NEONATAL MONOSODIUM GLUTAMATE TREATMENT INCREASES EPIDIDYMAL ADIPOSE-TISSUE SENSITIVITY TO INSULIN IN 3-MONTH OLD RATS

Citation
Mr. Marmo et al., NEONATAL MONOSODIUM GLUTAMATE TREATMENT INCREASES EPIDIDYMAL ADIPOSE-TISSUE SENSITIVITY TO INSULIN IN 3-MONTH OLD RATS, Brazilian journal of medical and biological research, 27(5), 1994, pp. 1249-1253
Citations number
18
Categorie Soggetti
Medicine, Research & Experimental
ISSN journal
0100879X
Volume
27
Issue
5
Year of publication
1994
Pages
1249 - 1253
Database
ISI
SICI code
0100-879X(1994)27:5<1249:NMGTIE>2.0.ZU;2-A
Abstract
We determined the response of glucose transport to insulin in isolated adipocytes and the lipogenic activity of insulin in fragments of epid idymal adipose tissue obtained from male MSG-obese rats. Basal glucose transport rates (pmol 3 min-1 10(5) cells-1) were 100% higher in MSG than in control cells (3-month old male Wistar rats) pre-incubated for 30 min (P<0.01). Nevertheless, when expressed as fmol 3 min-1 mum2 ce ll surface area-1, transport rates were similar for the two groups (31 .2 +/- 2.6 for MSG and 26.5 +/- 3.2 for controls, N = 7). No differenc es were observed in maximally insulin-stimulated glucose transport rat es between groups (72.6 +/- 10.6 for MSG and 101.0 +/- 12.0 for contro ls, N = 7). In contrast, for adipocytes pre-incubated for 2 h, the bas al uptake rates were 3.7 times higher and the maximal response to insu lin was 103% higher in cells from MSG rats compared to control cells. These alterations in MSG rat adipocytes were accompanied by changes in cell sensitivity to insulin (EC50, 0.13 +/- 0.02 ng/ml for MSG vs 0.4 6 +/- 0.10 ng/ml for controls, P<0.01). The rates of incorporation of labelled substrates (H2O)-H-3 and C-14-glucose) into total lipids show ed that in vitro lipogenesis was also 79% ((H2O)-H-3) and 250% (C-14-g lucose) higher in MSG adipose tissue fragments. The MSG animals were c onsistently hyperinsulinemic. These data suggest that the obesity of 3 -month old MSG rats is a metabolic alteration characterized by an enha nced adipocyte capacity to transport glucose and to synthetize lipids resulting in increased insulin sensitivity.