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.


METHODS
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.


METHODS
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.


CONCLUSIONS
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.
Papa
P C
PC
Department of Physiology and Biophysics, University of São Paulo, Brazil.
Seraphim
P M
PM
Machado
U F
UF
D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D004038:Diet, Reducing; D005503:Food Additives / Q000008:administration & dosage / Q000494:pharmacology*; D051275:Glucose Transporter Type 4; D007106:Immune Sera / Q000276:immunology; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008820:Mice, Obese; D009004:Monosaccharide Transport Proteins / Q000276:immunology / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009765:Obesity / Q000178:diet therapy / Q000503:physiopathology*; D012970:Sodium Glutamate / Q000008:administration & dosage / Q000494:pharmacology*; D015431:Weight Loss / Q000187:drug effects / Q000502:physiology*
D005503:Food Additives; D051275:Glucose Transporter Type 4; D007106:Immune Sera; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495693:Slc2a4 protein, mouse; D012970:Sodium Glutamate