The effects of amino-acid supplementation, diet and chronic exercise training on glucose tolerance in Sprague-Dawley rats

The purpose of this study was to look at the effects of an amino-acid mixture, highfat feeding and exercise on blood glucose and plasma insulin levels in skeletal muscle of female Sprague-Dawley rats. Rats were either fed a standard-diet only (SD-CON), a standard-diet plus a pre-established amino-acid mixture (CON-AA), a high-fat diet only (HF-CON), a high-fat diet plus a pre-established amino-acid mixture (HF-AA) or a high-fat diet, plus the amino-acid mixture coupled with chronic exercise training (HF-AA-EX). An Oral Glucose Tolerance Test (OGTT) was conducted after twoand four-weeks of treatment to assess blood glucose and plasma insulin levels. Rats were gavaged with a glucose bolus after a 12-h fast, and then blood was collected from the tail vein prior to, and 15, 30, 60, and 120 minutes after gavage. At the end of four weeks, rats were presented with an amino acid challenge and hind-limb muscles were removed for analysis of total GLUT-4 content. Results indicate that amino-acids are effective in lowering blood glucose in rats given either a standard diet or a high-fat diet despite elevated plasma insulin levels in rats fed a high-fat diet. Additionally, an exercise treatment coupled with amino-acids is more effective in lowering blood glucose than amino-acids alone in rats fed a high-fat diet. The addition of an exercise treatment may also help in the utilization of insulin by skeletal muscle cells. These results suggest that amino-acids and exercise may help control blood glucose levels thereby possibly alleviating some of the symptoms associated with insulin resistance.