Calorie restriction in mice does not affect LDL reverse cholesterol transport in vivo

Area of Science:

• Metabolism and Nutrition
• Cardiovascular Health
• Lipid Metabolism

Background:

• Calorie restriction (CR) extends lifespan in animal models.
• CR may negatively impact plasma high-density lipoprotein (HDL) levels, crucial for reverse cholesterol transport (RCT).
• Understanding CR's effect on RCT is vital for assessing its cardiovascular benefits.

Purpose of the Study:

• To investigate the impact of CR on in vivo cholesterol removal from muscle tissue.
• To evaluate cholesterol efflux from macrophages using sera from CR-fed mice.
• To determine if CR affects the efficiency of reverse cholesterol transport.

Main Methods:

• Studied C57BL male mice on CR (60% of ad libitum diet) versus AL diet.
• Assessed cholesterol removal from rectus femoris muscle after cationized LDL injection.
• Measured cholesterol efflux from macrophages incubated with CR or AL sera.

Main Results:

• In vivo RCT and macrophage cholesterol efflux were similar between CR and AL groups, despite a 22% reduction in plasma HDL-cholesterol (HDL-C).
• CR mice showed decreased total cholesterol and phospholipid levels, with a proportionally smaller decrease in HDL-C and HDL-phospholipid (HDL-PL).
• The elevated HDL-PL/Total-PL ratio in CR mice was associated with enhanced RCT.

Conclusions:

• Calorie restriction does not impede in vivo reverse cholesterol transport.
• CR may offer cardiovascular benefits by maintaining efficient cholesterol clearance mechanisms.
• Partial re-feeding normalized plasma lipids but maintained the beneficial HDL-PL/T-PL ratio.