The Effects of Amino Acid Supplementation and Endurance Exercise Training on Glucose Tolerance and Cell Signaling in High Fat Fed Rats
Authors: Bernard Jeffrey R , Lambrecht Nathalie J , Liao Yi‐Hung , Ivy John L 
Published: November 2023

Purpose

Many different modes have been used to reverse and/or prevent the effects of a High fat diet. The literature suggests that a combination of diet modification and exercise can be effective. Thus, this study employed a specific mixture of amino acids and aerobic exercise training to investigate their effects on glucose tolerance and cell signaling in high fat fed rats.

Methods

Thirty female Sprague Dawley rats were obtained at 7 weeks of age and assigned to one of five treatment groups (n = 6 for each group): 1) Standard Diet Control (SD‐CON), 2) High Fat Diet Control (HF‐CON), 3) High Fat Diet plus Amino Acid Supplementation (HF‐AA), 4) High Fat Diet and Exercise or 5) High Fat Diet plus Amino Acid Supplement and Exercise (HF‐AA‐EX). The control and high fat diets, as well as the amino acid supplementation, were provided ad libitum for 4 weeks. The high fat diet consisted of 60% of fat derived calories. The amino acid supplement was mixed into their drinking water and consisted of 8% amino acids (cysteine, methionine, valine, leucine, and isoleucine) and 2% sucrose. The exercise intervention consisted of swimming exercise 3 days/week for 4 weeks. Rats swam with up to 8% of their body weight attached to their tail for up to 1 hour. An oral glucose tolerance test (OGTT) was administered after 2 and 4 weeks. Following the 4 week OGTT rats were anesthetized, the gastrocnemius excised and then sacrificed. A glucometer was used to measure blood glucose levels. Enzyme‐linked immunosorbent assay (ELISA) was used to determine plasma insulin levels and Western Blot analysis for both skeletal muscle Akt and GLUT4 protein concentration.

Results

After 2 weeks of dietary and/or exercise intervention, HF‐CON blood glucose was significantly higher compared to SD‐CON in response to the OGTT. There were no differences to the OGTT for SD‐CON compared to HF‐AA, HF‐EX or HF‐AA‐EX. The insulin response to the OGTT was similar among treatment groups. After 4 weeks of dietary and/or exercise intervention the blood glucose and insulin response to the OGTT was significantly higher in HF‐CON compared to all other treatment groups. Blood glucose and insulin levels were not statistically different between SD‐CON, HF‐AA, HF‐EX or HF‐AA‐EX. In addition, there were no differences in Akt protein concentration between treatment groups. However, GLUT4 protein concentration was significantly lower in the HF‐CON group compared to all other treatment groups.

Conclusion

This study suggests that both aerobic exercise and amino acid supplementation can be used to prevent the adverse effects of a high fat diet. However, it does not appear that the effects of amino acid supplementation and exercise were additive. The benefits of these interventions appear to be independent the effects of insulin and may be associated with increased GLUT4 protein concentration.

Support or Funding Information

This study was funded by a Saint Mary's College of California Faculty Development Grant.