GLUT4 content decreases along with insulin resistance and high levels of inflammatory markers in rats with metabolic syndrome.
BACKGROUND
Metabolic syndrome is characterized by insulin resistance, which is closely related to GLUT4 content in insulin-sensitive tissues. Thus, we evaluated the GLUT4 expression, insulin resistance and inflammation, characteristics of the metabolic syndrome, in an experimental model.


METHODS
Spontaneously hypertensive neonate rats (18/group) were treated with monosodium glutamate (MetS) during 9 days, and compared with Wistar-Kyoto (C) and saline-treated SHR (H). Blood pressure (BP) and lipid levels, C-reactive protein (CRP), interleukin 6 (IL-6), TNF-α and adiponectin were evaluated. GLUT4 protein was analysed in the heart, white adipose tissue and gastrocnemius. Studies were performed at 3 (3-mo), 6 (6-mo) and 9 (9-mo) months of age.


RESULTS
MetS rats were more insulin resistant (p<0.001, all ages) and had higher BP (3-mo: p<0.001, 6-mo: p = 0.001, 9-mo: p = 0.015) as compared to C. At 6 months, CRP, IL-6 and TNF-α were higher (p<0.001, all comparisons) in MetS rats vs H, but adiponectin was lower in MetS at 9 months (MetS: 32 ± 2, H: 42 ± 2, C: 45 ± 2 pg/mL; p<0.001). GLUT4 protein was reduced in MetS as compared to C rats at 3, 6 and 9-mo, respectively (Heart: 54%, 50% and 57%; Gastrocnemius: 37%, 56% and 50%; Adipose tissue: 69%, 61% and 69%).


CONCLUSIONS
MSG-treated SHR presented all metabolic syndrome characteristics, as well as reduced GLUT4 content, which must play a key role in the impaired glycemic homeostasis of the metabolic syndrome.
Laboratório de Experimentação Animal e Laboratório de Cardiologia Molecular e Celular, Instituto de Cardiologia/Fundação, Universitária de Cardiologia, Bairro Santana, Porto Alegre, RS, Brazil.
Natalia M
NM
Leguisamo
Alexandre M
AM
Lehnen
Ubiratan F
UF
Machado
Maristela M
MM
Okamoto
Melissa M
MM
Markoski
Graziela H
GH
Pinto
Beatriz D
BD
Schaan
D052242:Adiponectin / Q000097:blood; D052436:Adipose Tissue, White / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D002097:C-Reactive Protein / Q000378:metabolism; D004195:Disease Models, Animal; D015536:Down-Regulation; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D006973:Hypertension / Q000097:blood / Q000150:complications / Q000503:physiopathology; D018836:Inflammation Mediators / Q000097:blood*; D007333:Insulin Resistance; D015850:Interleukin-6 / Q000097:blood; D008055:Lipids / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012970:Sodium Glutamate; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D052242:Adiponectin; C499920:Adipoq protein, rat; D015415:Biomarkers; D051275:Glucose Transporter Type 4; D018836:Inflammation Mediators; D015850:Interleukin-6; D008055:Lipids; C495694:Slc2a4 protein, rat; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein; D012970:Sodium Glutamate