelin with each other. The glucose levels reached after IV administration will match those reached during the oral glucose test. The effects of insulin and glucose on bioactive ghrelin have not been reported. Using assays developed in our laboratory, both bioactive and inactive ghrelin will be measured. Specific Aim 2. To determine whether the insulin-mediated decrease in circulating ghrelin levels is age dependent. Insulin sensitivity decreases with age. This is partially a result of the age-dependent increase in abdominal visceral fat. The studies proposed will investigate whether there are differences between young and older adults regarding the acute insulin mediated decrease in circulating ghrelin (bioactive, inactive form) levels.

描述（由申请人提供）：