Lipoprotein structure and metabolism during progression and regression of atherosclerosis in pigs fed with fish oil-derived fatty acids

Effect of simvastatin on culturing of kidney cells from pigs in vitro

Statins is an inhibitor in the cholesterol biosynthesis pathway. Simvastatin (SIM) has been found to have other clinical benefits besides those resulted from its actions of reducing plasma level of low density lipoprotein (LDL) cholesterol. Both mevastatin (MEV) and parvastatin (PAR) can increase release of nitric oxide (NO) which is a potent inhibitor of platelet aggregation and endothelial cell conglutination. In this study, we found different concentrations of SIM had different effects on 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) mRNA expression and NO and total cholesterol (TC) in normal cultural pig kidney cells. NO and TC were measured by using colorimetry in 550 nm and 546 nm, respectively. HMGR mRNA expression was tested by RT-PCR. Results showed that HMGR mRNA expression had a significant difference (P < 0.05) between different concentration of SIM treatment (0, 5, 10, or 25 micromol/l). HMGR mRNA expression and TC content decreased gradually with the elevation of SIM concentration. The content of NO increased with the elevation of SIM concentration, but the difference was not notable. SIM affects the expression of HMGR-CoA, TC and NO in normal cells, but the specific mechanism need to be further research.

Hamsters and guinea pigs differ in their plasma lipoprotein cholesterol distribution when fed diets varying in animal protein, soluble fiber, or cholesterol content

There were two objectives to these studies: 1) to compare the lipoprotein cholesterol distribution in two animal models in response to different dietary treatments and 2) to assess whether the hypercholesterolemia induced by high cholesterol intake could be reversed by consumption of vegetable-protein and/or dietary fiber. Guinea pigs, which carry the majority of plasma cholesterol in LDL, and hamsters, with a higher distribution of cholesterol in HDL, were evaluated in three different studies. In Study 1, animals were fed semi-purified diets for 4 wk with proportions of 60:40, 20:80 or 0:100 (w/w) of casein/ soybean protein. Hamsters and guinea pigs that consumed 100% soybean protein had lower plasma total cholesterol (TC) than those fed diets containing casein (P < 0.01). In Study 2, three doses of dietary pectin (2.7, 5.4, or 10.7 g/100g) added in place of cellulose were tested. Intake of 10.7 g/100 g pectin resulted in the lowest plasma TC concentrations for both species (P < 0.01). Although the TC lowering was similar in studies 1 and 2, the lipoprotein cholesterol distribution differed. Whereas the differences in plasma cholesterol were in LDL in guinea pigs, hamsters exhibited differences in both non-HDL and HDL cholesterol. In study 3, animals were fed 100% soybean protein, 10.7 g/100 g pectin, and three doses of dietary cholesterol: 0.04, 0.08, or 0.16 g/100 g, which is equivalent to 300, 600, or 1,200 mg/d in humans. Guinea pigs and hamsters had the highest plasma LDL and hepatic cholesterol concentrations when they consumed 0.16 g/100 g of cholesterol (P < 0.01). However, intake of 0.08 g/100 g of cholesterol resulted in lower plasma LDL cholesterol concentrations than did consuming high animal protein (60:40 casein/ soy) or low soluble fiber (2.7 g/100 g). Relatively high levels of dietary cholesterol combined with vegetable protein and soluble fiber resulted in desirable lipoprotein profiles in animal models that significantly differ in their lipoprotein cholesterol distribution.