Differential expression of lipoprotein lipase gene in tissues of the rat model with visceral obesity and postprandial hyperlipidemia

Postprandial hyperlipidemia is frequently accompanied with intra-abdominal visceral accumulation in human subjects. We have found that the decreased l ipoprotein lipase (LPL) mass and activity is negatively associated with the amount of visceral fat accumulation. Here, we studied the postprandial hyp erlipidemia using the OLETF rat, a model with visceral obesity, in order to clarify the molecular mechanism causing postprandial hyperlipidemia accomp anied with visceral obesity. At the same age of 32 weeks, the OLETF rats sh owed obviously higher plasma leptin, total cholesterol, triglyceride, and H DL-cholesterol levels than the control LETO rats, although the plasma gluco se level was not significantly different. Fat-loading test revealed the del ayed metabolism of exogenous fat in the OLETF rats compared to the LETO rat s, similar to human subjects with visceral obesity. In the obese rats, plas ma levels of LPL mass and activities were 60 and 49% of control rats. The e xpression of LPL gene was decreased in subcutaneous adipose tissues and ske letal muscle of OLETF rats to 40 and 52% compared to those of LETO rats. In OLETF rats, plasma tumor necrosis factor-alpha (TNF-alpha) and insulin lev els were increased to 2.0- and 2.3-folds compared to those in control rats. Furthermore, plasma insulin and TNF-alpha levels in OLETF rats were negati vely correlated with the expression levels of LPL gene in subcutaneous fat and muscle. These results indicate that decreased LPE mass and activity in the animal model with visceral obesity is possibly caused by decreased expr ession of LPL gene in tissues mediated by the increased levels of insulin a nd TNF-alpha. The different expression of LPL gene in tissues associated wi th the increased levels of insulin and TNF-alpha possibly elucidate the und erlying mechanisms involving the post-prandial hyperlipidemia observed in v isceral obesity. (C) 2000 Academic Press.