Neuroendocrine Modulation of Metabolic Effects in Overweight Adolescents

Obesity is an epidemic that is striking people at younger ages than ever before. Obesity is
associated with changes in the secretory patterns of several hormones including ghrelin,
growth hormone (GH), and insulin, which have not been examined in the adolescent age group.
Ghrelin, a primarily gastric hormone, increases appetite and is a GH secretagogue. This
study will compare the alteration in secretion of ghrelin and GH in overweight and normal
weight adolescent girls through frequent blood sampling and GH stimulation testing with
growth hormone releasing hormone and arginine. The relationship between these hormones and
insulin resistance, measured by 1H-nuclear magnetic resonance spectroscopy, and body
composition, measured by dual energy x-ray absorptiometry and magnetic resonance imaging,
will be investigated. This study will also determine the postprandial ghrelin response to
test meals that vary by the type of predominant macronutrient, which may predict the degree
of hunger and amount of intake at a subsequent meal. Understanding obesity-related changes
in ghrelin and GH and their relationship to body composition, insulin resistance, and
appetite will help in the development of strategies to reduce complications of obesity.