Loss of weight restores GLUT 4 content in insulin-sensitive tissues of monosodium glutamate-treated obese mice.

OBJECTIVE

To investigate the effect of weight loss on GLUT 4 content of insulin sensitive tissues of obese mice.

SUBJECTS

Mice were made obese by neonatal treatment with monosodium glutamate (MSG). In addition, one group of obese animals was submitted to a caloric restriction to promote 20% weight loss (MSG-L). Both groups were compared to age-matched control mice.

MEASUREMENTS

Anthropometric data, glycaemia and insulinaemia were measured. The GLUT 4 protein was assessed by Western blotting analysis in white (WAT) and brown (BAT) adipose tissue, and skeletal (SM) and cardiac (CM) muscles.

RESULTS

The MSG mice were very obese according to their morphometric analysis, showing moderate hyperglycaemia with severe hyperinsulinaemia, and reduced (P < 0.001) glucose/insulin (G/I) ratio. The procedure for weight loss promoted a significant (P < 0.001) reduction of both glycaemic and insulinaemic levels, and an increase in G/I ratio. Compared to control animals, the GLUT 4 content in obese MSG mice, was decreased by 30% (P < 0.05) in SM and CM, by 80% (P < 0.001) in BAT and in different subcellular membrane fractions of WAT. On the other hand, transporter protein content was restored to normal levels in MSG-L animals.

CONCLUSION

The reduced GLUT 4 content of insulin sensitive tissues from MSG-treated obese mice is recovered by a 20% loss in weight. This mechanism can be involved in the observed increase of insulin sensitivity.