Plasma lipoproteins of monosodium glutamate-induced obese rats

The plasma lipids and lipoproteins of rats developing obesity after neonatal administration of monosodium glutamate (MSG) were compared with those obtained from controls. The MSG-treated rats, in addition to being stunted and having enlarged adipose tissue stores, showed reduced body weight and food intake. These rats revealed a marked increase of plasma triglyceride and a slight but significant increase of phospholipids in both male and female. There was no significant difference in plasma cholesterol between MSG-treated rats and controls. The lipids and protein concentrations of very low density lipoprotein (VLDL: d less than 1.006 g/ml) were significantly greater in the MSG-treated rats than in the controls. There were no changes in the composition of these increased VLDL, which indicated that the number of VLDL particles was increased. Plasma triglyceride and lipids components of VLDL were significantly greater in males than in females. In spite of hypophagia, both male and female MSG-treated rats had higher plasma glucose levels than sex-matched controls. Plasma insulin level was higher in male MSG-treated rats (49.3 +/- 6.6 microU/ml [s.e.]) than in female MSG-treated rats (14.3 +/- 3.2 microU/ml) or in male control rats (34.6 +/- 6.6 microU/ml). These results suggested that hyperinsulinemia plays an important role in the increase of VLDL observed in the MSG-treated male rats.