Hormone Blocker Found to Help Prevent Obesity & Diabetes

A new study finds that a chemical found in the body is capable of promoting weight loss, improving insulin resistance and reversing diabetes in an animal model. The hormone is gastric inhibitory polypeptide (GIP) receptor blockade.

Background
GIP is a peptide hormone that is secreted in response to food. It inhibits the secretion of acids stimulates the releases insulin as part of the digestive process in response to food. It is found in a variety of tissues, including the intestine, heart, stomach, brain and in adipose (fat).

While the significance of its action is largely unknown, its potent and prolonged stimulation after a high-fat diet has led researchers to speculate it may play a key role in metabolizing fat. Research has shown that high fat feeding results in elevated circulating GIP concentrations, traits often found in patients who are obese with diabetes. GIP also effects the growth of fat cells. Other studies have shown that mice injected with the GIP receptor antagonist – (Pro3)GIP – can reverse or prevent many of the metabolic abnormalities associated with obesity.

The Study

A new study examined whether prolonged GIP receptor antagonism using daily injections of (Pro3) GIP was able to reverse well established diet-induced obesity and related metabolic abnormalities.

The new study is entitled, “GIP Receptor Antagonism Reverses Obesity, Insulin Resistance, and Associated Metabolic Disturbances Induced in Mice by Prolonged Consumption of High-Fat Diet.” It was conducted by Paula L. McClean, Nigel Irwin, Roslyn S. Cassidy, Victor A. Gault and Peter R. Flatt, all of the School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK; and Jens J. Holst, Department of Medical Physiology, The Panum Institute, University of Copenhagen, Copenhagen, Denmark. It is entitled The findings appear in the American Journal of Physiology – Endocrinology and Metabolism (doi:10.1152/ajpendo.00460.2007), a publication of the American Physiological Society (APS; the-aps.org/).

Methodology

The researchers used a model for diet-induced obesity that has been used extensively alongside genetic models and has close parallels with obesity, increasingly found in humans who consume a high-fat, energy-rich diet. In this model, young (8-week old) male, age matched mice were age-divided into groups and housed individually in an air-conditioned room at 22±2°C with a 12 hour light: 12 hour dark cycle. Experimental animals had free access to drinking water and a high fat diet (45 percent fat, 20 percent protein and 35 percent carbohydrate; percent of total energy of 26.15kj/g). Age-matched control mice from the same colony had free access to a standard rodent maintenance diet (10 percent fat; 30 percent protein; 60 percent carbohydrate; percent of total energy of 12.99kj/g.). The two were used for comparison purposes.