Abstract
Small molecular weight apo BS (B-48) originates mainly from the intestine and will be a metabolic marker of exogenous lipoprotein. We reported hypertriglyceridemia and high level of VLDL in MSG rats. In this study we have investigated abnormalities of lipoprotein metabolism by estimating percentage of apo BS, which will be a metabolic marker of exogenous lipoprotein, in total apo B (apo B ratio) and absolute amounts of apo BS, apo BL and apo E in MSG rats. At the 24th week after subcutaneous injection of MSG (4mg/g body weight) neonatally for 5 days, concentrations of lipids and lipoprotein fractions (VLDL, IDL, LDL and HDL) in fasting plasma were determined enzymatically. Apo B subspecies in VLDL were analyzed by SDS 3-15% gradient polyacrylamide gel electrophoresis. MSG rats showed a marked increase of plasma triglyceride and a slight but significant increase of phospholipids. Lipids and protein concentrations of VLDL were significantly higher in MSG rats than in control rats. But there were no changes in the composition of these increased VLDL. Apo BS ratio was significantly higher in male MSG rats (57.5±1.5%) than in male control rats (30.2±2.5%). However, this ratio was not different in female rats.
Absolute amounts of apo BS were extremely higher in MSG rats than in control rats (male: 5.0±0.8 vs. 1.1±0.2mg/dl, female: 9.3±1.4 vs. 1.3±0.1mg/dl.) Absolute amounts of apo BL were higher in female MSG rats (5.9±1.1mg/dl) than in female control rats (0.7±0.1mg/dl), but not different in male rats. Absolute amounts of apo E were higher in MSG rats than in control rats (male: 7.8±0.4 vs. 3.9±0.4mg/dl, female: 13.2±1.8 vs. 4.1±0.5mg/dl). The data presented indicate that MSG-induced obese rats have the metabolic derangement of exogenous lipoprotein, such as apo BS.
