title: Neonatal monosodium glutamate treatment increases epididymal adipose tissue sensitivity to insulin in three-month old rats.
abstract: We determined the response of glucose transport to insulin in isolated adipocytes and the lipogenic activity of insulin in fragments of epididymal 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 microns 2 cell 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 differences were observed in maximally insulin-stimulated glucose transport rates between groups (72.6 +/- 10.6 for MSG and 101.0 +/- 12.0 for controls, N = 7). In contrast, for adipocytes pre-incubated for 2 h, the basal uptake rates were 3.7 times higher and the maximal response to insulin 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 0.46 +/- 0.10 ng/ml for controls, P < 0.01). The rates of incorporation of labelled substrates (3H2O and 14C-glucose) into total lipids showed that in vitro lipogenesis was also 79% (3H2O) and 250% (14C-glucose) higher in MSG adipose tissue fragments. The MSG animals were consistently hyperinsulinemic. These data suggest that the obesity of 3-month old MSG rats is a metabolic alteration characterized by an enhanced adipocyte capacity to transport glucose and to synthetize lipids resulting in increased insulin sensitivity.
authors.affiliation: Departamento de Fisiologia, Escola Paulista de Medicina, São Paulo, Brasil.
authors.forename: M R
authors.initials: MR
authors.lastname: Marmo
authors.forename: M S
authors.initials: MS
authors.lastname: Dolnikoff
authors.forename: I C
authors.initials: IC
authors.lastname: Kettelhut
authors.forename: D M
authors.initials: DM
authors.lastname: Matsushita
authors.forename: N S
authors.initials: NS
authors.lastname: Hell
authors.forename: F B
authors.initials: FB
authors.lastname: Lima
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D003847:Deoxyglucose / Q000493:pharmacokinetics; D004822:Epididymis / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012970:Sodium Glutamate / Q000494:pharmacology*
chemical_list: D007328:Insulin; D003847:Deoxyglucose; D005947:Glucose; D012970:Sodium Glutamate