Review Article

Animal Models in Cardiovascular Research: Hypertension and Atherosclerosis

Table 3

Genetically modified animal models for atherosclerosis.

Experimental modelDescription

Apolipoprotein E knockout (ApoE−/−) miceApolipoprotein E (apoE), a constituent of lipoprotein responsible for packaging cholesterol and other fats and carrying them through the bloodstream, is inactivated by gene targeting. They exhibit a higher total plasma cholesterol concentration of 11 mM compared to 2 mM in their parent C57BL/6 mice [114].

LDL receptor knockout (LDLR−/−) miceLDL receptor (LDLR) is a cell surface receptor in liver cells that mediates the endocytosis of apoE to clear cholesterol-abundant LDL particles from the circulation. Total plasma cholesterol levels increase twofold compared to those of wild-type, owing to a seven- to ninefold increase in intermediate density lipoproteins (IDL) and LDL without a significant change in HDL [115].

Scavenger receptor class B member 1 knockout (SR-BI KO) mice Scavenger receptor class B member 1 (SR-BI) functions in facilitating the uptake of cholesterol from HDL in the liver. It plays a key role in determining the levels of plasma cholesterol (primarily HDL). Heterozygous and homozygous mutants show 31% and 125% increase, respectively, in plasma cholesterol concentrations than wild-types [116].

db/db miceOB-R is a high affinity receptor for leptin, an important circulating signal for the regulation of feeding, appetite, and body weight. Fatty acid oxidation rates are progressively higher in db/db mice in parallel with the earlier onset and greater duration of hyperglycemia [117].

ob/ob miceA mutation results in a structurally defective leptin that does not bind to the OB-R. Mice that are ob/ob have no leptin action and exhibit obesity and endothelial dysfunction [118].

Fatty Zucker ratsA spontaneous mutant gene (fa or fatty) that affects the action of the leptin. They have high levels of lipids and cholesterol in their bloodstream and become noticeably obese by 3 to 5 weeks of age and over 40% lipid of their body composition by 14 weeks of age [119].

Cholesterol ester transfer protein (CETP)
transgenic rats
CETP inhibits HDL-mediated reverse cholesterol transport by transferring cholesterol from HDL to very low-density lipoprotein (VLDL) and LDL, promoting atherogenesis. The animals exhibit 82% increase in non-HDL cholesterol in addition to 80% reduction in HDL cholesterol when compared to wild-type rats [120].

HDL: high-density lipoprotein; LDL: low-density lipoprotein.